Remove (H|L)JSArrayLength instructions

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 1147 matching lines @@
       AddInstruction(new(zone) HLoadElements(object, mapcheck));
   if (is_store && (fast_elements || fast_smi_only_elements) &&
       store_mode != STORE_NO_TRANSITION_HANDLE_COW) {
     HCheckMaps* check_cow_map = new(zone) HCheckMaps(
         elements, isolate()->factory()->fixed_array_map(), zone);
     check_cow_map->ClearGVNFlag(kDependsOnElementsKind);
     AddInstruction(check_cow_map);
   }
   HInstruction* length = NULL;
   if (is_js_array) {
-    length = AddInstruction(new(zone) HJSArrayLength(object, mapcheck,
-                                                     HType::Smi()));
+    length = AddInstruction(
+        HLoadNamedField::NewArrayLength(zone, object, mapcheck));

[danno, 2013/04/02 11:10:43]

I think you are losing the fact that the type of this instruction is a Smi. It
is used for optimization purposes later in the compilation pipeline. Some array
lengths are known to be Smis (if their map is guaranteed to fast elements), but
otherwise, they may be a tagged heap number, which will require more heavy
checks in the generated code. You will need to preserve the ability to specify
the return type of the load.

   } else {
     length = AddInstruction(new(zone) HFixedArrayBaseLength(elements));
   }
   HValue* checked_key = NULL;
   if (IsExternalArrayElementsKind(elements_kind)) {
     if (store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS) {
       HLoadExternalArrayPointer* external_elements =
           new(zone) HLoadExternalArrayPointer(elements);
       AddInstruction(external_elements);
       IfBuilder length_checker(this);
@@ skipping 50 matching lines @@
     }
   }
   return AddInstruction(
       BuildFastElementAccess(elements, checked_key, val, mapcheck,
                              elements_kind, is_store, store_mode));
 }
 
 
 HInstruction* HGraphBuilder::BuildFastArrayLengthLoad(HValue* object,
                                                       HValue* typecheck) {
-  Zone* zone = this->zone();
-  return new (zone) HJSArrayLength(object, typecheck, HType::Smi());
+  return HLoadNamedField::NewArrayLength(zone(), object, typecheck);
 }
 
 
 HValue* HGraphBuilder::BuildAllocateElements(HValue* context,
                                              ElementsKind kind,
                                              HValue* capacity) {
   BailoutId ast_id = current_block()->last_environment()->previous_ast_id();
   Zone* zone = this->zone();
 
   int elements_size = IsFastDoubleElementsKind(kind)
@@ skipping 6118 matching lines @@
         HBasicBlock* if_jsarray = graph()->CreateBasicBlock();
         HBasicBlock* if_fastobject = graph()->CreateBasicBlock();
         HHasInstanceTypeAndBranch* typecheck =
             new(zone()) HHasInstanceTypeAndBranch(object, JS_ARRAY_TYPE);
         typecheck->SetSuccessorAt(0, if_jsarray);
         typecheck->SetSuccessorAt(1, if_fastobject);
         current_block()->Finish(typecheck);
 
         set_current_block(if_jsarray);
         HInstruction* length;
-        length = AddInstruction(new(zone()) HJSArrayLength(object, typecheck,
-                                                           HType::Smi()));
+        length = AddInstruction(
+            HLoadNamedField::NewArrayLength(zone(), object, typecheck));
         checked_key = AddBoundsCheck(key, length, ALLOW_SMI_KEY);
         access = AddInstruction(BuildFastElementAccess(
             elements, checked_key, val, elements_kind_branch,
             elements_kind, is_store, STANDARD_STORE));
         if (!is_store) {
           Push(access);
         }
 
         *has_side_effects |= access->HasObservableSideEffects();
         if (position != -1) {
@@ skipping 3887 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal