compiler/optimizing/locations.h - LeafOS-Project/android_art - Gitiles

 /*
  * 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.
  */

 #ifndef ART_COMPILER_OPTIMIZING_LOCATIONS_H_
 #define ART_COMPILER_OPTIMIZING_LOCATIONS_H_

 #include "base/arena_containers.h"
 #include "base/arena_object.h"
 #include "base/bit_field.h"
 #include "base/bit_utils.h"
 #include "base/bit_vector.h"
 #include "base/macros.h"
 #include "base/value_object.h"

 namespace art HIDDEN {

 class HConstant;
 class HInstruction;
 class Location;

 std::ostream& operator<<(std::ostream& os, const Location& location);

 /**
  * A Location is an abstraction over the potential location
  * of an instruction. It could be in register or stack.
  */
 class Location : public ValueObject {
  public:
   enum OutputOverlap {
     // The liveness of the output overlaps the liveness of one or
     // several input(s); the register allocator cannot reuse an
     // input's location for the output's location.
     kOutputOverlap,
     // The liveness of the output does not overlap the liveness of any
     // input; the register allocator is allowed to reuse an input's
     // location for the output's location.
     kNoOutputOverlap
   };

   enum Kind {
     kInvalid = 0,
     kConstant = 1,
     kStackSlot = 2,  // 32bit stack slot.
     kDoubleStackSlot = 3,  // 64bit stack slot.

     kRegister = 4,  // Core register.

     // We do not use the value 5 because it conflicts with kLocationConstantMask.
     kDoNotUse5 = 5,

     kFpuRegister = 6,  // Float register.

     kRegisterPair = 7,  // Long register.

     kFpuRegisterPair = 8,  // Double register.

     // We do not use the value 9 because it conflicts with kLocationConstantMask.
     kDoNotUse9 = 9,

     kSIMDStackSlot = 10,  // 128bit stack slot. TODO: generalize with encoded #bytes?

     // Unallocated location represents a location that is not fixed and can be
     // allocated by a register allocator.  Each unallocated location has
     // a policy that specifies what kind of location is suitable. Payload
     // contains register allocation policy.
     kUnallocated = 11,
   };

   constexpr Location() : ValueObject(), value_(kInvalid) {
     // Verify that non-constant location kinds do not interfere with kConstant.
     static_assert((kInvalid & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kUnallocated & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kStackSlot & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kDoubleStackSlot & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kSIMDStackSlot & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kRegister & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kFpuRegister & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kRegisterPair & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kFpuRegisterPair & kLocationConstantMask) != kConstant, "TagError");
     static_assert((kConstant & kLocationConstantMask) == kConstant, "TagError");

     DCHECK(!IsValid());
   }

   constexpr Location(const Location& other) = default;

   Location& operator=(const Location& other) = default;

   bool IsConstant() const {
     return (value_ & kLocationConstantMask) == kConstant;
   }

   static Location ConstantLocation(HInstruction* constant) {
     DCHECK(constant != nullptr);
     if (kIsDebugBuild) {
       // Call out-of-line helper to avoid circular dependency with `nodes.h`.
       DCheckInstructionIsConstant(constant);
     }
     return Location(kConstant | reinterpret_cast<uintptr_t>(constant));
   }

   HConstant* GetConstant() const {
     DCHECK(IsConstant());
     return reinterpret_cast<HConstant*>(value_ & ~kLocationConstantMask);
   }

   bool IsValid() const {
     return value_ != kInvalid;
   }

   bool IsInvalid() const {
     return !IsValid();
   }

   // Empty location. Used if there the location should be ignored.
   static constexpr Location NoLocation() {
     return Location();
   }

