Reland of "[heap] Switch to 500k pages"

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index c035342bfa85058dd9be34024e17cbc6d5722be3..6e75abd39d014e0b897cd23839182f04890eaba3 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -689,7 +689,7 @@ class Page : public MemoryChunk {
   // account.
   // TODO(hpayer): This limit should be way smaller but we currently have
   // short living objects >256K.
-  static const int kMaxRegularHeapObjectSize = 600 * KB;
+  static const int kMaxRegularHeapObjectSize = 400 * KB;
 
   static inline Page* ConvertNewToOld(Page* old_page, PagedSpace* new_owner);
 
@@ -1270,6 +1270,8 @@ class MemoryAllocator {
                              intptr_t commit_area_size,
                              Executability executable, Space* space);
 
+  void ShrinkChunk(MemoryChunk* chunk, size_t bytes_to_shrink);
+
   Address ReserveAlignedMemory(size_t requested, size_t alignment,
                                base::VirtualMemory* controller);
   Address AllocateAlignedMemory(size_t reserve_size, size_t commit_size,
@@ -1575,6 +1577,7 @@ class AllocationStats BASE_EMBEDDED {
     capacity_ -= size_in_bytes;
     size_ -= size_in_bytes;
     CHECK_GE(size_, 0);
+    CHECK_GE(capacity_, 0);
   }
 
   // Allocate from available bytes (available -> size).
@@ -2140,6 +2143,10 @@ class PagedSpace : public Space {
   iterator begin() { return iterator(anchor_.next_page()); }
   iterator end() { return iterator(&anchor_); }
 
+  // Shrink all pages of the space to be exactly the size needed using the
+  // high water mark.

[Hannes Payer (out of office), 2016/08/10 21:17:35]

We only do that for immortal immovable pages.

[Michael Lippautz, 2016/08/11 09:48:10]

Done.

+  void ShrinkImmortalImmovablePages();
+
  protected:
   // PagedSpaces that should be included in snapshots have different, i.e.,
   // smaller, initial pages.