Config double register number as 1 for X87 Turbofan.

src/compiler/register-configuration.cc

Index: src/compiler/register-configuration.cc
diff --git a/src/compiler/register-configuration.cc b/src/compiler/register-configuration.cc
index 7257aca02f0f236cc6ab515bb57be85cd387276b..4216443e1495dcf94c43d65e99807b07816a4380 100644
--- a/src/compiler/register-configuration.cc
+++ b/src/compiler/register-configuration.cc
@@ -20,11 +20,12 @@ STATIC_ASSERT(RegisterConfiguration::kMaxDoubleRegisters >=
 class ArchDefaultRegisterConfiguration : public RegisterConfiguration {
  public:
   ArchDefaultRegisterConfiguration()
-      : RegisterConfiguration(Register::kMaxNumAllocatableRegisters,
-                              DoubleRegister::kMaxNumAllocatableRegisters,
-                              DoubleRegister::NumAllocatableAliasedRegisters(),
-                              general_register_name_table_,
-                              double_register_name_table_) {
+      : RegisterConfiguration(
+           Register::kMaxNumAllocatableRegisters,
+           DoubleRegister::NumAllocatableRegistersForTurbo(),

[titzer, 2015/06/09 14:47:00]

This is the class meant to configure turbofan. Why don't we add the logic here
instead of everywhere else?

+           DoubleRegister::NumAllocatableAliasedRegistersForTurbo(),
+           general_register_name_table_,
+           double_register_name_table_) {
     DCHECK_EQ(Register::kMaxNumAllocatableRegisters,
               Register::NumAllocatableRegisters());
     for (int i = 0; i < Register::kMaxNumAllocatableRegisters; ++i) {