   // Register locations.
   static constexpr Location RegisterLocation(int reg) {
     return Location(kRegister, reg);
   }

   static constexpr Location FpuRegisterLocation(int reg) {
     return Location(kFpuRegister, reg);
   }

   static constexpr Location RegisterPairLocation(int low, int high) {
     return Location(kRegisterPair, low << 16 | high);
   }

   static constexpr Location FpuRegisterPairLocation(int low, int high) {
     return Location(kFpuRegisterPair, low << 16 | high);
   }

   bool IsRegister() const {
     return GetKind() == kRegister;
   }

   bool IsFpuRegister() const {
     return GetKind() == kFpuRegister;
   }

   bool IsRegisterPair() const {
     return GetKind() == kRegisterPair;
   }

   bool IsFpuRegisterPair() const {
     return GetKind() == kFpuRegisterPair;
   }

   bool IsRegisterKind() const {
     return IsRegister() || IsFpuRegister() || IsRegisterPair() || IsFpuRegisterPair();
   }

   int reg() const {
     DCHECK(IsRegister() || IsFpuRegister());
     return GetPayload();
   }

   int low() const {
     DCHECK(IsPair());
     return GetPayload() >> 16;
   }

   int high() const {
     DCHECK(IsPair());
     return GetPayload() & 0xFFFF;
   }

   template <typename T>
   T AsRegister() const {
     DCHECK(IsRegister());
     return static_cast<T>(reg());
   }

   template <typename T>
   T AsFpuRegister() const {
     DCHECK(IsFpuRegister());
     return static_cast<T>(reg());
   }

   template <typename T>
   T AsRegisterPairLow() const {
     DCHECK(IsRegisterPair());
     return static_cast<T>(low());
   }

   template <typename T>
   T AsRegisterPairHigh() const {
     DCHECK(IsRegisterPair());
     return static_cast<T>(high());
   }

   template <typename T>
   T AsFpuRegisterPairLow() const {
     DCHECK(IsFpuRegisterPair());
     return static_cast<T>(low());
   }

   template <typename T>
   T AsFpuRegisterPairHigh() const {
     DCHECK(IsFpuRegisterPair());
     return static_cast<T>(high());
   }

   bool IsPair() const {
     return IsRegisterPair() || IsFpuRegisterPair();
   }

   Location ToLow() const {
     if (IsRegisterPair()) {
       return Location::RegisterLocation(low());
     } else if (IsFpuRegisterPair()) {
       return Location::FpuRegisterLocation(low());
     } else {
       DCHECK(IsDoubleStackSlot());
       return Location::StackSlot(GetStackIndex());
     }
   }

   Location ToHigh() const {
     if (IsRegisterPair()) {
       return Location::RegisterLocation(high());
     } else if (IsFpuRegisterPair()) {
       return Location::FpuRegisterLocation(high());
     } else {
       DCHECK(IsDoubleStackSlot());
       return Location::StackSlot(GetHighStackIndex(4));
     }
   }

   static uintptr_t EncodeStackIndex(intptr_t stack_index) {
     DCHECK(-kStackIndexBias <= stack_index);
     DCHECK(stack_index < kStackIndexBias);
     return static_cast<uintptr_t>(kStackIndexBias + stack_index);
   }

   static Location StackSlot(intptr_t stack_index) {
     uintptr_t payload = EncodeStackIndex(stack_index);
     Location loc(kStackSlot, payload);
     // Ensure that sign is preserved.
     DCHECK_EQ(loc.GetStackIndex(), stack_index);
     return loc;
   }

   bool IsStackSlot() const {
     return GetKind() == kStackSlot;
   }

   static Location DoubleStackSlot(intptr_t stack_index) {
     uintptr_t payload = EncodeStackIndex(stack_index);
     Location loc(kDoubleStackSlot, payload);
     // Ensure that sign is preserved.
     DCHECK_EQ(loc.GetStackIndex(), stack_index);
     return loc;
   }

   bool IsDoubleStackSlot() const {
     return GetKind() == kDoubleStackSlot;
   }

   static Location SIMDStackSlot(intptr_t stack_index) {
     uintptr_t payload = EncodeStackIndex(stack_index);
     Location loc(kSIMDStackSlot, payload);
     // Ensure that sign is preserved.
     DCHECK_EQ(loc.GetStackIndex(), stack_index);
     return loc;
   }

   bool IsSIMDStackSlot() const {
     return GetKind() == kSIMDStackSlot;
   }

   static Location StackSlotByNumOfSlots(size_t num_of_slots, int spill_slot) {
     DCHECK_NE(num_of_slots, 0u);
     switch (num_of_slots) {
       case 1u:
         return Location::StackSlot(spill_slot);
       case 2u:
         return Location::DoubleStackSlot(spill_slot);
       default:
         // Assume all other stack slot sizes correspond to SIMD slot size.
         return Location::SIMDStackSlot(spill_slot);
     }
   }

