Reland "Refactor compilation dependency handling."

src/compilation-dependencies.cc

Index: src/compilation-dependencies.cc
diff --git a/src/compilation-dependencies.cc b/src/compilation-dependencies.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9ea6a7a878962b05b383ea6e497f86a97f57c2b6
--- /dev/null
+++ b/src/compilation-dependencies.cc
@@ -0,0 +1,121 @@
+// Copyright 2015 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/factory.h"
+#include "src/handles-inl.h"
+#include "src/isolate.h"
+#include "src/objects-inl.h"
+#include "src/zone.h"
+
+#include "src/compilation-dependencies.h"
+
+namespace v8 {
+namespace internal {
+
+DependentCode* CompilationDependencies::Get(Handle<Object> object) {
+  if (object->IsMap()) {
+    return Handle<Map>::cast(object)->dependent_code();
+  } else if (object->IsPropertyCell()) {
+    return Handle<PropertyCell>::cast(object)->dependent_code();
+  } else if (object->IsAllocationSite()) {
+    return Handle<AllocationSite>::cast(object)->dependent_code();
+  }
+  UNREACHABLE();
+  return nullptr;
+}
+
+
+void CompilationDependencies::Set(Handle<Object> object,
+                                  Handle<DependentCode> dep) {
+  if (object->IsMap()) {
+    Handle<Map>::cast(object)->set_dependent_code(*dep);
+  } else if (object->IsPropertyCell()) {
+    Handle<PropertyCell>::cast(object)->set_dependent_code(*dep);
+  } else if (object->IsAllocationSite()) {
+    Handle<AllocationSite>::cast(object)->set_dependent_code(*dep);
+  } else {
+    UNREACHABLE();
+  }
+}
+
+
+void CompilationDependencies::Insert(DependentCode::DependencyGroup group,
+                                     Handle<HeapObject> object) {
+  if (groups_[group] == nullptr) {
+    groups_[group] = new (zone_) ZoneList<Handle<HeapObject>>(2, zone_);
+  }
+  groups_[group]->Add(object, zone_);
+
+  if (object_wrapper_.is_null()) {
+    // Allocate the wrapper if necessary.
+    object_wrapper_ =
+        isolate_->factory()->NewForeign(reinterpret_cast<Address>(this));
+  }
+
+  // Get the old dependent code list.
+  Handle<DependentCode> old_dependent_code =
+      Handle<DependentCode>(Get(object), isolate_);
+  Handle<DependentCode> new_dependent_code =
+      DependentCode::InsertCompilationDependencies(old_dependent_code, group,
+                                                   object_wrapper_);
+
+  // Set the new dependent code list if the head of the list changed.
+  if (!new_dependent_code.is_identical_to(old_dependent_code)) {
+    Set(object, new_dependent_code);
+  }
+}
+
+
+void CompilationDependencies::Commit(Handle<Code> code) {
+  if (IsEmpty()) return;
+
+  DCHECK(!object_wrapper_.is_null());
+  Handle<WeakCell> cell = Code::WeakCellFor(code);
+  AllowDeferredHandleDereference get_wrapper;
+  for (int i = 0; i < DependentCode::kGroupCount; i++) {
+    ZoneList<Handle<HeapObject>>* group_objects = groups_[i];
+    if (group_objects == nullptr) continue;
+    DependentCode::DependencyGroup group =
+        static_cast<DependentCode::DependencyGroup>(i);
+    for (int j = 0; j < group_objects->length(); j++) {
+      DependentCode* dependent_code = Get(group_objects->at(j));
+      dependent_code->UpdateToFinishedCode(group, *object_wrapper_, *cell);
+    }
+    groups_[i] = nullptr;  // Zone-allocated, no need to delete.
+  }
+}
+
+
+void CompilationDependencies::Rollback() {
+  if (IsEmpty()) return;
+
+  AllowDeferredHandleDereference get_wrapper;
+  // Unregister from all dependent maps if not yet committed.
+  for (int i = 0; i < DependentCode::kGroupCount; i++) {
+    ZoneList<Handle<HeapObject>>* group_objects = groups_[i];
+    if (group_objects == nullptr) continue;
+    DependentCode::DependencyGroup group =
+        static_cast<DependentCode::DependencyGroup>(i);
+    for (int j = 0; j < group_objects->length(); j++) {
+      DependentCode* dependent_code = Get(group_objects->at(j));
+      dependent_code->RemoveCompilationDependencies(group, *object_wrapper_);
+    }
+    groups_[i] = nullptr;  // Zone-allocated, no need to delete.
+  }
+}
+
+
+void CompilationDependencies::AssumeTransitionStable(
+    Handle<AllocationSite> site) {
+  // Do nothing if the object doesn't have any useful element transitions left.
+  ElementsKind kind =
+      site->SitePointsToLiteral()
+          ? JSObject::cast(site->transition_info())->GetElementsKind()
+          : site->GetElementsKind();
+  if (AllocationSite::GetMode(kind) == TRACK_ALLOCATION_SITE) {
+    Insert(DependentCode::kAllocationSiteTransitionChangedGroup, site);
+  }
+}
+}
+}  // namespace v8::internal