[clang] ec9eefc - [clang][bytecode] Fix a crash in overflow builtins (#147189)

[via cfe-commits]

Author: Timm Baeder
Date: 2025-07-06T16:42:06+02:00
New Revision: ec9eefcef560e4ea5b5d8ee6ed9cc6ef8c1f274c

URL: https://github.com/llvm/llvm-project/commit/ec9eefcef560e4ea5b5d8ee6ed9cc6ef8c1f274c
DIFF: https://github.com/llvm/llvm-project/commit/ec9eefcef560e4ea5b5d8ee6ed9cc6ef8c1f274c.diff

LOG: [clang][bytecode] Fix a crash in overflow builtins (#147189)

Only initialize pointers that can be initialized.

Added: 
    

Modified: 
    clang/lib/AST/ByteCode/InterpBuiltin.cpp
    clang/test/AST/ByteCode/builtin-functions.cpp

Removed: 
    


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diff  --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index 1d6f444fb352c..db18ad2aa9bcb 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