   intptr_t GetStackIndex() const {
     DCHECK(IsStackSlot() || IsDoubleStackSlot() || IsSIMDStackSlot());
     // Decode stack index manually to preserve sign.
     return GetPayload() - kStackIndexBias;
   }

   intptr_t GetHighStackIndex(uintptr_t word_size) const {
     DCHECK(IsDoubleStackSlot());
     // Decode stack index manually to preserve sign.
     return GetPayload() - kStackIndexBias + word_size;
   }

   Kind GetKind() const {
     return IsConstant() ? kConstant : KindField::Decode(value_);
   }

   bool Equals(Location other) const {
     return value_ == other.value_;
   }

   bool Contains(Location other) const {
     if (Equals(other)) {
       return true;
     } else if (IsPair() || IsDoubleStackSlot()) {
       return ToLow().Equals(other) || ToHigh().Equals(other);
     }
     return false;
   }

   bool OverlapsWith(Location other) const {
     // Only check the overlapping case that can happen with our register allocation algorithm.
     bool overlap = Contains(other) || other.Contains(*this);
     if (kIsDebugBuild && !overlap) {
       // Note: These are also overlapping cases. But we are not able to handle them in
       // ParallelMoveResolverWithSwap. Make sure that we do not meet such case with our compiler.
       if ((IsPair() && other.IsPair()) || (IsDoubleStackSlot() && other.IsDoubleStackSlot())) {
         DCHECK(!Contains(other.ToLow()));
         DCHECK(!Contains(other.ToHigh()));
       }
     }
     return overlap;
   }

   const char* DebugString() const {
     switch (GetKind()) {
       case kInvalid: return "I";
       case kRegister: return "R";
       case kStackSlot: return "S";
       case kDoubleStackSlot: return "DS";
       case kSIMDStackSlot: return "SIMD";
       case kUnallocated: return "U";
       case kConstant: return "C";
       case kFpuRegister: return "F";
       case kRegisterPair: return "RP";
       case kFpuRegisterPair: return "FP";
       case kDoNotUse5:  // fall-through
       case kDoNotUse9:
         LOG(FATAL) << "Should not use this location kind";
     }
     UNREACHABLE();
   }

   // Unallocated locations.
   enum Policy {
     kAny,
     kRequiresRegister,
     kRequiresFpuRegister,
     kSameAsFirstInput,
   };

   bool IsUnallocated() const {
     return GetKind() == kUnallocated;
   }

   static Location UnallocatedLocation(Policy policy) {
     return Location(kUnallocated, PolicyField::Encode(policy));
   }

   // Any free register is suitable to replace this unallocated location.
   static Location Any() {
     return UnallocatedLocation(kAny);
   }

   static Location RequiresRegister() {
     return UnallocatedLocation(kRequiresRegister);
   }

   static Location RequiresFpuRegister() {
     return UnallocatedLocation(kRequiresFpuRegister);
   }

   static Location RegisterOrConstant(HInstruction* instruction);
   static Location RegisterOrInt32Constant(HInstruction* instruction);
   static Location ByteRegisterOrConstant(int reg, HInstruction* instruction);
   static Location FpuRegisterOrConstant(HInstruction* instruction);
   static Location FpuRegisterOrInt32Constant(HInstruction* instruction);

   // The location of the first input to the instruction will be
   // used to replace this unallocated location.
   static Location SameAsFirstInput() {
     return UnallocatedLocation(kSameAsFirstInput);
   }

   Policy GetPolicy() const {
     DCHECK(IsUnallocated());
     return PolicyField::Decode(GetPayload());
   }

   bool RequiresRegisterKind() const {
     return GetPolicy() == kRequiresRegister || GetPolicy() == kRequiresFpuRegister;
   }

   uintptr_t GetEncoding() const {
     return GetPayload();
   }

  private:
   // Number of bits required to encode Kind value.
   static constexpr uint32_t kBitsForKind = 4;
   static constexpr uint32_t kBitsForPayload = kBitsPerIntPtrT - kBitsForKind;
   static constexpr uintptr_t kLocationConstantMask = 0x3;

   explicit Location(uintptr_t value) : value_(value) {}

   constexpr Location(Kind kind, uintptr_t payload)
       : value_(KindField::Encode(kind) | PayloadField::Encode(payload)) {}

   uintptr_t GetPayload() const {
     return PayloadField::Decode(value_);
   }

   static void DCheckInstructionIsConstant(HInstruction* instruction);

   using KindField = BitField<Kind, 0, kBitsForKind>;
   using PayloadField = BitField<uintptr_t, kBitsForKind, kBitsForPayload>;

