Add map check for COW elements to crankshaft array handling code.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index b3f428cb3a793ffbb2c940fd7040cda7d65b1c54..f8ccdb597fe16fd8aa2a5b219af90f36fc9828a0 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -3921,12 +3921,16 @@ HInstruction* HGraphBuilder::BuildMonomorphicElementAccess(HValue* object,
                                            val, map->elements_kind(), is_store);
   }
   ASSERT(map->has_fast_elements());
+  HInstruction* elements_cow_map_check = new(zone()) HCheckMap(

[Vyacheslav Egorov (Chromium), 2011/07/14 13:03:44]

I find the name of the variable confusing. We are checking exactly opposite
(that elements are NOT COW.

[Jakob Kummerow, 2011/07/14 14:44:49]

Done, sort of: I've removed the variable completely.

+      elements, isolate()->factory()->fixed_array_map());
   if (map->instance_type() == JS_ARRAY_TYPE) {
     length = AddInstruction(new(zone()) HJSArrayLength(object));
     checked_key = AddInstruction(new(zone()) HBoundsCheck(key, length));
     AddInstruction(elements);
+    AddInstruction(elements_cow_map_check);

[Vyacheslav Egorov (Chromium), 2011/07/14 13:03:44]

This map check is redundant if !is_store.

Can you also extend the regression testcase that tests monomorphic keyed stores
(current testcase tests polymorphic stores)? 

[Jakob Kummerow, 2011/07/14 14:44:49]

Done.
Done.

   } else {
     AddInstruction(elements);
+    AddInstruction(elements_cow_map_check);

[Vyacheslav Egorov (Chromium), 2011/07/14 13:03:44]

Ditto.

[Jakob Kummerow, 2011/07/14 14:44:49]

Done.

     length = AddInstruction(new(zone()) HFixedArrayLength(elements));
     checked_key = AddInstruction(new(zone()) HBoundsCheck(key, length));
   }
@@ -4032,6 +4036,8 @@ HValue* HGraphBuilder::HandlePolymorphicElementAccess(HValue* object,
         checked_key = AddInstruction(new(zone()) HBoundsCheck(key, length));
         elements = AddInstruction(new(zone()) HLoadElements(object));
         elements->ClearFlag(HValue::kUseGVN);
+        AddInstruction(new(zone()) HCheckMap(

[Vyacheslav Egorov (Chromium), 2011/07/14 13:03:44]

redundant if !is_store

[Jakob Kummerow, 2011/07/14 14:44:49]

Done.

+              elements, isolate()->factory()->fixed_array_map()));
         if (is_store) {
           access = AddInstruction(
               new(zone()) HStoreKeyedFastElement(elements, checked_key, val));
@@ -4049,6 +4055,8 @@ HValue* HGraphBuilder::HandlePolymorphicElementAccess(HValue* object,
         set_current_block(if_fastobject);
         elements = AddInstruction(new(zone()) HLoadElements(object));
         elements->ClearFlag(HValue::kUseGVN);
+        AddInstruction(new(zone()) HCheckMap(

[Vyacheslav Egorov (Chromium), 2011/07/14 13:03:44]

This map check is redundant if !is_store

[Jakob Kummerow, 2011/07/14 14:44:49]

Done.

+              elements, isolate()->factory()->fixed_array_map()));
         length = AddInstruction(new(zone()) HFixedArrayLength(elements));
         checked_key = AddInstruction(new(zone()) HBoundsCheck(key, length));
         if (is_store) {