Add a generic remembered set class.

src/heap/spaces-inl.h

Index: src/heap/spaces-inl.h
diff --git a/src/heap/spaces-inl.h b/src/heap/spaces-inl.h
index d578055229cf4638bba94097bd4e89ad7492234a..c1b3347ddb52acef9b3b6f63de19a0159f4e8dce 100644
--- a/src/heap/spaces-inl.h
+++ b/src/heap/spaces-inl.h
@@ -296,22 +296,16 @@ bool PagedSpace::Contains(Object* o) {
 }
 
 MemoryChunk* MemoryChunk::FromAnyPointerAddress(Heap* heap, Address addr) {
-  MemoryChunk* maybe = reinterpret_cast<MemoryChunk*>(
-      OffsetFrom(addr) & ~Page::kPageAlignmentMask);
-  if (maybe->owner() != NULL) return maybe;
-  LargeObjectIterator iterator(heap->lo_space());
-  for (HeapObject* o = iterator.Next(); o != NULL; o = iterator.Next()) {
-    // Fixed arrays are the only pointer-containing objects in large object
-    // space.
-    if (o->IsFixedArray()) {
-      MemoryChunk* chunk = MemoryChunk::FromAddress(o->address());
-      if (chunk->Contains(addr)) {
-        return chunk;
-      }
-    }
+  MemoryChunk* chunk = MemoryChunk::FromAddress(addr);
+  uintptr_t offset = addr - chunk->address();
+  if (offset < MemoryChunk::kHeaderSize || chunk->owner() == nullptr) {

[Hannes Payer (out of office), 2016/02/15 16:53:39]

We already check somewhere else for LO page with owner() == heap->lo_space(). I
think we should add a static check function to large pages that tells us if a
chunk* is a large page.

[ulan, 2016/02/16 10:24:52]

I added HasPageHeader predicate to chunk, which is what we want to test for in
this case.

+    chunk = heap->lo_space()->FindPage(addr);
   }
-  UNREACHABLE();
-  return NULL;
+  return chunk;
+}
+
+Page* Page::FromAnyPointerAddress(Heap* heap, Address addr) {
+  return static_cast<Page*>(MemoryChunk::FromAnyPointerAddress(heap, addr));
 }