src/register-configuration.cc - v8/v8 - Git at Google

 // 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/base/lazy-instance.h"
 #include "src/cpu-features.h"
 #include "src/globals.h"
 #include "src/register-arch.h"

 namespace v8 {
 namespace internal {

 namespace {

 #define REGISTER_COUNT(R) 1 +
 static const int kMaxAllocatableGeneralRegisterCount =
     ALLOCATABLE_GENERAL_REGISTERS(REGISTER_COUNT)0;
 static const int kMaxAllocatableDoubleRegisterCount =
     ALLOCATABLE_DOUBLE_REGISTERS(REGISTER_COUNT)0;

 static const int kAllocatableGeneralCodes[] = {
 #define REGISTER_CODE(R) kRegCode_##R,
     ALLOCATABLE_GENERAL_REGISTERS(REGISTER_CODE)};
 #undef REGISTER_CODE

 #define REGISTER_CODE(R) kDoubleCode_##R,
 static const int kAllocatableDoubleCodes[] = {
     ALLOCATABLE_DOUBLE_REGISTERS(REGISTER_CODE)};
 #if V8_TARGET_ARCH_ARM
 static const int kAllocatableNoVFP32DoubleCodes[] = {
     ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_CODE)};
 #endif  // V8_TARGET_ARCH_ARM
 #undef REGISTER_CODE

 STATIC_ASSERT(RegisterConfiguration::kMaxGeneralRegisters >=
               Register::kNumRegisters);
 STATIC_ASSERT(RegisterConfiguration::kMaxFPRegisters >=
               FloatRegister::kNumRegisters);
 STATIC_ASSERT(RegisterConfiguration::kMaxFPRegisters >=
               DoubleRegister::kNumRegisters);
 STATIC_ASSERT(RegisterConfiguration::kMaxFPRegisters >=
               Simd128Register::kNumRegisters);

 static int get_num_allocatable_double_registers() {
   return
 #if V8_TARGET_ARCH_IA32
       kMaxAllocatableDoubleRegisterCount;
 #elif V8_TARGET_ARCH_X64
       kMaxAllocatableDoubleRegisterCount;
 #elif V8_TARGET_ARCH_ARM
       CpuFeatures::IsSupported(VFP32DREGS)
           ? kMaxAllocatableDoubleRegisterCount
           : (ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_COUNT) 0);
 #elif V8_TARGET_ARCH_ARM64
       kMaxAllocatableDoubleRegisterCount;
 #elif V8_TARGET_ARCH_MIPS
       kMaxAllocatableDoubleRegisterCount;
 #elif V8_TARGET_ARCH_MIPS64
       kMaxAllocatableDoubleRegisterCount;
 #elif V8_TARGET_ARCH_PPC
       kMaxAllocatableDoubleRegisterCount;
 #elif V8_TARGET_ARCH_S390
       kMaxAllocatableDoubleRegisterCount;
 #else
 #error Unsupported target architecture.
 #endif
 }

 #undef REGISTER_COUNT

 static const int* get_allocatable_double_codes() {
   return
 #if V8_TARGET_ARCH_ARM
       CpuFeatures::IsSupported(VFP32DREGS) ? kAllocatableDoubleCodes
                                            : kAllocatableNoVFP32DoubleCodes;
 #else
       kAllocatableDoubleCodes;
 #endif
 }

 class ArchDefaultRegisterConfiguration : public RegisterConfiguration {
  public:
   ArchDefaultRegisterConfiguration()
       : RegisterConfiguration(
             Register::kNumRegisters, DoubleRegister::kNumRegisters,
             kMaxAllocatableGeneralRegisterCount,
             get_num_allocatable_double_registers(), kAllocatableGeneralCodes,
             get_allocatable_double_codes(),
             kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE) {
   }
 };

 DEFINE_LAZY_LEAKY_OBJECT_GETTER(ArchDefaultRegisterConfiguration,
                                 GetDefaultRegisterConfiguration);

