llvmbot wrote:

<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Artem Dergachev (haoNoQ)

<details>
<summary>Changes</summary>

Simularly to #<!-- -->178943, we need to make sure the old value does not stick 
around. And for correctness purposes it's better to conjure a fresh value than 
to leave it completely unknown.

---
Full diff: https://github.com/llvm/llvm-project/pull/179058.diff


2 Files Affected:

- (modified) clang/lib/Analysis/FlowSensitive/Transfer.cpp (+12-13) 
- (modified) clang/unittests/Analysis/FlowSensitive/TransferTest.cpp (+2-4) 


``````````diff
diff --git a/clang/lib/Analysis/FlowSensitive/Transfer.cpp 
b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
index 51cc1f9bc26ab..a22e6284df5bc 100644
--- a/clang/lib/Analysis/FlowSensitive/Transfer.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
@@ -155,21 +155,18 @@ class TransferVisitor : public 
ConstStmtVisitor<TransferVisitor> {
     const Expr *RHS = S->getRHS();
     assert(RHS != nullptr);
 
-    // Do compound assignments up-front, as there are so many of them and we
-    // don't want to list all of them in the switch statement below.
-    // To avoid generating unnecessary values, we don't create a new value but
-    // instead leave it to the specific analysis to do this if desired.
-    if (S->isCompoundAssignmentOp())
-      propagateStorageLocation(*S->getLHS(), *S, Env);
-
-    switch (S->getOpcode()) {
-    case BO_Assign: {
+    // Do assignments and compound assignments up-front, as there are
+    // so many of them and we don't want to list all of them in
+    // the switch statement below.
+    if (S->isAssignmentOp()) {
       auto *LHSLoc = Env.getStorageLocation(*LHS);
       if (LHSLoc == nullptr)
-        break;
+        return;
 
-      auto *RHSVal = Env.getValue(*RHS);
-      if (RHSVal == nullptr)
+      // Compound assignments involve arithmetic we don't model yet.
+      Value *RHSVal =
+          S->isCompoundAssignmentOp() ? nullptr : Env.getValue(*RHS);
+      if (!RHSVal)
         RHSVal = Env.createValue(LHS->getType());
 
       // Assign a value to the storage location of the left-hand side.
@@ -177,8 +174,10 @@ class TransferVisitor : public 
ConstStmtVisitor<TransferVisitor> {
 
       // Assign a storage location for the whole expression.
       Env.setStorageLocation(*S, *LHSLoc);
-      break;
+      return;
     }
+
+    switch (S->getOpcode()) {
     case BO_LAnd:
     case BO_LOr: {
       BoolValue &LHSVal = getLogicOperatorSubExprValue(*LHS);
diff --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp 
b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
index e528ca2221ad1..c0bcb220c3d76 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -990,8 +990,7 @@ TEST(TransferTest, BinaryOperatorAssignUnknown) {
         ASSERT_TRUE(isa_and_nonnull<IntegerValue>(FooAtCVal));
 
         EXPECT_NE(FooAtAVal, FooAtBVal);
-        // FIXME: Should be NE too.
-        EXPECT_EQ(FooAtBVal, FooAtCVal);
+        EXPECT_NE(FooAtBVal, FooAtCVal);
 
         // Check that the storage location is correctly propagated.
         auto MatchResult = match(binaryOperator().bind("bo"), ASTCtx);
@@ -1006,8 +1005,7 @@ TEST(TransferTest, BinaryOperatorAssignUnknown) {
         const Environment &EnvR = getEnvironmentAtAnnotation(Results, "r");
 
         EXPECT_FALSE(EnvQ.proves(EnvQ.arena().makeLiteral(false)));
-        // FIXME: Should be FALSE too.
-        EXPECT_TRUE(EnvR.proves(EnvR.arena().makeLiteral(false)));
+        EXPECT_FALSE(EnvR.proves(EnvR.arena().makeLiteral(false)));
       });
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/179058
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