Optimize Smi keys for KeyedLoads

src/ia32/lithium-ia32.h

Index: src/ia32/lithium-ia32.h
diff --git a/src/ia32/lithium-ia32.h b/src/ia32/lithium-ia32.h
index e05a936291760a49fffaaaf5402c0bd68f2ab67b..ee9bf79601da0a1f1bd9b97ed9fb33b172d89e6f 100644
--- a/src/ia32/lithium-ia32.h
+++ b/src/ia32/lithium-ia32.h
@@ -872,6 +872,7 @@ class LBoundsCheck: public LTemplateInstruction<0, 2, 0> {
   LOperand* length() { return inputs_[1]; }
 
   DECLARE_CONCRETE_INSTRUCTION(BoundsCheck, "bounds-check")
+  DECLARE_HYDROGEN_ACCESSOR(BoundsCheck)
 };
 
 
@@ -1277,6 +1278,19 @@ class LLoadKeyedFastDoubleElement: public LTemplateInstruction<1, 2, 0> {
 };
 
 
+inline static bool ExternalArrayOpRequiresTemp(
+    Representation key_representation,
+    ElementsKind elements_kind) {
+  // Operations that require the key to be divided by two to be converted into
+  // an index cannot fold the scale operation into a load and need an extra
+  // temp register to do the work.
+  return key_representation.IsTagged() &&
+      (elements_kind == EXTERNAL_BYTE_ELEMENTS ||
+       elements_kind == EXTERNAL_UNSIGNED_BYTE_ELEMENTS ||
+       elements_kind == EXTERNAL_PIXEL_ELEMENTS);
+}
+
+
 class LLoadKeyedSpecializedArrayElement: public LTemplateInstruction<1, 2, 0> {
  public:
   LLoadKeyedSpecializedArrayElement(LOperand* external_pointer, LOperand* key) {