   // Layout for kUnallocated locations payload.
   using PolicyField = BitField<Policy, 0, 3>;

   // Layout for stack slots.
   static const intptr_t kStackIndexBias =
       static_cast<intptr_t>(1) << (kBitsForPayload - 1);

   // Location either contains kind and payload fields or a tagged handle for
   // a constant locations. Values of enumeration Kind are selected in such a
   // way that none of them can be interpreted as a kConstant tag.
   uintptr_t value_;
 };
 std::ostream& operator<<(std::ostream& os, Location::Kind rhs);
 std::ostream& operator<<(std::ostream& os, Location::Policy rhs);

 class RegisterSet : public ValueObject {
  public:
   static RegisterSet Empty() { return RegisterSet(); }
   static RegisterSet AllFpu() { return RegisterSet(0, -1); }

   void Add(Location loc) {
     if (loc.IsRegister()) {
       core_registers_ |= (1 << loc.reg());
     } else {
       DCHECK(loc.IsFpuRegister());
       floating_point_registers_ |= (1 << loc.reg());
     }
   }

   void Remove(Location loc) {
     if (loc.IsRegister()) {
       core_registers_ &= ~(1 << loc.reg());
     } else {
       DCHECK(loc.IsFpuRegister()) << loc;
       floating_point_registers_ &= ~(1 << loc.reg());
     }
   }

   bool ContainsCoreRegister(uint32_t id) const {
     return Contains(core_registers_, id);
   }

   bool ContainsFloatingPointRegister(uint32_t id) const {
     return Contains(floating_point_registers_, id);
   }

   static bool Contains(uint32_t register_set, uint32_t reg) {
     return (register_set & (1 << reg)) != 0;
   }

   bool OverlapsRegisters(Location out) {
     DCHECK(out.IsRegisterKind());
     switch (out.GetKind()) {
       case Location::Kind::kRegister:
         return ContainsCoreRegister(out.reg());
       case Location::Kind::kFpuRegister:
         return ContainsFloatingPointRegister(out.reg());
       case Location::Kind::kRegisterPair:
         return ContainsCoreRegister(out.low()) || ContainsCoreRegister(out.high());
       case Location::Kind::kFpuRegisterPair:
         return ContainsFloatingPointRegister(out.low()) ||
                ContainsFloatingPointRegister(out.high());
       default:
         return false;
     }
   }

   size_t GetNumberOfRegisters() const {
     return POPCOUNT(core_registers_) + POPCOUNT(floating_point_registers_);
   }

   uint32_t GetCoreRegisters() const {
     return core_registers_;
   }

   uint32_t GetFloatingPointRegisters() const {
     return floating_point_registers_;
   }

  private:
   RegisterSet() : core_registers_(0), floating_point_registers_(0) {}
   RegisterSet(uint32_t core, uint32_t fp) : core_registers_(core), floating_point_registers_(fp) {}

   uint32_t core_registers_;
   uint32_t floating_point_registers_;
 };

 static constexpr bool kIntrinsified = true;

 /**
  * The code generator computes LocationSummary for each instruction so that
  * the instruction itself knows what code to generate: where to find the inputs
  * and where to place the result.
  *
  * The intent is to have the code for generating the instruction independent of
  * register allocation. A register allocator just has to provide a LocationSummary.
  */
 class LocationSummary : public ArenaObject<kArenaAllocLocationSummary> {
  public:
   enum CallKind {
     kNoCall,
     kCallOnMainAndSlowPath,
     kCallOnSlowPath,
     kCallOnMainOnly
   };

   explicit LocationSummary(HInstruction* instruction,
                            CallKind call_kind = kNoCall,
                            bool intrinsified = false);

