Implement shrinking of paged spaces during sweeping.

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 126 matching lines @@
       min_in_mutator_(kMaxInt),
       alive_after_last_gc_(0),
       last_gc_end_timestamp_(0.0),
       store_buffer_(this),
       marking_(this),
       incremental_marking_(this),
       number_idle_notifications_(0),
       last_idle_notification_gc_count_(0),
       last_idle_notification_gc_count_init_(false),
       configured_(false),
-      last_empty_page_was_given_back_to_the_os_(false),
       chunks_queued_for_free_(NULL) {
   // Allow build-time customization of the max semispace size. Building
   // V8 with snapshots and a non-default max semispace size is much
   // easier if you can define it as part of the build environment.
 #if defined(V8_MAX_SEMISPACE_SIZE)
   max_semispace_size_ = reserved_semispace_size_ = V8_MAX_SEMISPACE_SIZE;
 #endif
 
   intptr_t max_virtual = OS::MaxVirtualMemory();
 
@@ skipping 648 matching lines @@
   tracer->set_full_gc_count(ms_count_);
 
   MarkCompactPrologue();
 
   mark_compact_collector_.CollectGarbage();
 
   LOG(isolate_, ResourceEvent("markcompact", "end"));
 
   gc_state_ = NOT_IN_GC;
 
-  Shrink();
-
   isolate_->counters()->objs_since_last_full()->Set(0);
 
   contexts_disposed_ = 0;
 }
 
 
 void Heap::MarkCompactPrologue() {
   // At any old GC clear the keyed lookup cache to enable collection of unused
   // maps.
   isolate_->keyed_lookup_cache()->Clear();
@@ skipping 4792 matching lines @@
   delete debug_utils_;
   debug_utils_ = NULL;
 #endif
 }
 
 
 void Heap::Shrink() {
   // Try to shrink all paged spaces.
   PagedSpaces spaces;
   for (PagedSpace* space = spaces.next(); space != NULL; space = spaces.next())
-    space->Shrink();
+    space->ReleaseAllUnusedPages();
 }
 
 
 void Heap::AddGCPrologueCallback(GCPrologueCallback callback, GCType gc_type) {
   ASSERT(callback != NULL);
   GCPrologueCallbackPair pair(callback, gc_type);
   ASSERT(!gc_prologue_callbacks_.Contains(pair));
   return gc_prologue_callbacks_.Add(pair);
 }
 
@@ skipping 822 matching lines @@
         // Size of a large chunk is always a multiple of
         // OS::AllocationAlignment() so there is always
         // enough space for a fake MemoryChunk header.
         inner->set_owner(lo_space());
         inner->SetFlag(MemoryChunk::ABOUT_TO_BE_FREED);
         inner = MemoryChunk::FromAddress(
             inner->address() + Page::kPageSize);
       }
     }
   }
+  isolate_->heap()->store_buffer()->Compact();
   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