[turbofan] Support fast access to the current global object.

src/compiler/js-global-object-specialization.cc

Index: src/compiler/js-global-object-specialization.cc
diff --git a/src/compiler/js-global-object-specialization.cc b/src/compiler/js-global-object-specialization.cc
deleted file mode 100644
index 5f2bca9e6ad574bca4443430a5be3ceb0eedb427..0000000000000000000000000000000000000000
--- a/src/compiler/js-global-object-specialization.cc
+++ /dev/null
@@ -1,296 +0,0 @@
-// 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/compiler/js-global-object-specialization.h"
-
-#include "src/compilation-dependencies.h"
-#include "src/compiler/access-builder.h"
-#include "src/compiler/common-operator.h"
-#include "src/compiler/js-graph.h"
-#include "src/compiler/js-operator.h"
-#include "src/compiler/node-properties.h"
-#include "src/compiler/simplified-operator.h"
-#include "src/compiler/type-cache.h"
-#include "src/lookup.h"
-#include "src/objects-inl.h"
-
-namespace v8 {
-namespace internal {
-namespace compiler {
-
-struct JSGlobalObjectSpecialization::ScriptContextTableLookupResult {
-  Handle<Context> context;
-  bool immutable;
-  int index;
-};
-
-JSGlobalObjectSpecialization::JSGlobalObjectSpecialization(
-    Editor* editor, JSGraph* jsgraph, Handle<JSGlobalObject> global_object,
-    CompilationDependencies* dependencies)
-    : AdvancedReducer(editor),
-      jsgraph_(jsgraph),
-      global_object_(global_object),
-      dependencies_(dependencies),
-      type_cache_(TypeCache::Get()) {}
-
-Reduction JSGlobalObjectSpecialization::Reduce(Node* node) {
-  switch (node->opcode()) {
-    case IrOpcode::kJSLoadGlobal:
-      return ReduceJSLoadGlobal(node);
-    case IrOpcode::kJSStoreGlobal:
-      return ReduceJSStoreGlobal(node);
-    default:
-      break;
-  }
-  return NoChange();
-}
-
-namespace {
-
-FieldAccess ForPropertyCellValue(MachineRepresentation representation,
-                                 Type* type, MaybeHandle<Map> map,
-                                 Handle<Name> name) {
-  WriteBarrierKind kind = kFullWriteBarrier;
-  if (representation == MachineRepresentation::kTaggedSigned) {
-    kind = kNoWriteBarrier;
-  } else if (representation == MachineRepresentation::kTaggedPointer) {
-    kind = kPointerWriteBarrier;
-  }
-  MachineType r = MachineType::TypeForRepresentation(representation);
-  FieldAccess access = {
-      kTaggedBase, PropertyCell::kValueOffset, name, map, type, r, kind};
-  return access;
-}
-
-}  // namespace
-
-Reduction JSGlobalObjectSpecialization::ReduceJSLoadGlobal(Node* node) {
-  DCHECK_EQ(IrOpcode::kJSLoadGlobal, node->opcode());
-  Handle<Name> name = LoadGlobalParametersOf(node->op()).name();
-  Node* effect = NodeProperties::GetEffectInput(node);
-  Node* control = NodeProperties::GetControlInput(node);
-
-  // Try to lookup the name on the script context table first (lexical scoping).
-  ScriptContextTableLookupResult result;
-  if (LookupInScriptContextTable(name, &result)) {
-    if (result.context->is_the_hole(isolate(), result.index)) return NoChange();
-    Node* context = jsgraph()->HeapConstant(result.context);
-    Node* value = effect = graph()->NewNode(
-        javascript()->LoadContext(0, result.index, result.immutable), context,
-        effect);
-    ReplaceWithValue(node, value, effect);
-    return Replace(value);
-  }
-
-  // Lookup on the global object instead.  We only deal with own data
-  // properties of the global object here (represented as PropertyCell).
-  LookupIterator it(global_object(), name, LookupIterator::OWN);
-  it.TryLookupCachedProperty();
-  if (it.state() != LookupIterator::DATA) return NoChange();
-  if (!it.GetHolder<JSObject>()->IsJSGlobalObject()) return NoChange();
-  Handle<PropertyCell> property_cell = it.GetPropertyCell();
-  PropertyDetails property_details = property_cell->property_details();
-  Handle<Object> property_cell_value(property_cell->value(), isolate());
-
-  // Load from non-configurable, read-only data property on the global
-  // object can be constant-folded, even without deoptimization support.
