Merge branch 'main' into reachesperf

cpp/ql/lib/semmle/code/cpp/AutogeneratedFile.qll

@@ -84,6 +84,7 @@ private int fileHeaderLimit(File f) {
     fc = fileFirstComment(f) and
     result =
       min(int line |
+        // code ending the initial comments
         exists(DeclarationEntry de, Location l |
           l = de.getLocation() and
           l.getFile() = f and
@@ -105,7 +106,13 @@ private int fileHeaderLimit(File f) {
           line > fc
         )
         or
+        // end of the file
         line = f.getMetrics().getNumberOfLines()
+        or
+        // rarely, we've seen extremely long sequences of initial comments
+        // (and/or limitations in the above constraints) cause an overflow of
+        // the maximum string length. So don't look past 1000 lines regardless.
+        line = 1000
       )
   )
 }

cpp/ql/lib/semmle/code/cpp/Element.qll

@@ -109,10 +109,7 @@ class Element extends ElementBase {
     then
       exists(MacroInvocation mi |
         this = mi.getAGeneratedElement() and
-        not exists(MacroInvocation closer |
-          this = closer.getAGeneratedElement() and
-          mi = closer.getParentInvocation+()
-        ) and
+        not hasCloserMacroInvocation(this, mi) and
         result = mi.getMacro()
       )
     else result = this
@@ -236,6 +233,14 @@ class Element extends ElementBase {
   }
 }
 
+pragma[noinline]
+private predicate hasCloserMacroInvocation(Element elem, MacroInvocation mi) {
+  exists(MacroInvocation closer |
+    elem = closer.getAGeneratedElement() and
+    mi = closer.getParentInvocation()
+  )
+}
+
 private predicate isFromTemplateInstantiationRec(Element e, Element instantiation) {
   instantiation.(Function).isConstructedFrom(_) and
   e = instantiation

cpp/ql/lib/semmle/code/cpp/Field.qll

@@ -4,7 +4,6 @@
 
 import semmle.code.cpp.Variable
 import semmle.code.cpp.Enum
-import semmle.code.cpp.exprs.Access
 
 /**
  * A C structure member or C++ non-static member variable. For example the
@@ -32,7 +31,7 @@ class Field extends MemberVariable {
   int getByteOffset() { fieldoffsets(underlyingElement(this), result, _) }
 
   /**
-   * Gets the byte offset within `mostDerivedClass` of each occurence of this
+   * Gets the byte offset within `mostDerivedClass` of each occurrence of this
    * field within `mostDerivedClass` itself or a base class subobject of
    * `mostDerivedClass`.
    * Note that for fields of virtual base classes, and non-virtual base classes

cpp/ql/lib/semmle/code/cpp/Function.qll

@@ -38,8 +38,8 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * int z = min(5, 7);
    * ```
    * The full signature of the function called on the last line would be
-   * "min<int>(int, int) -> int", and the full signature of the uninstantiated
-   * template on the first line would be "min<T>(T, T) -> T".
+   * `min<int>(int, int) -> int`, and the full signature of the uninstantiated
+   * template on the first line would be `min<T>(T, T) -> T`.
    */
   string getFullSignature() {
     exists(string name, string templateArgs, string args |

cpp/ql/lib/semmle/code/cpp/PrintAST.qll

@@ -663,18 +663,24 @@ private predicate namedStmtChildPredicates(Locatable s, Element e, string pred)
     or
     s.(ComputedGotoStmt).getExpr() = e and pred = "getExpr()"
     or
+    s.(ConstexprIfStmt).getInitialization() = e and pred = "getInitialization()"
+    or
     s.(ConstexprIfStmt).getCondition() = e and pred = "getCondition()"
     or
     s.(ConstexprIfStmt).getThen() = e and pred = "getThen()"
     or
     s.(ConstexprIfStmt).getElse() = e and pred = "getElse()"
     or
+    s.(IfStmt).getInitialization() = e and pred = "getInitialization()"
+    or
     s.(IfStmt).getCondition() = e and pred = "getCondition()"
     or
     s.(IfStmt).getThen() = e and pred = "getThen()"
     or
     s.(IfStmt).getElse() = e and pred = "getElse()"
     or
+    s.(SwitchStmt).getInitialization() = e and pred = "getInitialization()"
+    or
     s.(SwitchStmt).getExpr() = e and pred = "getExpr()"
     or
     s.(SwitchStmt).getStmt() = e and pred = "getStmt()"

