C++: Generate IR for assertions in release builds.

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

@@ -104,7 +104,11 @@ newtype TInstructionTag =
   } or
   SizeofVlaDimensionTag(int index) {
     exists(VlaDeclStmt v | exists(v.getTransitiveVlaDimensionStmt(index)))
-  }
+  } or
+  AssertionVarAddressTag() or
+  AssertionVarLoadTag() or
+  AssertionOpTag() or
+  AssertionBranchTag()
 
 class InstructionTag extends TInstructionTag {
   final string toString() { result = getInstructionTagId(this) }
@@ -296,4 +300,12 @@ string getInstructionTagId(TInstructionTag tag) {
   tag = CoAwaitBranchTag() and result = "CoAwaitBranch"
   or
   tag = BoolToIntConversionTag() and result = "BoolToIntConversion"
+  or
+  tag = AssertionVarAddressTag() and result = "AssertionVarAddress"
+  or
+  tag = AssertionVarLoadTag() and result = "AssertionVarLoad"
+  or
+  tag = AssertionOpTag() and result = "AssertionOp"
+  or
+  tag = AssertionBranchTag() and result = "AssertionBranch"
 }

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

@@ -0,0 +1,373 @@
+private import cpp
+private import semmle.code.cpp.ir.internal.IRUtilities
+private import semmle.code.cpp.ir.implementation.internal.OperandTag
+private import semmle.code.cpp.ir.internal.CppType
+private import semmle.code.cpp.ir.internal.TempVariableTag
+private import InstructionTag
+private import TranslatedElement
+private import TranslatedStmt
+private import TranslatedFunction
+
+/**
+ * Holds if `s` is a statement that may be an expanded assertion in a
+ * release build.
+ */
+pragma[nomagic]
+private predicate stmtCandidate(Stmt s) {
+  not s.isFromUninstantiatedTemplate(_) and
+  (
+    // The expansion of `__analysis_assume(x != 0);` when `__analysis_assume` is
+    // empty is the empty statement.
+    s instanceof EmptyStmt
+    or
+    // The expansion of `assert(x != 0)` when `assert` is `((void)0)` is a zero literal
+    // with a void type.
+    exists(Expr e |
+      e = s.(ExprStmt).getExpr() and
+      e.getValue() = "0" and
+      e.getActualType() instanceof VoidType
+    )
+  )
+}
+
+pragma[nomagic]
+private predicate macroInvocationLocation(int startline, Function f, MacroInvocation mi) {
+  mi.getMacroName() = ["assert", "__analysis_assume"] and
+  mi.getLocation().hasLocationInfo(_, startline, _, _, _) and
+  f.getEntryPoint().isAffectedByMacro(mi)
+}
+
+pragma[nomagic]
+private predicate stmtParentLocation(int startline, Function f, StmtParent p) {
+  p.getEnclosingFunction() = f and
+  p.getLocation().hasLocationInfo(_, startline, _, _, _)
+}
+
+/**
+ * Holds if `mi` is a macro invocation with a name that is known
+ * to correspond to an assertion macro, and the macro invocation
+ * is the only thing on the line.
+ */
+pragma[nomagic]
+private predicate assertion0(MacroInvocation mi, Stmt s) {
+  stmtCandidate(s) and
+  s =
+    unique(StmtParent p, int startline, Function f |
+      macroInvocationLocation(startline, f, mi) and
+      stmtParentLocation(startline, f, p) and
+      // Also do not count the elements from the expanded macro. i.e., when checking
+      // if `assert(x)` is the only thing on the line we do not count the
+      // generated `((void)0)` expression.
+      not p = mi.getAnExpandedElement()
+    |
+      p
+    )
+}
+
+private Function getEnclosingFunctionForMacroInvocation(MacroInvocation mi) {
+  exists(Stmt s |
+    assertion0(mi, s) and
+    result = s.getEnclosingFunction()
+  )
+}
+
+/**
+ * Holds if `arg` has two components and the `i`'th component of the string
+ * `arg` is `s`, and the components are seperated by an operation with
+ * opcode `opcode`.
+ */
+bindingset[arg]
+pragma[inline_late]
+private predicate parseArgument(string arg, string s, int i, Opcode opcode) {
+  s =
+    arg.regexpCapture("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?<=\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)",
+      i + 1) and
+  opcode instanceof Opcode::CompareLE
+  or
+  s =
+    arg.regexpCapture("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?>=\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)",
+      i + 1) and
+  opcode instanceof Opcode::CompareGE
+  or
+  not arg.regexpMatch("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?<=\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)") and
+  s =
+    arg.regexpCapture("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?<\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)",
+      i + 1) and
+  opcode instanceof Opcode::CompareLT
+  or
+  not arg.regexpMatch("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?>=\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)") and
+  s =