-  if (!property_details.IsConfigurable() && property_details.IsReadOnly()) {
-    Node* value = jsgraph()->Constant(property_cell_value);
-    ReplaceWithValue(node, value);
-    return Replace(value);
-  }
-
-  // Record a code dependency on the cell if we can benefit from the
-  // additional feedback, or the global property is configurable (i.e.
-  // can be deleted or reconfigured to an accessor property).
-  if (property_details.cell_type() != PropertyCellType::kMutable ||
-      property_details.IsConfigurable()) {
-    dependencies()->AssumePropertyCell(property_cell);
-  }
-
-  // Load from constant/undefined global property can be constant-folded.
-  if (property_details.cell_type() == PropertyCellType::kConstant ||
-      property_details.cell_type() == PropertyCellType::kUndefined) {
-    Node* value = jsgraph()->Constant(property_cell_value);
-    ReplaceWithValue(node, value);
-    return Replace(value);
-  }
-
-  // Load from constant type cell can benefit from type feedback.
-  MaybeHandle<Map> map;
-  Type* property_cell_value_type = Type::NonInternal();
-  MachineRepresentation representation = MachineRepresentation::kTagged;
-  if (property_details.cell_type() == PropertyCellType::kConstantType) {
-    // Compute proper type based on the current value in the cell.
-    if (property_cell_value->IsSmi()) {
-      property_cell_value_type = Type::SignedSmall();
-      representation = MachineRepresentation::kTaggedSigned;
-    } else if (property_cell_value->IsNumber()) {
-      property_cell_value_type = Type::Number();
-      representation = MachineRepresentation::kTaggedPointer;
-    } else {
-      Handle<Map> property_cell_value_map(
-          Handle<HeapObject>::cast(property_cell_value)->map(), isolate());
-      property_cell_value_type = Type::For(property_cell_value_map);
-      representation = MachineRepresentation::kTaggedPointer;
-
-      // We can only use the property cell value map for map check elimination
-      // if it's stable, i.e. the HeapObject wasn't mutated without the cell
-      // state being updated.
-      if (property_cell_value_map->is_stable()) {
-        dependencies()->AssumeMapStable(property_cell_value_map);
-        map = property_cell_value_map;
-      }
-    }
-  }
-  Node* value = effect = graph()->NewNode(
-      simplified()->LoadField(ForPropertyCellValue(
-          representation, property_cell_value_type, map, name)),
-      jsgraph()->HeapConstant(property_cell), effect, control);
-  ReplaceWithValue(node, value, effect, control);
-  return Replace(value);
-}
-
-
-Reduction JSGlobalObjectSpecialization::ReduceJSStoreGlobal(Node* node) {
-  DCHECK_EQ(IrOpcode::kJSStoreGlobal, node->opcode());
-  Handle<Name> name = StoreGlobalParametersOf(node->op()).name();
-  Node* value = NodeProperties::GetValueInput(node, 0);
-  Node* effect = NodeProperties::GetEffectInput(node);
-  Node* control = NodeProperties::GetControlInput(node);
-
-  // Try to lookup the name on the script context table first (lexical scoping).
-  ScriptContextTableLookupResult result;
-  if (LookupInScriptContextTable(name, &result)) {
-    if (result.context->is_the_hole(isolate(), result.index)) return NoChange();
-    if (result.immutable) return NoChange();
-    Node* context = jsgraph()->HeapConstant(result.context);
-    effect = graph()->NewNode(javascript()->StoreContext(0, result.index),
-                              value, context, effect, control);
-    ReplaceWithValue(node, value, effect, control);
-    return Replace(value);
-  }
-
-  // Lookup on the global object instead.  We only deal with own data
-  // properties of the global object here (represented as PropertyCell).
-  LookupIterator it(global_object(), name, LookupIterator::OWN);
-  if (it.state() != LookupIterator::DATA) return NoChange();
-  if (!it.GetHolder<JSObject>()->IsJSGlobalObject()) return NoChange();
-  Handle<PropertyCell> property_cell = it.GetPropertyCell();
-  PropertyDetails property_details = property_cell->property_details();
-  Handle<Object> property_cell_value(property_cell->value(), isolate());
-
-  // Don't even bother trying to lower stores to read-only data properties.
-  if (property_details.IsReadOnly()) return NoChange();
-  switch (property_details.cell_type()) {
-    case PropertyCellType::kUndefined: {
-      return NoChange();
-    }
-    case PropertyCellType::kConstant: {
-      // Record a code dependency on the cell, and just deoptimize if the new
-      // value doesn't match the previous value stored inside the cell.
