Replace ICStub for array.length with hydrogen stub

src/hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1034 matching lines @@
     length = AddInstruction(new(zone) HJSArrayLength(object, mapcheck,
                                                      HType::Smi()));
   } else {
     length = AddInstruction(new(zone) HFixedArrayBaseLength(elements));
   }
   checked_key = AddBoundsCheck(
       key, length, ALLOW_SMI_KEY, checked_index_representation);
   return BuildFastElementAccess(elements, checked_key, val, mapcheck,
                                 elements_kind, is_store);
 }
 

[danno, 2013/03/22 14:25:40]

nit: two spaces before function

+HInstruction* HGraphBuilder::BuildFastArrayLengthLoad(HValue* object,
+                                                      HValue* typecheck) {
+  Zone* zone = this->zone();
+  return new (zone) HJSArrayLength(object, typecheck, HType::Smi());
+}
+
 
 HValue* HGraphBuilder::BuildAllocateElements(HContext* context,
                                              ElementsKind kind,
                                              HValue* capacity) {
   Zone* zone = this->zone();
 
   int elements_size = IsFastDoubleElementsKind(kind)
       ? kDoubleSize : kPointerSize;
   HConstant* elements_size_value =
       new(zone) HConstant(elements_size, Representation::Integer32());
@@ skipping 4923 matching lines @@
   ASSERT(lookup->IsField() || lookup->IsTransitionToField(*type));
   if (lookup->IsField()) {
     return lookup->GetLocalFieldIndexFromMap(*type);
   } else {
     Map* transition = lookup->GetTransitionMapFromMap(*type);
     return transition->PropertyIndexFor(*name) - type->inobject_properties();
   }
 }
 
 
+void HOptimizedGraphBuilder::AddCheckMap(HValue* object, Handle<Map> map) {
+  AddInstruction(new(zone()) HCheckNonSmi(object));
+  AddInstruction(new(zone()) HCheckMaps(object, map, zone()));
+}
+

[danno, 2013/03/22 14:25:40]

nit: two spaces after function

 void HOptimizedGraphBuilder::AddCheckMapsWithTransitions(HValue* object,
                                                          Handle<Map> map) {
   AddInstruction(new(zone()) HCheckNonSmi(object));
   AddInstruction(HCheckMaps::NewWithTransitions(object, map, zone()));
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildStoreNamedField(
     HValue* object,
     Handle<String> name,
@@ skipping 88 matching lines @@
     Handle<Map> map) {
   // Handle a store to a known field.
   LookupResult lookup(isolate());
   if (ComputeLoadStoreField(map, name, &lookup, true)) {
     AddCheckMapsWithTransitions(object, map);
     return BuildStoreNamedField(object, name, value, map, &lookup);
   }
 
   // No luck, do a generic store.
   return BuildStoreNamedGeneric(object, name, value);
 }

[danno, 2013/03/22 14:25:40]

nit: two spaces between functions

 
+bool HOptimizedGraphBuilder::HandlePolymorphicArrayLengthLoad(
+    Property* expr,
+    HValue* object,
+    SmallMapList* types,
+    Handle<String> name) {
+  if (!name->Equals(isolate()->heap()->length_string())) return false;
+
+  for (int i = 0; i < types->length(); i++) {
+    if (types->at(i)->instance_type() != JS_ARRAY_TYPE) return false;
+  }
+
+  AddInstruction(new(zone()) HCheckNonSmi(object));
+  HInstruction* typecheck =
+    AddInstruction(HCheckInstanceType::NewIsJSArray(object, zone()));
+  HInstruction* instr = BuildFastArrayLengthLoad(object, typecheck);
+  instr->set_position(expr->position());
+  ast_context()->ReturnInstruction(instr, expr->id());
+  return true;
+}

[danno, 2013/03/22 14:25:40]

nit: two spaces between functions.

