Introduce --zap-cpp-pointers (off by default)

src/factory.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/factory.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast.h"
 #include "src/base/bits.h"
@@ skipping 16 matching lines @@
 //
 // Warning: Do not use the identifiers __object__, __maybe_object__,
 // __allocation__ or __scope__ in a call to this macro.
 
 #define RETURN_OBJECT_UNLESS_RETRY(ISOLATE, TYPE)         \
   if (__allocation__.To(&__object__)) {                   \
     DCHECK(__object__ != (ISOLATE)->heap()->exception()); \
     return Handle<TYPE>(TYPE::cast(__object__), ISOLATE); \
   }
 
+// TODO(jkummerow): Handlify more of heap.cc to maintain the rule that
+// "there are no raw pointers anywhere on the stack when an allocation
+// is happening", and then move the ZapHeapPointersInCppFrames() call
+// into Heap::AllocateRaw.
+#if DEBUG
+#define MAYBE_ZAP_STACK(isolate)         \
+  if (FLAG_zap_cpp_pointers) {           \
+    ZapHeapPointersInCppFrames(isolate); \
+  }
+#else
+#define MAYBE_ZAP_STACK(isolate)
+#endif
+
 #define CALL_HEAP_FUNCTION(ISOLATE, FUNCTION_CALL, TYPE)                      \
   do {                                                                        \
+    MAYBE_ZAP_STACK(ISOLATE);                                                 \
     AllocationResult __allocation__ = FUNCTION_CALL;                          \
     Object* __object__ = NULL;                                                \
     RETURN_OBJECT_UNLESS_RETRY(ISOLATE, TYPE)                                 \
     /* Two GCs before panicking.  In newspace will almost always succeed. */  \
     for (int __i__ = 0; __i__ < 2; __i__++) {                                 \
       (ISOLATE)->heap()->CollectGarbage(                                      \
           __allocation__.RetrySpace(),                                        \
           GarbageCollectionReason::kAllocationFailure);                       \
       __allocation__ = FUNCTION_CALL;                                         \
       RETURN_OBJECT_UNLESS_RETRY(ISOLATE, TYPE)                               \
@@ skipping 2897 matching lines @@
     Handle<AccessorInfo> prototype =
         Accessors::FunctionPrototypeInfo(isolate(), rw_attribs);
     Descriptor d = Descriptor::AccessorConstant(
         Handle<Name>(Name::cast(prototype->name())), prototype, rw_attribs);
     map->AppendDescriptor(&d);
   }
 }
 
 }  // namespace internal
 }  // namespace v8