[clang][bytecode] Fix a crash in overflow builtins

[tbaederr]

Only initialize pointers that can be initialized.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

Changes

Only initialize pointers that can be initialized.

---

Full diff: https://github.com/llvm/llvm-project/pull/147189.diff

2 Files Affected:

• (modified) clang/lib/AST/ByteCode/InterpBuiltin.cpp (+3-1)
• (modified) clang/test/AST/ByteCode/builtin-functions.cpp (+8)

diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index a73fc6c7bf2b3..907b6c79a377f 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -861,7 +861,9 @@ static bool interp__builtin_overflowop(InterpState &S, CodePtr OpPC,
 
   // Write Result to ResultPtr and put Overflow on the stack.
   assignInteger(S, ResultPtr, ResultT, Result);
-  ResultPtr.initialize();
+  if (ResultPtr.canBeInitialized())
+    ResultPtr.initialize();
+
   assert(Call->getDirectCallee()->getReturnType()->isBooleanType());
   S.Stk.push<Boolean>(Overflow);
   return true;
diff --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp
index 3b95a8ea48596..1bb6d22db9823 100644
--- a/clang/test/AST/ByteCode/builtin-functions.cpp
+++ b/clang/test/AST/ByteCode/builtin-functions.cpp
@@ -1753,4 +1753,12 @@ namespace I128Mul {
 }
 #endif
 
+namespace InitParam {
+  constexpr int foo(int a) {
+      __builtin_mul_overflow(20, 10, &a);
+      return a;
+  }
+  static_assert(foo(10) == 200);
+}
+
 #endif