Merge pull request #81040 from etcwilde/ewilde/6.2-runtime-fix-clobbered-memories

[🍒][SwiftCore]: Don't always clobber memory

Author: etcwilde

Runtimes/Core/CMakeLists.txt

@@ -159,7 +159,7 @@ add_compile_definitions(
   $<$<BOOL:${SwiftCore_HAS_DARWIN_LIBMALLOC}>:-DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC> # Anything that includes include/swift/Runtime/Config.h
   $<$<COMPILE_LANGUAGE:C,CXX>:-DSWIFT_THREADING_${SwiftCore_THREADING_PACKAGE}>
   $<$<COMPILE_LANGUAGE:C,CXX>:-DSWIFT_RUNTIME_ENABLE_LEAK_CHECKER=$<BOOL:${SwiftCore_ENABLE_RUNTIME_LEAK_CHECKER}>>
-  $<$<COMPILE_LANGUAGE:C,CXX>:-DSWIFT_RUNTIME_CLOBBER_FREED_OBJECTS=$<BOOL:${SwiftCore_ENABLE_CLOBBER_FREED_OBJECTS}>>)
+  $<$<BOOL:${SwiftCore_ENABLE_CLOBBER_FREED_OBJECTS}>:-DSWIFT_RUNTIME_CLOBBER_FREED_OBJECTS>)
 
 add_compile_options(
   $<$<COMPILE_LANGUAGE:CXX>:-fno-rtti>

stdlib/public/runtime/HeapObject.cpp

@@ -875,7 +875,7 @@ void swift::swift_deallocPartialClassInstance(HeapObject *object,
   swift_deallocClassInstance(object, allocatedSize, allocatedAlignMask);
 }
 
-#if !defined(__APPLE__) && defined(SWIFT_RUNTIME_CLOBBER_FREED_OBJECTS)
+#if !defined(__APPLE__) && SWIFT_RUNTIME_CLOBBER_FREED_OBJECTS
 static inline void memset_pattern8(void *b, const void *pattern8, size_t len) {
   char *ptr = static_cast<char *>(b);
   while (len >= 8) {
@@ -898,9 +898,9 @@ static inline void swift_deallocObjectImpl(HeapObject *object,
   }
   assert(object->refCounts.isDeiniting());
   SWIFT_RT_TRACK_INVOCATION(object, swift_deallocObject);
-#ifdef SWIFT_RUNTIME_CLOBBER_FREED_OBJECTS
+#if SWIFT_RUNTIME_CLOBBER_FREED_OBJECTS
   memset_pattern8((uint8_t *)object + sizeof(HeapObject),
-                  "\xAB\xAD\x1D\xEA\xF4\xEE\xD0\bB9",
+                  "\xF0\xEF\xBE\xAD\xDE\xED\xFE\x0F", // 0x0ffeeddeadbeeff0
                   allocatedSize - sizeof(HeapObject));
 #endif