 // Allocatable registers with the masking register removed.
 class ArchDefaultPoisoningRegisterConfiguration : public RegisterConfiguration {
  public:
   ArchDefaultPoisoningRegisterConfiguration()
       : RegisterConfiguration(
             Register::kNumRegisters, DoubleRegister::kNumRegisters,
             kMaxAllocatableGeneralRegisterCount - 1,
             get_num_allocatable_double_registers(),
             InitializeGeneralRegisterCodes(), get_allocatable_double_codes(),
             kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE) {
   }

  private:
   static const int* InitializeGeneralRegisterCodes() {
     int filtered_index = 0;
     for (int i = 0; i < kMaxAllocatableGeneralRegisterCount; ++i) {
       if (kAllocatableGeneralCodes[i] != kSpeculationPoisonRegister.code()) {
         allocatable_general_codes_[filtered_index] =
             kAllocatableGeneralCodes[i];
         filtered_index++;
       }
     }
     DCHECK_EQ(filtered_index, kMaxAllocatableGeneralRegisterCount - 1);
     return allocatable_general_codes_;
   }

   static int
       allocatable_general_codes_[kMaxAllocatableGeneralRegisterCount - 1];
 };

 int ArchDefaultPoisoningRegisterConfiguration::allocatable_general_codes_
     [kMaxAllocatableGeneralRegisterCount - 1];

 DEFINE_LAZY_LEAKY_OBJECT_GETTER(ArchDefaultPoisoningRegisterConfiguration,
                                 GetDefaultPoisoningRegisterConfiguration);

 // RestrictedRegisterConfiguration uses the subset of allocatable general
 // registers the architecture support, which results into generating assembly
 // to use less registers. Currently, it's only used by RecordWrite code stub.
 class RestrictedRegisterConfiguration : public RegisterConfiguration {
  public:
   RestrictedRegisterConfiguration(
       int num_allocatable_general_registers,
       std::unique_ptr<int[]> allocatable_general_register_codes,
       std::unique_ptr<char const* []> allocatable_general_register_names)
       : RegisterConfiguration(
             Register::kNumRegisters, DoubleRegister::kNumRegisters,
             num_allocatable_general_registers,
             get_num_allocatable_double_registers(),
             allocatable_general_register_codes.get(),
             get_allocatable_double_codes(),
             kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE),
         allocatable_general_register_codes_(
             std::move(allocatable_general_register_codes)),
         allocatable_general_register_names_(
             std::move(allocatable_general_register_names)) {
     for (int i = 0; i < num_allocatable_general_registers; ++i) {
       DCHECK(
           IsAllocatableGeneralRegister(allocatable_general_register_codes_[i]));
     }
   }

   bool IsAllocatableGeneralRegister(int code) {
     for (int i = 0; i < kMaxAllocatableGeneralRegisterCount; ++i) {
       if (code == kAllocatableGeneralCodes[i]) {
         return true;
       }
     }
     return false;
   }

  private:
   std::unique_ptr<int[]> allocatable_general_register_codes_;
   std::unique_ptr<char const* []> allocatable_general_register_names_;
 };

 }  // namespace

 const RegisterConfiguration* RegisterConfiguration::Default() {
   return GetDefaultRegisterConfiguration();
 }

 const RegisterConfiguration* RegisterConfiguration::Poisoning() {
   return GetDefaultPoisoningRegisterConfiguration();
 }

 const RegisterConfiguration* RegisterConfiguration::RestrictGeneralRegisters(
     RegList registers) {
   int num = NumRegs(registers);
   std::unique_ptr<int[]> codes{new int[num]};
   std::unique_ptr<char const* []> names { new char const*[num] };
   int counter = 0;
   for (int i = 0; i < Default()->num_allocatable_general_registers(); ++i) {
     auto reg = Register::from_code(Default()->GetAllocatableGeneralCode(i));
     if (reg.bit() & registers) {
       DCHECK(counter < num);
       codes[counter] = reg.code();
       names[counter] = RegisterName(Register::from_code(i));
       counter++;
     }
   }

   return new RestrictedRegisterConfiguration(num, std::move(codes),
                                              std::move(names));
 }

