compiler/jni/quick/arm64/calling_convention_arm64.cc - platform/art - Git at Google

 /*
  * Copyright (C) 2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "calling_convention_arm64.h"

 #include <android-base/logging.h>

 #include "arch/instruction_set.h"
 #include "handle_scope-inl.h"
 #include "utils/arm64/managed_register_arm64.h"

 namespace art {
 namespace arm64 {

 static_assert(kArm64PointerSize == PointerSize::k64, "Unexpected ARM64 pointer size");

 // Up to how many float-like (float, double) args can be enregistered.
 // The rest of the args must go on the stack.
 constexpr size_t kMaxFloatOrDoubleRegisterArguments = 8u;
 // Up to how many integer-like (pointers, objects, longs, int, short, bool, etc) args can be
 // enregistered. The rest of the args must go on the stack.
 constexpr size_t kMaxIntLikeRegisterArguments = 8u;

 static const XRegister kXArgumentRegisters[] = {
   X0, X1, X2, X3, X4, X5, X6, X7
 };

 static const WRegister kWArgumentRegisters[] = {
   W0, W1, W2, W3, W4, W5, W6, W7
 };

 static const DRegister kDArgumentRegisters[] = {
   D0, D1, D2, D3, D4, D5, D6, D7
 };

 static const SRegister kSArgumentRegisters[] = {
   S0, S1, S2, S3, S4, S5, S6, S7
 };

 static constexpr ManagedRegister kCalleeSaveRegisters[] = {
     // Core registers.
     // Note: The native jni function may call to some VM runtime functions which may suspend
     // or trigger GC. And the jni method frame will become top quick frame in those cases.
     // So we need to satisfy GC to save LR and callee-save registers which is similar to
     // CalleeSaveMethod(RefOnly) frame.
     // Jni function is the native function which the java code wants to call.
     // Jni method is the method that is compiled by jni compiler.
     // Call chain: managed code(java) --> jni method --> jni function.
     // Thread register(X19) is saved on stack.
     Arm64ManagedRegister::FromXRegister(X19),
     Arm64ManagedRegister::FromXRegister(X20),
     Arm64ManagedRegister::FromXRegister(X21),
     Arm64ManagedRegister::FromXRegister(X22),
     Arm64ManagedRegister::FromXRegister(X23),
     Arm64ManagedRegister::FromXRegister(X24),
     Arm64ManagedRegister::FromXRegister(X25),
     Arm64ManagedRegister::FromXRegister(X26),
     Arm64ManagedRegister::FromXRegister(X27),
     Arm64ManagedRegister::FromXRegister(X28),
     Arm64ManagedRegister::FromXRegister(X29),
     Arm64ManagedRegister::FromXRegister(LR),
     // Hard float registers.
     // Considering the case, java_method_1 --> jni method --> jni function --> java_method_2,
     // we may break on java_method_2 and we still need to find out the values of DEX registers
     // in java_method_1. So all callee-saves(in managed code) need to be saved.
     Arm64ManagedRegister::FromDRegister(D8),
     Arm64ManagedRegister::FromDRegister(D9),
     Arm64ManagedRegister::FromDRegister(D10),
     Arm64ManagedRegister::FromDRegister(D11),
     Arm64ManagedRegister::FromDRegister(D12),
     Arm64ManagedRegister::FromDRegister(D13),
     Arm64ManagedRegister::FromDRegister(D14),
     Arm64ManagedRegister::FromDRegister(D15),
 };

 static constexpr uint32_t CalculateCoreCalleeSpillMask() {
   uint32_t result = 0u;
   for (auto&& r : kCalleeSaveRegisters) {
     if (r.AsArm64().IsXRegister()) {
       result |= (1 << r.AsArm64().AsXRegister());
     }
   }
   return result;
 }

 static constexpr uint32_t CalculateFpCalleeSpillMask() {
   uint32_t result = 0;
   for (auto&& r : kCalleeSaveRegisters) {
     if (r.AsArm64().IsDRegister()) {
       result |= (1 << r.AsArm64().AsDRegister());
     }
   }
   return result;
 }

 static constexpr uint32_t kCoreCalleeSpillMask = CalculateCoreCalleeSpillMask();
 static constexpr uint32_t kFpCalleeSpillMask = CalculateFpCalleeSpillMask();

