Ruby: Add tests for phi reads

ruby/ql/lib/codeql/ruby/dataflow/internal/SsaImpl.qll

@@ -2,6 +2,7 @@ private import codeql.ssa.Ssa as SsaImplCommon
 private import codeql.ruby.AST
 private import codeql.ruby.CFG as Cfg
 private import codeql.ruby.controlflow.internal.ControlFlowGraphImplShared as ControlFlowGraphImplShared
+private import codeql.ruby.dataflow.SSA
 private import codeql.ruby.ast.Variable
 private import Cfg::CfgNodes::ExprNodes
 
@@ -61,7 +62,23 @@ private module SsaInput implements SsaImplCommon::InputSig {
   }
 }
 
-import SsaImplCommon::Make<SsaInput>
+private import SsaImplCommon::Make<SsaInput> as Impl
+
+class Definition = Impl::Definition;
+
+class WriteDefinition = Impl::WriteDefinition;
+
+class UncertainWriteDefinition = Impl::UncertainWriteDefinition;
+
+class PhiNode = Impl::PhiNode;
+
+module Consistency = Impl::Consistency;
+
+module ExposedForTestingOnly {
+  predicate ssaDefReachesReadExt = Impl::ssaDefReachesReadExt/4;
+
+  predicate phiHasInputFromBlockExt = Impl::phiHasInputFromBlockExt/3;
+}
 
 /** Holds if `v` is uninitialized at index `i` in entry block `bb`. */
 predicate uninitializedWrite(Cfg::EntryBasicBlock bb, int i, LocalVariable v) {
@@ -204,7 +221,7 @@ private predicate adjacentDefRead(
   Definition def, SsaInput::BasicBlock bb1, int i1, SsaInput::BasicBlock bb2, int i2,
   SsaInput::SourceVariable v
 ) {
-  adjacentDefRead(def, bb1, i1, bb2, i2) and
+  Impl::adjacentDefRead(def, bb1, i1, bb2, i2) and
   v = def.getSourceVariable()
 }
 
@@ -220,7 +237,7 @@ private predicate adjacentDefReachesRead(
   exists(SsaInput::BasicBlock bb3, int i3 |
     adjacentDefReachesRead(def, bb1, i1, bb3, i3) and
     SsaInput::variableRead(bb3, i3, _, false) and
-    adjacentDefRead(def, bb3, i3, bb2, i2)
+    Impl::adjacentDefRead(def, bb3, i3, bb2, i2)
   )
 }
 
@@ -243,11 +260,11 @@ private predicate adjacentDefReachesUncertainRead(
 /** Same as `lastRefRedef`, but skips uncertain reads. */
 pragma[nomagic]
 private predicate lastRefSkipUncertainReads(Definition def, SsaInput::BasicBlock bb, int i) {
-  lastRef(def, bb, i) and
+  Impl::lastRef(def, bb, i) and
   not SsaInput::variableRead(bb, i, def.getSourceVariable(), false)
   or
   exists(SsaInput::BasicBlock bb0, int i0 |
-    lastRef(def, bb0, i0) and
+    Impl::lastRef(def, bb0, i0) and
     adjacentDefReachesUncertainRead(def, bb, i, bb0, i0)
   )
 }
@@ -304,7 +321,7 @@ private module Cached {
   cached
   VariableReadAccessCfgNode getARead(Definition def) {
     exists(LocalVariable v, Cfg::BasicBlock bb, int i |
-      ssaDefReachesRead(v, def, bb, i) and
+      Impl::ssaDefReachesRead(v, def, bb, i) and
       variableReadActual(bb, i, v) and
       result = bb.getNode(i)
     )
@@ -315,7 +332,7 @@ private module Cached {
     Definition def, CallCfgNode call, LocalVariable v, Cfg::CfgScope scope
   ) {
     exists(Cfg::BasicBlock bb, int i |
-      ssaDefReachesRead(v, def, bb, i) and
+      Impl::ssaDefReachesRead(v, def, bb, i) and
       capturedCallRead(call, bb, i, v) and
       scope.getOuterCfgScope() = bb.getScope()
     )
@@ -360,7 +377,7 @@ private module Cached {
     Definition def, LocalVariable v, Cfg::CfgScope scope
   ) {
     exists(Cfg::BasicBlock bb, int i |
-      ssaDefReachesRead(v, def, bb, i) and
+      Impl::ssaDefReachesRead(v, def, bb, i) and
       capturedExitRead(bb, i, v) and
       scope = bb.getScope().getOuterCfgScope*()
     )
@@ -403,7 +420,7 @@ private module Cached {
 
   cached
   Definition phiHasInputFromBlock(PhiNode phi, Cfg::BasicBlock bb) {
-    phiHasInputFromBlock(phi, result, bb)
+    Impl::phiHasInputFromBlock(phi, result, bb)
   }
 
   /**
@@ -459,19 +476,45 @@ private module Cached {
    */
   cached
   predicate lastRefBeforeRedef(Definition def, Cfg::BasicBlock bb, int i, Definition next) {
-    lastRefRedef(def, bb, i, next) and
+    Impl::lastRefRedef(def, bb, i, next) and
     not SsaInput::variableRead(bb, i, def.getSourceVariable(), false)
     or
     exists(SsaInput::BasicBlock bb0, int i0 |
-      lastRefRedef(def, bb0, i0, next) and
+      Impl::lastRefRedef(def, bb0, i0, next) and
       adjacentDefReachesUncertainRead(def, bb, i, bb0, i0)
     )
   }
 
   cached
   Definition uncertainWriteDefinitionInput(UncertainWriteDefinition def) {
-    uncertainWriteDefinitionInput(def, result)
+    Impl::uncertainWriteDefinitionInput(def, result)
   }
 }
 
 import Cached
+
+/**
+ * An extended static single assignment (SSA) definition.
+ *
+ * This is either a normal SSA definition (`Definition`) or a
+ * phi-read node (`PhiReadNode`).
+ *
+ * Only intended for internal use.
+ */
+class DefinitionExt extends Impl::DefinitionExt {
+  override string toString() { result = this.(Ssa::Definition).toString() }
+
+  /** Gets the location of this definition. */
+  Location getLocation() { result = this.(Ssa::Definition).getLocation() }
+}
+
+/**
+ * A phi-read node.
+ *
+ * Only intended for internal use.
+ */
+class PhiReadNode extends DefinitionExt, Impl::PhiReadNode {
+  override string toString() { result = "SSA phi read(" + this.getSourceVariable() + ")" }
+
+  override Location getLocation() { result = this.getBasicBlock().getLocation() }
+}