 RegisterConfiguration::RegisterConfiguration(
     int num_general_registers, int num_double_registers,
     int num_allocatable_general_registers, int num_allocatable_double_registers,
     const int* allocatable_general_codes, const int* allocatable_double_codes,
     AliasingKind fp_aliasing_kind)
     : num_general_registers_(num_general_registers),
       num_float_registers_(0),
       num_double_registers_(num_double_registers),
       num_simd128_registers_(0),
       num_allocatable_general_registers_(num_allocatable_general_registers),
       num_allocatable_float_registers_(0),
       num_allocatable_double_registers_(num_allocatable_double_registers),
       num_allocatable_simd128_registers_(0),
       allocatable_general_codes_mask_(0),
       allocatable_float_codes_mask_(0),
       allocatable_double_codes_mask_(0),
       allocatable_simd128_codes_mask_(0),
       allocatable_general_codes_(allocatable_general_codes),
       allocatable_double_codes_(allocatable_double_codes),
       fp_aliasing_kind_(fp_aliasing_kind) {
   DCHECK_LE(num_general_registers_,
             RegisterConfiguration::kMaxGeneralRegisters);
   DCHECK_LE(num_double_registers_, RegisterConfiguration::kMaxFPRegisters);
   for (int i = 0; i < num_allocatable_general_registers_; ++i) {
     allocatable_general_codes_mask_ |= (1 << allocatable_general_codes_[i]);
   }
   for (int i = 0; i < num_allocatable_double_registers_; ++i) {
     allocatable_double_codes_mask_ |= (1 << allocatable_double_codes_[i]);
   }

   if (fp_aliasing_kind_ == COMBINE) {
     num_float_registers_ = num_double_registers_ * 2 <= kMaxFPRegisters
                                ? num_double_registers_ * 2
                                : kMaxFPRegisters;
     num_allocatable_float_registers_ = 0;
     for (int i = 0; i < num_allocatable_double_registers_; i++) {
       int base_code = allocatable_double_codes_[i] * 2;
       if (base_code >= kMaxFPRegisters) continue;
       allocatable_float_codes_[num_allocatable_float_registers_++] = base_code;
       allocatable_float_codes_[num_allocatable_float_registers_++] =
           base_code + 1;
       allocatable_float_codes_mask_ |= (0x3 << base_code);
     }
     num_simd128_registers_ = num_double_registers_ / 2;
     num_allocatable_simd128_registers_ = 0;
     int last_simd128_code = allocatable_double_codes_[0] / 2;
     for (int i = 1; i < num_allocatable_double_registers_; i++) {
       int next_simd128_code = allocatable_double_codes_[i] / 2;
       // This scheme assumes allocatable_double_codes_ are strictly increasing.
       DCHECK_GE(next_simd128_code, last_simd128_code);
       if (last_simd128_code == next_simd128_code) {
         allocatable_simd128_codes_[num_allocatable_simd128_registers_++] =
             next_simd128_code;
         allocatable_simd128_codes_mask_ |= (0x1 << next_simd128_code);
       }
       last_simd128_code = next_simd128_code;
     }
   } else {
     DCHECK(fp_aliasing_kind_ == OVERLAP);
     num_float_registers_ = num_simd128_registers_ = num_double_registers_;
     num_allocatable_float_registers_ = num_allocatable_simd128_registers_ =
         num_allocatable_double_registers_;
     for (int i = 0; i < num_allocatable_float_registers_; ++i) {
       allocatable_float_codes_[i] = allocatable_simd128_codes_[i] =
           allocatable_double_codes_[i];
     }
     allocatable_float_codes_mask_ = allocatable_simd128_codes_mask_ =
         allocatable_double_codes_mask_;
   }
 }

 // Assert that kFloat32, kFloat64, and kSimd128 are consecutive values.
 STATIC_ASSERT(static_cast<int>(MachineRepresentation::kSimd128) ==
               static_cast<int>(MachineRepresentation::kFloat64) + 1);
 STATIC_ASSERT(static_cast<int>(MachineRepresentation::kFloat64) ==
               static_cast<int>(MachineRepresentation::kFloat32) + 1);

 int RegisterConfiguration::GetAliases(MachineRepresentation rep, int index,
                                       MachineRepresentation other_rep,
                                       int* alias_base_index) const {
   DCHECK(fp_aliasing_kind_ == COMBINE);
   DCHECK(IsFloatingPoint(rep) && IsFloatingPoint(other_rep));
   if (rep == other_rep) {
     *alias_base_index = index;
     return 1;
   }
   int rep_int = static_cast<int>(rep);
   int other_rep_int = static_cast<int>(other_rep);
   if (rep_int > other_rep_int) {
     int shift = rep_int - other_rep_int;
     int base_index = index << shift;
     if (base_index >= kMaxFPRegisters) {
       // Alias indices would be out of FP register range.
       return 0;
     }
     *alias_base_index = base_index;
     return 1 << shift;
   }
   int shift = other_rep_int - rep_int;
   *alias_base_index = index >> shift;
   return 1;
 }

 bool RegisterConfiguration::AreAliases(MachineRepresentation rep, int index,
                                        MachineRepresentation other_rep,
                                        int other_index) const {
   DCHECK(fp_aliasing_kind_ == COMBINE);
   DCHECK(IsFloatingPoint(rep) && IsFloatingPoint(other_rep));
   if (rep == other_rep) {
     return index == other_index;
   }
   int rep_int = static_cast<int>(rep);
   int other_rep_int = static_cast<int>(other_rep);
   if (rep_int > other_rep_int) {
     int shift = rep_int - other_rep_int;
     return index == other_index >> shift;
   }
   int shift = other_rep_int - rep_int;
   return index >> shift == other_index;
 }

 }  // namespace internal
 }  // namespace v8
	// 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/base/lazy-instance.h"
	#include "src/cpu-features.h"
	#include "src/globals.h"
	#include "src/register-arch.h"

	namespace v8 {
	namespace internal {

	namespace {

	#define REGISTER_COUNT(R) 1 +
	static const int kMaxAllocatableGeneralRegisterCount =
	ALLOCATABLE_GENERAL_REGISTERS(REGISTER_COUNT)0;
	static const int kMaxAllocatableDoubleRegisterCount =
	ALLOCATABLE_DOUBLE_REGISTERS(REGISTER_COUNT)0;

	static const int kAllocatableGeneralCodes[] = {
	#define REGISTER_CODE(R) kRegCode_##R,
	ALLOCATABLE_GENERAL_REGISTERS(REGISTER_CODE)};
	#undef REGISTER_CODE

	#define REGISTER_CODE(R) kDoubleCode_##R,
	static const int kAllocatableDoubleCodes[] = {
	ALLOCATABLE_DOUBLE_REGISTERS(REGISTER_CODE)};
	#if V8_TARGET_ARCH_ARM
	static const int kAllocatableNoVFP32DoubleCodes[] = {
	ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_CODE)};
	#endif // V8_TARGET_ARCH_ARM
	#undef REGISTER_CODE

	STATIC_ASSERT(RegisterConfiguration::kMaxGeneralRegisters >=
	Register::kNumRegisters);
	STATIC_ASSERT(RegisterConfiguration::kMaxFPRegisters >=
	FloatRegister::kNumRegisters);
	STATIC_ASSERT(RegisterConfiguration::kMaxFPRegisters >=
	DoubleRegister::kNumRegisters);
	STATIC_ASSERT(RegisterConfiguration::kMaxFPRegisters >=
	Simd128Register::kNumRegisters);