-      dependencies()->AssumePropertyCell(property_cell);
-      Node* check = graph()->NewNode(simplified()->ReferenceEqual(), value,
-                                     jsgraph()->Constant(property_cell_value));
-      effect =
-          graph()->NewNode(simplified()->CheckIf(), check, effect, control);
-      break;
-    }
-    case PropertyCellType::kConstantType: {
-      // Record a code dependency on the cell, and just deoptimize if the new
-      // values' type doesn't match the type of the previous value in the cell.
-      dependencies()->AssumePropertyCell(property_cell);
-      Type* property_cell_value_type;
-      MachineRepresentation representation = MachineRepresentation::kTagged;
-      if (property_cell_value->IsHeapObject()) {
-        // We cannot do anything if the {property_cell_value}s map is no
-        // longer stable.
-        Handle<Map> property_cell_value_map(
-            Handle<HeapObject>::cast(property_cell_value)->map(), isolate());
-        if (!property_cell_value_map->is_stable()) return NoChange();
-        dependencies()->AssumeMapStable(property_cell_value_map);
-
-        // Check that the {value} is a HeapObject.
-        value = effect = graph()->NewNode(simplified()->CheckHeapObject(),
-                                          value, effect, control);
-
-        // Check {value} map agains the {property_cell} map.
-        effect =
-            graph()->NewNode(simplified()->CheckMaps(
-                                 CheckMapsFlag::kNone,
-                                 ZoneHandleSet<Map>(property_cell_value_map)),
-                             value, effect, control);
-        property_cell_value_type = Type::OtherInternal();
-        representation = MachineRepresentation::kTaggedPointer;
-      } else {
-        // Check that the {value} is a Smi.
-        value = effect =
-            graph()->NewNode(simplified()->CheckSmi(), value, effect, control);
-        property_cell_value_type = Type::SignedSmall();
-        representation = MachineRepresentation::kTaggedSigned;
-      }
-      effect = graph()->NewNode(simplified()->StoreField(ForPropertyCellValue(
-                                    representation, property_cell_value_type,
-                                    MaybeHandle<Map>(), name)),
-                                jsgraph()->HeapConstant(property_cell), value,
-                                effect, control);
-      break;
-    }
-    case PropertyCellType::kMutable: {
-      // Record a code dependency on the cell, and just deoptimize if the
-      // property ever becomes read-only.
-      dependencies()->AssumePropertyCell(property_cell);
-      effect = graph()->NewNode(
-          simplified()->StoreField(ForPropertyCellValue(
-              MachineRepresentation::kTagged, Type::NonInternal(),
-              MaybeHandle<Map>(), name)),
-          jsgraph()->HeapConstant(property_cell), value, effect, control);
-      break;
-    }
-  }
-  ReplaceWithValue(node, value, effect, control);
-  return Replace(value);
-}
-
-bool JSGlobalObjectSpecialization::LookupInScriptContextTable(
-    Handle<Name> name, ScriptContextTableLookupResult* result) {
-  if (!name->IsString()) return false;
-  Handle<ScriptContextTable> script_context_table(
-      global_object()->native_context()->script_context_table(), isolate());
-  ScriptContextTable::LookupResult lookup_result;
-  if (!ScriptContextTable::Lookup(script_context_table,
-                                  Handle<String>::cast(name), &lookup_result)) {
-    return false;
-  }
-  Handle<Context> script_context = ScriptContextTable::GetContext(
-      script_context_table, lookup_result.context_index);
-  result->context = script_context;
-  result->immutable = lookup_result.mode == CONST;
-  result->index = lookup_result.slot_index;
-  return true;
-}
-
-Graph* JSGlobalObjectSpecialization::graph() const {
-  return jsgraph()->graph();
-}
-
-Isolate* JSGlobalObjectSpecialization::isolate() const {
-  return jsgraph()->isolate();
-}
-
-CommonOperatorBuilder* JSGlobalObjectSpecialization::common() const {
-  return jsgraph()->common();
-}
-
-JSOperatorBuilder* JSGlobalObjectSpecialization::javascript() const {
-  return jsgraph()->javascript();
-}
-
-SimplifiedOperatorBuilder* JSGlobalObjectSpecialization::simplified() const {
-  return jsgraph()->simplified();
-}
-
-}  // namespace compiler
-}  // namespace internal
-}  // namespace v8