[clang] 5d1e1cf - [clang][bytecode] Check memcmp for block pointers (#165070)

[via cfe-commits]

Author: Timm Baeder
Date: 2025-10-27T10:43:01+01:00
New Revision: 5d1e1cfa086a8ef7e9a74a41f5d626d4d20a3708

URL: https://github.com/llvm/llvm-project/commit/5d1e1cfa086a8ef7e9a74a41f5d626d4d20a3708
DIFF: https://github.com/llvm/llvm-project/commit/5d1e1cfa086a8ef7e9a74a41f5d626d4d20a3708.diff

LOG: [clang][bytecode] Check memcmp for block pointers (#165070)

We can't read from non-block pointers anyway.

Fixes https://github.com/llvm/llvm-project/issues/165061

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index d0b97a18e1815..839e84fd85bea 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -1941,6 +1941,9 @@ static bool interp__builtin_memcmp(InterpState &S, CodePtr OpPC,
     return true;
   }
 
+  if (!PtrA.isBlockPointer() || !PtrB.isBlockPointer())
+    return false;
+
   bool IsWide =
       (ID == Builtin::BIwmemcmp || ID == Builtin::BI__builtin_wmemcmp);
 

diff  --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp
index 0b7d51be8d824..d8572ba722d69 100644
--- a/clang/test/AST/ByteCode/builtin-functions.cpp
+++ b/clang/test/AST/ByteCode/builtin-functions.cpp
@@ -1510,6 +1510,8 @@ namespace Memcmp {
   static_assert(f());
 #endif
 
+  int unknown;
+  void foo(void) { unknown *= __builtin_memcmp(0, 0, 2); }
 }
 
 namespace Memchr {