Revert of Remove register index/code indirection

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 55438ad888620a2275c897b1e6b719f27739f34e..99c0938b6a4b5110d0b28a7f70c61c2c9ac9c732 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -101,7 +101,7 @@
   BitVector::Iterator save_iterator(doubles);
   while (!save_iterator.Done()) {
     __ movsd(MemOperand(esp, count * kDoubleSize),
-             XMMRegister::from_code(save_iterator.Current()));
+              XMMRegister::FromAllocationIndex(save_iterator.Current()));
     save_iterator.Advance();
     count++;
   }
@@ -116,8 +116,8 @@
   BitVector::Iterator save_iterator(doubles);
   int count = 0;
   while (!save_iterator.Done()) {
-    __ movsd(XMMRegister::from_code(save_iterator.Current()),
-             MemOperand(esp, count * kDoubleSize));
+    __ movsd(XMMRegister::FromAllocationIndex(save_iterator.Current()),
+              MemOperand(esp, count * kDoubleSize));
     save_iterator.Advance();
     count++;
   }
@@ -515,13 +515,13 @@
 }
 
 
-Register LCodeGen::ToRegister(int code) const {
-  return Register::from_code(code);
-}
-
-
-XMMRegister LCodeGen::ToDoubleRegister(int code) const {
-  return XMMRegister::from_code(code);
+Register LCodeGen::ToRegister(int index) const {
+  return Register::FromAllocationIndex(index);
+}
+
+
+XMMRegister LCodeGen::ToDoubleRegister(int index) const {
+  return XMMRegister::FromAllocationIndex(index);
 }