cpp/ql/lib/semmle/code/cpp/commons/Buffer.qll

@@ -10,11 +10,18 @@ import semmle.code.cpp.dataflow.DataFlow
  *   char data[1]; // v
  * };
  * ```
- * This requires that `v` is an array of size 0 or 1.
+ * or
+ * ```
+ * struct myStruct { // c
+ *   int amount;
+ *   char data[]; // v
+ * };
+ * ```
+ * This requires that `v` is an array of size 0 or 1, or that the array has no size.
  */
 predicate memberMayBeVarSize(Class c, MemberVariable v) {
   c = v.getDeclaringType() and
-  v.getUnspecifiedType().(ArrayType).getArraySize() <= 1
+  exists(ArrayType t | t = v.getUnspecifiedType() | not t.getArraySize() > 1)
 }
 
 /**
@@ -27,11 +34,11 @@ int getBufferSize(Expr bufferExpr, Element why) {
     result = bufferVar.getUnspecifiedType().(ArrayType).getSize() and
     why = bufferVar and
     not memberMayBeVarSize(_, bufferVar) and
-    not result = 0 // zero sized arrays are likely to have special usage, for example
-    or
+    // zero sized arrays are likely to have special usage, for example
     // behaving a bit like a 'union' overlapping other fields.
-    // buffer is an initialized array
-    //  e.g. int buffer[] = {1, 2, 3};
+    not result = 0
+    or
+    // buffer is an initialized array, e.g., int buffer[] = {1, 2, 3};
     why = bufferVar.getInitializer().getExpr() and
     (
       why instanceof AggregateLiteral or
@@ -40,13 +47,18 @@ int getBufferSize(Expr bufferExpr, Element why) {
     result = why.(Expr).getType().(ArrayType).getSize() and
     not exists(bufferVar.getUnspecifiedType().(ArrayType).getSize())
     or
-    exists(Class parentClass, VariableAccess parentPtr |
+    exists(Class parentClass, VariableAccess parentPtr, int bufferSize |
       // buffer is the parentPtr->bufferVar of a 'variable size struct'
       memberMayBeVarSize(parentClass, bufferVar) and
       why = bufferVar and
       parentPtr = bufferExpr.(VariableAccess).getQualifier() and
       parentPtr.getTarget().getUnspecifiedType().(PointerType).getBaseType() = parentClass and
-      result = getBufferSize(parentPtr, _) + bufferVar.getType().getSize() - parentClass.getSize()
+      (
+        if exists(bufferVar.getType().getSize())
+        then bufferSize = bufferVar.getType().getSize()
+        else bufferSize = 0
+      ) and
+      result = getBufferSize(parentPtr, _) + bufferSize - parentClass.getSize()
     )
   )
   or

cpp/ql/lib/semmle/code/cpp/commons/Printf.qll

@@ -872,7 +872,7 @@ class FormatLiteral extends Literal {
 
   private Type getConversionType1(int n) {
     exists(string cnv | cnv = this.getConversionChar(n) |
-      cnv.regexpMatch("d|i") and
+      cnv = ["d", "i"] and
       result = this.getIntegralConversion(n) and
       not result.getUnderlyingType().(IntegralType).isExplicitlySigned() and
       not result.getUnderlyingType().(IntegralType).isExplicitlyUnsigned()
@@ -912,7 +912,7 @@ class FormatLiteral extends Literal {
 
   private Type getConversionType2(int n) {
     exists(string cnv | cnv = this.getConversionChar(n) |
-      cnv.regexpMatch("o|u|x|X") and
+      cnv = ["o", "u", "x", "X"] and
       result = this.getIntegralConversion(n) and
       result.getUnderlyingType().(IntegralType).isUnsigned()
     )
@@ -920,7 +920,7 @@ class FormatLiteral extends Literal {
 
   private Type getConversionType3(int n) {
     exists(string cnv | cnv = this.getConversionChar(n) |
-      cnv.regexpMatch("a|A|e|E|f|F|g|G") and result = this.getFloatingPointConversion(n)
+      cnv = ["a", "A", "e", "E", "f", "F", "g", "G"] and result = this.getFloatingPointConversion(n)
     )
   }
 
@@ -1312,7 +1312,7 @@ class FormatLiteral extends Literal {
         len =
           min(int v |
             v = this.getPrecision(n) or
-            v = this.getUse().getFormatArgument(n).(AnalysedString).getMaxLength() - 1 // (don't count null terminator)
+            v = this.getUse().getFormatArgument(n).(AnalyzedString).getMaxLength() - 1 // (don't count null terminator)
           ) and
         reason = TValueFlowAnalysis()
       )

cpp/ql/lib/semmle/code/cpp/commons/StringAnalysis.qll

@@ -27,11 +27,14 @@ predicate canValueFlow(Expr fromExpr, Expr toExpr) {
   fromExpr = toExpr.(ConditionalExpr).getElse()
 }
 
+/** DEPRECATED: Alias for AnalyzedString */
+deprecated class AnalysedString = AnalyzedString;
+
 /**
- * An analysed null terminated string.
+ * An analyzed null terminated string.
  */
-class AnalysedString extends Expr {
-  AnalysedString() {
+class AnalyzedString extends Expr {
+  AnalyzedString() {
     this.getUnspecifiedType() instanceof ArrayType or
     this.getUnspecifiedType() instanceof PointerType
   }
@@ -41,15 +44,15 @@ class AnalysedString extends Expr {
    * can be calculated.
    */
   int getMaxLength() {
-    // take the longest AnalysedString it's value could 'flow' from; however if even one doesn't
+    // take the longest AnalyzedString its value could 'flow' from; however if even one doesn't
     // return a value (this essentially means 'infinity') we can't return a value either.
     result =
-      max(AnalysedString expr, int toMax |
+      max(AnalyzedString expr, int toMax |
         canValueFlow*(expr, this) and toMax = expr.(StringLiteral).getOriginalLength()
       |
         toMax
       ) and // maximum length
-    forall(AnalysedString expr | canValueFlow(expr, this) | exists(expr.getMaxLength())) // all sources return a value (recursive)
+    forall(AnalyzedString expr | canValueFlow(expr, this) | exists(expr.getMaxLength())) // all sources return a value (recursive)
   }
 }
 

cpp/ql/lib/semmle/code/cpp/controlflow/StackVariableReachability.qll

@@ -80,7 +80,11 @@ abstract class StackVariableReachability extends string {
         j > i and
         sink = bb.getNode(j) and
         this.isSink(sink, v) and
-        not exists(int k | this.isBarrier(bb.getNode(k), v) | k in [i + 1 .. j - 1])
+        not exists(int k, ControlFlowNode node |
+          node = bb.getNode(k) and this.isBarrier(pragma[only_bind_into](node), v)
+        |
+          k in [i + 1 .. j - 1]
+        )
       )
       or
       not exists(int k | this.isBarrier(bb.getNode(k), v) | k > i) and

cpp/ql/lib/semmle/code/cpp/controlflow/internal/CFG.qll

@@ -708,30 +708,33 @@ private predicate straightLineSparse(Node scope, int i, Node ni, Spec spec) {
   or
   scope =
     any(SwitchStmt s |
+      // SwitchStmt [-> init] -> expr
       i = -1 and ni = s and spec.isAt()
       or
-      i = 0 and ni = s.getExpr() and spec.isAround()
+      i = 0 and ni = s.getInitialization() and spec.isAround()
+      or
+      i = 1 and ni = s.getExpr() and spec.isAround()
       or
       // If the switch body is not a block then this step is skipped, and the
       // expression jumps directly to the cases.
-      i = 1 and ni = s.getStmt().(BlockStmt) and spec.isAt()
+      i = 2 and ni = s.getStmt().(BlockStmt) and spec.isAt()
       or
-      i = 2 and ni = s.getASwitchCase() and spec.isBefore()
+      i = 3 and ni = s.getASwitchCase() and spec.isBefore()
       or
       // If there is no default case, we can jump to after the block. Note: `i`
       // is same value as above.
       not s.getASwitchCase() instanceof DefaultCase and
-      i = 2 and
+      i = 3 and
       ni = s.getStmt() and
       spec.isAfter()
       or
-      i = 3 and /* BARRIER */ ni = s and spec.isBarrier()
+      i = 4 and /* BARRIER */ ni = s and spec.isBarrier()
       or
-      i = 4 and ni = s.getStmt() and spec.isAfter()
+      i = 5 and ni = s.getStmt() and spec.isAfter()
       or
-      i = 5 and ni = s and spec.isAroundDestructors()
+      i = 6 and ni = s and spec.isAroundDestructors()
       or
-      i = 6 and ni = s and spec.isAfter()
+      i = 7 and ni = s and spec.isAfter()
     )
   or
   scope =
@@ -836,8 +839,15 @@ private predicate subEdge(Pos p1, Node n1, Node n2, Pos p2) {
     p2.nodeAt(n2, f)
   )
   or
-  // IfStmt -> condition ; { then, else } ->
+  // IfStmt -> [ init -> ] condition ; { then, else } ->
   exists(IfStmt s |
+    p1.nodeAt(n1, s) and
+    p2.nodeBefore(n2, s.getInitialization())
+    or
+    p1.nodeAfter(n1, s.getInitialization()) and
+    p2.nodeBefore(n2, s.getCondition())
+    or
+    not exists(s.getInitialization()) and
     p1.nodeAt(n1, s) and
     p2.nodeBefore(n2, s.getCondition())
     or
@@ -851,8 +861,15 @@ private predicate subEdge(Pos p1, Node n1, Node n2, Pos p2) {
     p2.nodeAfter(n2, s)
   )
   or
-  // ConstexprIfStmt -> condition ; { then, else } -> // same as IfStmt
+  // ConstexprIfStmt -> [ init -> ] condition ; { then, else } -> // same as IfStmt
   exists(ConstexprIfStmt s |
+    p1.nodeAt(n1, s) and
+    p2.nodeBefore(n2, s.getInitialization())
+    or
+    p1.nodeAfter(n1, s.getInitialization()) and
+    p2.nodeBefore(n2, s.getCondition())
+    or
+    not exists(s.getInitialization()) and
     p1.nodeAt(n1, s) and
     p2.nodeBefore(n2, s.getCondition())
     or
@@ -953,7 +970,7 @@ private predicate subEdge(Pos p1, Node n1, Node n2, Pos p2) {
 private predicate subEdgeIncludingDestructors(Pos p1, Node n1, Node n2, Pos p2) {
   subEdge(p1, n1, n2, p2)
   or
-  // If `n1` has sub-nodes to accomodate destructors, but there are none to be
+  // If `n1` has sub-nodes to accommodate destructors, but there are none to be
   // called, connect the "before destructors" node directly to the "after
   // destructors" node. For performance, only do this when the nodes exist.
   exists(Pos afterDtors | afterDtors.isAfterDestructors() | subEdge(afterDtors, n1, _, _)) and

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplCommon.qll

@@ -216,10 +216,9 @@ private module LambdaFlow {
     or
     // jump step
     exists(Node mid, DataFlowType t0 |
-      revLambdaFlow(lambdaCall, kind, mid, t0, _, _, _) and
+      revLambdaFlow(lambdaCall, kind, mid, t0, _, _, lastCall) and
       toReturn = false and
-      toJump = true and
-      lastCall = TDataFlowCallNone()
+      toJump = true
     |
       jumpStepCached(node, mid) and
       t = t0
@@ -305,7 +304,7 @@ cached
 private module Cached {
   /**
    * If needed, call this predicate from `DataFlowImplSpecific.qll` in order to
-   * force a stage-dependency on the `DataFlowImplCommon.qll` stage and therby
