Revert of Remove register index/code indirection

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 3eb3b2ff0b4a4c301c7050ec4eb01433ae005e4f..0361828eb5f901823404ca4ad571cfcc189b5f30 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -11,7 +11,6 @@
 #include "src/cpu-profiler.h"
 #include "src/debug/debug.h"
 #include "src/heap/heap.h"
-#include "src/register-configuration.h"
 #include "src/x64/assembler-x64.h"
 #include "src/x64/macro-assembler-x64.h"
 
@@ -731,8 +730,7 @@
 }
 
 
-#define REG(Name) \
-  { Register::kCode_##Name }
+#define REG(Name) { kRegister_ ## Name ## _Code }
 
 static const Register saved_regs[] = {
   REG(rax), REG(rcx), REG(rdx), REG(rbx), REG(rbp), REG(rsi), REG(rdi), REG(r8),
@@ -3706,14 +3704,12 @@
 #endif
   // Optionally save all XMM registers.
   if (save_doubles) {
-    int space = XMMRegister::kMaxNumRegisters * kDoubleSize +
-                arg_stack_space * kRegisterSize;
+    int space = XMMRegister::kMaxNumAllocatableRegisters * kDoubleSize +
+        arg_stack_space * kRegisterSize;
     subp(rsp, Immediate(space));
     int offset = -2 * kPointerSize;
-    const RegisterConfiguration* config = RegisterConfiguration::ArchDefault();
-    for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
-      DoubleRegister reg =
-          DoubleRegister::from_code(config->GetAllocatableDoubleCode(i));
+    for (int i = 0; i < XMMRegister::NumAllocatableRegisters(); i++) {
+      XMMRegister reg = XMMRegister::FromAllocationIndex(i);
       movsd(Operand(rbp, offset - ((i + 1) * kDoubleSize)), reg);
     }
   } else if (arg_stack_space > 0) {
@@ -3756,10 +3752,8 @@
   // r15 : argv
   if (save_doubles) {
     int offset = -2 * kPointerSize;
-    const RegisterConfiguration* config = RegisterConfiguration::ArchDefault();
-    for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
-      DoubleRegister reg =
-          DoubleRegister::from_code(config->GetAllocatableDoubleCode(i));
+    for (int i = 0; i < XMMRegister::NumAllocatableRegisters(); i++) {
+      XMMRegister reg = XMMRegister::FromAllocationIndex(i);
       movsd(reg, Operand(rbp, offset - ((i + 1) * kDoubleSize)));
     }
   }