[clang][bytecode] Check builtin carryops for dummy pointers (#157490)

Fixes #157422

Author: tbaederr

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -913,6 +913,9 @@ static bool interp__builtin_carryop(InterpState &S, CodePtr OpPC,
   APSInt RHS = popToAPSInt(S.Stk, RHST);
   APSInt LHS = popToAPSInt(S.Stk, LHST);
 
+  if (CarryOutPtr.isDummy())
+    return false;
+
   APSInt CarryOut;
 
   APSInt Result;

clang/test/AST/ByteCode/builtins.cpp

@@ -36,3 +36,10 @@ void test_builtin_os_log(void *buf, int i, const char *data) {
   constexpr int len = __builtin_os_log_format_buffer_size("%d %{public}s %{private}.16P", i, data, data);
   static_assert(len > 0, "Expect len > 0");
 }
+
+void addc_dummy()
+{
+  unsigned int a;
+  if (__builtin_addc (1, 42, 0, &a))
+    __builtin_abort ();
+}