Re-reland: Remove register index/code indirection

src/mips64/macro-assembler-mips64.cc

Index: src/mips64/macro-assembler-mips64.cc
diff --git a/src/mips64/macro-assembler-mips64.cc b/src/mips64/macro-assembler-mips64.cc
index 26229c9d8725c55cdf750f3cd3dbda3c827038db..8f4db303d27f6a651d0a874f542afd405ea593a3 100644
--- a/src/mips64/macro-assembler-mips64.cc
+++ b/src/mips64/macro-assembler-mips64.cc
@@ -11,6 +11,7 @@
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/mips64/macro-assembler-mips64.h"
+#include "src/register-configuration.h"
 #include "src/runtime/runtime.h"
 
 namespace v8 {
@@ -148,7 +149,7 @@ MemOperand MacroAssembler::SafepointRegisterSlot(Register reg) {
 MemOperand MacroAssembler::SafepointRegistersAndDoublesSlot(Register reg) {
   UNIMPLEMENTED_MIPS();
   // General purpose registers are pushed last on the stack.
-  int doubles_size = FPURegister::NumAllocatableRegisters() * kDoubleSize;
+  int doubles_size = DoubleRegister::kMaxNumRegisters * kDoubleSize;
   int register_offset = SafepointRegisterStackIndex(reg.code()) * kPointerSize;
   return MemOperand(sp, doubles_size + register_offset);
 }
@@ -3761,7 +3762,7 @@ void MacroAssembler::CopyFields(Register dst,
   // Find a temp register in temps list.
   for (int i = 0; i < kNumRegisters; i++) {
     if ((temps & (1 << i)) != 0) {
-      tmp.code_ = i;
+      tmp.reg_code = i;
       break;
     }
   }
@@ -6042,8 +6043,10 @@ Register GetRegisterThatIsNotOneOf(Register reg1,
   if (reg5.is_valid()) regs |= reg5.bit();
   if (reg6.is_valid()) regs |= reg6.bit();
 
-  for (int i = 0; i < Register::NumAllocatableRegisters(); i++) {
-    Register candidate = Register::FromAllocationIndex(i);
+  const RegisterConfiguration* config = RegisterConfiguration::ArchDefault();
+  for (int i = 0; i < config->num_allocatable_general_registers(); ++i) {
+    int code = config->GetAllocatableGeneralCode(i);
+    Register candidate = Register::from_code(code);
     if (regs & candidate.bit()) continue;
     return candidate;
   }