+   * force a stage-dependency on the `DataFlowImplCommon.qll` stage and thereby
    * collapsing the two stages.
    */
   cached
@@ -326,7 +325,10 @@ private module Cached {
   predicate jumpStepCached(Node node1, Node node2) { jumpStep(node1, node2) }
 
   cached
-  predicate clearsContentCached(Node n, Content c) { clearsContent(n, c) }
+  predicate clearsContentCached(Node n, ContentSet c) { clearsContent(n, c) }
+
+  cached
+  predicate expectsContentCached(Node n, ContentSet c) { expectsContent(n, c) }
 
   cached
   predicate isUnreachableInCallCached(Node n, DataFlowCall call) { isUnreachableInCall(n, call) }
@@ -373,7 +375,7 @@ private module Cached {
     // For reads, `x.f`, we want to check that the tracked type after the read (which
     // is obtained by popping the head of the access path stack) is compatible with
     // the type of `x.f`.
-    read(_, _, n)
+    readSet(_, _, n)
   }
 
   cached
@@ -469,7 +471,7 @@ private module Cached {
         // read
         exists(Node mid |
           parameterValueFlowCand(p, mid, false) and
-          read(mid, _, node) and
+          readSet(mid, _, node) and
           read = true
         )
         or
@@ -657,8 +659,10 @@ private module Cached {
        * Holds if `arg` flows to `out` through a call using only
        * value-preserving steps and a single read step, not taking call
        * contexts into account, thus representing a getter-step.
+       *
+       * This predicate is exposed for testing only.
        */
-      predicate getterStep(ArgNode arg, Content c, Node out) {
+      predicate getterStep(ArgNode arg, ContentSet c, Node out) {
         argumentValueFlowsThrough(arg, TReadStepTypesSome(_, c, _), out)
       }
 
@@ -781,28 +785,30 @@ private module Cached {
     parameterValueFlow(p, n.getPreUpdateNode(), TReadStepTypesNone())
   }
 
+  cached
+  predicate readSet(Node node1, ContentSet c, Node node2) { readStep(node1, c, node2) }
+
   private predicate store(
     Node node1, Content c, Node node2, DataFlowType contentType, DataFlowType containerType
   ) {
-    storeStep(node1, c, node2) and
-    contentType = getNodeDataFlowType(node1) and
-    containerType = getNodeDataFlowType(node2)
-    or
-    exists(Node n1, Node n2 |
-      n1 = node1.(PostUpdateNode).getPreUpdateNode() and
-      n2 = node2.(PostUpdateNode).getPreUpdateNode()
-    |
-      argumentValueFlowsThrough(n2, TReadStepTypesSome(containerType, c, contentType), n1)
+    exists(ContentSet cs | c = cs.getAStoreContent() |
+      storeStep(node1, cs, node2) and
+      contentType = getNodeDataFlowType(node1) and
+      containerType = getNodeDataFlowType(node2)
       or
-      read(n2, c, n1) and
-      contentType = getNodeDataFlowType(n1) and
-      containerType = getNodeDataFlowType(n2)
+      exists(Node n1, Node n2 |
+        n1 = node1.(PostUpdateNode).getPreUpdateNode() and
+        n2 = node2.(PostUpdateNode).getPreUpdateNode()
+      |
+        argumentValueFlowsThrough(n2, TReadStepTypesSome(containerType, cs, contentType), n1)
+        or
+        readSet(n2, cs, n1) and
+        contentType = getNodeDataFlowType(n1) and
+        containerType = getNodeDataFlowType(n2)
+      )
     )
   }
 
-  cached
-  predicate read(Node node1, Content c, Node node2) { readStep(node1, c, node2) }
-
   /**
    * Holds if data can flow from `node1` to `node2` via a direct assignment to
    * `f`.
@@ -932,16 +938,16 @@ class CastingNode extends Node {
 }
 
 private predicate readStepWithTypes(
-  Node n1, DataFlowType container, Content c, Node n2, DataFlowType content
+  Node n1, DataFlowType container, ContentSet c, Node n2, DataFlowType content
 ) {
-  read(n1, c, n2) and
+  readSet(n1, c, n2) and
   container = getNodeDataFlowType(n1) and
   content = getNodeDataFlowType(n2)
 }
 
 private newtype TReadStepTypesOption =
   TReadStepTypesNone() or
-  TReadStepTypesSome(DataFlowType container, Content c, DataFlowType content) {
+  TReadStepTypesSome(DataFlowType container, ContentSet c, DataFlowType content) {
     readStepWithTypes(_, container, c, _, content)
   }
 
@@ -950,7 +956,7 @@ private class ReadStepTypesOption extends TReadStepTypesOption {
 
   DataFlowType getContainerType() { this = TReadStepTypesSome(result, _, _) }
 
-  Content getContent() { this = TReadStepTypesSome(_, result, _) }
+  ContentSet getContent() { this = TReadStepTypesSome(_, result, _) }
 
   DataFlowType getContentType() { this = TReadStepTypesSome(_, _, result) }
 
@@ -1325,8 +1331,6 @@ abstract class AccessPathFront extends TAccessPathFront {
   abstract boolean toBoolNonEmpty();
 
   TypedContent getHead() { this = TFrontHead(result) }
-
-  predicate isClearedAt(Node n) { clearsContentCached(n, this.getHead().getContent()) }
 }
 
 class AccessPathFrontNil extends AccessPathFront, TFrontNil {

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplLocal.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowPrivate.qll

@@ -198,6 +198,12 @@ predicate clearsContent(Node n, Content c) {
   none() // stub implementation
 }
 
+/**
+ * Holds if the value that is being tracked is expected to be stored inside content `c`
+ * at node `n`.
+ */
+predicate expectsContent(Node n, ContentSet c) { none() }
+
 /** Gets the type of `n` used for type pruning. */
 Type getNodeType(Node n) {
   suppressUnusedNode(n) and

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll

@@ -821,6 +821,34 @@ private class CollectionContent extends Content, TCollectionContent {
   override string toString() { result = "<element>" }
 }
 
+/**
+ * An entity that represents a set of `Content`s.
+ *
+ * The set may be interpreted differently depending on whether it is
+ * stored into (`getAStoreContent`) or read from (`getAReadContent`).
+ */
+class ContentSet instanceof Content {
+  /** Gets a content that may be stored into when storing into this set. */
+  Content getAStoreContent() { result = this }
+
+  /** Gets a content that may be read from when reading from this set. */
+  Content getAReadContent() { result = this }
+
+  /** Gets a textual representation of this content set. */
+  string toString() { result = super.toString() }
+
+  /**
+   * Holds if this element is at the specified location.
+   * The location spans column `startcolumn` of line `startline` to
+   * column `endcolumn` of line `endline` in file `filepath`.
+   * For more information, see
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
+   */
+  predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
+    super.hasLocationInfo(path, sl, sc, el, ec)
+  }
+}
+
 /**
  * A guard that validates some expression.
  *

cpp/ql/lib/semmle/code/cpp/dataflow/internal/tainttracking1/TaintTrackingImpl.qll

@@ -109,16 +109,6 @@ abstract class Configuration extends DataFlow::Configuration {
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  /**
-   * Holds if taint propagation into `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerIn(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierIn(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerIn(node, state)
-  }
-
   final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
@@ -126,16 +116,6 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /**
-   * Holds if taint propagation out of `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerOut(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierOut(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerOut(node, state)
-  }
-
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
@@ -181,7 +161,7 @@ abstract class Configuration extends DataFlow::Configuration {
     this.isAdditionalTaintStep(node1, state1, node2, state2)
   }
 
-  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::Content c) {
+  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet c) {
     (this.isSink(node) or this.isAdditionalTaintStep(node, _)) and
     defaultImplicitTaintRead(node, c)
   }

cpp/ql/lib/semmle/code/cpp/dataflow/internal/tainttracking2/TaintTrackingImpl.qll

@@ -109,16 +109,6 @@ abstract class Configuration extends DataFlow::Configuration {
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  /**
-   * Holds if taint propagation into `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerIn(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierIn(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerIn(node, state)
-  }
-
   final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
@@ -126,16 +116,6 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /**
-   * Holds if taint propagation out of `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerOut(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierOut(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerOut(node, state)
-  }
-
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
@@ -181,7 +161,7 @@ abstract class Configuration extends DataFlow::Configuration {
     this.isAdditionalTaintStep(node1, state1, node2, state2)
   }
 
-  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::Content c) {
+  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet c) {
     (this.isSink(node) or this.isAdditionalTaintStep(node, _)) and
     defaultImplicitTaintRead(node, c)
   }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll

@@ -87,21 +87,9 @@ abstract class Configuration extends string {
   /** Holds if data flow into `node` is prohibited. */
   predicate isBarrierIn(Node node) { none() }
 
-  /**
-   * Holds if data flow into `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierIn(Node node, FlowState state) { none() }
-
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /**
-   * Holds if data flow out of `node` is prohibited when the flow state is
-   * `state`
-   */
-  predicate isBarrierOut(Node node, FlowState state) { none() }
-
   /** Holds if data flow through nodes guarded by `guard` is prohibited. */
   predicate isBarrierGuard(BarrierGuard guard) { none() }
 
@@ -128,7 +116,7 @@ abstract class Configuration extends string {
    * Holds if an arbitrary number of implicit read steps of content `c` may be
    * taken at `node`.
    */
-  predicate allowImplicitRead(Node node, Content c) { none() }