 // Calling convention
 ManagedRegister Arm64ManagedRuntimeCallingConvention::InterproceduralScratchRegister() {
   // X20 is safe to use as a scratch register:
   // - with Baker read barriers (in the case of a non-critical native
   //   method), it is reserved as Marking Register, and thus does not
   //   actually need to be saved/restored; it is refreshed on exit
   //   (see Arm64JNIMacroAssembler::RemoveFrame);
   // - in other cases, it is saved on entry (in
   //   Arm64JNIMacroAssembler::BuildFrame) and restored on exit (in
   //   Arm64JNIMacroAssembler::RemoveFrame). This is also expected in
   //   the case of a critical native method in the Baker read barrier
   //   configuration, where the value of MR must be preserved across
   //   the JNI call (as there is no MR refresh in that case).
   return Arm64ManagedRegister::FromXRegister(X20);
 }

 ManagedRegister Arm64JniCallingConvention::InterproceduralScratchRegister() {
   // X20 is safe to use as a scratch register:
   // - with Baker read barriers (in the case of a non-critical native
   //   method), it is reserved as Marking Register, and thus does not
   //   actually need to be saved/restored; it is refreshed on exit
   //   (see Arm64JNIMacroAssembler::RemoveFrame);
   // - in other cases, it is saved on entry (in
   //   Arm64JNIMacroAssembler::BuildFrame) and restored on exit (in
   //   Arm64JNIMacroAssembler::RemoveFrame). This is also expected in
   //   the case of a critical native method in the Baker read barrier
   //   configuration, where the value of MR must be preserved across
   //   the JNI call (as there is no MR refresh in that case).
   return Arm64ManagedRegister::FromXRegister(X20);
 }

 static ManagedRegister ReturnRegisterForShorty(const char* shorty) {
   if (shorty[0] == 'F') {
     return Arm64ManagedRegister::FromSRegister(S0);
   } else if (shorty[0] == 'D') {
     return Arm64ManagedRegister::FromDRegister(D0);
   } else if (shorty[0] == 'J') {
     return Arm64ManagedRegister::FromXRegister(X0);
   } else if (shorty[0] == 'V') {
     return Arm64ManagedRegister::NoRegister();
   } else {
     return Arm64ManagedRegister::FromWRegister(W0);
   }
 }

 ManagedRegister Arm64ManagedRuntimeCallingConvention::ReturnRegister() {
   return ReturnRegisterForShorty(GetShorty());
 }

 ManagedRegister Arm64JniCallingConvention::ReturnRegister() {
   return ReturnRegisterForShorty(GetShorty());
 }

 ManagedRegister Arm64JniCallingConvention::IntReturnRegister() {
   return Arm64ManagedRegister::FromWRegister(W0);
 }

 // Managed runtime calling convention

 ManagedRegister Arm64ManagedRuntimeCallingConvention::MethodRegister() {
   return Arm64ManagedRegister::FromXRegister(X0);
 }

 bool Arm64ManagedRuntimeCallingConvention::IsCurrentParamInRegister() {
   return false;  // Everything moved to stack on entry.
 }

 bool Arm64ManagedRuntimeCallingConvention::IsCurrentParamOnStack() {
   return true;
 }

 ManagedRegister Arm64ManagedRuntimeCallingConvention::CurrentParamRegister() {
   LOG(FATAL) << "Should not reach here";
   UNREACHABLE();
 }

