Chang Heap::FreeQueuedChunks to prepare queued large chunks for StoreBuffer::Filter.

src/heap.cc

 // 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 5957 matching lines @@
 }
 
 
 void Heap::FreeQueuedChunks() {
   if (chunks_queued_for_free_ == NULL) return;
   MemoryChunk* next;
   MemoryChunk* chunk;
   for (chunk = chunks_queued_for_free_; chunk != NULL; chunk = next) {
     next = chunk->next_chunk();
     chunk->SetFlag(MemoryChunk::ABOUT_TO_BE_FREED);
+
+    if (chunk->owner()->identity() == LO_SPACE) {
+      // StoreBuffer::Filter relies on MemoryChunk::FromAnyPointerAddress.
+      // If FromAnyPointerAddress encounters a slot that belongs to a large
+      // chunk queued for deletion it will fail to find the chunk because
+      // it try to perform a search in the list of pages owned by of the large
+      // object space and queued chunks were detached from that list.
+      // To work around this we split large chunk into normal kPageSize aligned
+      // pieces and initialize owner field and flags of every piece.
+      // If FromAnyPointerAddress encounteres a slot that belongs to one of
+      // these smaller pieces it will treat it as a slot on a normal Page.
+      MemoryChunk* inner = MemoryChunk::FromAddress(
+          chunk->address() + Page::kPageSize);
+      MemoryChunk* inner_last = MemoryChunk::FromAddress(
+          chunk->address() + chunk->size() - 1);
+      while (inner <= inner_last) {

[Lasse Reichstein, 2011/07/13 07:07:13]

It's not obvious why this can't crash, if the end of the large object chunk is
just a few bytes into the inner_last chunk.
Make a comment saying why it won't crash.

+        inner->set_owner(lo_space());
+        inner->SetFlag(MemoryChunk::ABOUT_TO_BE_FREED);
+        inner = MemoryChunk::FromAddress(
+            inner->address() + Page::kPageSize);
+      }
+    }
   }
   isolate_->heap()->store_buffer()->Filter(MemoryChunk::ABOUT_TO_BE_FREED);
   for (chunk = chunks_queued_for_free_; chunk != NULL; chunk = next) {
     next = chunk->next_chunk();
     isolate_->memory_allocator()->Free(chunk);
   }
   chunks_queued_for_free_ = NULL;
 }
 
 } }  // namespace v8::internal