When shrinking semispace don't relink pages if semispace is not committed

R=mstarzinger@chromium.org

Review URL: http://codereview.chromium.org/9086005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10333 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

diff --git a/src/spaces.cc b/src/spaces.cc
index 84b0f1b..ebd3e65 100644 (file)
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -1256,24 +1256,29 @@ bool SemiSpace::ShrinkTo(int new_capacity) {
   ASSERT((new_capacity & Page::kPageAlignmentMask) == 0);
   ASSERT(new_capacity >= initial_capacity_);
   ASSERT(new_capacity < capacity_);
-  // Semispaces grow backwards from the end of their allocated capacity,
-  // so we find the before and after start addresses relative to the
-  // end of the space.
-  Address space_end = start_ + maximum_capacity_;
-  Address old_start = space_end - capacity_;
-  size_t delta = capacity_ - new_capacity;
-  ASSERT(IsAligned(delta, OS::AllocateAlignment()));
-  if (!heap()->isolate()->memory_allocator()->UncommitBlock(old_start, delta)) {
-    return false;
+  if (is_committed()) {
+    // Semispaces grow backwards from the end of their allocated capacity,
+    // so we find the before and after start addresses relative to the
+    // end of the space.
+    Address space_end = start_ + maximum_capacity_;
+    Address old_start = space_end - capacity_;
+    size_t delta = capacity_ - new_capacity;
+    ASSERT(IsAligned(delta, OS::AllocateAlignment()));
+
+    MemoryAllocator* allocator = heap()->isolate()->memory_allocator();
+    if (!allocator->UncommitBlock(old_start, delta)) {
+      return false;
+    }
+
+    int pages_after = new_capacity / Page::kPageSize;
+    NewSpacePage* new_last_page =
+        NewSpacePage::FromAddress(space_end - pages_after * Page::kPageSize);
+    new_last_page->set_next_page(anchor());
+    anchor()->set_prev_page(new_last_page);
+    ASSERT((current_page_ <= first_page()) && (current_page_ >= new_last_page));
   }
-  capacity_ = new_capacity;
 
-  int pages_after = capacity_ / Page::kPageSize;
-  NewSpacePage* new_last_page =
-      NewSpacePage::FromAddress(space_end - pages_after * Page::kPageSize);
-  new_last_page->set_next_page(anchor());
-  anchor()->set_prev_page(new_last_page);
-  ASSERT((current_page_ <= first_page()) && (current_page_ >= new_last_page));
+  capacity_ = new_capacity;
 
   return true;
 }