+  predicate allowImplicitRead(Node node, ContentSet c) { none() }
 
   /**
    * Gets the virtual dispatch branching limit when calculating field flow.
@@ -182,6 +170,14 @@ abstract class Configuration extends string {
    */
   int explorationLimit() { none() }
 
+  /**
+   * Holds if hidden nodes should be included in the data flow graph.
+   *
+   * This feature should only be used for debugging or when the data flow graph
+   * is not visualized (for example in a `path-problem` query).
+   */
+  predicate includeHiddenNodes() { none() }
+
   /**
    * Holds if there is a partial data flow path from `source` to `node`. The
    * approximate distance between `node` and the closest source is `dist` and
@@ -321,7 +317,7 @@ private class RetNodeEx extends NodeEx {
   ReturnKindExt getKind() { result = this.asNode().(ReturnNodeExt).getKind() }
 }
 
-private predicate fullInBarrier(NodeEx node, Configuration config) {
+private predicate inBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierIn(n)
@@ -330,16 +326,7 @@ private predicate fullInBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateInBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierIn(n, state)
-  |
-    config.isSource(n, state)
-  )
-}
-
-private predicate fullOutBarrier(NodeEx node, Configuration config) {
+private predicate outBarrier(NodeEx node, Configuration config) {
   exists(Node n |
     node.asNode() = n and
     config.isBarrierOut(n)
@@ -348,15 +335,6 @@ private predicate fullOutBarrier(NodeEx node, Configuration config) {
   )
 }
 
-private predicate stateOutBarrier(NodeEx node, FlowState state, Configuration config) {
-  exists(Node n |
-    node.asNode() = n and
-    config.isBarrierOut(n, state)
-  |
-    config.isSink(n, state)
-  )
-}
-
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -382,12 +360,6 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    config.isBarrierIn(n, state) and
-    not config.isSource(n, state)
-    or
-    config.isBarrierOut(n, state) and
-    not config.isSink(n, state)
-    or
     exists(BarrierGuard g |
       config.isBarrierGuard(g, state) and
       n = g.getAGuardedNode()
@@ -420,8 +392,8 @@ private predicate sinkNode(NodeEx node, FlowState state, Configuration config) {
 /** Provides the relevant barriers for a step from `node1` to `node2`. */
 pragma[inline]
 private predicate stepFilter(NodeEx node1, NodeEx node2, Configuration config) {
-  not fullOutBarrier(node1, config) and
-  not fullInBarrier(node2, config) and
+  not outBarrier(node1, config) and
+  not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
   not fullBarrier(node2, config)
 }
@@ -474,8 +446,6 @@ private predicate additionalLocalStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) = getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config)
   )
@@ -517,16 +487,15 @@ private predicate additionalJumpStateStep(
     config.isAdditionalFlowStep(n1, s1, n2, s2) and
     getNodeEnclosingCallable(n1) != getNodeEnclosingCallable(n2) and
     stepFilter(node1, node2, config) and
-    not stateOutBarrier(node1, s1, config) and
-    not stateInBarrier(node2, s2, config) and
     not stateBarrier(node1, s1, config) and
     not stateBarrier(node2, s2, config) and
     not config.getAFeature() instanceof FeatureEqualSourceSinkCallContext
   )
 }
 
-private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
-  read(node1.asNode(), c, node2.asNode()) and
+pragma[nomagic]
+private predicate readSet(NodeEx node1, ContentSet c, NodeEx node2, Configuration config) {
+  readSet(node1.asNode(), c, node2.asNode()) and
   stepFilter(node1, node2, config)
   or
   exists(Node n |
@@ -536,6 +505,37 @@ private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration conf
   )
 }
 
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate read(NodeEx node1, Content c, NodeEx node2, Configuration config) {
+  exists(ContentSet cs |
+    readSet(node1, cs, node2, config) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate clearsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    clearsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+// inline to reduce fan-out via `getAReadContent`
+bindingset[c]
+private predicate expectsContentEx(NodeEx n, Content c) {
+  exists(ContentSet cs |
+    expectsContentCached(n.asNode(), cs) and
+    pragma[only_bind_out](c) = pragma[only_bind_into](cs).getAReadContent()
+  )
+}
+
+pragma[nomagic]
+private predicate notExpectsContent(NodeEx n) { not expectsContentCached(n.asNode(), _) }
+
+pragma[nomagic]
 private predicate store(
   NodeEx node1, TypedContent tc, NodeEx node2, DataFlowType contentType, Configuration config
 ) {
@@ -613,9 +613,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(Content c |
-      fwdFlowRead(c, node, cc, config) and
-      fwdFlowConsCand(c, config)
+    exists(ContentSet c |
+      fwdFlowReadSet(c, node, cc, config) and
+      fwdFlowConsCandSet(c, _, config)
     )
     or
     // flow into a callable
@@ -639,10 +639,10 @@ private module Stage1 {
   private predicate fwdFlow(NodeEx node, Configuration config) { fwdFlow(node, _, config) }
 
   pragma[nomagic]
-  private predicate fwdFlowRead(Content c, NodeEx node, Cc cc, Configuration config) {
+  private predicate fwdFlowReadSet(ContentSet c, NodeEx node, Cc cc, Configuration config) {
     exists(NodeEx mid |
       fwdFlow(mid, cc, config) and
-      read(mid, c, node, config)
+      readSet(mid, c, node, config)
     )
   }
 
@@ -660,6 +660,16 @@ private module Stage1 {
     )
   }
 
+  /**
+   * Holds if `cs` may be interpreted in a read as the target of some store
+   * into `c`, in the flow covered by `fwdFlow`.
+   */
+  pragma[nomagic]
+  private predicate fwdFlowConsCandSet(ContentSet cs, Content c, Configuration config) {
+    fwdFlowConsCand(c, config) and
+    c = cs.getAReadContent()
+  }
+
   pragma[nomagic]
   private predicate fwdFlowReturnPosition(ReturnPosition pos, Cc cc, Configuration config) {
     exists(RetNodeEx ret |
@@ -752,9 +762,9 @@ private module Stage1 {
     )
     or
     // read
-    exists(NodeEx mid, Content c |
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+    exists(NodeEx mid, ContentSet c |
+      readSet(node, c, mid, config) and
+      fwdFlowConsCandSet(c, _, pragma[only_bind_into](config)) and
       revFlow(mid, toReturn, pragma[only_bind_into](config))
     )
     or
@@ -780,10 +790,10 @@ private module Stage1 {
    */
   pragma[nomagic]
   private predicate revFlowConsCand(Content c, Configuration config) {
-    exists(NodeEx mid, NodeEx node |
+    exists(NodeEx mid, NodeEx node, ContentSet cs |
       fwdFlow(node, pragma[only_bind_into](config)) and
-      read(node, c, mid, config) and
-      fwdFlowConsCand(c, pragma[only_bind_into](config)) and
+      readSet(node, cs, mid, config) and
+      fwdFlowConsCandSet(cs, c, pragma[only_bind_into](config)) and
       revFlow(pragma[only_bind_into](mid), _, pragma[only_bind_into](config))
     )
   }
@@ -802,7 +812,8 @@ private module Stage1 {
    * Holds if `c` is the target of both a read and a store in the flow covered
    * by `revFlow`.
    */
-  private predicate revFlowIsReadAndStored(Content c, Configuration conf) {
+  pragma[nomagic]
+  predicate revFlowIsReadAndStored(Content c, Configuration conf) {
     revFlowConsCand(c, conf) and
     revFlowStore(c, _, _, conf)
   }
@@ -901,8 +912,8 @@ private module Stage1 {
   pragma[nomagic]
   predicate readStepCand(NodeEx n1, Content c, NodeEx n2, Configuration config) {
     revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
-    revFlow(n2, pragma[only_bind_into](config)) and
-    read(n1, c, n2, pragma[only_bind_into](config))
+    read(n1, c, n2, pragma[only_bind_into](config)) and
+    revFlow(n2, pragma[only_bind_into](config))
   }
 
   pragma[nomagic]
@@ -912,14 +923,17 @@ private module Stage1 {
   predicate revFlow(
     NodeEx node, FlowState state, boolean toReturn, ApOption returnAp, Ap ap, Configuration config
   ) {
-    revFlow(node, toReturn, config) and exists(state) and exists(returnAp) and exists(ap)
+    revFlow(node, toReturn, pragma[only_bind_into](config)) and
+    exists(state) and
+    exists(returnAp) and
+    exists(ap)
   }
 
   private predicate throughFlowNodeCand(NodeEx node, Configuration config) {
     revFlow(node, true, config) and
     fwdFlow(node, true, config) and
-    not fullInBarrier(node, config) and
-    not fullOutBarrier(node, config)
+    not inBarrier(node, config) and
+    not outBarrier(node, config)
   }
 
   /** Holds if flow may return from `callable`. */
@@ -1014,8 +1028,8 @@ private predicate flowOutOfCallNodeCand1(
 ) {
   viableReturnPosOutNodeCand1(call, ret.getReturnPosition(), out, config) and
   Stage1::revFlow(ret, config) and
-  not fullOutBarrier(ret, config) and
-  not fullInBarrier(out, config)
+  not outBarrier(ret, config) and
+  not inBarrier(out, config)
 }
 
 pragma[nomagic]
@@ -1036,8 +1050,8 @@ private predicate flowIntoCallNodeCand1(
 ) {
   viableParamArgNodeCand1(call, p, arg, config) and
   Stage1::revFlow(p, config) and
-  not fullOutBarrier(arg, config) and
-  not fullInBarrier(p, config)
+  not outBarrier(arg, config) and
+  not inBarrier(p, config)
 }
 
 /**
@@ -1158,8 +1172,8 @@ private module Stage2 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   bindingset[node1, state1, config]
   bindingset[node2, state2, config]
@@ -1187,11 +1201,26 @@ private module Stage2 {
 
   private predicate flowIntoCall = flowIntoCallNodeCand1/5;
 
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::revFlowIsReadAndStored(c, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c)
+    )
+  }
+
   bindingset[node, state, ap, config]
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
-    PrevStage::revFlowState(state, config) and
+    PrevStage::revFlowState(state, pragma[only_bind_into](config)) and
     exists(ap) and
-    not stateBarrier(node, state, config)
+    not stateBarrier(node, state, config) and
+    (
+      notExpectsContent(node)
+      or
+      ap = true and
