Revert of Remove register index/code indirection

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 80153ae7fc2e2ba507bf06b740174a41b0029e99..b163061458ec1376cfd4623c957df2138a0df90c 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -72,7 +72,7 @@
   BitVector* doubles = chunk()->allocated_double_registers();
   BitVector::Iterator save_iterator(doubles);
   while (!save_iterator.Done()) {
-    __ vstr(DoubleRegister::from_code(save_iterator.Current()),
+    __ vstr(DwVfpRegister::FromAllocationIndex(save_iterator.Current()),
             MemOperand(sp, count * kDoubleSize));
     save_iterator.Advance();
     count++;
@@ -88,8 +88,8 @@
   BitVector::Iterator save_iterator(doubles);
   int count = 0;
   while (!save_iterator.Done()) {
-    __ vldr(DoubleRegister::from_code(save_iterator.Current()),
-            MemOperand(sp, count * kDoubleSize));
+    __ vldr(DwVfpRegister::FromAllocationIndex(save_iterator.Current()),
+             MemOperand(sp, count * kDoubleSize));
     save_iterator.Advance();
     count++;
   }
@@ -405,13 +405,13 @@
 }
 
 
-Register LCodeGen::ToRegister(int code) const {
-  return Register::from_code(code);
-}
-
-
-DwVfpRegister LCodeGen::ToDoubleRegister(int code) const {
-  return DwVfpRegister::from_code(code);
+Register LCodeGen::ToRegister(int index) const {
+  return Register::FromAllocationIndex(index);
+}
+
+
+DwVfpRegister LCodeGen::ToDoubleRegister(int index) const {
+  return DwVfpRegister::FromAllocationIndex(index);
 }