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

src/register-configuration.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/register-configuration.h"
 #include "src/globals.h"
 #include "src/macro-assembler.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 18 matching lines @@
 #undef REGISTER_NAME
 };
 
 STATIC_ASSERT(RegisterConfiguration::kMaxGeneralRegisters >=
               Register::kNumRegisters);
 STATIC_ASSERT(RegisterConfiguration::kMaxDoubleRegisters >=
               DoubleRegister::kMaxNumRegisters);
 
 class ArchDefaultRegisterConfiguration : public RegisterConfiguration {
  public:
-  ArchDefaultRegisterConfiguration()
+  explicit ArchDefaultRegisterConfiguration(CompilerSelector compiler)
       : RegisterConfiguration(
             Register::kNumRegisters, DoubleRegister::kMaxNumRegisters,
 #if V8_TARGET_ARCH_IA32
             kMaxAllocatableGeneralRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_X87
-            kMaxAllocatableGeneralRegisterCount, 1, 1,
+            kMaxAllocatableGeneralRegisterCount,
+            compiler == TURBOFAN ? 1 : kMaxAllocatableDoubleRegisterCount,
+            compiler == TURBOFAN ? 1 : kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_X64
             kMaxAllocatableGeneralRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_ARM
             FLAG_enable_embedded_constant_pool
                 ? (kMaxAllocatableGeneralRegisterCount - 1)
                 : kMaxAllocatableGeneralRegisterCount,
             CpuFeatures::IsSupported(VFP32DREGS)
                 ? kMaxAllocatableDoubleRegisterCount
@@ skipping 39 matching lines @@
   static const int* GetAllocatableDoubleCodes() {
 #define REGISTER_CODE(R) DoubleRegister::kCode_##R,
     static const int double_codes[] = {
         ALLOCATABLE_DOUBLE_REGISTERS(REGISTER_CODE)};
 #undef REGISTER_CODE
     return double_codes;
   }
 };
 
 
-static base::LazyInstance<ArchDefaultRegisterConfiguration>::type
-    kDefaultRegisterConfiguration = LAZY_INSTANCE_INITIALIZER;
+template <RegisterConfiguration::CompilerSelector compiler>
+struct RegisterConfigurationInitializer {
+  static void Construct(ArchDefaultRegisterConfiguration* config) {
+    new (config) ArchDefaultRegisterConfiguration(compiler);
+  }
+};
+
+static base::LazyInstance<
+    ArchDefaultRegisterConfiguration,
+    RegisterConfigurationInitializer<RegisterConfiguration::CRANKSHAFT>>::type
+    kDefaultRegisterConfigurationForCrankshaft = LAZY_INSTANCE_INITIALIZER;
+
+
+static base::LazyInstance<
+    ArchDefaultRegisterConfiguration,
+    RegisterConfigurationInitializer<RegisterConfiguration::TURBOFAN>>::type
+    kDefaultRegisterConfigurationForTurboFan = LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
 
-const RegisterConfiguration* RegisterConfiguration::ArchDefault() {
-  return &kDefaultRegisterConfiguration.Get();
+const RegisterConfiguration* RegisterConfiguration::ArchDefault(
+    CompilerSelector compiler) {
+  return compiler == TURBOFAN
+             ? &kDefaultRegisterConfigurationForTurboFan.Get()
+             : &kDefaultRegisterConfigurationForCrankshaft.Get();
 }
 
+
 RegisterConfiguration::RegisterConfiguration(
     int num_general_registers, int num_double_registers,
     int num_allocatable_general_registers, int num_allocatable_double_registers,
     int num_allocatable_aliased_double_registers,
     const int* allocatable_general_codes, const int* allocatable_double_codes,
     const char* const* general_register_names,
     const char* const* double_register_names)
     : num_general_registers_(num_general_registers),
       num_double_registers_(num_double_registers),
       num_allocatable_general_registers_(num_allocatable_general_registers),
@@ skipping 11 matching lines @@
   }
   for (int i = 0; i < num_allocatable_double_registers_; ++i) {
     allocatable_double_codes_mask_ |= (1 << allocatable_double_codes_[i]);
   }
 }
 
 #undef REGISTER_COUNT
 
 }  // namespace internal
 }  // namespace v8