+    arg.regexpCapture("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?>\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)",
+      i + 1) and
+  opcode instanceof Opcode::CompareGT
+  or
+  s =
+    arg.regexpCapture("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?!=\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)",
+      i + 1) and
+  opcode instanceof Opcode::CompareNE
+  or
+  s =
+    arg.regexpCapture("([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)\\s?==\\s?([a-zA-Z_][a-zA-Z_0-9]*|[0-9]+)",
+      i + 1) and
+  opcode instanceof Opcode::CompareEQ
+}
+
+/** Gets a local variable named `s` in `f`. */
+pragma[nomagic]
+private LocalScopeVariable getAVariableWithNameInFunction(Function f, string s) {
+  result.getName() = s and
+  result.getFunction() = f
+}
+
+/**
+ * Holds if the `i`'th component of the macro invocation `mi` with opcode
+ * `opcode` is a reference to `var`.
+ */
+private predicate hasVarAccessMacroArgument(MacroInvocation mi, Variable var, int i, Opcode opcode) {
+  exists(string arg, string s, Function f |
+    arg = mi.getUnexpandedArgument(0) and
+    f = getEnclosingFunctionForMacroInvocation(mi) and
+    not exists(s.toInt()) and
+    parseArgument(arg, s, i, opcode) and
+    var = unique( | | getAVariableWithNameInFunction(f, s))
+  )
+}
+
+/**
+ * Holds if the `i`'th component of the macro invocation `mi` with opcode
+ * `opcode` is a
+ * constant with the value `k`.
+ */
+private predicate hasConstMacroArgument(MacroInvocation mi, int k, int i, Opcode opcode) {
+  exists(string arg, string s |
+    assertion0(mi, _) and
+    arg = mi.getUnexpandedArgument(0) and
+    s.toInt() = k and
+    parseArgument(arg, s, i, opcode)
+  )
+}
+
+predicate hasAssertionOperand(MacroInvocation mi, int i) {
+  hasVarAccessMacroArgument(mi, _, i, _)
+  or
+  hasConstMacroArgument(mi, _, i, _)
+}
+
+private predicate hasAssertionOpcode(MacroInvocation mi, Opcode opcode) {
+  hasVarAccessMacroArgument(mi, _, _, opcode)
+  or
+  hasConstMacroArgument(mi, _, _, opcode)
+}
+
+/**
+ * Holds if `mi` is a macro invocation that is an assertion that should be generated
+ * in the control-flow graph at `s`.
+ */
+predicate assertion(MacroInvocation mi, Stmt s) {
+  assertion0(mi, s) and
+  hasAssertionOperand(mi, 0) and
+  hasAssertionOperand(mi, 1)
+}
+
+/** The translation of an operand of an assertion. */
+abstract private class TranslatedAssertionOperand extends TranslatedElement,
+  TTranslatedAssertionOperand
+{
+  MacroInvocation mi;
+  int index;
+
+  TranslatedAssertionOperand() { this = TTranslatedAssertionOperand(mi, index) }
+
+  MacroInvocation getMacroInvocation() { result = mi }
+
+  /**
+   * Gets the statement that is being replaced by the assertion that uses this
+   * operand.
+   */
+  Stmt getStmt() { assertion(mi, result) }
+
+  final override Locatable getAst() { result = this.getStmt() }
+
+  final override TranslatedElement getChild(int id) { none() }
+
+  final override Declaration getFunction() { result = this.getStmt().getEnclosingFunction() }
+
+  /** Gets the instruction which holds the result of this operand. */
+  abstract Instruction getResult();
+
+  final override string toString() { result = "Operand of assertion: " + mi }
+
+  /** Gets the index of this operand (i.e., `0` or `1`). */
+  final int getIndex() { result = index }
+}
+
+/** An operand of an assertion that is a variable access. */
+private class TranslatedAssertionVarAccess extends TranslatedAssertionOperand {
+  TranslatedAssertionVarAccess() { hasVarAccessMacroArgument(mi, _, index, _) }
+
+  Variable getVariable() { hasVarAccessMacroArgument(mi, result, index, _) }
+
+  final override IRUserVariable getInstructionVariable(InstructionTag tag) {
+    tag = AssertionVarAddressTag() and
+    result.getVariable() = this.getVariable()
+  }
+
+  final override Instruction getFirstInstruction(EdgeKind kind) {
+    result = this.getInstruction(AssertionVarAddressTag()) and kind instanceof GotoEdge
+  }
+
+  final override Instruction getInstructionSuccessorInternal(InstructionTag tag, EdgeKind kind) {
+    tag = AssertionVarAddressTag() and
+    kind instanceof GotoEdge and
+    result = this.getInstruction(AssertionVarLoadTag())
+    or
+    tag = AssertionVarLoadTag() and
+    result = getTranslatedAssertionMacroInvocation(mi).getChildSuccessor(this, kind)
+  }
+
+  final override Instruction getALastInstructionInternal() {
+    result = this.getInstruction(AssertionVarLoadTag())
+  }
+
+  override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType resultType) {
+    exists(Variable v | v = this.getVariable() |
+      opcode instanceof Opcode::VariableAddress and