   void SetInAt(uint32_t at, Location location) {
     inputs_[at] = location;
   }

   Location InAt(uint32_t at) const {
     return inputs_[at];
   }

   size_t GetInputCount() const {
     return inputs_.size();
   }

   // Set the output location.  Argument `overlaps` tells whether the
   // output overlaps any of the inputs (if so, it cannot share the
   // same register as one of the inputs); it is set to
   // `Location::kOutputOverlap` by default for safety.
   void SetOut(Location location, Location::OutputOverlap overlaps = Location::kOutputOverlap) {
     DCHECK(output_.IsInvalid());
     output_overlaps_ = overlaps;
     output_ = location;
   }

   void UpdateOut(Location location) {
     // There are two reasons for updating an output:
     // 1) Parameters, where we only know the exact stack slot after
     //    doing full register allocation.
     // 2) Unallocated location.
     DCHECK(output_.IsStackSlot() || output_.IsDoubleStackSlot() || output_.IsUnallocated());
     output_ = location;
   }

   void AddTemp(Location location) {
     temps_.push_back(location);
   }

   void AddRegisterTemps(size_t count) {
     for (size_t i = 0; i < count; ++i) {
       AddTemp(Location::RequiresRegister());
     }
   }

   Location GetTemp(uint32_t at) const {
     return temps_[at];
   }

   void SetTempAt(uint32_t at, Location location) {
     DCHECK(temps_[at].IsUnallocated() || temps_[at].IsInvalid());
     temps_[at] = location;
   }

   size_t GetTempCount() const {
     return temps_.size();
   }

   bool HasTemps() const { return !temps_.empty(); }

   Location Out() const { return output_; }

   bool CanCall() const {
     return call_kind_ != kNoCall;
   }

   bool WillCall() const {
     return call_kind_ == kCallOnMainOnly || call_kind_ == kCallOnMainAndSlowPath;
   }

   bool CallsOnSlowPath() const {
     return OnlyCallsOnSlowPath() || CallsOnMainAndSlowPath();
   }

   bool OnlyCallsOnSlowPath() const {
     return call_kind_ == kCallOnSlowPath;
   }

   bool NeedsSuspendCheckEntry() const {
     // Slow path calls do not need a SuspendCheck at method entry since they go into the runtime,
     // which we expect to either do a suspend check or return quickly.
     return WillCall();
   }

   bool CallsOnMainAndSlowPath() const {
     return call_kind_ == kCallOnMainAndSlowPath;
   }

   bool NeedsSafepoint() const {
     return CanCall();
   }

   void SetCustomSlowPathCallerSaves(const RegisterSet& caller_saves) {
     DCHECK(OnlyCallsOnSlowPath());
     has_custom_slow_path_calling_convention_ = true;
     custom_slow_path_caller_saves_ = caller_saves;
   }

   bool HasCustomSlowPathCallingConvention() const {
     return has_custom_slow_path_calling_convention_;
   }

   const RegisterSet& GetCustomSlowPathCallerSaves() const {
     DCHECK(HasCustomSlowPathCallingConvention());
     return custom_slow_path_caller_saves_;
   }

   void SetStackBit(uint32_t index) {
     stack_mask_->SetBit(index);
   }

   void ClearStackBit(uint32_t index) {
     stack_mask_->ClearBit(index);
   }

   void SetRegisterBit(uint32_t reg_id) {
     register_mask_ |= (1 << reg_id);
   }

   uint32_t GetRegisterMask() const {
     return register_mask_;
   }

   bool RegisterContainsObject(uint32_t reg_id) {
     return RegisterSet::Contains(register_mask_, reg_id);
   }

   void AddLiveRegister(Location location) {
     live_registers_.Add(location);
   }