+      expectsContentCand(node, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -1246,7 +1275,7 @@ private module Stage2 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -1614,7 +1643,7 @@ private module Stage2 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -1652,10 +1681,24 @@ private module Stage2 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -1746,7 +1789,8 @@ private module LocalFlowBigStep {
   private class FlowCheckNode extends NodeEx {
     FlowCheckNode() {
       castNode(this.asNode()) or
-      clearsContentCached(this.asNode(), _)
+      clearsContentCached(this.asNode(), _) or
+      expectsContentCached(this.asNode(), _)
     }
   }
 
@@ -1769,9 +1813,9 @@ private module LocalFlowBigStep {
       or
       node.asNode() instanceof OutNodeExt
       or
-      store(_, _, node, _, config)
+      Stage2::storeStepCand(_, _, _, node, _, config)
       or
-      read(_, _, node, config)
+      Stage2::readStepCand(_, _, node, config)
       or
       node instanceof FlowCheckNode
       or
@@ -1792,8 +1836,8 @@ private module LocalFlowBigStep {
       additionalJumpStep(node, next, config) or
       flowIntoCallNodeCand1(_, node, next, config) or
       flowOutOfCallNodeCand1(_, node, next, config) or
-      store(node, _, next, _, config) or
-      read(node, _, next, config)
+      Stage2::storeStepCand(node, _, _, next, _, config) or
+      Stage2::readStepCand(node, _, next, config)
     )
     or
     exists(NodeEx next, FlowState s | Stage2::revFlow(next, s, config) |
@@ -1951,8 +1995,8 @@ private module Stage3 {
   bindingset[call, c, innercc]
   private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) { any() }
 
   private predicate localStep(
     NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
@@ -1966,7 +2010,34 @@ private module Stage3 {
   private predicate flowIntoCall = flowIntoCallNodeCand2/5;
 
   pragma[nomagic]
-  private predicate clear(NodeEx node, Ap ap) { ap.isClearedAt(node.asNode()) }
+  private predicate clearSet(NodeEx node, ContentSet c, Configuration config) {
+    PrevStage::revFlow(node, config) and
+    clearsContentCached(node.asNode(), c)
+  }
+
+  pragma[nomagic]
+  private predicate clearContent(NodeEx node, Content c, Configuration config) {
+    exists(ContentSet cs |
+      PrevStage::readStepCand(_, pragma[only_bind_into](c), _, pragma[only_bind_into](config)) and
+      c = cs.getAReadContent() and
+      clearSet(node, cs, pragma[only_bind_into](config))
+    )
+  }
+
+  pragma[nomagic]
+  private predicate clear(NodeEx node, Ap ap, Configuration config) {
+    clearContent(node, ap.getHead().getContent(), config)
+  }
+
+  pragma[nomagic]
+  private predicate expectsContentCand(NodeEx node, Ap ap, Configuration config) {
+    exists(Content c |
+      PrevStage::revFlow(node, pragma[only_bind_into](config)) and
+      PrevStage::readStepCand(_, c, _, pragma[only_bind_into](config)) and
+      expectsContentEx(node, c) and
+      c = ap.getHead().getContent()
+    )
+  }
 
   pragma[nomagic]
   private predicate castingNodeEx(NodeEx node) { node.asNode() instanceof CastingNode }
@@ -1975,8 +2046,13 @@ private module Stage3 {
   private predicate filter(NodeEx node, FlowState state, Ap ap, Configuration config) {
     exists(state) and
     exists(config) and
-    not clear(node, ap) and
-    if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()
+    not clear(node, ap, config) and
+    (if castingNodeEx(node) then compatibleTypes(node.getDataFlowType(), ap.getType()) else any()) and
+    (
+      notExpectsContent(node)
+      or
+      expectsContentCand(node, ap, config)
+    )
   }
 
   bindingset[ap, contentType]
@@ -2035,7 +2111,7 @@ private module Stage3 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -2403,7 +2479,7 @@ private module Stage3 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -2441,10 +2517,24 @@ private module Stage3 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -2765,12 +2855,11 @@ private module Stage4 {
     if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
   }
 
-  bindingset[node, cc, config]
-  private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) {
+  bindingset[node, cc]
+  private LocalCc getLocalCc(NodeEx node, Cc cc) {
     result =
       getLocalCallContext(pragma[only_bind_into](pragma[only_bind_out](cc)),
-        node.getEnclosingCallable()) and
-    exists(config)
+        node.getEnclosingCallable())
   }
 
   private predicate localStep(
@@ -2863,7 +2952,7 @@ private module Stage4 {
     or
     exists(NodeEx mid, FlowState state0, Ap ap0, LocalCc localCc |
       fwdFlow(mid, state0, cc, argAp, ap0, config) and
-      localCc = getLocalCc(mid, cc, config)
+      localCc = getLocalCc(mid, cc)
     |
       localStep(mid, state0, node, state, true, _, config, localCc) and
       ap = ap0
@@ -3231,7 +3320,7 @@ private module Stage4 {
     Configuration config
   ) {
     exists(Ap ap2, Content c |
-      store(node1, tc, node2, contentType, config) and
+      PrevStage::storeStepCand(node1, _, tc, node2, contentType, config) and
       revFlowStore(ap2, c, ap1, node1, _, tc, node2, _, _, config) and
       revFlowConsCand(ap2, c, ap1, config)
     )
@@ -3269,10 +3358,24 @@ private module Stage4 {
     storeStepFwd(_, ap, tc, _, _, config)
   }
 
-  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+  private predicate revConsCand(TypedContent tc, Ap ap, Configuration config) {
     storeStepCand(_, ap, tc, _, _, config)
   }
 
+  private predicate validAp(Ap ap, Configuration config) {
+    revFlow(_, _, _, _, ap, config) and ap instanceof ApNil
+    or
+    exists(TypedContent head, Ap tail |
+      consCand(head, tail, config) and
+      ap = apCons(head, tail)
+    )
+  }
+
+  predicate consCand(TypedContent tc, Ap ap, Configuration config) {
+    revConsCand(tc, ap, config) and
+    validAp(ap, config)
+  }
+
   pragma[noinline]
   private predicate parameterFlow(
     ParamNodeEx p, Ap ap, Ap ap0, DataFlowCallable c, Configuration config
@@ -3341,17 +3444,28 @@ private Configuration unbindConf(Configuration conf) {
   exists(Configuration c | result = pragma[only_bind_into](c) and conf = pragma[only_bind_into](c))
 }
 
-private predicate nodeMayUseSummary(
-  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+pragma[nomagic]
+private predicate nodeMayUseSummary0(
+  NodeEx n, DataFlowCallable c, FlowState state, AccessPathApprox apa, Configuration config
 ) {
-  exists(DataFlowCallable c, AccessPathApprox apa0 |
-    Stage4::parameterMayFlowThrough(_, c, apa, _) and
+  exists(AccessPathApprox apa0 |
+    Stage4::parameterMayFlowThrough(_, c, _, _) and
     Stage4::revFlow(n, state, true, _, apa0, config) and
     Stage4::fwdFlow(n, state, any(CallContextCall ccc), TAccessPathApproxSome(apa), apa0, config) and
     n.getEnclosingCallable() = c
   )
 }
 
+pragma[nomagic]
+private predicate nodeMayUseSummary(
+  NodeEx n, FlowState state, AccessPathApprox apa, Configuration config
+) {
+  exists(DataFlowCallable c |
+    Stage4::parameterMayFlowThrough(_, c, apa, config) and
+    nodeMayUseSummary0(n, c, state, apa, config)
+  )
+}
+
 private newtype TSummaryCtx =
   TSummaryCtxNone() or
   TSummaryCtxSome(ParamNodeEx p, FlowState state, AccessPath ap) {
@@ -3547,7 +3661,7 @@ private newtype TPathNode =
  * of dereference operations needed to get from the value in the node to the
  * tracked object. The final type indicates the type of the tracked object.
  */
-abstract private class AccessPath extends TAccessPath {
+private class AccessPath extends TAccessPath {
   /** Gets the head of this access path, if any. */
   abstract TypedContent getHead();
 
@@ -3762,11 +3876,14 @@ abstract private class PathNodeImpl extends PathNode {
   abstract NodeEx getNodeEx();
 
   predicate isHidden() {
-    hiddenNode(this.getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.getNodeEx() instanceof TNodeImplicitRead
+    not this.getConfiguration().includeHiddenNodes() and
+    (
+      hiddenNode(this.getNodeEx().asNode()) and
+      not this.isSource() and
+      not this instanceof PathNodeSink
+      or
+      this.getNodeEx() instanceof TNodeImplicitRead
+    )
   }
 
   private string ppAp() {
@@ -4243,10 +4360,16 @@ private module Subpaths {
     exists(NodeEx n1, NodeEx n2 | n1 = n.getNodeEx() and n2 = result.getNodeEx() |
       localFlowBigStep(n1, _, n2, _, _, _, _, _) or
       store(n1, _, n2, _, _) or
-      read(n1, _, n2, _)
+      readSet(n1, _, n2, _)
     )
   }
 
+  pragma[nomagic]
+  private predicate hasSuccessor(PathNode pred, PathNodeMid succ, NodeEx succNode) {
+    succ = pred.getASuccessor() and
+    succNode = succ.getNodeEx()
+  }
+
   /**
    * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
    * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
@@ -4254,15 +4377,13 @@ private module Subpaths {
    */
   predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeImpl ret, PathNode out) {
     exists(ParamNodeEx p, NodeEx o, FlowState sout, AccessPath apout, PathNodeMid out0 |
-      pragma[only_bind_into](arg).getASuccessor() = par and
-      pragma[only_bind_into](arg).getASuccessor() = out0 and
-      subpaths03(arg, p, localStepToHidden*(ret), o, sout, apout) and
+      pragma[only_bind_into](arg).getASuccessor() = pragma[only_bind_into](out0) and
+      subpaths03(pragma[only_bind_into](arg), p, localStepToHidden*(ret), o, sout, apout) and
+      hasSuccessor(pragma[only_bind_into](arg), par, p) and
       not ret.isHidden() and
-      par.getNodeEx() = p and
-      out0.getNodeEx() = o and
-      out0.getState() = sout and
-      out0.getAp() = apout and
-      (out = out0 or out = out0.projectToSink())
+      pathNode(out0, o, sout, _, _, apout, _, _)
+    |
+      out = out0 or out = out0.projectToSink()
     )
   }
 
@@ -4598,7 +4719,11 @@ private module FlowExploration {
       or
       exists(PartialPathNodeRev mid |
         revPartialPathStep(mid, node, state, sc1, sc2, sc3, ap, config) and
-        not clearsContentCached(node.asNode(), ap.getHead()) and
+        not clearsContentEx(node, ap.getHead()) and
+        (
+          notExpectsContent(node) or
+          expectsContentEx(node, ap.getHead())
+        ) and
         not fullBarrier(node, config) and
         not stateBarrier(node, state, config) and