 FrameOffset Arm64ManagedRuntimeCallingConvention::CurrentParamStackOffset() {
   CHECK(IsCurrentParamOnStack());
   FrameOffset result =
       FrameOffset(displacement_.Int32Value() +  // displacement
                   kFramePointerSize +  // Method ref
                   (itr_slots_ * sizeof(uint32_t)));  // offset into in args
   return result;
 }

 const ManagedRegisterEntrySpills& Arm64ManagedRuntimeCallingConvention::EntrySpills() {
   // We spill the argument registers on ARM64 to free them up for scratch use, we then assume
   // all arguments are on the stack.
   if ((entry_spills_.size() == 0) && (NumArgs() > 0)) {
     int gp_reg_index = 1;   // we start from X1/W1, X0 holds ArtMethod*.
     int fp_reg_index = 0;   // D0/S0.

     // We need to choose the correct register (D/S or X/W) since the managed
     // stack uses 32bit stack slots.
     ResetIterator(FrameOffset(0));
     while (HasNext()) {
       if (IsCurrentParamAFloatOrDouble()) {  // FP regs.
           if (fp_reg_index < 8) {
             if (!IsCurrentParamADouble()) {
               entry_spills_.push_back(Arm64ManagedRegister::FromSRegister(kSArgumentRegisters[fp_reg_index]));
             } else {
               entry_spills_.push_back(Arm64ManagedRegister::FromDRegister(kDArgumentRegisters[fp_reg_index]));
             }
             fp_reg_index++;
           } else {  // just increase the stack offset.
             if (!IsCurrentParamADouble()) {
               entry_spills_.push_back(ManagedRegister::NoRegister(), 4);
             } else {
               entry_spills_.push_back(ManagedRegister::NoRegister(), 8);
             }
           }
       } else {  // GP regs.
         if (gp_reg_index < 8) {
           if (IsCurrentParamALong() && (!IsCurrentParamAReference())) {
             entry_spills_.push_back(Arm64ManagedRegister::FromXRegister(kXArgumentRegisters[gp_reg_index]));
           } else {
             entry_spills_.push_back(Arm64ManagedRegister::FromWRegister(kWArgumentRegisters[gp_reg_index]));
           }
           gp_reg_index++;
         } else {  // just increase the stack offset.
           if (IsCurrentParamALong() && (!IsCurrentParamAReference())) {
               entry_spills_.push_back(ManagedRegister::NoRegister(), 8);
           } else {
               entry_spills_.push_back(ManagedRegister::NoRegister(), 4);
           }
         }
       }
       Next();
     }
   }
   return entry_spills_;
 }

 // JNI calling convention
 Arm64JniCallingConvention::Arm64JniCallingConvention(bool is_static,
                                                      bool is_synchronized,
                                                      bool is_critical_native,
                                                      const char* shorty)
     : JniCallingConvention(is_static,
                            is_synchronized,
                            is_critical_native,
                            shorty,
                            kArm64PointerSize) {
 }

 uint32_t Arm64JniCallingConvention::CoreSpillMask() const {
   return kCoreCalleeSpillMask;
 }

 uint32_t Arm64JniCallingConvention::FpSpillMask() const {
   return kFpCalleeSpillMask;
 }

 ManagedRegister Arm64JniCallingConvention::ReturnScratchRegister() const {
   return ManagedRegister::NoRegister();
 }

 size_t Arm64JniCallingConvention::FrameSize() {
   // Method*, callee save area size, local reference segment state
   //
   // (Unlike x86_64, do not include return address, and the segment state is uint32
   // instead of pointer).
   size_t method_ptr_size = static_cast<size_t>(kFramePointerSize);
   size_t callee_save_area_size = CalleeSaveRegisters().size() * kFramePointerSize;

   size_t frame_data_size = method_ptr_size + callee_save_area_size;
   if (LIKELY(HasLocalReferenceSegmentState())) {
     frame_data_size += sizeof(uint32_t);
   }
   // References plus 2 words for HandleScope header
   size_t handle_scope_size = HandleScope::SizeOf(kArm64PointerSize, ReferenceCount());

   size_t total_size = frame_data_size;
   if (LIKELY(HasHandleScope())) {
     // HandleScope is sometimes excluded.
     total_size += handle_scope_size;                                 // handle scope size
   }