 
 void HOptimizedGraphBuilder::HandlePolymorphicLoadNamedField(
     Property* expr,
     HValue* object,
     SmallMapList* types,
     Handle<String> name) {
   int count = 0;
   int previous_field_offset = 0;
   bool previous_field_is_in_object = false;
   bool is_monomorphic_field = true;
+
+  if (HandlePolymorphicArrayLengthLoad(expr, object, types, name))
+    return;
+
   Handle<Map> map;
   LookupResult lookup(isolate());
   for (int i = 0; i < types->length() && count < kMaxLoadPolymorphism; ++i) {
     map = types->at(i);
     if (ComputeLoadStoreField(map, name, &lookup, false)) {
       int index = ComputeLoadStoreFieldIndex(map, name, &lookup);
       bool is_in_object = index < 0;
       int offset = index * kPointerSize;
       if (index < 0) {
         // Negative property indices are in-object properties, indexed
@@ skipping 615 matching lines @@
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildLoadNamedMonomorphic(
     HValue* object,
     Handle<String> name,
     Property* expr,
     Handle<Map> map) {
   // Handle a load from a known field.
   ASSERT(!map->is_dictionary_map());
+
+  // Handle access to various length properties
+  if (name->Equals(isolate()->heap()->length_string())) {
+    if (map->instance_type() == JS_ARRAY_TYPE) {
+      AddCheckMapsWithTransitions(object, map);
+      return BuildFastArrayLengthLoad(object, NULL);
+    }
+  }
+
   LookupResult lookup(isolate());
   map->LookupDescriptor(NULL, *name, &lookup);
   if (lookup.IsField()) {
-    AddCheckMapsWithTransitions(object, map);
+    AddCheckMap(object, map);
     return BuildLoadNamedField(object, map, &lookup);
   }
 
   // Handle a load of a constant known function.
   if (lookup.IsConstantFunction()) {
-    AddCheckMapsWithTransitions(object, map);
+    AddCheckMap(object, map);
     Handle<JSFunction> function(lookup.GetConstantFunctionFromMap(*map));
     return new(zone()) HConstant(function, Representation::Tagged());
   }
 
   // Handle a load from a known field somewhere in the prototype chain.
   LookupInPrototypes(map, name, &lookup);
   if (lookup.IsField()) {
     Handle<JSObject> prototype(JSObject::cast(map->prototype()));
     Handle<JSObject> holder(lookup.holder());
     Handle<Map> holder_map(holder->map());
-    AddCheckMapsWithTransitions(object, map);
+    AddCheckMap(object, map);
     HInstruction* holder_value = AddInstruction(
         new(zone()) HCheckPrototypeMaps(prototype, holder, zone()));
     return BuildLoadNamedField(holder_value, holder_map, &lookup);
   }
 
   // Handle a load of a constant function somewhere in the prototype chain.
   if (lookup.IsConstantFunction()) {
     Handle<JSObject> prototype(JSObject::cast(map->prototype()));
     Handle<JSObject> holder(lookup.holder());
     Handle<Map> holder_map(holder->map());
-    AddCheckMapsWithTransitions(object, map);
+    AddCheckMap(object, map);
     AddInstruction(new(zone()) HCheckPrototypeMaps(prototype, holder, zone()));
     Handle<JSFunction> function(lookup.GetConstantFunctionFromMap(*holder_map));
     return new(zone()) HConstant(function, Representation::Tagged());
   }
 
   // No luck, do a generic load.
   return BuildLoadNamedGeneric(object, name, expr);
 }
 
 
@@ skipping 434 matching lines @@
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   expr->RecordTypeFeedback(oracle(), zone());
 
   if (TryArgumentsAccess(expr)) return;
 
   CHECK_ALIVE(VisitForValue(expr->obj()));
 
   HInstruction* instr = NULL;
-  if (expr->AsProperty()->IsArrayLength()) {
-    HValue* array = Pop();
-    AddInstruction(new(zone()) HCheckNonSmi(array));
-    HInstruction* mapcheck =
-        AddInstruction(HCheckInstanceType::NewIsJSArray(array, zone()));
-    instr = new(zone()) HJSArrayLength(array, mapcheck);
-  } else if (expr->IsStringLength()) {
+  if (expr->IsStringLength()) {
     HValue* string = Pop();
     AddInstruction(new(zone()) HCheckNonSmi(string));
     AddInstruction(HCheckInstanceType::NewIsString(string, zone()));
     instr = HStringLength::New(zone(), string);
   } else if (expr->IsStringAccess()) {
     CHECK_ALIVE(VisitForValue(expr->key()));
     HValue* index = Pop();
     HValue* string = Pop();
     HValue* context = environment()->LookupContext();
     HInstruction* char_code =
@@ skipping 3692 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal