Store mode for keyed stores should be passed in from type feedback

src/hydrogen.cc

 // Copyright 2013 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 1201 matching lines @@
                               array_length, elements_length);
 
     if_builder.End();
   }
 
   Add<HStoreNamedField>(object, HObjectAccess::ForMap(), map);
 }
 
 
 HInstruction* HGraphBuilder::BuildUncheckedMonomorphicElementAccess(
-    HValue* object,
+    HValue* checked_object,
     HValue* key,
     HValue* val,
-    HCheckMaps* checked_object,
     bool is_js_array,
     ElementsKind elements_kind,
     bool is_store,
     LoadKeyedHoleMode load_mode,
     KeyedAccessStoreMode store_mode) {
   ASSERT(!IsExternalArrayElementsKind(elements_kind) || !is_js_array);
   // No GVNFlag is necessary for ElementsKind if there is an explicit dependency
   // on a HElementsTransition instruction. The flag can also be removed if the
   // map to check has FAST_HOLEY_ELEMENTS, since there can be no further
   // ElementsKind transitions. Finally, the dependency can be removed for stores
   // for FAST_ELEMENTS, since a transition to HOLEY elements won't change the
   // generated store code.
   if ((elements_kind == FAST_HOLEY_ELEMENTS) ||
       (elements_kind == FAST_ELEMENTS && is_store)) {
-    if (checked_object != NULL) {
-      checked_object->ClearGVNFlag(kDependsOnElementsKind);
-    }
+    checked_object->ClearGVNFlag(kDependsOnElementsKind);
   }
-  if (checked_object != NULL) object = checked_object;
+
   bool fast_smi_only_elements = IsFastSmiElementsKind(elements_kind);
   bool fast_elements = IsFastObjectElementsKind(elements_kind);
-  HValue* elements = AddLoadElements(object);
+  HValue* elements = AddLoadElements(checked_object);
   if (is_store && (fast_elements || fast_smi_only_elements) &&
       store_mode != STORE_NO_TRANSITION_HANDLE_COW) {
     HCheckMaps* check_cow_map = Add<HCheckMaps>(
         elements, isolate()->factory()->fixed_array_map(), top_info());
     check_cow_map->ClearGVNFlag(kDependsOnElementsKind);
   }
   HInstruction* length = NULL;
   if (is_js_array) {
     length = Add<HLoadNamedField>(
-        object, HObjectAccess::ForArrayLength(elements_kind));
+        checked_object, HObjectAccess::ForArrayLength(elements_kind));
   } else {
     length = AddLoadFixedArrayLength(elements);
   }
   length->set_type(HType::Smi());
   HValue* checked_key = NULL;
   if (IsExternalArrayElementsKind(elements_kind)) {
     if (store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS) {
       NoObservableSideEffectsScope no_effects(this);
        HLoadExternalArrayPointer* external_elements =
            Add<HLoadExternalArrayPointer>(elements);
@@ skipping 26 matching lines @@
   // In case val is stored into a fast smi array, assure that the value is a smi
   // before manipulating the backing store. Otherwise the actual store may
   // deopt, leaving the backing store in an invalid state.
   if (is_store && IsFastSmiElementsKind(elements_kind) &&
       !val->type().IsSmi()) {
     val = Add<HForceRepresentation>(val, Representation::Smi());
   }
 
   if (IsGrowStoreMode(store_mode)) {
     NoObservableSideEffectsScope no_effects(this);
-    elements = BuildCheckForCapacityGrow(object, elements, elements_kind,
-                                         length, key, is_js_array);
+    elements = BuildCheckForCapacityGrow(checked_object, elements,
+                                         elements_kind, length, key,
+                                         is_js_array);
     checked_key = key;
   } else {
     checked_key = Add<HBoundsCheck>(key, length);
 
     if (is_store && (fast_elements || fast_smi_only_elements)) {
       if (store_mode == STORE_NO_TRANSITION_HANDLE_COW) {
         NoObservableSideEffectsScope no_effects(this);
-
-        elements = BuildCopyElementsOnWrite(object, elements, elements_kind,
-                                            length);
+        elements = BuildCopyElementsOnWrite(checked_object, elements,
+                                            elements_kind, length);
       } else {
         HCheckMaps* check_cow_map = Add<HCheckMaps>(
             elements, isolate()->factory()->fixed_array_map(),
             top_info());
         check_cow_map->ClearGVNFlag(kDependsOnElementsKind);
       }
     }
   }
   return AddFastElementAccess(elements, checked_key, val, checked_object,
                               elements_kind, is_store, load_mode, store_mode);
@@ skipping 4168 matching lines @@
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildLoadKeyedGeneric(HValue* object,
                                                             HValue* key) {
   HValue* context = environment()->context();
   return new(zone()) HLoadKeyedGeneric(context, object, key);
 }
 
 
-HInstruction* HOptimizedGraphBuilder::BuildMonomorphicElementAccess(
-    HValue* object,
-    HValue* key,
-    HValue* val,
-    HValue* dependency,
-    Handle<Map> map,
-    bool is_store,
-    KeyedAccessStoreMode store_mode) {
-  HCheckMaps* mapcheck = Add<HCheckMaps>(object, map, top_info(), dependency);
-  if (dependency) {
-    mapcheck->ClearGVNFlag(kDependsOnElementsKind);
-  }
-
+LoadKeyedHoleMode HOptimizedGraphBuilder::BuildKeyedHoleMode(Handle<Map> map) {
   // Loads from a "stock" fast holey double arrays can elide the hole check.
   LoadKeyedHoleMode load_mode = NEVER_RETURN_HOLE;
   if (*map == isolate()->get_initial_js_array_map(FAST_HOLEY_DOUBLE_ELEMENTS) &&
       isolate()->IsFastArrayConstructorPrototypeChainIntact()) {
     Handle<JSObject> prototype(JSObject::cast(map->prototype()), isolate());
     Handle<JSObject> object_prototype = isolate()->initial_object_prototype();
     BuildCheckPrototypeMaps(prototype, object_prototype);
     load_mode = ALLOW_RETURN_HOLE;
     graph()->MarkDependsOnEmptyArrayProtoElements();
   }
 
-  return BuildUncheckedMonomorphicElementAccess(
-      object, key, val,
-      mapcheck, map->instance_type() == JS_ARRAY_TYPE,
-      map->elements_kind(), is_store, load_mode, store_mode);
+  return load_mode;
 }
 
 
+HInstruction* HOptimizedGraphBuilder::BuildMonomorphicElementAccess(
+    HValue* object,
+    HValue* key,
+    HValue* val,
+    HValue* dependency,
+    Handle<Map> map,
+    bool is_store,
+    KeyedAccessStoreMode store_mode) {
+  HCheckMaps* checked_object = Add<HCheckMaps>(object, map, top_info(),
+                                               dependency);
+  if (dependency) {
+    checked_object->ClearGVNFlag(kDependsOnElementsKind);
+  }
+
+  LoadKeyedHoleMode load_mode = BuildKeyedHoleMode(map);
+  return BuildUncheckedMonomorphicElementAccess(
+      checked_object, key, val,
+      map->instance_type() == JS_ARRAY_TYPE,
+      map->elements_kind(), is_store,
+      load_mode, store_mode);
+}
+
+
 HInstruction* HOptimizedGraphBuilder::TryBuildConsolidatedElementLoad(
     HValue* object,
     HValue* key,
     HValue* val,
     SmallMapList* maps) {
   // For polymorphic loads of similar elements kinds (i.e. all tagged or all
   // double), always use the "worst case" code without a transition.  This is
   // much faster than transitioning the elements to the worst case, trading a
   // HTransitionElements for a HCheckMaps, and avoiding mutation of the array.
   bool has_double_maps = false;
@@ skipping 30 matching lines @@
     // Remember the most general elements kind, the code for its load will
     // properly handle all of the more specific cases.
     if ((i == 0) || IsMoreGeneralElementsKindTransition(
             most_general_consolidated_map->elements_kind(),
             map->elements_kind())) {
       most_general_consolidated_map = map;
     }
   }
   if (!has_double_maps && !has_smi_or_object_maps) return NULL;
 
-  HCheckMaps* check_maps = Add<HCheckMaps>(object, maps);
+  HCheckMaps* checked_object = Add<HCheckMaps>(object, maps);
   // FAST_ELEMENTS is considered more general than FAST_HOLEY_SMI_ELEMENTS.
   // If we've seen both, the consolidated load must use FAST_HOLEY_ELEMENTS.
   ElementsKind consolidated_elements_kind = has_seen_holey_elements
       ? GetHoleyElementsKind(most_general_consolidated_map->elements_kind())
       : most_general_consolidated_map->elements_kind();
   HInstruction* instr = BuildUncheckedMonomorphicElementAccess(
-      object, key, val, check_maps,
+      checked_object, key, val,
       most_general_consolidated_map->instance_type() == JS_ARRAY_TYPE,
       consolidated_elements_kind,
       false, NEVER_RETURN_HOLE, STANDARD_STORE);
   return instr;
 }
 
 
 HValue* HOptimizedGraphBuilder::HandlePolymorphicElementAccess(
     HValue* object,
     HValue* key,
@@ skipping 68 matching lines @@
     } else {
       instr = BuildMonomorphicElementAccess(
           object, key, val, transition, untransitionable_map, is_store,
           store_mode);
     }
     *has_side_effects |= instr->HasObservableSideEffects();
     if (position != RelocInfo::kNoPosition) instr->set_position(position);
     return is_store ? NULL : instr;
   }
 
-  HInstruction* checked_object =
-      AddInstruction(HCheckInstanceType::NewIsSpecObject(object, zone()));
   HBasicBlock* join = graph()->CreateBasicBlock();
 
-  HInstruction* elements = AddLoadElements(checked_object);
-
   for (int i = 0; i < untransitionable_maps.length(); ++i) {
     Handle<Map> map = untransitionable_maps[i];
     ElementsKind elements_kind = map->elements_kind();
     HBasicBlock* this_map = graph()->CreateBasicBlock();
     HBasicBlock* other_map = graph()->CreateBasicBlock();
     HCompareMap* mapcompare =
         new(zone()) HCompareMap(object, map, this_map, other_map);
     current_block()->Finish(mapcompare);
 
     set_current_block(this_map);
-    HInstruction* checked_key = NULL;
     HInstruction* access = NULL;
-    if (IsFastElementsKind(elements_kind)) {
-      if (is_store && !IsFastDoubleElementsKind(elements_kind)) {
-        Add<HCheckMaps>(
-            elements, isolate()->factory()->fixed_array_map(),
-            top_info(), mapcompare);
-      }
-      if (map->instance_type() == JS_ARRAY_TYPE) {
-        HInstruction* length = Add<HLoadNamedField>(
-            mapcompare, HObjectAccess::ForArrayLength(elements_kind));
-        checked_key = Add<HBoundsCheck>(key, length);
-      } else {
-        HInstruction* length = AddLoadFixedArrayLength(elements);
-        checked_key = Add<HBoundsCheck>(key, length);
-      }
-      access = AddFastElementAccess(
-          elements, checked_key, val, mapcompare,
-          elements_kind, is_store, NEVER_RETURN_HOLE, STANDARD_STORE);
-    } else if (IsDictionaryElementsKind(elements_kind)) {
-      if (is_store) {
-        access = AddInstruction(BuildStoreKeyedGeneric(object, key, val));
-      } else {
-        access = AddInstruction(BuildLoadKeyedGeneric(object, key));
-      }
+    if (IsDictionaryElementsKind(elements_kind)) {
+      access = is_store
+          ? AddInstruction(BuildStoreKeyedGeneric(object, key, val))
+          : AddInstruction(BuildLoadKeyedGeneric(object, key));
     } else {
-      ASSERT(IsExternalArrayElementsKind(elements_kind));
-      HInstruction* length = AddLoadFixedArrayLength(elements);
-      checked_key = Add<HBoundsCheck>(key, length);
-      HLoadExternalArrayPointer* external_elements =
-          Add<HLoadExternalArrayPointer>(elements);
-      access = AddExternalArrayElementAccess(
-          external_elements, checked_key, val,
-          mapcompare, elements_kind, is_store);
+      ASSERT(IsFastElementsKind(elements_kind) ||
+             IsExternalArrayElementsKind(elements_kind));
+      LoadKeyedHoleMode load_mode = BuildKeyedHoleMode(map);
+      // mapcompare is a checked object

[Jakob Kummerow, 2013/08/26 12:24:51]

nit: Capitalization and punctuation, please.

[mvstanton, 2013/08/26 12:27:50]

Done.

+      access = BuildUncheckedMonomorphicElementAccess(
+          mapcompare, key, val,
+          map->instance_type() == JS_ARRAY_TYPE,
+          elements_kind, is_store,
+          load_mode,
+          store_mode);
     }
     *has_side_effects |= access->HasObservableSideEffects();
     // The caller will use has_side_effects and add a correct Simulate.
     access->SetFlag(HValue::kHasNoObservableSideEffects);
     if (position != RelocInfo::kNoPosition) access->set_position(position);
     if (!is_store) {
       Push(access);
     }
     NoObservableSideEffectsScope scope(this);
     current_block()->GotoNoSimulate(join);
@@ skipping 4125 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal