provides a mechanism for optimizing compilers to select the different Register configuration.

src/compiler/register-allocator.cc

Index: src/compiler/register-allocator.cc
diff --git a/src/compiler/register-allocator.cc b/src/compiler/register-allocator.cc
index 1dea881fe2b0b19dd00a0ef52a983cf7e145eaa7..b8a1ea9a4dd244ad9344b046ff9fe582c639cf31 100644
--- a/src/compiler/register-allocator.cc
+++ b/src/compiler/register-allocator.cc
@@ -35,7 +35,7 @@ int GetRegisterCount(const RegisterConfiguration* cfg, RegisterKind kind) {
 int GetAllocatableRegisterCount(const RegisterConfiguration* cfg,
                                 RegisterKind kind) {
   return kind == DOUBLE_REGISTERS
-             ? cfg->num_allocatable_aliased_double_registers()
+             ? cfg->num_allocatable_aliased_double_registers(true)
              : cfg->num_allocatable_general_registers();
 }
 
@@ -1956,8 +1956,8 @@ void LiveRangeBuilder::ProcessInstructions(const InstructionBlock* block,
     }
 
     if (instr->ClobbersDoubleRegisters()) {
-      for (int i = 0; i < config()->num_allocatable_aliased_double_registers();
-           ++i) {
+      for (int i = 0;
+           i < config()->num_allocatable_aliased_double_registers(true); ++i) {
         int code = config()->GetAllocatableDoubleCode(i);
         if (!IsOutputDoubleRegisterOf(instr, DoubleRegister::from_code(code))) {
           auto range = FixedDoubleLiveRangeFor(code);