[clang]Avoid to check created local variable multiple time when evaluating

[HerrCai0907]

When evaluating variable initialized from compound literal multiple times, it will be converted to evaluting the compound literal itself multiple times, which causes clang crash in assertions.
Further evaluating is not rely on this assertion.

Fixes: #69065

[llvmbot]

@llvm/pr-subscribers-clang

Author: Congcong Cai (HerrCai0907)

Changes

When evaluating variable initialized from compound literal multiple times, it will be converted to evaluting the compound literal itself multiple times, which causes clang crash in assertions.
Further evaluating is not rely on this assertion.

Fixes: #69065

---

Full diff: https://github.com/llvm/llvm-project/pull/69106.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+3)
• (modified) clang/lib/AST/ExprConstant.cpp (-1)
• (added) clang/test/AST/issue69065.c (+17)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index be7c8bf247f7af5..5578663a90f104a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -393,6 +393,9 @@ Bug Fixes in This Version
   operator in C. No longer issuing a confusing diagnostic along the lines of
   "incompatible operand types ('foo' and 'foo')" with extensions such as matrix
   types. Fixes (`#69008 <https://github.com/llvm/llvm-project/issues/69008>`_)
+- Fix a crash when evaluating comparasion between the field from the same variable
+  which initialized from compound literals in C. Fixes
+  (`#69065 <https://github.com/llvm/llvm-project/issues/69065>`_)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index e5539dedec02a4b..9948b516745a30b 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -1912,7 +1912,6 @@ APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
   assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
   unsigned Version = Base.getVersion();
   APValue &Result = Temporaries[MapKeyTy(Key, Version)];
-  assert(Result.isAbsent() && "local created multiple times");
 
   // If we're creating a local immediately in the operand of a speculative
   // evaluation, don't register a cleanup to be run outside the speculative
diff --git a/clang/test/AST/issue69065.c b/clang/test/AST/issue69065.c
new file mode 100644
index 000000000000000..11428932019418d
--- /dev/null
+++ b/clang/test/AST/issue69065.c
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -fsyntax-only %s -verify
+// expected-no-diagnostics
+
+struct A {
+  int i;
+};
+struct B {
+  struct A *a;
+};
+const struct B c = {&(struct A){1}};
+
+int main(void) {
+  if ((c.a->i != 1) || (c.a->i)) {
+    return 1;
+  }
+  return 0;
+}

[mzyKi]

I test example in branch llvmorg-16.0.6,ExprConstant.cpp also has this assertion but it will not result in crash.So I think you should not remove this assertion and try to find the reason !Result.isAbsent() Maybe its valueKind changed somewhere(just my guess).

[HerrCai0907]

I test example in branch llvmorg-16.0.6,ExprConstant.cpp also has this assertion but it will not result in crash.

Have you find the exact commit to break this case? @mzyKi

[mzyKi]

I test example in branch llvmorg-16.0.6,ExprConstant.cpp also has this assertion but it will not result in crash.

Have you find the exact commit to break this case? @mzyKi

@HerrCai0907 after this commit 610ec95 , clang will crash in test code.

[HerrCai0907]

I think it would be better to disable assert instead of revert this change.

[erichkeane]

I test example in branch llvmorg-16.0.6,ExprConstant.cpp also has this assertion but it will not result in crash.So I think you should not remove this assertion and try to find the reason !Result.isAbsent() Maybe its valueKind changed somewhere(just my guess).

I agree here, we shouldn't be double-creating variables like this, removing the assert doesn't seem right to me.