   BitVector* GetStackMask() const {
     return stack_mask_;
   }

   RegisterSet* GetLiveRegisters() {
     return &live_registers_;
   }

   size_t GetNumberOfLiveRegisters() const {
     return live_registers_.GetNumberOfRegisters();
   }

   bool OutputUsesSameAs(uint32_t input_index) const {
     return (input_index == 0)
         && output_.IsUnallocated()
         && (output_.GetPolicy() == Location::kSameAsFirstInput);
   }

   bool IsFixedInput(uint32_t input_index) const {
     Location input = inputs_[input_index];
     return input.IsRegister()
         || input.IsFpuRegister()
         || input.IsPair()
         || input.IsStackSlot()
         || input.IsDoubleStackSlot();
   }

   bool OutputCanOverlapWithInputs() const {
     return output_overlaps_ == Location::kOutputOverlap;
   }

   bool Intrinsified() const {
     return intrinsified_;
   }

  private:
   LocationSummary(HInstruction* instruction,
                   CallKind call_kind,
                   bool intrinsified,
                   ArenaAllocator* allocator);

   ArenaVector<Location> inputs_;
   ArenaVector<Location> temps_;
   const CallKind call_kind_;
   // Whether these are locations for an intrinsified call.
   const bool intrinsified_;
   // Whether the slow path has default or custom calling convention.
   bool has_custom_slow_path_calling_convention_;
   // Whether the output overlaps with any of the inputs. If it overlaps, then it cannot
   // share the same register as the inputs.
   Location::OutputOverlap output_overlaps_;
   Location output_;

   // Mask of objects that live in the stack.
   BitVector* stack_mask_;

   // Mask of objects that live in register.
   uint32_t register_mask_;

   // Registers that are in use at this position.
   RegisterSet live_registers_;

   // Custom slow path caller saves. Valid only if indicated by slow_path_calling_convention_.
   RegisterSet custom_slow_path_caller_saves_;

   friend class RegisterAllocatorTest;
   DISALLOW_COPY_AND_ASSIGN(LocationSummary);
 };

 }  // namespace art

 #endif  // ART_COMPILER_OPTIMIZING_LOCATIONS_H_
	/*
	* 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.
	*/

	#ifndef ART_COMPILER_OPTIMIZING_LOCATIONS_H_
	#define ART_COMPILER_OPTIMIZING_LOCATIONS_H_

	#include "base/arena_containers.h"
	#include "base/arena_object.h"
	#include "base/bit_field.h"
	#include "base/bit_utils.h"
	#include "base/bit_vector.h"
	#include "base/macros.h"
	#include "base/value_object.h"

	namespace art HIDDEN {

	class HConstant;
	class HInstruction;
	class Location;

	std::ostream& operator<<(std::ostream& os, const Location& location);

	/**
	* A Location is an abstraction over the potential location
	* of an instruction. It could be in register or stack.
	*/
	class Location : public ValueObject {
	public:
	enum OutputOverlap {
	// The liveness of the output overlaps the liveness of one or
	// several input(s); the register allocator cannot reuse an
	// input's location for the output's location.
	kOutputOverlap,
	// The liveness of the output does not overlap the liveness of any
	// input; the register allocator is allowed to reuse an input's
	// location for the output's location.
	kNoOutputOverlap
	};

	enum Kind {
	kInvalid = 0,
	kConstant = 1,
	kStackSlot = 2, // 32bit stack slot.
	kDoubleStackSlot = 3, // 64bit stack slot.

	kRegister = 4, // Core register.

	// We do not use the value 5 because it conflicts with kLocationConstantMask.
	kDoNotUse5 = 5,

	kFpuRegister = 6, // Float register.

	kRegisterPair = 7, // Long register.

	kFpuRegisterPair = 8, // Double register.

	// We do not use the value 9 because it conflicts with kLocationConstantMask.
	kDoNotUse9 = 9,

	kSIMDStackSlot = 10, // 128bit stack slot. TODO: generalize with encoded #bytes?

	// Unallocated location represents a location that is not fixed and can be
	// allocated by a register allocator. Each unallocated location has
	// a policy that specifies what kind of location is suitable. Payload
	// contains register allocation policy.
	kUnallocated = 11,
	};

	constexpr Location() : ValueObject(), value_(kInvalid) {
	// Verify that non-constant location kinds do not interfere with kConstant.
	static_assert((kInvalid & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kUnallocated & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kStackSlot & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kDoubleStackSlot & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kSIMDStackSlot & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kRegister & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kFpuRegister & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kRegisterPair & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kFpuRegisterPair & kLocationConstantMask) != kConstant, "TagError");
	static_assert((kConstant & kLocationConstantMask) == kConstant, "TagError");