         distSink(node.getEnclosingCallable(), config) <= config.explorationLimit()
@@ -4614,7 +4739,11 @@ private module FlowExploration {
       partialPathStep(mid, node, state, cc, sc1, sc2, sc3, ap, config) and
       not fullBarrier(node, config) and
       not stateBarrier(node, state, config) and
-      not clearsContentCached(node.asNode(), ap.getHead().getContent()) and
+      not clearsContentEx(node, ap.getHead().getContent()) and
+      (
+        notExpectsContent(node) or
+        expectsContentEx(node, ap.getHead().getContent())
+      ) and
       if node.asNode() instanceof CastingNode
       then compatibleTypes(node.getDataFlowType(), ap.getType())
       else any()
@@ -5048,6 +5177,7 @@ private module FlowExploration {
     )
   }
 
+  pragma[nomagic]
   private predicate revPartialPathStep(
     PartialPathNodeRev mid, NodeEx node, FlowState state, TRevSummaryCtx1 sc1, TRevSummaryCtx2 sc2,
     TRevSummaryCtx3 sc3, RevPartialAccessPath ap, Configuration config

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll

@@ -216,10 +216,9 @@ private module LambdaFlow {
     or
     // jump step
     exists(Node mid, DataFlowType t0 |
-      revLambdaFlow(lambdaCall, kind, mid, t0, _, _, _) and
+      revLambdaFlow(lambdaCall, kind, mid, t0, _, _, lastCall) and
       toReturn = false and
-      toJump = true and
-      lastCall = TDataFlowCallNone()
+      toJump = true
     |
       jumpStepCached(node, mid) and
       t = t0
@@ -305,7 +304,7 @@ cached
 private module Cached {
   /**
    * If needed, call this predicate from `DataFlowImplSpecific.qll` in order to
-   * force a stage-dependency on the `DataFlowImplCommon.qll` stage and therby
+   * force a stage-dependency on the `DataFlowImplCommon.qll` stage and thereby
    * collapsing the two stages.
    */
   cached
@@ -326,7 +325,10 @@ private module Cached {
   predicate jumpStepCached(Node node1, Node node2) { jumpStep(node1, node2) }
 
   cached
-  predicate clearsContentCached(Node n, Content c) { clearsContent(n, c) }
+  predicate clearsContentCached(Node n, ContentSet c) { clearsContent(n, c) }
+
+  cached
+  predicate expectsContentCached(Node n, ContentSet c) { expectsContent(n, c) }
 
   cached
   predicate isUnreachableInCallCached(Node n, DataFlowCall call) { isUnreachableInCall(n, call) }
@@ -373,7 +375,7 @@ private module Cached {
     // For reads, `x.f`, we want to check that the tracked type after the read (which
     // is obtained by popping the head of the access path stack) is compatible with
     // the type of `x.f`.
-    read(_, _, n)
+    readSet(_, _, n)
   }
 
   cached
@@ -469,7 +471,7 @@ private module Cached {
         // read
         exists(Node mid |
           parameterValueFlowCand(p, mid, false) and
-          read(mid, _, node) and
+          readSet(mid, _, node) and
           read = true
         )
         or
@@ -657,8 +659,10 @@ private module Cached {
        * Holds if `arg` flows to `out` through a call using only
        * value-preserving steps and a single read step, not taking call
        * contexts into account, thus representing a getter-step.
+       *
+       * This predicate is exposed for testing only.
        */
-      predicate getterStep(ArgNode arg, Content c, Node out) {
+      predicate getterStep(ArgNode arg, ContentSet c, Node out) {
         argumentValueFlowsThrough(arg, TReadStepTypesSome(_, c, _), out)
       }
 
@@ -781,28 +785,30 @@ private module Cached {
     parameterValueFlow(p, n.getPreUpdateNode(), TReadStepTypesNone())
   }
 
+  cached
+  predicate readSet(Node node1, ContentSet c, Node node2) { readStep(node1, c, node2) }
+
   private predicate store(
     Node node1, Content c, Node node2, DataFlowType contentType, DataFlowType containerType
   ) {
-    storeStep(node1, c, node2) and
-    contentType = getNodeDataFlowType(node1) and
-    containerType = getNodeDataFlowType(node2)
-    or
-    exists(Node n1, Node n2 |
-      n1 = node1.(PostUpdateNode).getPreUpdateNode() and
-      n2 = node2.(PostUpdateNode).getPreUpdateNode()
-    |
-      argumentValueFlowsThrough(n2, TReadStepTypesSome(containerType, c, contentType), n1)
+    exists(ContentSet cs | c = cs.getAStoreContent() |
+      storeStep(node1, cs, node2) and
+      contentType = getNodeDataFlowType(node1) and
+      containerType = getNodeDataFlowType(node2)
       or
-      read(n2, c, n1) and
-      contentType = getNodeDataFlowType(n1) and
-      containerType = getNodeDataFlowType(n2)
+      exists(Node n1, Node n2 |
+        n1 = node1.(PostUpdateNode).getPreUpdateNode() and
+        n2 = node2.(PostUpdateNode).getPreUpdateNode()
+      |
+        argumentValueFlowsThrough(n2, TReadStepTypesSome(containerType, cs, contentType), n1)
+        or
+        readSet(n2, cs, n1) and
+        contentType = getNodeDataFlowType(n1) and
+        containerType = getNodeDataFlowType(n2)
+      )
     )
   }
 
-  cached
-  predicate read(Node node1, Content c, Node node2) { readStep(node1, c, node2) }
-
   /**
    * Holds if data can flow from `node1` to `node2` via a direct assignment to
    * `f`.
@@ -932,16 +938,16 @@ class CastingNode extends Node {
 }
 
 private predicate readStepWithTypes(
-  Node n1, DataFlowType container, Content c, Node n2, DataFlowType content
+  Node n1, DataFlowType container, ContentSet c, Node n2, DataFlowType content
 ) {
-  read(n1, c, n2) and
+  readSet(n1, c, n2) and
   container = getNodeDataFlowType(n1) and
   content = getNodeDataFlowType(n2)
 }
 
 private newtype TReadStepTypesOption =
   TReadStepTypesNone() or
-  TReadStepTypesSome(DataFlowType container, Content c, DataFlowType content) {
+  TReadStepTypesSome(DataFlowType container, ContentSet c, DataFlowType content) {
     readStepWithTypes(_, container, c, _, content)
   }
 
@@ -950,7 +956,7 @@ private class ReadStepTypesOption extends TReadStepTypesOption {
 
   DataFlowType getContainerType() { this = TReadStepTypesSome(result, _, _) }
 
-  Content getContent() { this = TReadStepTypesSome(_, result, _) }
+  ContentSet getContent() { this = TReadStepTypesSome(_, result, _) }
 
   DataFlowType getContentType() { this = TReadStepTypesSome(_, _, result) }
 
@@ -1325,8 +1331,6 @@ abstract class AccessPathFront extends TAccessPathFront {
   abstract boolean toBoolNonEmpty();
 
   TypedContent getHead() { this = TFrontHead(result) }
-
-  predicate isClearedAt(Node n) { clearsContentCached(n, this.getHead().getContent()) }
 }
 
 class AccessPathFrontNil extends AccessPathFront, TFrontNil {

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowPrivate.qll

@@ -279,6 +279,12 @@ predicate clearsContent(Node n, Content c) {
   none() // stub implementation
 }
 
+/**
+ * Holds if the value that is being tracked is expected to be stored inside content `c`
+ * at node `n`.
+ */
+predicate expectsContent(Node n, ContentSet c) { none() }
+
 /** Gets the type of `n` used for type pruning. */
 IRType getNodeType(Node n) {
   suppressUnusedNode(n) and

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll

@@ -37,7 +37,7 @@ private module Cached {
    *      along the chain of addresses computed by `StoreNodeInstr.getInner` to identify field writes
    *      and call `storeStep` accordingly (i.e., for an expression like `a.b.c = x`, we visit `c`, then
    *      `b`, then `a`).
-   *   2. Flow is transfered from a `WriteSideEffectInstruction` to a `StoreNodeOperand` after flow
+   *   2. Flow is transferred from a `WriteSideEffectInstruction` to a `StoreNodeOperand` after flow
    *      returns to a caller. Flow will then proceed to the defining instruction of the operand (because
    *      the `StoreNodeInstr` computed by `StoreNodeOperand.getInner()` is the `StoreNode` containing
    *      the defining instruction), and then along the chain computed by `StoreNodeInstr.getInner` like
@@ -1063,6 +1063,34 @@ private class CollectionContent extends Content, TCollectionContent {
   override string toString() { result = "<element>" }
 }
 
+/**
+ * An entity that represents a set of `Content`s.
+ *
+ * The set may be interpreted differently depending on whether it is
+ * stored into (`getAStoreContent`) or read from (`getAReadContent`).
+ */
+class ContentSet instanceof Content {
+  /** Gets a content that may be stored into when storing into this set. */
+  Content getAStoreContent() { result = this }
+
+  /** Gets a content that may be read from when reading from this set. */
+  Content getAReadContent() { result = this }
+
+  /** Gets a textual representation of this content set. */
+  string toString() { result = super.toString() }
+
+  /**
+   * Holds if this element is at the specified location.
+   * The location spans column `startcolumn` of line `startline` to
+   * column `endcolumn` of line `endline` in file `filepath`.
+   * For more information, see
+   * [Locations](https://codeql.github.com/docs/writing-codeql-queries/providing-locations-in-codeql-queries/).
+   */
+  predicate hasLocationInfo(string path, int sl, int sc, int el, int ec) {
+    super.hasLocationInfo(path, sl, sc, el, ec)
+  }
+}
+
 /**
  * A guard that validates some instruction.
  *

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking1/TaintTrackingImpl.qll

@@ -109,16 +109,6 @@ abstract class Configuration extends DataFlow::Configuration {
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  /**
-   * Holds if taint propagation into `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerIn(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierIn(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerIn(node, state)
-  }
-
   final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
@@ -126,16 +116,6 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /**
-   * Holds if taint propagation out of `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerOut(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierOut(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerOut(node, state)
-  }
-
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
@@ -181,7 +161,7 @@ abstract class Configuration extends DataFlow::Configuration {
     this.isAdditionalTaintStep(node1, state1, node2, state2)
   }
 
