Use a dictionary-mode code cache on the map rather than a dual system.

src/heap/incremental-marking.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/incremental-marking.h"
 
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/conversions.h"
 #include "src/heap/gc-idle-time-handler.h"
@@ skipping 535 matching lines @@
 // Marking bits are cleared by the sweeper.
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     heap_->mark_compact_collector()->VerifyMarkbitsAreClean();
   }
 #endif
 
   heap_->CompletelyClearInstanceofCache();
   heap_->isolate()->compilation_cache()->MarkCompactPrologue();
 
-  if (FLAG_cleanup_code_caches_at_gc) {
-    // We will mark cache black with a separate pass
-    // when we finish marking.
-    MarkObjectGreyDoNotEnqueue(heap_->polymorphic_code_cache());
-  }
-
   // Mark strong roots grey.
   IncrementalMarkingRootMarkingVisitor visitor(this);
   heap_->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG);
 
   if (FLAG_black_allocation) {
     StartBlackAllocation();
   }
 
   // Ready to start incremental marking.
   if (FLAG_trace_incremental_marking) {
@@ skipping 346 matching lines @@
       double end = heap_->MonotonicallyIncreasingTimeInMs();
       double delta = end - start;
       heap_->tracer()->AddMarkingTime(delta);
       if (FLAG_trace_incremental_marking) {
         PrintF("[IncrementalMarking] Complete (hurry), spent %d ms.\n",
                static_cast<int>(delta));
       }
     }
   }
 
-  if (FLAG_cleanup_code_caches_at_gc) {
-    PolymorphicCodeCache* poly_cache = heap_->polymorphic_code_cache();
-    Marking::GreyToBlack(Marking::MarkBitFrom(poly_cache));
-    MemoryChunk::IncrementLiveBytesFromGC(poly_cache,
-                                          PolymorphicCodeCache::kSize);
-  }
-
   Object* context = heap_->native_contexts_list();
   while (!context->IsUndefined()) {
     // GC can happen when the context is not fully initialized,
     // so the cache can be undefined.
     HeapObject* cache = HeapObject::cast(
         Context::cast(context)->get(Context::NORMALIZED_MAP_CACHE_INDEX));
     if (!cache->IsUndefined()) {
       MarkBit mark_bit = Marking::MarkBitFrom(cache);
       if (Marking::IsGrey(mark_bit)) {
         Marking::GreyToBlack(mark_bit);
@@ skipping 297 matching lines @@
 void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
   idle_marking_delay_counter_++;
 }
 
 
 void IncrementalMarking::ClearIdleMarkingDelayCounter() {
   idle_marking_delay_counter_ = 0;
 }
 }  // namespace internal
 }  // namespace v8