	DCHECK(!IsValid());
	}

	constexpr Location(const Location& other) = default;

	Location& operator=(const Location& other) = default;

	bool IsConstant() const {
	return (value_ & kLocationConstantMask) == kConstant;
	}

	static Location ConstantLocation(HInstruction* constant) {
	DCHECK(constant != nullptr);
	if (kIsDebugBuild) {
	// Call out-of-line helper to avoid circular dependency with `nodes.h`.
	DCheckInstructionIsConstant(constant);
	}
	return Location(kConstant \| reinterpret_cast<uintptr_t>(constant));
	}

	HConstant* GetConstant() const {
	DCHECK(IsConstant());
	return reinterpret_cast<HConstant*>(value_ & ~kLocationConstantMask);
	}

	bool IsValid() const {
	return value_ != kInvalid;
	}

	bool IsInvalid() const {
	return !IsValid();
	}

	// Empty location. Used if there the location should be ignored.
	static constexpr Location NoLocation() {
	return Location();
	}

	// Register locations.
	static constexpr Location RegisterLocation(int reg) {
	return Location(kRegister, reg);
	}

	static constexpr Location FpuRegisterLocation(int reg) {
	return Location(kFpuRegister, reg);
	}

	static constexpr Location RegisterPairLocation(int low, int high) {
	return Location(kRegisterPair, low << 16 \| high);
	}

	static constexpr Location FpuRegisterPairLocation(int low, int high) {
	return Location(kFpuRegisterPair, low << 16 \| high);
	}

	bool IsRegister() const {
	return GetKind() == kRegister;
	}

	bool IsFpuRegister() const {
	return GetKind() == kFpuRegister;
	}

	bool IsRegisterPair() const {
	return GetKind() == kRegisterPair;
	}

	bool IsFpuRegisterPair() const {
	return GetKind() == kFpuRegisterPair;
	}

	bool IsRegisterKind() const {
	return IsRegister() \|\| IsFpuRegister() \|\| IsRegisterPair() \|\| IsFpuRegisterPair();
	}

	int reg() const {
	DCHECK(IsRegister() \|\| IsFpuRegister());
	return GetPayload();
	}

	int low() const {
	DCHECK(IsPair());
	return GetPayload() >> 16;
	}

	int high() const {
	DCHECK(IsPair());
	return GetPayload() & 0xFFFF;
	}

	template <typename T>
	T AsRegister() const {
	DCHECK(IsRegister());
	return static_cast<T>(reg());
	}

	template <typename T>
	T AsFpuRegister() const {
	DCHECK(IsFpuRegister());
	return static_cast<T>(reg());
	}

	template <typename T>
	T AsRegisterPairLow() const {
	DCHECK(IsRegisterPair());
	return static_cast<T>(low());
	}

	template <typename T>
	T AsRegisterPairHigh() const {
	DCHECK(IsRegisterPair());
	return static_cast<T>(high());
	}

	template <typename T>
	T AsFpuRegisterPairLow() const {
	DCHECK(IsFpuRegisterPair());
	return static_cast<T>(low());
	}

	template <typename T>
	T AsFpuRegisterPairHigh() const {
	DCHECK(IsFpuRegisterPair());
	return static_cast<T>(high());
	}

	bool IsPair() const {
	return IsRegisterPair() \|\| IsFpuRegisterPair();
	}

	Location ToLow() const {
	if (IsRegisterPair()) {
	return Location::RegisterLocation(low());
	} else if (IsFpuRegisterPair()) {
	return Location::FpuRegisterLocation(low());
	} else {
	DCHECK(IsDoubleStackSlot());
	return Location::StackSlot(GetStackIndex());
	}
	}

