Basic support for tracking smi-only arrays on ia32.

src/code-stubs.cc

Index: src/code-stubs.cc
diff --git a/src/code-stubs.cc b/src/code-stubs.cc
index 9c87c8490ac8a90cd1d8b8e141710d33f81b4639..1cb4b98e0f2af03fd148c812567b0857b5376ab6 100644
--- a/src/code-stubs.cc
+++ b/src/code-stubs.cc
@@ -247,6 +247,7 @@ void InstanceofStub::PrintName(StringStream* stream) {
 void KeyedLoadElementStub::Generate(MacroAssembler* masm) {
   switch (elements_kind_) {
     case FAST_ELEMENTS:
+    case FAST_SMI_ONLY_ELEMENTS:
       KeyedLoadStubCompiler::GenerateLoadFastElement(masm);
       break;
     case FAST_DOUBLE_ELEMENTS:
@@ -276,7 +277,15 @@ void KeyedLoadElementStub::Generate(MacroAssembler* masm) {
 void KeyedStoreElementStub::Generate(MacroAssembler* masm) {
   switch (elements_kind_) {
     case FAST_ELEMENTS:
-      KeyedStoreStubCompiler::GenerateStoreFastElement(masm, is_js_array_);
+    case FAST_SMI_ONLY_ELEMENTS: {
+      KeyedStoreStubCompiler::StoreObjectAction store_object_action =
+          elements_kind_ == FAST_SMI_ONLY_ELEMENTS
+              ? KeyedStoreStubCompiler::kObjectStoreForcesGeneric
+              : KeyedStoreStubCompiler::kObjectStoreCausesWriteBarrier;
+      KeyedStoreStubCompiler::GenerateStoreFastElement(masm,
+                                                       is_js_array_,
+                                                       store_object_action);
+    }
       break;
     case FAST_DOUBLE_ELEMENTS:
       KeyedStoreStubCompiler::GenerateStoreFastDoubleElement(masm,