   // Plus return value spill area size
   total_size += SizeOfReturnValue();

   return RoundUp(total_size, kStackAlignment);
 }

 size_t Arm64JniCallingConvention::OutArgSize() {
   // Same as X86_64
   return RoundUp(NumberOfOutgoingStackArgs() * kFramePointerSize, kStackAlignment);
 }

 ArrayRef<const ManagedRegister> Arm64JniCallingConvention::CalleeSaveRegisters() const {
   // Same as X86_64
   return ArrayRef<const ManagedRegister>(kCalleeSaveRegisters);
 }

 bool Arm64JniCallingConvention::IsCurrentParamInRegister() {
   if (IsCurrentParamAFloatOrDouble()) {
     return (itr_float_and_doubles_ < kMaxFloatOrDoubleRegisterArguments);
   } else {
     return ((itr_args_ - itr_float_and_doubles_) < kMaxIntLikeRegisterArguments);
   }
   // TODO: Can we just call CurrentParamRegister to figure this out?
 }

 bool Arm64JniCallingConvention::IsCurrentParamOnStack() {
   // Is this ever not the same for all the architectures?
   return !IsCurrentParamInRegister();
 }

 ManagedRegister Arm64JniCallingConvention::CurrentParamRegister() {
   CHECK(IsCurrentParamInRegister());
   if (IsCurrentParamAFloatOrDouble()) {
     CHECK_LT(itr_float_and_doubles_, kMaxFloatOrDoubleRegisterArguments);
     if (IsCurrentParamADouble()) {
       return Arm64ManagedRegister::FromDRegister(kDArgumentRegisters[itr_float_and_doubles_]);
     } else {
       return Arm64ManagedRegister::FromSRegister(kSArgumentRegisters[itr_float_and_doubles_]);
     }
   } else {
     int gp_reg = itr_args_ - itr_float_and_doubles_;
     CHECK_LT(static_cast<unsigned int>(gp_reg), kMaxIntLikeRegisterArguments);
     if (IsCurrentParamALong() || IsCurrentParamAReference() || IsCurrentParamJniEnv())  {
       return Arm64ManagedRegister::FromXRegister(kXArgumentRegisters[gp_reg]);
     } else {
       return Arm64ManagedRegister::FromWRegister(kWArgumentRegisters[gp_reg]);
     }
   }
 }

 FrameOffset Arm64JniCallingConvention::CurrentParamStackOffset() {
   CHECK(IsCurrentParamOnStack());
   size_t args_on_stack = itr_args_
                   - std::min(kMaxFloatOrDoubleRegisterArguments,
                              static_cast<size_t>(itr_float_and_doubles_))
                   - std::min(kMaxIntLikeRegisterArguments,
                              static_cast<size_t>(itr_args_ - itr_float_and_doubles_));
   size_t offset = displacement_.Int32Value() - OutArgSize() + (args_on_stack * kFramePointerSize);
   CHECK_LT(offset, OutArgSize());
   return FrameOffset(offset);
   // TODO: Seems identical to X86_64 code.
 }

 size_t Arm64JniCallingConvention::NumberOfOutgoingStackArgs() {
   // all arguments including JNI args
   size_t all_args = NumArgs() + NumberOfExtraArgumentsForJni();

   DCHECK_GE(all_args, NumFloatOrDoubleArgs());

   size_t all_stack_args =
       all_args
       - std::min(kMaxFloatOrDoubleRegisterArguments,
                  static_cast<size_t>(NumFloatOrDoubleArgs()))
       - std::min(kMaxIntLikeRegisterArguments,
                  static_cast<size_t>((all_args - NumFloatOrDoubleArgs())));

   // TODO: Seems similar to X86_64 code except it doesn't count return pc.

   return all_stack_args;
 }

 }  // namespace arm64
 }  // namespace art
	/*
	* Copyright (C) 2014 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "calling_convention_arm64.h"

	#include <android-base/logging.h>

	#include "arch/instruction_set.h"
	#include "handle_scope-inl.h"
	#include "utils/arm64/managed_register_arm64.h"

	namespace art {
	namespace arm64 {

	static_assert(kArm64PointerSize == PointerSize::k64, "Unexpected ARM64 pointer size");

	// Up to how many float-like (float, double) args can be enregistered.
	// The rest of the args must go on the stack.
	constexpr size_t kMaxFloatOrDoubleRegisterArguments = 8u;
	// Up to how many integer-like (pointers, objects, longs, int, short, bool, etc) args can be
	// enregistered. The rest of the args must go on the stack.
	constexpr size_t kMaxIntLikeRegisterArguments = 8u;

	static const XRegister kXArgumentRegisters[] = {
	X0, X1, X2, X3, X4, X5, X6, X7
	};

	static const WRegister kWArgumentRegisters[] = {
	W0, W1, W2, W3, W4, W5, W6, W7
	};

	static const DRegister kDArgumentRegisters[] = {
	D0, D1, D2, D3, D4, D5, D6, D7
	};

	static const SRegister kSArgumentRegisters[] = {
	S0, S1, S2, S3, S4, S5, S6, S7
	};

	static constexpr ManagedRegister kCalleeSaveRegisters[] = {
	// Core registers.
	// Note: The native jni function may call to some VM runtime functions which may suspend
	// or trigger GC. And the jni method frame will become top quick frame in those cases.
	// So we need to satisfy GC to save LR and callee-save registers which is similar to
	// CalleeSaveMethod(RefOnly) frame.
	// Jni function is the native function which the java code wants to call.
	// Jni method is the method that is compiled by jni compiler.
	// Call chain: managed code(java) --> jni method --> jni function.
	// Thread register(X19) is saved on stack.
	Arm64ManagedRegister::FromXRegister(X19),
	Arm64ManagedRegister::FromXRegister(X20),
	Arm64ManagedRegister::FromXRegister(X21),
	Arm64ManagedRegister::FromXRegister(X22),
	Arm64ManagedRegister::FromXRegister(X23),
	Arm64ManagedRegister::FromXRegister(X24),
	Arm64ManagedRegister::FromXRegister(X25),
	Arm64ManagedRegister::FromXRegister(X26),
	Arm64ManagedRegister::FromXRegister(X27),
	Arm64ManagedRegister::FromXRegister(X28),
	Arm64ManagedRegister::FromXRegister(X29),
	Arm64ManagedRegister::FromXRegister(LR),
	// Hard float registers.
	// Considering the case, java_method_1 --> jni method --> jni function --> java_method_2,
	// we may break on java_method_2 and we still need to find out the values of DEX registers
	// in java_method_1. So all callee-saves(in managed code) need to be saved.
	Arm64ManagedRegister::FromDRegister(D8),
	Arm64ManagedRegister::FromDRegister(D9),
	Arm64ManagedRegister::FromDRegister(D10),
	Arm64ManagedRegister::FromDRegister(D11),
	Arm64ManagedRegister::FromDRegister(D12),
	Arm64ManagedRegister::FromDRegister(D13),
	Arm64ManagedRegister::FromDRegister(D14),
	Arm64ManagedRegister::FromDRegister(D15),
	};

	static constexpr uint32_t CalculateCoreCalleeSpillMask() {
	uint32_t result = 0u;
	for (auto&& r : kCalleeSaveRegisters) {
	if (r.AsArm64().IsXRegister()) {
	result \|= (1 << r.AsArm64().AsXRegister());
	}
	}
	return result;
	}

	static constexpr uint32_t CalculateFpCalleeSpillMask() {
	uint32_t result = 0;
	for (auto&& r : kCalleeSaveRegisters) {
	if (r.AsArm64().IsDRegister()) {
	result \|= (1 << r.AsArm64().AsDRegister());
	}
	}
	return result;
	}

	static constexpr uint32_t kCoreCalleeSpillMask = CalculateCoreCalleeSpillMask();
	static constexpr uint32_t kFpCalleeSpillMask = CalculateFpCalleeSpillMask();