-  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::Content c) {
+  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet c) {
     (this.isSink(node) or this.isAdditionalTaintStep(node, _)) and
     defaultImplicitTaintRead(node, c)
   }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking2/TaintTrackingImpl.qll

@@ -109,16 +109,6 @@ abstract class Configuration extends DataFlow::Configuration {
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  /**
-   * Holds if taint propagation into `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerIn(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierIn(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerIn(node, state)
-  }
-
   final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
@@ -126,16 +116,6 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /**
-   * Holds if taint propagation out of `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerOut(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierOut(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerOut(node, state)
-  }
-
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
@@ -181,7 +161,7 @@ abstract class Configuration extends DataFlow::Configuration {
     this.isAdditionalTaintStep(node1, state1, node2, state2)
   }
 
-  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::Content c) {
+  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet c) {
     (this.isSink(node) or this.isAdditionalTaintStep(node, _)) and
     defaultImplicitTaintRead(node, c)
   }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking3/TaintTrackingImpl.qll

@@ -109,16 +109,6 @@ abstract class Configuration extends DataFlow::Configuration {
   /** Holds if taint propagation into `node` is prohibited. */
   predicate isSanitizerIn(DataFlow::Node node) { none() }
 
-  /**
-   * Holds if taint propagation into `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerIn(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierIn(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerIn(node, state)
-  }
-
   final override predicate isBarrierIn(DataFlow::Node node) { this.isSanitizerIn(node) }
 
   /** Holds if taint propagation out of `node` is prohibited. */
@@ -126,16 +116,6 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /**
-   * Holds if taint propagation out of `node` is prohibited when the flow state is
-   * `state`.
-   */
-  predicate isSanitizerOut(DataFlow::Node node, DataFlow::FlowState state) { none() }
-
-  final override predicate isBarrierOut(DataFlow::Node node, DataFlow::FlowState state) {
-    this.isSanitizerOut(node, state)
-  }
-
   /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
   predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
@@ -181,7 +161,7 @@ abstract class Configuration extends DataFlow::Configuration {
     this.isAdditionalTaintStep(node1, state1, node2, state2)
   }
 
-  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::Content c) {
+  override predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet c) {
     (this.isSink(node) or this.isAdditionalTaintStep(node, _)) and
     defaultImplicitTaintRead(node, c)
   }

cpp/ql/lib/semmle/code/cpp/ir/implementation/EdgeKind.qll

@@ -67,7 +67,7 @@ class DefaultEdge extends EdgeKind, TDefaultEdge {
 
 /**
  * A "case" edge, representing the successor of a `Switch` instruction when the
- * the condition value matches a correponding `case` label.
+ * the condition value matches a corresponding `case` label.
  */
 class CaseEdge extends EdgeKind, TCaseEdge {
   string minValue;

cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/gvn/ValueNumbering.qll

@@ -34,7 +34,7 @@ class ValueNumber extends TValueNumber {
   final Instruction getAnInstruction() { this = valueNumber(result) }
 
   /**
-   * Gets one of the instructions that was assigned this value number. The chosen instuction is
+   * Gets one of the instructions that was assigned this value number. The chosen instruction is
    * deterministic but arbitrary. Intended for use only in debugging.
    */
   final Instruction getExampleInstruction() {

cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/internal/SSAConstruction.qll

@@ -1005,7 +1005,7 @@ predicate canReuseSsaForMemoryResult(Instruction instruction) {
 deprecated predicate canReuseSSAForMemoryResult = canReuseSsaForMemoryResult/1;
 
 /**
- * Expose some of the internal predicates to PrintSSA.qll. We do this by publically importing those modules in the
+ * Expose some of the internal predicates to PrintSSA.qll. We do this by publicly importing those modules in the
  * `DebugSSA` module, which is then imported by PrintSSA.
  */
 module DebugSsa {

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/gvn/ValueNumbering.qll

@@ -34,7 +34,7 @@ class ValueNumber extends TValueNumber {
   final Instruction getAnInstruction() { this = valueNumber(result) }
 
   /**
-   * Gets one of the instructions that was assigned this value number. The chosen instuction is
+   * Gets one of the instructions that was assigned this value number. The chosen instruction is
    * deterministic but arbitrary. Intended for use only in debugging.
    */
   final Instruction getExampleInstruction() {

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/TranslatedExpr.qll

@@ -11,7 +11,6 @@ private import TranslatedDeclarationEntry
 private import TranslatedElement
 private import TranslatedFunction
 private import TranslatedInitialization
-private import TranslatedFunction
 private import TranslatedStmt
 import TranslatedCall
 

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/TranslatedStmt.qll

@@ -421,20 +421,36 @@ class TranslatedCatchAnyHandler extends TranslatedHandler {
 class TranslatedIfStmt extends TranslatedStmt, ConditionContext {
   override IfStmt stmt;
 
-  override Instruction getFirstInstruction() { result = getCondition().getFirstInstruction() }
+  override Instruction getFirstInstruction() {
+    if hasInitialization()
+    then result = getInitialization().getFirstInstruction()
+    else result = getFirstConditionInstruction()
+  }
 
   override TranslatedElement getChild(int id) {
-    id = 0 and result = getCondition()
+    id = 0 and result = getInitialization()
     or
-    id = 1 and result = getThen()
+    id = 1 and result = getCondition()
     or
-    id = 2 and result = getElse()
+    id = 2 and result = getThen()
+    or
+    id = 3 and result = getElse()
+  }
+
+  private predicate hasInitialization() { exists(stmt.getInitialization()) }
+
+  private TranslatedStmt getInitialization() {
+    result = getTranslatedStmt(stmt.getInitialization())
   }
 
   private TranslatedCondition getCondition() {
     result = getTranslatedCondition(stmt.getCondition().getFullyConverted())
   }
 
+  private Instruction getFirstConditionInstruction() {
+    result = getCondition().getFirstInstruction()
+  }
+
   private TranslatedStmt getThen() { result = getTranslatedStmt(stmt.getThen()) }
 
   private TranslatedStmt getElse() { result = getTranslatedStmt(stmt.getElse()) }
@@ -456,6 +472,9 @@ class TranslatedIfStmt extends TranslatedStmt, ConditionContext {
   }
 
   override Instruction getChildSuccessor(TranslatedElement child) {
+    child = getInitialization() and
+    result = getFirstConditionInstruction()
+    or
     (child = getThen() or child = getElse()) and
     result = getParent().getChildSuccessor(this)
   }
@@ -698,14 +717,28 @@ class TranslatedSwitchStmt extends TranslatedStmt {
     result = getTranslatedExpr(stmt.getExpr().getFullyConverted())
   }
 
+  private Instruction getFirstExprInstruction() { result = getExpr().getFirstInstruction() }
+
   private TranslatedStmt getBody() { result = getTranslatedStmt(stmt.getStmt()) }
 
-  override Instruction getFirstInstruction() { result = getExpr().getFirstInstruction() }
+  override Instruction getFirstInstruction() {
+    if hasInitialization()
+    then result = getInitialization().getFirstInstruction()
+    else result = getFirstExprInstruction()
+  }
 
   override TranslatedElement getChild(int id) {
-    id = 0 and result = getExpr()
+    id = 0 and result = getInitialization()
     or
-    id = 1 and result = getBody()
+    id = 1 and result = getExpr()
+    or
+    id = 2 and result = getBody()
+  }
+
+  private predicate hasInitialization() { exists(stmt.getInitialization()) }
+
+  private TranslatedStmt getInitialization() {
+    result = getTranslatedStmt(stmt.getInitialization())
   }
 
   override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType resultType) {
@@ -735,6 +768,8 @@ class TranslatedSwitchStmt extends TranslatedStmt {
   }
 
   override Instruction getChildSuccessor(TranslatedElement child) {
+    child = getInitialization() and result = getFirstExprInstruction()
+    or
     child = getExpr() and result = getInstruction(SwitchBranchTag())
     or
     child = getBody() and result = getParent().getChildSuccessor(this)

cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/gvn/ValueNumbering.qll

@@ -34,7 +34,7 @@ class ValueNumber extends TValueNumber {
   final Instruction getAnInstruction() { this = valueNumber(result) }
 
   /**
-   * Gets one of the instructions that was assigned this value number. The chosen instuction is
+   * Gets one of the instructions that was assigned this value number. The chosen instruction is
    * deterministic but arbitrary. Intended for use only in debugging.
    */
   final Instruction getExampleInstruction() {

cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/internal/SSAConstruction.qll

@@ -1005,7 +1005,7 @@ predicate canReuseSsaForMemoryResult(Instruction instruction) {
 deprecated predicate canReuseSSAForMemoryResult = canReuseSsaForMemoryResult/1;
 
 /**
- * Expose some of the internal predicates to PrintSSA.qll. We do this by publically importing those modules in the
+ * Expose some of the internal predicates to PrintSSA.qll. We do this by publicly importing those modules in the
  * `DebugSSA` module, which is then imported by PrintSSA.
  */
 module DebugSsa {

cpp/ql/lib/semmle/code/cpp/ir/internal/CppType.qll

@@ -141,7 +141,7 @@ private predicate isOpaqueType(Type type) {
