Use weak cells in dependent code.

src/compiler.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/v8.h"
 
 #include "src/compiler.h"
 
 #include "src/ast-numbering.h"
 #include "src/ast-this-access-visitor.h"
@@ skipping 196 matching lines @@
   // Check that no dependent maps have been added or added dependent maps have
   // been rolled back or committed.
   for (int i = 0; i < DependentCode::kGroupCount; i++) {
     DCHECK_EQ(NULL, dependencies_[i]);
   }
 #endif  // DEBUG
 }
 
 
 void CompilationInfo::CommitDependencies(Handle<Code> code) {
+  bool has_dependencies = false;
+  for (int i = 0; i < DependentCode::kGroupCount; i++) {
+    has_dependencies |=
+        dependencies_[i] != NULL && dependencies_[i]->length() > 0;
+  }
+  // Avoid creating a weak cell for code with no dependencies.
+  if (!has_dependencies) return;
+
+  AllowDeferredHandleDereference get_object_wrapper;
+  Handle<WeakCell> cell = Code::WeakCellFor(code);
   for (int i = 0; i < DependentCode::kGroupCount; i++) {
     ZoneList<Handle<HeapObject> >* group_objects = dependencies_[i];
     if (group_objects == NULL) continue;
     DCHECK(!object_wrapper_.is_null());
     for (int j = 0; j < group_objects->length(); j++) {
       DependentCode::DependencyGroup group =
           static_cast<DependentCode::DependencyGroup>(i);
       DependentCode* dependent_code =
           DependentCode::ForObject(group_objects->at(j), group);
-      dependent_code->UpdateToFinishedCode(group, this, *code);
+      dependent_code->UpdateToFinishedCode(group, *object_wrapper(), *cell);
     }
     dependencies_[i] = NULL;  // Zone-allocated, no need to delete.
   }
 }
 
 
 void CompilationInfo::RollbackDependencies() {
+  AllowDeferredHandleDereference get_object_wrapper;
   // Unregister from all dependent maps if not yet committed.
   for (int i = 0; i < DependentCode::kGroupCount; i++) {
     ZoneList<Handle<HeapObject> >* group_objects = dependencies_[i];
     if (group_objects == NULL) continue;
     for (int j = 0; j < group_objects->length(); j++) {
       DependentCode::DependencyGroup group =
           static_cast<DependentCode::DependencyGroup>(i);
       DependentCode* dependent_code =
           DependentCode::ForObject(group_objects->at(j), group);
-      dependent_code->RemoveCompilationInfo(group, this);
+      dependent_code->RemoveCompilationInfo(group, *object_wrapper());
     }
     dependencies_[i] = NULL;  // Zone-allocated, no need to delete.
   }
 }
 
 
 int CompilationInfo::num_parameters() const {
   if (IsStub()) {
     DCHECK(parameter_count_ > 0);
     return parameter_count_;
@@ skipping 1329 matching lines @@
   AllowHandleDereference allow_deref;
   bool tracing_on = info()->IsStub()
       ? FLAG_trace_hydrogen_stubs
       : (FLAG_trace_hydrogen &&
          info()->closure()->PassesFilter(FLAG_trace_hydrogen_filter));
   return (tracing_on &&
       base::OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) != NULL);
 }
 
 } }  // namespace v8::internal