+      tag = AssertionVarAddressTag() and
+      resultType = getTypeForGLValue(v.getType())
+      or
+      opcode instanceof Opcode::Load and
+      tag = AssertionVarLoadTag() and
+      resultType = getTypeForPRValue(v.getType())
+    )
+  }
+
+  final override Instruction getInstructionRegisterOperand(InstructionTag tag, OperandTag operandTag) {
+    tag = AssertionVarLoadTag() and
+    operandTag instanceof AddressOperandTag and
+    result = this.getInstruction(AssertionVarAddressTag())
+  }
+
+  final override Instruction getResult() { result = this.getInstruction(AssertionVarLoadTag()) }
+}
+
+/** An operand of an assertion that is a constant access. */
+private class TranslatedAssertionConst extends TranslatedAssertionOperand {
+  TranslatedAssertionConst() { hasConstMacroArgument(mi, _, index, _) }
+
+  int getConst() { hasConstMacroArgument(mi, result, index, _) }
+
+  final override string getInstructionConstantValue(InstructionTag tag) {
+    tag = OnlyInstructionTag() and
+    result = this.getConst().toString()
+  }
+
+  final override Instruction getFirstInstruction(EdgeKind kind) {
+    result = this.getInstruction(OnlyInstructionTag()) and
+    kind instanceof GotoEdge
+  }
+
+  final override Instruction getInstructionSuccessorInternal(InstructionTag tag, EdgeKind kind) {
+    tag = OnlyInstructionTag() and
+    result = getTranslatedAssertionMacroInvocation(mi).getChildSuccessor(this, kind)
+  }
+
+  final override Instruction getALastInstructionInternal() {
+    result = this.getInstruction(OnlyInstructionTag())
+  }
+
+  override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType resultType) {
+    opcode instanceof Opcode::Constant and
+    tag = OnlyInstructionTag() and
+    resultType = getIntType()
+  }
+
+  final override Instruction getResult() { result = this.getInstruction(OnlyInstructionTag()) }
+}
+
+/**
+ * Gets the `TranslatedAssertionMacroInvocation` corresponding to the macro
+ * invocation `mi`.
+ */
+TranslatedAssertionMacroInvocation getTranslatedAssertionMacroInvocation(MacroInvocation mi) {
+  result.getMacroInvocation() = mi
+}
+
+/**
+ * A synthesized assertion which would have otherwise been invisible because the
+ * database represents a release build where assertions are disabled.
+ */
+private class TranslatedAssertionMacroInvocation extends TranslatedStmt {
+  MacroInvocation mi;
+
+  TranslatedAssertionMacroInvocation() { assertion(mi, stmt) }
+
+  final override Instruction getFirstInstruction(EdgeKind kind) {
+    result = this.getLeft().getFirstInstruction(kind)
+  }
+
+  TranslatedAssertionOperand getLeft() {
+    result.getMacroInvocation() = mi and
+    result.getIndex() = 0
+  }
+
+  TranslatedAssertionOperand getRight() {
+    result.getMacroInvocation() = mi and
+    result.getIndex() = 1
+  }
+
+  final override Instruction getInstructionSuccessorInternal(InstructionTag tag, EdgeKind kind) {
+    tag = AssertionOpTag() and
+    kind instanceof GotoEdge and
+    result = this.getInstruction(AssertionBranchTag())
+    or
+    tag = AssertionBranchTag() and
+    kind instanceof TrueEdge and
+    result = this.getParent().getChildSuccessor(this, _)
+  }
+
+  final override TranslatedElement getChildInternal(int id) {
+    id = 0 and result = this.getLeft()
+    or
+    id = 1 and result = this.getRight()
+  }
+
+  final override Instruction getALastInstructionInternal() {
+    result = this.getInstruction(AssertionBranchTag())
+  }
+
+  final override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType resultType) {
+    tag = AssertionOpTag() and
+    resultType = getBoolType() and
+    hasAssertionOpcode(mi, opcode)
+    or
+    tag = AssertionBranchTag() and
+    resultType = getVoidType() and
+    opcode instanceof Opcode::ConditionalBranch
+  }
+
+  final override Instruction getChildSuccessorInternal(TranslatedElement child, EdgeKind kind) {
+    child = this.getLeft() and
+    result = this.getRight().getFirstInstruction(kind)
+    or
+    child = this.getRight() and
+    kind instanceof GotoEdge and
+    result = this.getInstruction(AssertionOpTag())
+  }
+
+  final override Instruction getInstructionRegisterOperand(InstructionTag tag, OperandTag operandTag) {
+    tag = AssertionOpTag() and
+    (
+      operandTag instanceof LeftOperandTag and
+      result = this.getLeft().getResult()
+      or
+      operandTag instanceof RightOperandTag and
+      result = this.getRight().getResult()
+    )
+    or
+    tag = AssertionBranchTag() and
+    operandTag instanceof ConditionOperandTag and
+    result = this.getInstruction(AssertionOpTag())
+  }
+
+  MacroInvocation getMacroInvocation() { result = mi }
+}

