--verify-predictable mode added for ensuring that GC behaves deterministically.

src/heap-inl.h

Index: src/heap-inl.h
diff --git a/src/heap-inl.h b/src/heap-inl.h
index 64125bc302c7d275133974a54f0566eb0126c916..6cf6da0993e6a84ccbc8b9b57ae23fb2ba089c2e 100644
--- a/src/heap-inl.h
+++ b/src/heap-inl.h
@@ -235,6 +235,43 @@ AllocationResult Heap::AllocateRaw(int size_in_bytes,
 }
 
 
+void Heap::OnAllocationEvent(HeapObject* object, int size_in_bytes) {
+  ++allocations_count_;
+
+  Address object_address = object->address();
+  MemoryChunk* memory_chunk = MemoryChunk::FromAddress(object_address);
+  uint32_t offset =
+      static_cast<uint32_t>(object_address - memory_chunk->address());
+
+  UpdateAllocationsHash(offset);
+  UpdateAllocationsHash(size_in_bytes);
+  UpdateAllocationsHash(memory_chunk->owner()->identity());
+
+  if (FLAG_dump_allocations_digest_at_alloc > 0) {
+    if (--dump_allocations_hash_countdown_ == 0) {
+      dump_allocations_hash_countdown_ = FLAG_dump_allocations_digest_at_alloc;
+      PrintAlloctionsHash();
+    }
+  }
+}
+
+
+void Heap::UpdateAllocationsHash(uint32_t value) {
+  uint16_t c1 = static_cast<uint16_t>(value);
+  uint16_t c2 = static_cast<uint16_t>(value >> 16);
+  raw_allocations_hash_ =
+      StringHasher::AddCharacterCore(raw_allocations_hash_, c1);
+  raw_allocations_hash_ =
+      StringHasher::AddCharacterCore(raw_allocations_hash_, c2);
+}
+
+
+void Heap::PrintAlloctionsHash() {
+  uint32_t hash = StringHasher::GetHashCore(raw_allocations_hash_);
+  PrintF("\n### Allocations = %u, hash = 0x%08x\n", allocations_count_, hash);
+}
+
+
 void Heap::FinalizeExternalString(String* string) {
   ASSERT(string->IsExternalString());
   v8::String::ExternalStringResourceBase** resource_addr =