	static int get_num_allocatable_double_registers() {
	return
	#if V8_TARGET_ARCH_IA32
	kMaxAllocatableDoubleRegisterCount;
	#elif V8_TARGET_ARCH_X64
	kMaxAllocatableDoubleRegisterCount;
	#elif V8_TARGET_ARCH_ARM
	CpuFeatures::IsSupported(VFP32DREGS)
	? kMaxAllocatableDoubleRegisterCount
	: (ALLOCATABLE_NO_VFP32_DOUBLE_REGISTERS(REGISTER_COUNT) 0);
	#elif V8_TARGET_ARCH_ARM64
	kMaxAllocatableDoubleRegisterCount;
	#elif V8_TARGET_ARCH_MIPS
	kMaxAllocatableDoubleRegisterCount;
	#elif V8_TARGET_ARCH_MIPS64
	kMaxAllocatableDoubleRegisterCount;
	#elif V8_TARGET_ARCH_PPC
	kMaxAllocatableDoubleRegisterCount;
	#elif V8_TARGET_ARCH_S390
	kMaxAllocatableDoubleRegisterCount;
	#else
	#error Unsupported target architecture.
	#endif
	}

	#undef REGISTER_COUNT

	static const int* get_allocatable_double_codes() {
	return
	#if V8_TARGET_ARCH_ARM
	CpuFeatures::IsSupported(VFP32DREGS) ? kAllocatableDoubleCodes
	: kAllocatableNoVFP32DoubleCodes;
	#else
	kAllocatableDoubleCodes;
	#endif
	}

	class ArchDefaultRegisterConfiguration : public RegisterConfiguration {
	public:
	ArchDefaultRegisterConfiguration()
	: RegisterConfiguration(
	Register::kNumRegisters, DoubleRegister::kNumRegisters,
	kMaxAllocatableGeneralRegisterCount,
	get_num_allocatable_double_registers(), kAllocatableGeneralCodes,
	get_allocatable_double_codes(),
	kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE) {
	}
	};

	DEFINE_LAZY_LEAKY_OBJECT_GETTER(ArchDefaultRegisterConfiguration,
	GetDefaultRegisterConfiguration);

	// Allocatable registers with the masking register removed.
	class ArchDefaultPoisoningRegisterConfiguration : public RegisterConfiguration {
	public:
	ArchDefaultPoisoningRegisterConfiguration()
	: RegisterConfiguration(
	Register::kNumRegisters, DoubleRegister::kNumRegisters,
	kMaxAllocatableGeneralRegisterCount - 1,
	get_num_allocatable_double_registers(),
	InitializeGeneralRegisterCodes(), get_allocatable_double_codes(),
	kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE) {
	}

	private:
	static const int* InitializeGeneralRegisterCodes() {
	int filtered_index = 0;
	for (int i = 0; i < kMaxAllocatableGeneralRegisterCount; ++i) {
	if (kAllocatableGeneralCodes[i] != kSpeculationPoisonRegister.code()) {
	allocatable_general_codes_[filtered_index] =
	kAllocatableGeneralCodes[i];
	filtered_index++;
	}
	}
	DCHECK_EQ(filtered_index, kMaxAllocatableGeneralRegisterCount - 1);
	return allocatable_general_codes_;
	}

	static int
	allocatable_general_codes_[kMaxAllocatableGeneralRegisterCount - 1];
	};

	int ArchDefaultPoisoningRegisterConfiguration::allocatable_general_codes_
	[kMaxAllocatableGeneralRegisterCount - 1];

	DEFINE_LAZY_LEAKY_OBJECT_GETTER(ArchDefaultPoisoningRegisterConfiguration,
	GetDefaultPoisoningRegisterConfiguration);

