Fix new space shrinking to compute correct capacity.

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index 9aacf9603e42ada46f2c1953d1453695dfdeb3f8..a1bc3b9d80886afdb878685d28d0aec62391d4dd 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -924,10 +924,14 @@ void NewSpace::Flip() {
 
 
 void NewSpace::Grow() {
+  // Double the semispace size but only up to maximum capacity.
   ASSERT(Capacity() < MaximumCapacity());
-  if (to_space_.Grow()) {
+  ASSERT(static_cast<size_t>(Page::kPageSize) > OS::AllocateAlignment());

[Vyacheslav Egorov (Chromium), 2011/09/20 14:26:40]

I don't think we really need this assert here. There are checks in routines that
deal with virtual memory.

[Michael Starzinger, 2011/09/20 15:29:03]

Done.

+  int new_capacity = Min(MaximumCapacity(), 2 * static_cast<int>(Capacity()));

[Vyacheslav Egorov (Chromium), 2011/09/20 14:26:40]

We should ensure that MaxCapacity & Capacity is _always_ kPageSize aligned. 

That would clean the code (e.g. Rounding would not be needed here).

And I really would expect that capacities are always aligned as we are managing
new space with kPageSize granularity.

[Michael Starzinger, 2011/09/20 15:29:03]

Done. I just checked that it is only modified in a way that keeps it aligned to
kPageSize. The assertion which checks that is exactly the one being triggered
(in SemiSpace::ShrinkTo and SemiSpace::GrowTo).

+  int rounded_new_capacity = RoundUp(new_capacity, Page::kPageSize);
+  if (to_space_.GrowTo(rounded_new_capacity)) {
     // Only grow from space if we managed to grow to-space.
-    if (!from_space_.Grow()) {
+    if (!from_space_.GrowTo(rounded_new_capacity)) {
       // If we managed to grow to-space but couldn't grow from-space,
       // attempt to shrink to-space.
       if (!to_space_.ShrinkTo(from_space_.Capacity())) {
@@ -942,9 +946,9 @@ void NewSpace::Grow() {
 
 
 void NewSpace::Shrink() {
+  ASSERT(static_cast<size_t>(Page::kPageSize) > OS::AllocateAlignment());

[Vyacheslav Egorov (Chromium), 2011/09/20 14:26:40]

I don't think we really need this assert here. There are checks in routines that
deal with virtual memory. 

[Michael Starzinger, 2011/09/20 15:29:03]

Done.

   int new_capacity = Max(InitialCapacity(), 2 * SizeAsInt());
-  int rounded_new_capacity =
-      RoundUp(new_capacity, static_cast<int>(OS::AllocateAlignment()));
+  int rounded_new_capacity = RoundUp(new_capacity, Page::kPageSize);
   if (rounded_new_capacity < Capacity() &&
       to_space_.ShrinkTo(rounded_new_capacity))  {
     // Only shrink from-space if we managed to shrink to-space.
@@ -1144,15 +1148,6 @@ bool SemiSpace::Uncommit() {
 }
 
 
-bool SemiSpace::Grow() {
-  // Double the semispace size but only up to maximum capacity.
-  ASSERT(static_cast<size_t>(Page::kPageSize) > OS::AllocateAlignment());
-  int new_capacity = Min(maximum_capacity_,
-      RoundUp(capacity_ * 2, static_cast<int>(Page::kPageSize)));
-  return GrowTo(new_capacity);
-}
-
-
 bool SemiSpace::GrowTo(int new_capacity) {
   ASSERT((new_capacity & Page::kPageAlignmentMask) == 0);
   ASSERT(new_capacity <= maximum_capacity_);