	// Calling convention
	ManagedRegister Arm64ManagedRuntimeCallingConvention::InterproceduralScratchRegister() {
	// X20 is safe to use as a scratch register:
	// - with Baker read barriers (in the case of a non-critical native
	// method), it is reserved as Marking Register, and thus does not
	// actually need to be saved/restored; it is refreshed on exit
	// (see Arm64JNIMacroAssembler::RemoveFrame);
	// - in other cases, it is saved on entry (in
	// Arm64JNIMacroAssembler::BuildFrame) and restored on exit (in
	// Arm64JNIMacroAssembler::RemoveFrame). This is also expected in
	// the case of a critical native method in the Baker read barrier
	// configuration, where the value of MR must be preserved across
	// the JNI call (as there is no MR refresh in that case).
	return Arm64ManagedRegister::FromXRegister(X20);
	}

	ManagedRegister Arm64JniCallingConvention::InterproceduralScratchRegister() {
	// X20 is safe to use as a scratch register:
	// - with Baker read barriers (in the case of a non-critical native
	// method), it is reserved as Marking Register, and thus does not
	// actually need to be saved/restored; it is refreshed on exit
	// (see Arm64JNIMacroAssembler::RemoveFrame);
	// - in other cases, it is saved on entry (in
	// Arm64JNIMacroAssembler::BuildFrame) and restored on exit (in
	// Arm64JNIMacroAssembler::RemoveFrame). This is also expected in
	// the case of a critical native method in the Baker read barrier
	// configuration, where the value of MR must be preserved across
	// the JNI call (as there is no MR refresh in that case).
	return Arm64ManagedRegister::FromXRegister(X20);
	}

	static ManagedRegister ReturnRegisterForShorty(const char* shorty) {
	if (shorty[0] == 'F') {
	return Arm64ManagedRegister::FromSRegister(S0);
	} else if (shorty[0] == 'D') {
	return Arm64ManagedRegister::FromDRegister(D0);
	} else if (shorty[0] == 'J') {
	return Arm64ManagedRegister::FromXRegister(X0);
	} else if (shorty[0] == 'V') {
	return Arm64ManagedRegister::NoRegister();
	} else {
	return Arm64ManagedRegister::FromWRegister(W0);
	}
	}

	ManagedRegister Arm64ManagedRuntimeCallingConvention::ReturnRegister() {
	return ReturnRegisterForShorty(GetShorty());
	}

	ManagedRegister Arm64JniCallingConvention::ReturnRegister() {
	return ReturnRegisterForShorty(GetShorty());
	}

	ManagedRegister Arm64JniCallingConvention::IntReturnRegister() {
	return Arm64ManagedRegister::FromWRegister(W0);
	}

	// Managed runtime calling convention

	ManagedRegister Arm64ManagedRuntimeCallingConvention::MethodRegister() {
	return Arm64ManagedRegister::FromXRegister(X0);
	}

	bool Arm64ManagedRuntimeCallingConvention::IsCurrentParamInRegister() {
	return false; // Everything moved to stack on entry.
	}

	bool Arm64ManagedRuntimeCallingConvention::IsCurrentParamOnStack() {
	return true;
	}

	ManagedRegister Arm64ManagedRuntimeCallingConvention::CurrentParamRegister() {
	LOG(FATAL) << "Should not reach here";
	UNREACHABLE();
	}

	FrameOffset Arm64ManagedRuntimeCallingConvention::CurrentParamStackOffset() {
	CHECK(IsCurrentParamOnStack());
	FrameOffset result =
	FrameOffset(displacement_.Int32Value() + // displacement
	kFramePointerSize + // Method ref
	(itr_slots_ * sizeof(uint32_t))); // offset into in args
	return result;
	}

	const ManagedRegisterEntrySpills& Arm64ManagedRuntimeCallingConvention::EntrySpills() {
	// We spill the argument registers on ARM64 to free them up for scratch use, we then assume
	// all arguments are on the stack.
	if ((entry_spills_.size() == 0) && (NumArgs() > 0)) {
	int gp_reg_index = 1; // we start from X1/W1, X0 holds ArtMethod*.
	int fp_reg_index = 0; // D0/S0.

	// We need to choose the correct register (D/S or X/W) since the managed
	// stack uses 32bit stack slots.
	ResetIterator(FrameOffset(0));
	while (HasNext()) {
	if (IsCurrentParamAFloatOrDouble()) { // FP regs.
	if (fp_reg_index < 8) {
	if (!IsCurrentParamADouble()) {
	entry_spills_.push_back(Arm64ManagedRegister::FromSRegister(kSArgumentRegisters[fp_reg_index]));
	} else {
	entry_spills_.push_back(Arm64ManagedRegister::FromDRegister(kDArgumentRegisters[fp_reg_index]));
	}
	fp_reg_index++;
	} else { // just increase the stack offset.
	if (!IsCurrentParamADouble()) {
	entry_spills_.push_back(ManagedRegister::NoRegister(), 4);
	} else {
	entry_spills_.push_back(ManagedRegister::NoRegister(), 8);
	}
	}
	} else { // GP regs.
	if (gp_reg_index < 8) {
	if (IsCurrentParamALong() && (!IsCurrentParamAReference())) {
	entry_spills_.push_back(Arm64ManagedRegister::FromXRegister(kXArgumentRegisters[gp_reg_index]));
	} else {
	entry_spills_.push_back(Arm64ManagedRegister::FromWRegister(kWArgumentRegisters[gp_reg_index]));
	}
	gp_reg_index++;
	} else { // just increase the stack offset.
	if (IsCurrentParamALong() && (!IsCurrentParamAReference())) {
	entry_spills_.push_back(ManagedRegister::NoRegister(), 8);
	} else {
	entry_spills_.push_back(ManagedRegister::NoRegister(), 4);
	}
	}
	}
	Next();
	}
	}
	return entry_spills_;
	}

	// JNI calling convention
	Arm64JniCallingConvention::Arm64JniCallingConvention(bool is_static,
	bool is_synchronized,
	bool is_critical_native,
	const char* shorty)
	: JniCallingConvention(is_static,
	is_synchronized,
	is_critical_native,
	shorty,
	kArm64PointerSize) {
	}

	uint32_t Arm64JniCallingConvention::CoreSpillMask() const {
	return kCoreCalleeSpillMask;
	}

	uint32_t Arm64JniCallingConvention::FpSpillMask() const {
	return kFpCalleeSpillMask;
	}

	ManagedRegister Arm64JniCallingConvention::ReturnScratchRegister() const {
	return ManagedRegister::NoRegister();
	}

	size_t Arm64JniCallingConvention::FrameSize() {
	// Method*, callee save area size, local reference segment state
	//
	// (Unlike x86_64, do not include return address, and the segment state is uint32
	// instead of pointer).
	size_t method_ptr_size = static_cast<size_t>(kFramePointerSize);
	size_t callee_save_area_size = CalleeSaveRegisters().size() * kFramePointerSize;

	size_t frame_data_size = method_ptr_size + callee_save_area_size;
	if (LIKELY(HasLocalReferenceSegmentState())) {
	frame_data_size += sizeof(uint32_t);
	}
	// References plus 2 words for HandleScope header
	size_t handle_scope_size = HandleScope::SizeOf(kArm64PointerSize, ReferenceCount());

	size_t total_size = frame_data_size;
	if (LIKELY(HasHandleScope())) {
	// HandleScope is sometimes excluded.
	total_size += handle_scope_size; // handle scope size
	}

