Use the same registers for StoreIC and KeyedStoreIC.

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index c0ab7e9e5a17cdb243db3224d5636aef572e8880..f6ae893b398d8433015e321584e03976f3898055 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -2455,6 +2455,23 @@ class ElementsTransitionAndStoreStub : public HydrogenCodeStub {
   virtual void InitializeInterfaceDescriptor(
       CodeStubInterfaceDescriptor* descriptor) V8_OVERRIDE;
 
+  enum RegisterInfo {

[Michael Starzinger, 2014/07/11 08:27:08]

nit: Let's add a comment "// Parameters accessed via
CodeStubGraphBuilder::GetParameter()" similar to the other hydrogen stubs here.
Also does it really increase readability to have an enum for this instead of a
list of const ints? I would prefer the latter.

[mvstanton, 2014/07/11 08:43:09]

Cool, I'll add the comment. As for the enum format, I'm following the convention
laid down in a few previous CLs in ic.h for Load/StoreKeyed. You get an enum
which gives you ordering for stack-based calls, then the registers. If it's cool
I'll keep that convention for now, perhaps later do a refactoring CL to turn
them into const ints monolithically.

[Michael Starzinger, 2014/07/11 09:04:10]

As discussed offline: In this case I am fine with keeping the enum as it is. But
please add the comment.

+    kValueIndex,
+    kMapIndex,
+    kKeyIndex,
+    kObjectIndex,
+    kRegisterArgumentCount

[Michael Starzinger, 2014/07/11 08:27:08]

nit: The register count doesn't seem to be used. Can we drop it to avoid
confusion?

[mvstanton, 2014/07/11 08:43:09]

It's part of the convention, and is used in some asserts for some ICs, but it's
true, I don't use this one. Actually, how about this idea: the bailout method
uses the constant in an assert around arguments length, the bailout method could
also use those indexes to extract arguments instead of 0, 1, 2, etc.

[Michael Starzinger, 2014/07/11 09:04:10]

Acknowledged.

+  };
+
+  static const Register ValueRegister() {
+    return KeyedStoreIC::ValueRegister();
+  }
+  static const Register MapRegister() { return KeyedStoreIC::MapRegister(); }
+  static const Register KeyRegister() { return KeyedStoreIC::NameRegister(); }
+  static const Register ObjectRegister() {
+    return KeyedStoreIC::ReceiverRegister();
+  }
+
  private:
   class FromBits:      public BitField<ElementsKind,          0, 8> {};
   class ToBits:        public BitField<ElementsKind,          8, 8> {};