[heap] Optimize NewSpace::AllocatedSinceLastGC

src/heap/spaces-inl.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_SPACES_INL_H_
 #define V8_HEAP_SPACES_INL_H_
 
 #include "src/heap/incremental-marking.h"
 #include "src/heap/spaces.h"
 #include "src/isolate.h"
@@ skipping 225 matching lines @@
   return to_space_.ContainsSlow(a);
 }
 
 bool NewSpace::FromSpaceContainsSlow(Address a) {
   return from_space_.ContainsSlow(a);
 }
 
 bool NewSpace::ToSpaceContains(Object* o) { return to_space_.Contains(o); }
 bool NewSpace::FromSpaceContains(Object* o) { return from_space_.Contains(o); }
 
+size_t NewSpace::AllocatedSinceLastGC() {
+  const intptr_t age_mark_offset =
+      NewSpacePage::OffsetInPage(to_space_.age_mark());
+  const intptr_t top_offset =
+      NewSpacePage::OffsetInPage(allocation_info_.top());
+  const intptr_t age_mark_delta =
+      age_mark_offset >= NewSpacePage::kObjectStartOffset
+          ? age_mark_offset - NewSpacePage::kObjectStartOffset
+          : NewSpacePage::kAllocatableMemory;
+  const intptr_t top_delta = top_offset >= NewSpacePage::kObjectStartOffset
+                                 ? top_offset - NewSpacePage::kObjectStartOffset
+                                 : NewSpacePage::kAllocatableMemory;
+  DCHECK((allocated_since_last_gc_ > 0) ||
+         (NewSpacePage::FromLimit(allocation_info_.top()) ==
+          NewSpacePage::FromLimit(to_space_.age_mark())));
+  return static_cast<size_t>(allocated_since_last_gc_ + top_delta -
+                             age_mark_delta);
+}
+
 // --------------------------------------------------------------------------
 // AllocationResult
 
 AllocationSpace AllocationResult::RetrySpace() {
   DCHECK(IsRetry());
   return static_cast<AllocationSpace>(Smi::cast(object_)->value());
 }
 
 NewSpacePage* NewSpacePage::Initialize(Heap* heap, MemoryChunk* chunk,
                                        Executability executable,
@@ skipping 454 matching lines @@
     other->allocation_info_.Reset(nullptr, nullptr);
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_INL_H_