	// Plus return value spill area size
	total_size += SizeOfReturnValue();

	return RoundUp(total_size, kStackAlignment);
	}

	size_t Arm64JniCallingConvention::OutArgSize() {
	// Same as X86_64
	return RoundUp(NumberOfOutgoingStackArgs() * kFramePointerSize, kStackAlignment);
	}

	ArrayRef<const ManagedRegister> Arm64JniCallingConvention::CalleeSaveRegisters() const {
	// Same as X86_64
	return ArrayRef<const ManagedRegister>(kCalleeSaveRegisters);
	}

	bool Arm64JniCallingConvention::IsCurrentParamInRegister() {
	if (IsCurrentParamAFloatOrDouble()) {
	return (itr_float_and_doubles_ < kMaxFloatOrDoubleRegisterArguments);
	} else {
	return ((itr_args_ - itr_float_and_doubles_) < kMaxIntLikeRegisterArguments);
	}
	// TODO: Can we just call CurrentParamRegister to figure this out?
	}

	bool Arm64JniCallingConvention::IsCurrentParamOnStack() {
	// Is this ever not the same for all the architectures?
	return !IsCurrentParamInRegister();
	}

	ManagedRegister Arm64JniCallingConvention::CurrentParamRegister() {
	CHECK(IsCurrentParamInRegister());
	if (IsCurrentParamAFloatOrDouble()) {
	CHECK_LT(itr_float_and_doubles_, kMaxFloatOrDoubleRegisterArguments);
	if (IsCurrentParamADouble()) {
	return Arm64ManagedRegister::FromDRegister(kDArgumentRegisters[itr_float_and_doubles_]);
	} else {
	return Arm64ManagedRegister::FromSRegister(kSArgumentRegisters[itr_float_and_doubles_]);
	}
	} else {
	int gp_reg = itr_args_ - itr_float_and_doubles_;
	CHECK_LT(static_cast<unsigned int>(gp_reg), kMaxIntLikeRegisterArguments);
	if (IsCurrentParamALong() \|\| IsCurrentParamAReference() \|\| IsCurrentParamJniEnv()) {
	return Arm64ManagedRegister::FromXRegister(kXArgumentRegisters[gp_reg]);
	} else {
	return Arm64ManagedRegister::FromWRegister(kWArgumentRegisters[gp_reg]);
	}
	}
	}

	FrameOffset Arm64JniCallingConvention::CurrentParamStackOffset() {
	CHECK(IsCurrentParamOnStack());
	size_t args_on_stack = itr_args_
	- std::min(kMaxFloatOrDoubleRegisterArguments,
	static_cast<size_t>(itr_float_and_doubles_))
	- std::min(kMaxIntLikeRegisterArguments,
	static_cast<size_t>(itr_args_ - itr_float_and_doubles_));
	size_t offset = displacement_.Int32Value() - OutArgSize() + (args_on_stack * kFramePointerSize);
	CHECK_LT(offset, OutArgSize());
	return FrameOffset(offset);
	// TODO: Seems identical to X86_64 code.
	}

	size_t Arm64JniCallingConvention::NumberOfOutgoingStackArgs() {
	// all arguments including JNI args
	size_t all_args = NumArgs() + NumberOfExtraArgumentsForJni();

	DCHECK_GE(all_args, NumFloatOrDoubleArgs());

	size_t all_stack_args =
	all_args
	- std::min(kMaxFloatOrDoubleRegisterArguments,
	static_cast<size_t>(NumFloatOrDoubleArgs()))
	- std::min(kMaxIntLikeRegisterArguments,
	static_cast<size_t>((all_args - NumFloatOrDoubleArgs())));

	// TODO: Seems similar to X86_64 code except it doesn't count return pc.

	return all_stack_args;
	}

	} // namespace arm64
	} // namespace art