[clang][dataflow] Fix bug in Value comparison.

Makes value equivalence require that the values have no properties, except in
the case of equivalence by pointer equality (if the pointers are equal, nothing
else is checked).

Fixes issue #76459.

Author: ymand

clang/lib/Analysis/FlowSensitive/Value.cpp

@@ -27,9 +27,17 @@ static bool areEquivalentIndirectionValues(const Value &Val1,
 }
 
 bool areEquivalentValues(const Value &Val1, const Value &Val2) {
-  return &Val1 == &Val2 || (Val1.getKind() == Val2.getKind() &&
-                            (isa<TopBoolValue>(&Val1) ||
-                             areEquivalentIndirectionValues(Val1, Val2)));
+  if (&Val1 == &Val2)
+    return true;
+  if (Val1.getKind() != Val2.getKind())
+    return false;
+  // If values are distinct and have properties, we don't consider them equal,
+  // leaving equality up to the user model.
+  if (!Val1.properties().empty() || !Val2.properties().empty())
+    return false;
+  if (isa<TopBoolValue>(&Val1))
+    return true;
+  return areEquivalentIndirectionValues(Val1, Val2);
 }
 
 raw_ostream &operator<<(raw_ostream &OS, const Value &Val) {

clang/unittests/Analysis/FlowSensitive/ValueTest.cpp

@@ -45,16 +45,40 @@ TEST(ValueTest, TopsEquivalent) {
   EXPECT_TRUE(areEquivalentValues(V2, V1));
 }
 
-TEST(ValueTest, EquivalentValuesWithDifferentPropsEquivalent) {
+// The framework does not (currently) consider equivalence for values with
+// properties, leaving such to individual analyses.
+TEST(ValueTest, ValuesWithSamePropsDifferent) {
+  Arena A;
+  TopBoolValue Prop(A.makeAtomRef(Atom(0)));
+  TopBoolValue V1(A.makeAtomRef(Atom(2)));
+  TopBoolValue V2(A.makeAtomRef(Atom(3)));
+  V1.setProperty("foo", Prop);
+  V2.setProperty("foo", Prop);
+  EXPECT_FALSE(areEquivalentValues(V1, V2));
+  EXPECT_FALSE(areEquivalentValues(V2, V1));
+}
+
+TEST(ValueTest, ValuesWithDifferentPropsDifferent) {
   Arena A;
   TopBoolValue Prop1(A.makeAtomRef(Atom(0)));
   TopBoolValue Prop2(A.makeAtomRef(Atom(1)));
   TopBoolValue V1(A.makeAtomRef(Atom(2)));
   TopBoolValue V2(A.makeAtomRef(Atom(3)));
   V1.setProperty("foo", Prop1);
   V2.setProperty("bar", Prop2);
-  EXPECT_TRUE(areEquivalentValues(V1, V2));
-  EXPECT_TRUE(areEquivalentValues(V2, V1));
+  EXPECT_FALSE(areEquivalentValues(V1, V2));
+  EXPECT_FALSE(areEquivalentValues(V2, V1));
+}
+
+TEST(ValueTest, ValuesWithDifferentNumberPropsDifferent) {
+  Arena A;
+  TopBoolValue Prop(A.makeAtomRef(Atom(0)));
+  TopBoolValue V1(A.makeAtomRef(Atom(2)));
+  TopBoolValue V2(A.makeAtomRef(Atom(3)));
+  // Only set a property on `V1`.
+  V1.setProperty("foo", Prop);
+  EXPECT_FALSE(areEquivalentValues(V1, V2));
+  EXPECT_FALSE(areEquivalentValues(V2, V1));
 }
 
 TEST(ValueTest, DifferentKindsNotEquivalent) {