	// RestrictedRegisterConfiguration uses the subset of allocatable general
	// registers the architecture support, which results into generating assembly
	// to use less registers. Currently, it's only used by RecordWrite code stub.
	class RestrictedRegisterConfiguration : public RegisterConfiguration {
	public:
	RestrictedRegisterConfiguration(
	int num_allocatable_general_registers,
	std::unique_ptr<int[]> allocatable_general_register_codes,
	std::unique_ptr<char const* []> allocatable_general_register_names)
	: RegisterConfiguration(
	Register::kNumRegisters, DoubleRegister::kNumRegisters,
	num_allocatable_general_registers,
	get_num_allocatable_double_registers(),
	allocatable_general_register_codes.get(),
	get_allocatable_double_codes(),
	kSimpleFPAliasing ? AliasingKind::OVERLAP : AliasingKind::COMBINE),
	allocatable_general_register_codes_(
	std::move(allocatable_general_register_codes)),
	allocatable_general_register_names_(
	std::move(allocatable_general_register_names)) {
	for (int i = 0; i < num_allocatable_general_registers; ++i) {
	DCHECK(
	IsAllocatableGeneralRegister(allocatable_general_register_codes_[i]));
	}
	}

	bool IsAllocatableGeneralRegister(int code) {
	for (int i = 0; i < kMaxAllocatableGeneralRegisterCount; ++i) {
	if (code == kAllocatableGeneralCodes[i]) {
	return true;
	}
	}
	return false;
	}

	private:
	std::unique_ptr<int[]> allocatable_general_register_codes_;
	std::unique_ptr<char const* []> allocatable_general_register_names_;
	};

	} // namespace

	const RegisterConfiguration* RegisterConfiguration::Default() {
	return GetDefaultRegisterConfiguration();
	}

	const RegisterConfiguration* RegisterConfiguration::Poisoning() {
	return GetDefaultPoisoningRegisterConfiguration();
	}

	const RegisterConfiguration* RegisterConfiguration::RestrictGeneralRegisters(
	RegList registers) {
	int num = NumRegs(registers);
	std::unique_ptr<int[]> codes{new int[num]};
	std::unique_ptr<char const* []> names { new char const*[num] };
	int counter = 0;
	for (int i = 0; i < Default()->num_allocatable_general_registers(); ++i) {
	auto reg = Register::from_code(Default()->GetAllocatableGeneralCode(i));
	if (reg.bit() & registers) {
	DCHECK(counter < num);
	codes[counter] = reg.code();
	names[counter] = RegisterName(Register::from_code(i));
	counter++;
	}
	}

	return new RestrictedRegisterConfiguration(num, std::move(codes),
	std::move(names));
	}

	RegisterConfiguration::RegisterConfiguration(
	int num_general_registers, int num_double_registers,
	int num_allocatable_general_registers, int num_allocatable_double_registers,
	const int* allocatable_general_codes, const int* allocatable_double_codes,
	AliasingKind fp_aliasing_kind)
	: num_general_registers_(num_general_registers),
	num_float_registers_(0),
	num_double_registers_(num_double_registers),
	num_simd128_registers_(0),
	num_allocatable_general_registers_(num_allocatable_general_registers),
	num_allocatable_float_registers_(0),
	num_allocatable_double_registers_(num_allocatable_double_registers),
	num_allocatable_simd128_registers_(0),
	allocatable_general_codes_mask_(0),
	allocatable_float_codes_mask_(0),
	allocatable_double_codes_mask_(0),
	allocatable_simd128_codes_mask_(0),
	allocatable_general_codes_(allocatable_general_codes),
	allocatable_double_codes_(allocatable_double_codes),
	fp_aliasing_kind_(fp_aliasing_kind) {
	DCHECK_LE(num_general_registers_,
	RegisterConfiguration::kMaxGeneralRegisters);
	DCHECK_LE(num_double_registers_, RegisterConfiguration::kMaxFPRegisters);
	for (int i = 0; i < num_allocatable_general_registers_; ++i) {
	allocatable_general_codes_mask_ \|= (1 << allocatable_general_codes_[i]);
	}
	for (int i = 0; i < num_allocatable_double_registers_; ++i) {
	allocatable_double_codes_mask_ \|= (1 << allocatable_double_codes_[i]);
	}

