Add ability to disable inline bump-pointer allocation.

src/spaces.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 1332 matching lines @@
     if (!from_space_.ShrinkTo(rounded_new_capacity)) {
       // If we managed to shrink to-space but couldn't shrink from
       // space, attempt to grow to-space again.
       if (!to_space_.GrowTo(from_space_.Capacity())) {
         // We are in an inconsistent state because we could not
         // commit/uncommit memory from new space.
         V8::FatalProcessOutOfMemory("Failed to shrink new space.");
       }
     }
   }
-  allocation_info_.set_limit(to_space_.page_high());
   ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
 }
 
 
 void NewSpace::UpdateAllocationInfo() {
   MemoryChunk::UpdateHighWaterMark(allocation_info_.top());
   allocation_info_.set_top(to_space_.page_low());
   allocation_info_.set_limit(to_space_.page_high());
-
-  // Lower limit during incremental marking.
-  if (heap()->incremental_marking()->IsMarking() &&
-      inline_allocation_limit_step() != 0) {
-    Address new_limit =
-        allocation_info_.top() + inline_allocation_limit_step();
-    allocation_info_.set_limit(Min(new_limit, allocation_info_.limit()));
-  }
+  UpdateInlineAllocationLimit(0);
   ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
 }
 
 
 void NewSpace::ResetAllocationInfo() {
   to_space_.Reset();
   UpdateAllocationInfo();
   pages_used_ = 0;
   // Clear all mark-bits in the to-space.
   NewSpacePageIterator it(&to_space_);
   while (it.has_next()) {
     Bitmap::Clear(it.next());
   }
 }
 
 
+void NewSpace::UpdateInlineAllocationLimit(int size_in_bytes) {
+  if (heap()->inline_allocation_disabled()) {
+    // Lowest limit when linear allocation was disabled.
+    Address high = to_space_.page_high();
+    Address new_top = allocation_info_.top() + size_in_bytes;
+    allocation_info_.set_limit(Min(new_top, high));
+  } else if (inline_allocation_limit_step() == 0) {
+    // Normal limit is the end of the current page.
+    allocation_info_.set_limit(to_space_.page_high());
+  } else {
+    // Lower limit during incremental marking.
+    Address high = to_space_.page_high();
+    Address new_top = allocation_info_.top() + size_in_bytes;
+    Address new_limit = new_top + inline_allocation_limit_step_;
+    allocation_info_.set_limit(Min(new_limit, high));
+  }
+  ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
+}
+
+
 bool NewSpace::AddFreshPage() {
   Address top = allocation_info_.top();
   if (NewSpacePage::IsAtStart(top)) {
     // The current page is already empty. Don't try to make another.
 
     // We should only get here if someone asks to allocate more
     // than what can be stored in a single page.
     // TODO(gc): Change the limit on new-space allocation to prevent this
     // from happening (all such allocations should go directly to LOSpace).
     return false;
@@ skipping 14 matching lines @@
   heap()->CreateFillerObjectAt(top, remaining_in_page);
   pages_used_++;
   UpdateAllocationInfo();
 
   return true;
 }
 
 
 MaybeObject* NewSpace::SlowAllocateRaw(int size_in_bytes) {
   Address old_top = allocation_info_.top();
-  Address new_top = old_top + size_in_bytes;
   Address high = to_space_.page_high();
   if (allocation_info_.limit() < high) {
-    // Incremental marking has lowered the limit to get a
-    // chance to do a step.
-    Address new_limit = Min(
-        allocation_info_.limit() + inline_allocation_limit_step_,
-        high);
-    allocation_info_.set_limit(new_limit);
+    // Either the limit has been lowered because linear allocation was disabled
+    // or because incremental marking wants to get a chance to do a step. Set
+    // the new limit accordingly.
+    Address new_top = old_top + size_in_bytes;
     int bytes_allocated = static_cast<int>(new_top - top_on_previous_step_);
     heap()->incremental_marking()->Step(
         bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
+    UpdateInlineAllocationLimit(size_in_bytes);
     top_on_previous_step_ = new_top;
     return AllocateRaw(size_in_bytes);
   } else if (AddFreshPage()) {
     // Switched to new page. Try allocating again.
     int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
     heap()->incremental_marking()->Step(
         bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
     top_on_previous_step_ = to_space_.page_low();
     return AllocateRaw(size_in_bytes);
   } else {
@@ skipping 925 matching lines @@
   // skipped when scanning the heap.  This also puts it back in the free list
   // if it is big enough.
   owner_->Free(owner_->top(), old_linear_size);
 