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

@@ -12,6 +12,7 @@ private import TranslatedFunction
 private import TranslatedStmt
 private import TranslatedExpr
 private import IRConstruction
+private import TranslatedAssertion
 private import semmle.code.cpp.models.interfaces.SideEffect
 private import SideEffects
 
@@ -138,6 +139,14 @@ private predicate ignoreExprAndDescendants(Expr expr) {
   // conditionally constructed (until we have a mechanism for calling these only when the
   // temporary's constructor was run)
   isConditionalTemporaryDestructorCall(expr)
+  or
+  // An assertion in a release build is often defined as `#define assert(x) ((void)0)`.
+  // We generate a synthetic assertion in release builds, and when we do that the
+  // expression `((void)0)` should not be translated.
+  exists(MacroInvocation mi |
+    assertion(mi, _) and
+    expr = mi.getExpr().getFullyConverted()
+  )
 }
 
 /**
@@ -909,7 +918,8 @@ newtype TTranslatedElement =
   } or
   // The side effect that initializes newly-allocated memory.
   TTranslatedAllocationSideEffect(AllocationExpr expr) { not ignoreSideEffects(expr) } or
-  TTranslatedStaticStorageDurationVarInit(Variable var) { Raw::varHasIRFunc(var) }
+  TTranslatedStaticStorageDurationVarInit(Variable var) { Raw::varHasIRFunc(var) } or
+  TTranslatedAssertionOperand(MacroInvocation mi, int index) { hasAssertionOperand(mi, index) }
 
 /**
  * Gets the index of the first explicitly initialized element in `initList`