	if (fp_aliasing_kind_ == COMBINE) {
	num_float_registers_ = num_double_registers_ * 2 <= kMaxFPRegisters
	? num_double_registers_ * 2
	: kMaxFPRegisters;
	num_allocatable_float_registers_ = 0;
	for (int i = 0; i < num_allocatable_double_registers_; i++) {
	int base_code = allocatable_double_codes_[i] * 2;
	if (base_code >= kMaxFPRegisters) continue;
	allocatable_float_codes_[num_allocatable_float_registers_++] = base_code;
	allocatable_float_codes_[num_allocatable_float_registers_++] =
	base_code + 1;
	allocatable_float_codes_mask_ \|= (0x3 << base_code);
	}
	num_simd128_registers_ = num_double_registers_ / 2;
	num_allocatable_simd128_registers_ = 0;
	int last_simd128_code = allocatable_double_codes_[0] / 2;
	for (int i = 1; i < num_allocatable_double_registers_; i++) {
	int next_simd128_code = allocatable_double_codes_[i] / 2;
	// This scheme assumes allocatable_double_codes_ are strictly increasing.
	DCHECK_GE(next_simd128_code, last_simd128_code);
	if (last_simd128_code == next_simd128_code) {
	allocatable_simd128_codes_[num_allocatable_simd128_registers_++] =
	next_simd128_code;
	allocatable_simd128_codes_mask_ \|= (0x1 << next_simd128_code);
	}
	last_simd128_code = next_simd128_code;
	}
	} else {
	DCHECK(fp_aliasing_kind_ == OVERLAP);
	num_float_registers_ = num_simd128_registers_ = num_double_registers_;
	num_allocatable_float_registers_ = num_allocatable_simd128_registers_ =
	num_allocatable_double_registers_;
	for (int i = 0; i < num_allocatable_float_registers_; ++i) {
	allocatable_float_codes_[i] = allocatable_simd128_codes_[i] =
	allocatable_double_codes_[i];
	}
	allocatable_float_codes_mask_ = allocatable_simd128_codes_mask_ =
	allocatable_double_codes_mask_;
	}
	}

	// Assert that kFloat32, kFloat64, and kSimd128 are consecutive values.
	STATIC_ASSERT(static_cast<int>(MachineRepresentation::kSimd128) ==
	static_cast<int>(MachineRepresentation::kFloat64) + 1);
	STATIC_ASSERT(static_cast<int>(MachineRepresentation::kFloat64) ==
	static_cast<int>(MachineRepresentation::kFloat32) + 1);

	int RegisterConfiguration::GetAliases(MachineRepresentation rep, int index,
	MachineRepresentation other_rep,
	int* alias_base_index) const {
	DCHECK(fp_aliasing_kind_ == COMBINE);
	DCHECK(IsFloatingPoint(rep) && IsFloatingPoint(other_rep));
	if (rep == other_rep) {
	*alias_base_index = index;
	return 1;
	}
	int rep_int = static_cast<int>(rep);
	int other_rep_int = static_cast<int>(other_rep);
	if (rep_int > other_rep_int) {
	int shift = rep_int - other_rep_int;
	int base_index = index << shift;
	if (base_index >= kMaxFPRegisters) {
	// Alias indices would be out of FP register range.
	return 0;
	}
	*alias_base_index = base_index;
	return 1 << shift;
	}
	int shift = other_rep_int - rep_int;
	*alias_base_index = index >> shift;
	return 1;
	}

	bool RegisterConfiguration::AreAliases(MachineRepresentation rep, int index,
	MachineRepresentation other_rep,
	int other_index) const {
	DCHECK(fp_aliasing_kind_ == COMBINE);
	DCHECK(IsFloatingPoint(rep) && IsFloatingPoint(other_rep));
	if (rep == other_rep) {
	return index == other_index;
	}
	int rep_int = static_cast<int>(rep);
	int other_rep_int = static_cast<int>(other_rep);
	if (rep_int > other_rep_int) {
	int shift = rep_int - other_rep_int;
	return index == other_index >> shift;
	}
	int shift = other_rep_int - rep_int;
	return index >> shift == other_index;
	}

	} // namespace internal
	} // namespace v8