Re-reland: Remove register index/code indirection

test/cctest/test-code-stubs-mips64.cc

Index: test/cctest/test-code-stubs-mips64.cc
diff --git a/test/cctest/test-code-stubs-mips64.cc b/test/cctest/test-code-stubs-mips64.cc
index a8dd13cc0735929631db2da5d349d3ec07418bc0..fde2d07a9c12864b3096b9e9d7d9dec8daa3cbb6 100644
--- a/test/cctest/test-code-stubs-mips64.cc
+++ b/test/cctest/test-code-stubs-mips64.cc
@@ -34,6 +34,7 @@
 #include "src/factory.h"
 #include "src/macro-assembler.h"
 #include "src/mips64/constants-mips64.h"
+#include "src/register-configuration.h"
 #include "src/simulator.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/test-code-stubs.h"
@@ -79,7 +80,8 @@ ConvertDToIFunc MakeConvertDToIFuncTrampoline(Isolate* isolate,
   // Save registers make sure they don't get clobbered.
   int source_reg_offset = kDoubleSize;
   int reg_num = 2;
-  for (; reg_num < Register::NumAllocatableRegisters(); ++reg_num) {
+  const RegisterConfiguration* config = RegisterConfiguration::ArchDefault();
+  for (; reg_num < config->num_allocatable_general_registers(); ++reg_num) {
     Register reg = Register::from_code(reg_num);
     if (!reg.is(destination_reg)) {
       __ push(reg);