[clang] [clang][dataflow] Fix bug in `Value` comparison. (PR #76746)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Yitzhak Mandelbaum (ymand)

<details>
<summary>Changes</summary>

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.


---
Full diff: https://github.com/llvm/llvm-project/pull/76746.diff


2 Files Affected:

- (modified) clang/lib/Analysis/FlowSensitive/Value.cpp (+7-3) 
- (modified) clang/unittests/Analysis/FlowSensitive/ValueTest.cpp (+2-2) 


``````````diff
diff --git a/clang/lib/Analysis/FlowSensitive/Value.cpp b/clang/lib/Analysis/FlowSensitive/Value.cpp
index 349f873f1e6c4d..50475ef5553036 100644
--- a/clang/lib/Analysis/FlowSensitive/Value.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Value.cpp
@@ -27,9 +27,13 @@ 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 values are distinct and have properties, we don't consider them equal,
+  // leaving equality up to the user model.
+  return &Val1 == &Val2 ||
+         (Val1.getKind() == Val2.getKind() &&
+          // (Val1.properties().empty() && Val2.properties().empty()) &&
+          (isa<TopBoolValue>(&Val1) ||
+           areEquivalentIndirectionValues(Val1, Val2)));
 }
 
 raw_ostream &operator<<(raw_ostream &OS, const Value &Val) {
diff --git a/clang/unittests/Analysis/FlowSensitive/ValueTest.cpp b/clang/unittests/Analysis/FlowSensitive/ValueTest.cpp
index c5d18ba74c3ed6..2060b7eb264f74 100644
--- a/clang/unittests/Analysis/FlowSensitive/ValueTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/ValueTest.cpp
@@ -53,8 +53,8 @@ TEST(ValueTest, EquivalentValuesWithDifferentPropsEquivalent) {
   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, DifferentKindsNotEquivalent) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/76746