Remove HFixedArrayBaseLength instruction and replace with regular HLoadNamedField.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 840abea86c1b5c6495207956d612717a3cced8be..1d9e1f5e69e5fca477f718b8eb6fde4439ac1e22 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -1131,7 +1131,7 @@ HValue* HGraphBuilder::BuildCheckForCapacityGrow(HValue* object,
   length_checker.IfCompare(length, key, Token::EQ);
   length_checker.Then();
 
-  HValue* current_capacity = Add<HFixedArrayBaseLength>(elements);
+  HValue* current_capacity = AddLoadFixedArrayLength(elements);
 
   IfBuilder capacity_checker(this);
 
@@ -1187,7 +1187,7 @@ HValue* HGraphBuilder::BuildCopyElementsOnWrite(HValue* object,
                            Handle<Map>(heap->fixed_cow_array_map()));
   cow_checker.Then();
 
-  HValue* capacity = Add<HFixedArrayBaseLength>(elements);
+  HValue* capacity = AddLoadFixedArrayLength(elements);
 
   HValue* new_elements = BuildGrowElementsCapacity(object, elements,
                                                    kind, length, capacity);
@@ -1242,10 +1242,10 @@ HInstruction* HGraphBuilder::BuildUncheckedMonomorphicElementAccess(
   if (is_js_array) {
     length = AddLoad(object, HObjectAccess::ForArrayLength(), mapcheck,
         Representation::Smi());
-    length->set_type(HType::Smi());
   } else {
-    length = Add<HFixedArrayBaseLength>(elements);
+    length = AddLoadFixedArrayLength(elements);
   }
+  length->set_type(HType::Smi());

[Massi, 2013/07/02 10:48:26]

AddLoadFixedArrayLength already sets the type to Smi.
Wouldn't it be better to set the Smi type in the is_js_array branch above, and
here maybe just ASSERT that the type is Smi?

   HValue* checked_key = NULL;
   if (IsExternalArrayElementsKind(elements_kind)) {
     if (store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS) {
@@ -1415,6 +1415,14 @@ HLoadNamedField* HGraphBuilder::AddLoadElements(HValue* object,
 }
 
 
+HLoadNamedField* HGraphBuilder::AddLoadFixedArrayLength(HValue* object) {
+  HLoadNamedField* instr = AddLoad(object, HObjectAccess::ForFixedArrayLength(),
+                                   NULL, Representation::Smi());
+  instr->set_type(HType::Smi());
+  return instr;
+}
+
+
 HValue* HGraphBuilder::BuildNewElementsCapacity(HValue* context,
                                                 HValue* old_capacity) {
   Zone* zone = this->zone();
@@ -7030,7 +7038,7 @@ HValue* HOptimizedGraphBuilder::HandlePolymorphicElementAccess(
                   LAST_ELEMENTS_KIND);
     if (elements_kind == FIRST_EXTERNAL_ARRAY_ELEMENTS_KIND
         && todo_external_array) {
-      HInstruction* length = Add<HFixedArrayBaseLength>(elements);
+      HInstruction* length = AddLoadFixedArrayLength(elements);
       checked_key = Add<HBoundsCheck>(key, length);
       external_elements = Add<HLoadExternalArrayPointer>(elements);
     }
@@ -7090,7 +7098,7 @@ HValue* HOptimizedGraphBuilder::HandlePolymorphicElementAccess(
         if_jsarray->GotoNoSimulate(join);
 
         set_current_block(if_fastobject);
-        length = AddInstruction(new(zone()) HFixedArrayBaseLength(elements));
+        length = AddLoadFixedArrayLength(elements);
         checked_key = Add<HBoundsCheck>(key, length);
         access = AddInstruction(BuildFastElementAccess(
             elements, checked_key, val, elements_kind_branch,