Remake of the load elimination fix made earlier (r18884).

src/hydrogen-instructions.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 3600 matching lines @@
       HInnerAllocatedObject::New(zone, context(), dominating_allocate_,
       dominating_allocate_->size(), type());
   free_space_instr->InsertBefore(this);
   HConstant* filler_map = HConstant::New(
       zone,
       context(),
       isolate()->factory()->free_space_map());
   filler_map->FinalizeUniqueness();  // TODO(titzer): should be init'd a'ready
   filler_map->InsertAfter(free_space_instr);
   HInstruction* store_map = HStoreNamedField::New(zone, context(),
-      free_space_instr, HObjectAccess::ForMap(), filler_map,
-      INITIALIZING_STORE);
+      free_space_instr, HObjectAccess::ForMap(), filler_map);
   store_map->SetFlag(HValue::kHasNoObservableSideEffects);
   store_map->InsertAfter(filler_map);
 
   // We must explicitly force Smi representation here because on x64 we
   // would otherwise automatically choose int32, but the actual store
   // requires a Smi-tagged value.
   HConstant* filler_size = HConstant::CreateAndInsertAfter(
       zone, context(), free_space_size, Representation::Smi(), store_map);
   // Must force Smi representation for x64 (see comment above).
   HObjectAccess access =
-      HObjectAccess::ForJSObjectOffset(FreeSpace::kSizeOffset,
-          Representation::Smi());
+      HObjectAccess::ForMapAndOffset(isolate()->factory()->free_space_map(),
+                                     FreeSpace::kSizeOffset,
+                                     Representation::Smi());
   HStoreNamedField* store_size = HStoreNamedField::New(zone, context(),
-      free_space_instr, access, filler_size, INITIALIZING_STORE);
+      free_space_instr, access, filler_size);
   store_size->SetFlag(HValue::kHasNoObservableSideEffects);
   store_size->InsertAfter(filler_size);
   filler_free_space_size_ = store_size;
 }
 
 
 void HAllocate::ClearNextMapWord(int offset) {
   if (MustClearNextMapWord()) {
     Zone* zone = block()->zone();
-    HObjectAccess access = HObjectAccess::ForJSObjectOffset(offset);
+    HObjectAccess access =
+        HObjectAccess::ForObservableJSObjectOffset(offset);
     HStoreNamedField* clear_next_map =
         HStoreNamedField::New(zone, context(), this, access,
-            block()->graph()->GetConstant0(), INITIALIZING_STORE);
+            block()->graph()->GetConstant0());
     clear_next_map->ClearAllSideEffects();
     clear_next_map->InsertAfter(this);
   }
 }
 
 
 void HAllocate::PrintDataTo(StringStream* stream) {
   size()->PrintNameTo(stream);
   stream->Add(" (");
   if (IsNewSpaceAllocation()) stream->Add("N");
@@ skipping 603 matching lines @@
 
 
 HObjectAccess HObjectAccess::ForFixedArrayHeader(int offset) {
   ASSERT(offset >= 0);
   ASSERT(offset < FixedArray::kHeaderSize);
   if (offset == FixedArray::kLengthOffset) return ForFixedArrayLength();
   return HObjectAccess(kInobject, offset);
 }
 
 
-HObjectAccess HObjectAccess::ForJSObjectOffset(int offset,
+HObjectAccess HObjectAccess::ForMapAndOffset(Handle<Map> map, int offset,
     Representation representation) {
   ASSERT(offset >= 0);
   Portion portion = kInobject;
 
   if (offset == JSObject::kElementsOffset) {
     portion = kElementsPointer;
   } else if (offset == JSObject::kMapOffset) {
     portion = kMaps;
   }
-  return HObjectAccess(portion, offset, representation);
+  bool existing_inobject_property = true;
+  if (!map.is_null()) {
+    existing_inobject_property = (offset <
+        map->instance_size() - map->unused_property_fields() * kPointerSize);
+  }
+  return HObjectAccess(portion, offset, representation, Handle<String>::null(),
+                       false, existing_inobject_property);
 }
 
 
 HObjectAccess HObjectAccess::ForAllocationSiteOffset(int offset) {
   switch (offset) {
     case AllocationSite::kTransitionInfoOffset:
       return HObjectAccess(kInobject, offset, Representation::Tagged());
     case AllocationSite::kNestedSiteOffset:
       return HObjectAccess(kInobject, offset, Representation::Tagged());
     case AllocationSite::kPretenureDataOffset:
@@ skipping 31 matching lines @@
   } else if (offset == JSObject::kMapOffset) {
     portion = kMaps;
   }
   return HObjectAccess(portion, offset);
 }
 
 
 HObjectAccess HObjectAccess::ForBackingStoreOffset(int offset,
     Representation representation) {
   ASSERT(offset >= 0);
-  return HObjectAccess(kBackingStore, offset, representation);
+  return HObjectAccess(kBackingStore, offset, representation,
+                       Handle<String>::null(), false, false);
 }
 
 
 HObjectAccess HObjectAccess::ForField(Handle<Map> map,
     LookupResult *lookup, Handle<String> name) {
   ASSERT(lookup->IsField() || lookup->IsTransitionToField(*map));
   int index;
   Representation representation;
   if (lookup->IsField()) {
     index = lookup->GetLocalFieldIndexFromMap(*map);
     representation = lookup->representation();
   } else {
     Map* transition = lookup->GetTransitionMapFromMap(*map);
     int descriptor = transition->LastAdded();
     index = transition->instance_descriptors()->GetFieldIndex(descriptor) -
         map->inobject_properties();
     PropertyDetails details =
         transition->instance_descriptors()->GetDetails(descriptor);
     representation = details.representation();
   }
   if (index < 0) {
     // Negative property indices are in-object properties, indexed
     // from the end of the fixed part of the object.
     int offset = (index * kPointerSize) + map->instance_size();
-    return HObjectAccess(kInobject, offset, representation, name);
+    return HObjectAccess(kInobject, offset, representation, name, false, true);
   } else {
     // Non-negative property indices are in the properties array.
     int offset = (index * kPointerSize) + FixedArray::kHeaderSize;
-    return HObjectAccess(kBackingStore, offset, representation, name);
+    return HObjectAccess(kBackingStore, offset, representation, name,
+                         false, false);
   }
 }
 
 
 HObjectAccess HObjectAccess::ForCellPayload(Isolate* isolate) {
   return HObjectAccess(
       kInobject, Cell::kValueOffset, Representation::Tagged(),
       Handle<String>(isolate->heap()->cell_value_string()));
 }
 
@@ skipping 76 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal