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()

[danno, 2015/10/16 08:47:02]

If you pass the enum value mentioned elsewhere in my comments to the
constructor, you can have a single ArchDefaultRegisterConfiguration class with a
very local decision based on the parameter for x87 and removes the need to
duplicate all the code below.

       : RegisterConfiguration(
             Register::kNumRegisters, DoubleRegister::kMaxNumRegisters,
 #if V8_TARGET_ARCH_IA32
             kMaxAllocatableGeneralRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_X87
+            kMaxAllocatableGeneralRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+            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
+                : (ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_COUNT)0),
+            ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_COUNT)0,
+#elif V8_TARGET_ARCH_ARM64
+            kMaxAllocatableGeneralRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+#elif V8_TARGET_ARCH_MIPS
+            kMaxAllocatableGeneralRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+#elif V8_TARGET_ARCH_MIPS64
+            kMaxAllocatableGeneralRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+#elif V8_TARGET_ARCH_PPC
+            kMaxAllocatableGeneralRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+#else
+            GetAllocatableGeneralRegisterCount(),
+            GetAllocatableDoubleRegisterCount(),
+            GetAllocatableAliasedDoubleRegisterCount(),
+#endif
+            GetAllocatableGeneralCodes(), GetAllocatableDoubleCodes(),
+            kGeneralRegisterNames, kDoubleRegisterNames) {
+  }
+
+  const char* general_register_name_table_[Register::kNumRegisters];
+  const char* double_register_name_table_[DoubleRegister::kMaxNumRegisters];
+
+ private:
+  static const int* GetAllocatableGeneralCodes() {
+#define REGISTER_CODE(R) Register::kCode_##R,
+    static const int general_codes[] = {
+        ALLOCATABLE_GENERAL_REGISTERS(REGISTER_CODE)};
+#undef REGISTER_CODE
+    return general_codes;
+  }
+
+  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;
+  }
+};
+
+
+class ArchDefaultRegisterConfigurationForTurbofan
+    : public RegisterConfiguration {
+ public:
+  ArchDefaultRegisterConfigurationForTurbofan()
+      : RegisterConfiguration(
+            Register::kNumRegisters, DoubleRegister::kMaxNumRegisters,
+#if V8_TARGET_ARCH_IA32
+            kMaxAllocatableGeneralRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+            kMaxAllocatableDoubleRegisterCount,
+#elif V8_TARGET_ARCH_X87
             kMaxAllocatableGeneralRegisterCount, 1, 1,
 #elif V8_TARGET_ARCH_X64
             kMaxAllocatableGeneralRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
             kMaxAllocatableDoubleRegisterCount,
 #elif V8_TARGET_ARCH_ARM
             FLAG_enable_embedded_constant_pool
                 ? (kMaxAllocatableGeneralRegisterCount - 1)
                 : kMaxAllocatableGeneralRegisterCount,
             CpuFeatures::IsSupported(VFP32DREGS)
@@ skipping 43 matching lines @@
         ALLOCATABLE_DOUBLE_REGISTERS(REGISTER_CODE)};
 #undef REGISTER_CODE
     return double_codes;
   }
 };
 
 
 static base::LazyInstance<ArchDefaultRegisterConfiguration>::type
     kDefaultRegisterConfiguration = LAZY_INSTANCE_INITIALIZER;
 
+static base::LazyInstance<ArchDefaultRegisterConfigurationForTurbofan>::type
+    kDefaultRegisterConfigurationForTurbo = LAZY_INSTANCE_INITIALIZER;
+
 }  // namespace
 
 
 const RegisterConfiguration* RegisterConfiguration::ArchDefault() {
   return &kDefaultRegisterConfiguration.Get();
 }
 
+
+const RegisterConfiguration* RegisterConfiguration::ArchDefaultForTurbo() {
+  return &kDefaultRegisterConfiguration.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