Ensure that promotion queue does not overlap with objects relocated to ToSpace.

src/heap-inl.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 22 matching lines @@
 #include "list-inl.h"
 #include "objects.h"
 #include "v8-counters.h"
 #include "store-buffer.h"
 #include "store-buffer-inl.h"
 
 namespace v8 {
 namespace internal {
 
 void PromotionQueue::insert(HeapObject* target, int size) {
+  if (emergency_stack_ != NULL) {
+    emergency_stack_->Add(Entry(target, size));
+    return;
+  }
+
   if (NewSpacePage::IsAtStart(reinterpret_cast<Address>(rear_))) {
     NewSpacePage* rear_page =
         NewSpacePage::FromAddress(reinterpret_cast<Address>(rear_));
     ASSERT(!rear_page->prev_page()->is_anchor());
     rear_ = reinterpret_cast<intptr_t*>(rear_page->prev_page()->body_limit());
+    ActivateGuardIfOnTheSamePage();
   }
+
+  if (guard_) {
+    ASSERT(GetHeadPage() ==
+           Page::FromAllocationTop(reinterpret_cast<Address>(limit_)));
+
+    if ((rear_ - 2) < limit_) {
+      RelocateQueueHead();
+      emergency_stack_->Add(Entry(target, size));
+      return;
+    }
+  }
+
   *(--rear_) = reinterpret_cast<intptr_t>(target);
   *(--rear_) = size;
   // Assert no overflow into live objects.
 #ifdef DEBUG
   SemiSpace::AssertValidRange(HEAP->new_space()->top(),
                               reinterpret_cast<Address>(rear_));
 #endif
 }
 
 
+void PromotionQueue::ActivateGuardIfOnTheSamePage() {
+  guard_ = guard_ ||
+      heap_->new_space()->active_space()->current_page()->address() ==
+      GetHeadPage()->address();
+}
+
+
 int Heap::MaxObjectSizeInPagedSpace() {
   return Page::kMaxHeapObjectSize;
 }
 
 
 MaybeObject* Heap::AllocateStringFromUtf8(Vector<const char> str,
                                           PretenureFlag pretenure) {
   // Check for ASCII first since this is the common case.
   if (String::IsAscii(str.start(), str.length())) {
     // If the string is ASCII, we do not need to convert the characters
@@ skipping 607 matching lines @@
 
 
 Heap* _inline_get_heap_() {
   return HEAP;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_INL_H_