   owner_->heap()->incremental_marking()->OldSpaceStep(
       size_in_bytes - old_linear_size);
 
   int new_node_size = 0;
   FreeListNode* new_node = FindNodeFor(size_in_bytes, &new_node_size);
   if (new_node == NULL) {
-    owner_->SetTop(NULL, NULL);
+    owner_->SetTopAndLimit(NULL, NULL);
     return NULL;
   }
 
   int bytes_left = new_node_size - size_in_bytes;
   ASSERT(bytes_left >= 0);
 
 #ifdef DEBUG
   for (int i = 0; i < size_in_bytes / kPointerSize; i++) {
     reinterpret_cast<Object**>(new_node->address())[i] =
         Smi::FromInt(kCodeZapValue);
   }
 #endif
 
   // The old-space-step might have finished sweeping and restarted marking.
   // Verify that it did not turn the page of the new node into an evacuation
   // candidate.
   ASSERT(!MarkCompactCollector::IsOnEvacuationCandidate(new_node));
 
   const int kThreshold = IncrementalMarking::kAllocatedThreshold;
 
   // Memory in the linear allocation area is counted as allocated.  We may free
   // a little of this again immediately - see below.
   owner_->Allocate(new_node_size);
 
-  if (bytes_left > kThreshold &&
-      owner_->heap()->incremental_marking()->IsMarkingIncomplete() &&
-      FLAG_incremental_marking_steps) {
+  if (owner_->heap()->inline_allocation_disabled()) {
+    // Keep the linear allocation area empty if requested to do so, just
+    // return area back to the free list instead.
+    owner_->Free(new_node->address() + size_in_bytes, bytes_left);
+    ASSERT(owner_->top() == NULL && owner_->limit() == NULL);
+  } else if (bytes_left > kThreshold &&
+             owner_->heap()->incremental_marking()->IsMarkingIncomplete() &&
+             FLAG_incremental_marking_steps) {
     int linear_size = owner_->RoundSizeDownToObjectAlignment(kThreshold);
     // We don't want to give too large linear areas to the allocator while
     // incremental marking is going on, because we won't check again whether
     // we want to do another increment until the linear area is used up.
     owner_->Free(new_node->address() + size_in_bytes + linear_size,
                  new_node_size - size_in_bytes - linear_size);
-    owner_->SetTop(new_node->address() + size_in_bytes,
-                   new_node->address() + size_in_bytes + linear_size);
+    owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
+                           new_node->address() + size_in_bytes + linear_size);
   } else if (bytes_left > 0) {
     // Normally we give the rest of the node to the allocator as its new
     // linear allocation area.
-    owner_->SetTop(new_node->address() + size_in_bytes,
-                   new_node->address() + new_node_size);
+    owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
+                           new_node->address() + new_node_size);
   } else {
     // TODO(gc) Try not freeing linear allocation region when bytes_left
     // are zero.
-    owner_->SetTop(NULL, NULL);
+    owner_->SetTopAndLimit(NULL, NULL);
   }
 
   return new_node;
 }
 
 
 intptr_t FreeList::EvictFreeListItems(Page* p) {
   intptr_t sum = huge_list_.EvictFreeListItemsInList(p);
   p->set_available_in_huge_free_list(0);
 
@@ skipping 68 matching lines @@
 }
 #endif
 
 
 // -----------------------------------------------------------------------------
 // OldSpace implementation
 
 void PagedSpace::PrepareForMarkCompact() {
   // We don't have a linear allocation area while sweeping.  It will be restored
   // on the first allocation after the sweep.
-  // Mark the old linear allocation area with a free space map so it can be
-  // skipped when scanning the heap.
-  int old_linear_size = static_cast<int>(limit() - top());
-  Free(top(), old_linear_size);
-  SetTop(NULL, NULL);
+  EmptyAllocationInfo();
 
   // Stop lazy sweeping and clear marking bits for unswept pages.
   if (first_unswept_page_ != NULL) {
     Page* p = first_unswept_page_;
     do {
       // Do not use ShouldBeSweptLazily predicate here.
       // New evacuation candidates were selected but they still have
       // to be swept before collection starts.
       if (!p->WasSwept()) {
         Bitmap::Clear(p);
@@ skipping 647 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal