[turbofan] Port Crankshaft's weak objects mechanism to TurboFan.

src/crankshaft/lithium.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/crankshaft/lithium.h"
 
 #include "src/ast/scopes.h"
 
 #if V8_TARGET_ARCH_IA32
 #include "src/crankshaft/ia32/lithium-ia32.h"  // NOLINT
@@ skipping 388 matching lines @@
   return HConstant::cast(graph_->LookupValue(operand->index()));
 }
 
 
 Representation LChunk::LookupLiteralRepresentation(
     LConstantOperand* operand) const {
   return graph_->LookupValue(operand->index())->representation();
 }
 
 
-static void AddWeakObjectToCodeDependency(Isolate* isolate,
-                                          Handle<HeapObject> object,
-                                          Handle<Code> code) {
-  Handle<WeakCell> cell = Code::WeakCellFor(code);
-  Heap* heap = isolate->heap();
-  Handle<DependentCode> dep(heap->LookupWeakObjectToCodeDependency(object));
-  dep = DependentCode::InsertWeakCode(dep, DependentCode::kWeakCodeGroup, cell);
-  heap->AddWeakObjectToCodeDependency(object, dep);
-}
-
-
-void LChunk::RegisterWeakObjectsInOptimizedCode(Handle<Code> code) const {
-  DCHECK(code->is_optimized_code());
-  ZoneList<Handle<Map> > maps(1, zone());
-  ZoneList<Handle<HeapObject> > objects(1, zone());
-  int mode_mask = RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
-                  RelocInfo::ModeMask(RelocInfo::CELL);
-  for (RelocIterator it(*code, mode_mask); !it.done(); it.next()) {
-    RelocInfo::Mode mode = it.rinfo()->rmode();
-    if (mode == RelocInfo::CELL &&
-        code->IsWeakObjectInOptimizedCode(it.rinfo()->target_cell())) {
-      objects.Add(Handle<HeapObject>(it.rinfo()->target_cell()), zone());
-    } else if (mode == RelocInfo::EMBEDDED_OBJECT &&
-               code->IsWeakObjectInOptimizedCode(it.rinfo()->target_object())) {
-      if (it.rinfo()->target_object()->IsMap()) {
-        Handle<Map> map(Map::cast(it.rinfo()->target_object()));
-        maps.Add(map, zone());
-      } else {
-        Handle<HeapObject> object(
-            HeapObject::cast(it.rinfo()->target_object()));
-        objects.Add(object, zone());
-      }
-    }
-  }
-  for (int i = 0; i < maps.length(); i++) {
-    if (maps.at(i)->dependent_code()->IsEmpty(DependentCode::kWeakCodeGroup)) {
-      isolate()->heap()->AddRetainedMap(maps.at(i));
-    }
-    Map::AddDependentCode(maps.at(i), DependentCode::kWeakCodeGroup, code);
-  }
-  for (int i = 0; i < objects.length(); i++) {
-    AddWeakObjectToCodeDependency(isolate(), objects.at(i), code);
-  }
-  code->set_can_have_weak_objects(true);
-}
-
-
 void LChunk::CommitDependencies(Handle<Code> code) const {
   if (!code->is_optimized_code()) return;
   HandleScope scope(isolate());
 
   for (Handle<Map> map : deprecation_dependencies_) {
     DCHECK(!map->is_deprecated());
     DCHECK(map->CanBeDeprecated());
     Map::AddDependentCode(map, DependentCode::kTransitionGroup, code);
   }
 
   for (Handle<Map> map : stability_dependencies_) {
     DCHECK(map->is_stable());
     DCHECK(map->CanTransition());
     Map::AddDependentCode(map, DependentCode::kPrototypeCheckGroup, code);
   }
 
   info_->dependencies()->Commit(code);
-  RegisterWeakObjectsInOptimizedCode(code);
 }
 
 
 LChunk* LChunk::NewChunk(HGraph* graph) {
   DisallowHandleAllocation no_handles;
   DisallowHeapAllocation no_gc;
   graph->DisallowAddingNewValues();
   int values = graph->GetMaximumValueID();
   CompilationInfo* info = graph->info();
   if (values > LUnallocated::kMaxVirtualRegisters) {
@@ skipping 221 matching lines @@
 
 LPhase::~LPhase() {
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceLithium(name(), chunk_);
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8