  * Holds if an `IROpaqueType` with the specified `tag` and `byteSize` should exist.
  */
 predicate hasOpaqueType(Type tag, int byteSize) {
-  isOpaqueType(tag) and byteSize = getTypeSize(tag)
+  isOpaqueType(tag) and byteSize = getTypeSize(tag.getUnspecifiedType())
   or
   tag instanceof UnknownType and Raw::needsUnknownOpaqueType(byteSize)
 }
@@ -153,17 +153,18 @@ private IRType getIRTypeForPRValue(Type type) {
   exists(Type unspecifiedType | unspecifiedType = type.getUnspecifiedType() |
     isOpaqueType(unspecifiedType) and
     exists(IROpaqueType opaqueType | opaqueType = result |
-      opaqueType.getByteSize() = getTypeSize(type) and
+      opaqueType.getByteSize() = getTypeSize(unspecifiedType) and
       opaqueType.getTag() = unspecifiedType
     )
     or
-    unspecifiedType instanceof BoolType and result.(IRBooleanType).getByteSize() = type.getSize()
+    unspecifiedType instanceof BoolType and
+    result.(IRBooleanType).getByteSize() = unspecifiedType.getSize()
     or
     isSignedIntegerType(unspecifiedType) and
-    result.(IRSignedIntegerType).getByteSize() = type.getSize()
+    result.(IRSignedIntegerType).getByteSize() = unspecifiedType.getSize()
     or
     isUnsignedIntegerType(unspecifiedType) and
-    result.(IRUnsignedIntegerType).getByteSize() = type.getSize()
+    result.(IRUnsignedIntegerType).getByteSize() = unspecifiedType.getSize()
     or
     exists(FloatingPointType floatType, IRFloatingPointType irFloatType |
       floatType = unspecifiedType and
@@ -173,7 +174,8 @@ private IRType getIRTypeForPRValue(Type type) {
       irFloatType.getDomain() = floatType.getDomain()
     )
     or
-    isPointerIshType(unspecifiedType) and result.(IRAddressType).getByteSize() = getTypeSize(type)
+    isPointerIshType(unspecifiedType) and
+    result.(IRAddressType).getByteSize() = getTypeSize(unspecifiedType)
     or
     unspecifiedType instanceof FunctionPointerIshType and
     result.(IRFunctionAddressType).getByteSize() = getTypeSize(type)

cpp/ql/lib/semmle/code/cpp/models/implementations/Allocation.qll

@@ -42,10 +42,13 @@ private class MallocAllocationFunction extends AllocationFunction {
     this.hasGlobalName([
         // --- Windows Memory Management for Windows Drivers
         "ExAllocatePool", // ExAllocatePool(type, size)
+        "ExAllocatePool2", // ExAllocatePool2(flags, size, tag)
+        "ExAllocatePool3", // ExAllocatePool3(flags, size, tag, extparams, extparamscount)
         "ExAllocatePoolWithTag", // ExAllocatePool(type, size, tag)
         "ExAllocatePoolWithTagPriority", // ExAllocatePoolWithTagPriority(type, size, tag, priority)
         "ExAllocatePoolWithQuota", // ExAllocatePoolWithQuota(type, size)
         "ExAllocatePoolWithQuotaTag", // ExAllocatePoolWithQuotaTag(type, size, tag)
+        "ExAllocatePoolZero", // ExAllocatePoolZero(type, size, tag)
         "IoAllocateMdl", // IoAllocateMdl(address, size, flag, flag, irp)
         "IoAllocateErrorLogEntry", // IoAllocateErrorLogEntry(object, size)
         // --- Windows Global / Local legacy allocation

cpp/ql/lib/semmle/code/cpp/models/implementations/Strtok.qll

@@ -5,7 +5,6 @@
 
 import semmle.code.cpp.Function
 import semmle.code.cpp.models.interfaces.ArrayFunction
-import semmle.code.cpp.models.interfaces.ArrayFunction
 import semmle.code.cpp.models.interfaces.Alias
 import semmle.code.cpp.models.interfaces.SideEffect
 import semmle.code.cpp.models.interfaces.Taint

cpp/ql/lib/semmle/code/cpp/rangeanalysis/SimpleRangeAnalysis.qll

@@ -1802,5 +1802,3 @@ module SimpleRangeAnalysisInternal {
     defMightOverflowNegatively(def, v) and result = varMaxVal(v)
   }
 }
-
-private import SimpleRangeAnalysisInternal

cpp/ql/lib/semmle/code/cpp/security/BufferWrite.qll

@@ -6,7 +6,6 @@
  */
 
 import cpp
-import semmle.code.cpp.commons.Alloc
 import semmle.code.cpp.commons.Buffer
 import semmle.code.cpp.commons.Scanf
 import semmle.code.cpp.models.implementations.Strcat
@@ -156,7 +155,7 @@ class StrCopyBW extends BufferWriteCall {
     // when result exists, it is an exact flow analysis
     reason instanceof ValueFlowAnalysis and
     result =
-      this.getArgument(this.getParamSrc()).(AnalysedString).getMaxLength() * this.getCharSize()
+      this.getArgument(this.getParamSrc()).(AnalyzedString).getMaxLength() * this.getCharSize()
   }
 
   override int getMaxData(BufferWriteEstimationReason reason) {
@@ -202,7 +201,7 @@ class StrCatBW extends BufferWriteCall {
     // when result exists, it is an exact flow analysis
     reason instanceof ValueFlowAnalysis and
     result =
-      this.getArgument(this.getParamSrc()).(AnalysedString).getMaxLength() * this.getCharSize()
+      this.getArgument(this.getParamSrc()).(AnalyzedString).getMaxLength() * this.getCharSize()
   }
 
   override int getMaxData(BufferWriteEstimationReason reason) {

cpp/ql/lib/semmle/code/cpp/security/Encryption.qll

@@ -59,7 +59,7 @@ predicate isInsecureEncryption(string name) { name.regexpMatch(getInsecureAlgori
 /**
  * Holds if there is additional evidence that `name` looks like it might be
  * related to operations with an encyption algorithm, besides the name of a
- * specific algorithm. This can be used in conjuction with
+ * specific algorithm. This can be used in conjunction with
  * `isInsecureEncryption` to produce a stronger heuristic.
  */
 bindingset[name]

cpp/ql/lib/semmle/code/cpp/security/Overflow.qll

@@ -5,8 +5,6 @@
 
 import cpp
 import semmle.code.cpp.controlflow.Dominance
-// `GlobalValueNumbering` is only imported to prevent IR re-evaluation.
-private import semmle.code.cpp.valuenumbering.GlobalValueNumbering
 import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
 import semmle.code.cpp.rangeanalysis.RangeAnalysisUtils
 import semmle.code.cpp.controlflow.Guards
@@ -25,6 +23,7 @@ predicate guardedAbs(Operation e, Expr use) {
  * Holds if the value of `use` is guarded to be less than something, and `e`
  * is in code controlled by that guard (where the guard condition held).
  */
+pragma[nomagic]
 predicate guardedLesser(Operation e, Expr use) {
   exists(GuardCondition c | c.ensuresLt(use, _, _, e.getBasicBlock(), true))
   or
@@ -35,6 +34,7 @@ predicate guardedLesser(Operation e, Expr use) {
  * Holds if the value of `use` is guarded to be greater than something, and `e`
  * is in code controlled by that guard (where the guard condition held).
  */
+pragma[nomagic]
 predicate guardedGreater(Operation e, Expr use) {
   exists(GuardCondition c | c.ensuresLt(use, _, _, e.getBasicBlock(), false))
   or

cpp/ql/lib/semmle/code/cpp/stmts/Stmt.qll

@@ -213,6 +213,26 @@ class ConditionalStmt extends ControlStructure, TConditionalStmt { }
 class IfStmt extends ConditionalStmt, @stmt_if {
   override string getAPrimaryQlClass() { result = "IfStmt" }
 
+  /**
+   * Gets the initialization statement of this 'if' statement, if any.
+   *
+   * For example, for
+   * ```
+   * if (int x = y; b) { f(); }
+   * ```
+   * the result is `int x = y;`.
+   *
+   * Does not hold if the initialization statement is missing or an empty statement, as in
+   * ```
+   * if (b) { f(); }
+   * ```
+   * or
+   * ```
+   * if (; b) { f(); }
+   * ```
+   */
+  Stmt getInitialization() { if_initialization(underlyingElement(this), unresolveElement(result)) }
+
   /**
    * Gets the condition expression of this 'if' statement.
    *
@@ -222,7 +242,7 @@ class IfStmt extends ConditionalStmt, @stmt_if {
    * ```
    * the result is `b`.
    */
-  Expr getCondition() { result = this.getChild(0) }
+  Expr getCondition() { result = this.getChild(1) }
 
   override Expr getControllingExpr() { result = this.getCondition() }
 
@@ -299,6 +319,28 @@ class IfStmt extends ConditionalStmt, @stmt_if {
 class ConstexprIfStmt extends ConditionalStmt, @stmt_constexpr_if {
   override string getAPrimaryQlClass() { result = "ConstexprIfStmt" }
 
+  /**
+   * Gets the initialization statement of this 'constexpr if' statement, if any.
+   *
+   * For example, for
+   * ```
+   * if constexpr (int x = y; b) { f(); }
+   * ```
+   * the result is `int x = y;`.
+   *
+   * Does not hold if the initialization statement is missing or an empty statement, as in
+   * ```
+   * if constexpr (b) { f(); }
+   * ```
+   * or
+   * ```
+   * if constexpr (; b) { f(); }
+   * ```
+   */
+  Stmt getInitialization() {
+    constexpr_if_initialization(underlyingElement(this), unresolveElement(result))
+  }
+
   /**
    * Gets the condition expression of this 'constexpr if' statement.
    *
@@ -308,7 +350,7 @@ class ConstexprIfStmt extends ConditionalStmt, @stmt_constexpr_if {
    * ```
    * the result is `b`.
    */
-  Expr getCondition() { result = this.getChild(0) }
+  Expr getCondition() { result = this.getChild(1) }
 
   override Expr getControllingExpr() { result = this.getCondition() }
 
@@ -926,7 +968,7 @@ class ForStmt extends Loop, @stmt_for {
    *
    * Does not hold if the initialization statement is an empty statement, as in
    * ```
-   * for (; i < 10; i++) { j++ }
+   * for (; i < 10; i++) { j++; }
    * ```
    */
   Stmt getInitialization() { for_initialization(underlyingElement(this), unresolveElement(result)) }
@@ -1470,6 +1512,28 @@ class DefaultCase extends SwitchCase {
 class SwitchStmt extends ConditionalStmt, @stmt_switch {
   override string getAPrimaryQlClass() { result = "SwitchStmt" }
 
+  /**
+   * Gets the initialization statement of this 'switch' statement, if any.
+   *
+   * For example, for
+   * ```
+   * switch (int x = y; b) { }
+   * ```
+   * the result is `int x = y;`.
+   *
+   * Does not hold if the initialization statement is missing or an empty statement, as in
+   * ```
+   * switch (b) { }
+   * ```
+   * or
+   * ```
+   * switch (; b) { }
+   * ```
+   */
+  Stmt getInitialization() {
+    switch_initialization(underlyingElement(this), unresolveElement(result))
+  }
+
   /**
    * Gets the expression that this 'switch' statement switches on.
    *
@@ -1485,7 +1549,7 @@ class SwitchStmt extends ConditionalStmt, @stmt_switch {
    * ```
    * the result is `i`.
    */
-  Expr getExpr() { result = this.getChild(0) }
+  Expr getExpr() { result = this.getChild(1) }
 
   override Expr getControllingExpr() { result = this.getExpr() }