[heap] Do not invoke GC to make heap iterable.

src/heap/heap.cc

 // Copyright 2012 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.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 875 matching lines @@
   // garbage.
   // Note: as weak callbacks can execute arbitrary code, we cannot
   // hope that eventually there will be no weak callbacks invocations.
   // Therefore stop recollecting after several attempts.
   if (isolate()->concurrent_recompilation_enabled()) {
     // The optimizing compiler may be unnecessarily holding on to memory.
     DisallowHeapAllocation no_recursive_gc;
     isolate()->optimizing_compile_dispatcher()->Flush();
   }
   isolate()->ClearSerializerData();
-  set_current_gc_flags(kMakeHeapIterableMask | kReduceMemoryFootprintMask);
+  set_current_gc_flags(kAbortIncrementalMarkingMask |
+                       kReduceMemoryFootprintMask);
   isolate_->compilation_cache()->Clear();
   const int kMaxNumberOfAttempts = 7;
   const int kMinNumberOfAttempts = 2;
   for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) {
     if (!CollectGarbage(MARK_COMPACTOR, gc_reason, NULL,
                         v8::kGCCallbackFlagCollectAllAvailableGarbage) &&
         attempt + 1 >= kMinNumberOfAttempts) {
       break;
     }
   }
@@ skipping 3118 matching lines @@
   Struct* result = nullptr;
   {
     AllocationResult allocation = Allocate(map, OLD_SPACE);
     if (!allocation.To(&result)) return allocation;
   }
   result->InitializeBody(size);
   return result;
 }
 
 
-bool Heap::IsHeapIterable() {
-  // TODO(hpayer): This function is not correct. Allocation folding in old
-  // space breaks the iterability.
-  return new_space_top_after_last_gc_ == new_space()->top();
-}
-
-
 void Heap::MakeHeapIterable() {
-  DCHECK(AllowHeapAllocation::IsAllowed());
-  if (!IsHeapIterable()) {
-    CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
-  }
   if (mark_compact_collector()->sweeping_in_progress()) {
     mark_compact_collector()->EnsureSweepingCompleted();
   }
-  DCHECK(IsHeapIterable());
 }
 
 
 static double ComputeMutatorUtilization(double mutator_speed, double gc_speed) {
   const double kMinMutatorUtilization = 0.0;
   const double kConservativeGcSpeedInBytesPerMillisecond = 200000;
   if (mutator_speed == 0) return kMinMutatorUtilization;
   if (gc_speed == 0) gc_speed = kConservativeGcSpeedInBytesPerMillisecond;
   // Derivation:
   // mutator_utilization = mutator_time / (mutator_time + gc_time)
@@ skipping 524 matching lines @@
       return false;
   }
 }
 
 
 #ifdef VERIFY_HEAP
 void Heap::Verify() {
   CHECK(HasBeenSetUp());
   HandleScope scope(isolate());
 
-  if (mark_compact_collector()->sweeping_in_progress()) {
-    // We have to wait here for the sweeper threads to have an iterable heap.
-    mark_compact_collector()->EnsureSweepingCompleted();
-  }
+  MakeHeapIterable();
 
   VerifyPointersVisitor visitor;
   IterateRoots(&visitor, VISIT_ONLY_STRONG);
 
   VerifySmisVisitor smis_visitor;
   IterateSmiRoots(&smis_visitor);
 
   new_space_.Verify();
 
   old_space_->Verify(&visitor);
@@ skipping 1738 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8