	Location ToHigh() const {
	if (IsRegisterPair()) {
	return Location::RegisterLocation(high());
	} else if (IsFpuRegisterPair()) {
	return Location::FpuRegisterLocation(high());
	} else {
	DCHECK(IsDoubleStackSlot());
	return Location::StackSlot(GetHighStackIndex(4));
	}
	}

	static uintptr_t EncodeStackIndex(intptr_t stack_index) {
	DCHECK(-kStackIndexBias <= stack_index);
	DCHECK(stack_index < kStackIndexBias);
	return static_cast<uintptr_t>(kStackIndexBias + stack_index);
	}

	static Location StackSlot(intptr_t stack_index) {
	uintptr_t payload = EncodeStackIndex(stack_index);
	Location loc(kStackSlot, payload);
	// Ensure that sign is preserved.
	DCHECK_EQ(loc.GetStackIndex(), stack_index);
	return loc;
	}

	bool IsStackSlot() const {
	return GetKind() == kStackSlot;
	}

	static Location DoubleStackSlot(intptr_t stack_index) {
	uintptr_t payload = EncodeStackIndex(stack_index);
	Location loc(kDoubleStackSlot, payload);
	// Ensure that sign is preserved.
	DCHECK_EQ(loc.GetStackIndex(), stack_index);
	return loc;
	}

	bool IsDoubleStackSlot() const {
	return GetKind() == kDoubleStackSlot;
	}

	static Location SIMDStackSlot(intptr_t stack_index) {
	uintptr_t payload = EncodeStackIndex(stack_index);
	Location loc(kSIMDStackSlot, payload);
	// Ensure that sign is preserved.
	DCHECK_EQ(loc.GetStackIndex(), stack_index);
	return loc;
	}

	bool IsSIMDStackSlot() const {
	return GetKind() == kSIMDStackSlot;
	}

	static Location StackSlotByNumOfSlots(size_t num_of_slots, int spill_slot) {
	DCHECK_NE(num_of_slots, 0u);
	switch (num_of_slots) {
	case 1u:
	return Location::StackSlot(spill_slot);
	case 2u:
	return Location::DoubleStackSlot(spill_slot);
	default:
	// Assume all other stack slot sizes correspond to SIMD slot size.
	return Location::SIMDStackSlot(spill_slot);
	}
	}

	intptr_t GetStackIndex() const {
	DCHECK(IsStackSlot() \|\| IsDoubleStackSlot() \|\| IsSIMDStackSlot());
	// Decode stack index manually to preserve sign.
	return GetPayload() - kStackIndexBias;
	}

	intptr_t GetHighStackIndex(uintptr_t word_size) const {
	DCHECK(IsDoubleStackSlot());
	// Decode stack index manually to preserve sign.
	return GetPayload() - kStackIndexBias + word_size;
	}

	Kind GetKind() const {
	return IsConstant() ? kConstant : KindField::Decode(value_);
	}

	bool Equals(Location other) const {
	return value_ == other.value_;
	}

	bool Contains(Location other) const {
	if (Equals(other)) {
	return true;
	} else if (IsPair() \|\| IsDoubleStackSlot()) {
	return ToLow().Equals(other) \|\| ToHigh().Equals(other);
	}
	return false;
	}

	bool OverlapsWith(Location other) const {
	// Only check the overlapping case that can happen with our register allocation algorithm.
	bool overlap = Contains(other) \|\| other.Contains(*this);
	if (kIsDebugBuild && !overlap) {
	// Note: These are also overlapping cases. But we are not able to handle them in
	// ParallelMoveResolverWithSwap. Make sure that we do not meet such case with our compiler.
	if ((IsPair() && other.IsPair()) \|\| (IsDoubleStackSlot() && other.IsDoubleStackSlot())) {
	DCHECK(!Contains(other.ToLow()));
	DCHECK(!Contains(other.ToHigh()));
	}
	}
	return overlap;
	}

	const char* DebugString() const {
	switch (GetKind()) {
	case kInvalid: return "I";
	case kRegister: return "R";
	case kStackSlot: return "S";
	case kDoubleStackSlot: return "DS";
	case kSIMDStackSlot: return "SIMD";
	case kUnallocated: return "U";
	case kConstant: return "C";
	case kFpuRegister: return "F";
	case kRegisterPair: return "RP";
	case kFpuRegisterPair: return "FP";
	case kDoNotUse5: // fall-through
	case kDoNotUse9:
	LOG(FATAL) << "Should not use this location kind";
	}
	UNREACHABLE();
	}

	// Unallocated locations.
	enum Policy {
	kAny,
	kRequiresRegister,
	kRequiresFpuRegister,
	kSameAsFirstInput,
	};

	bool IsUnallocated() const {
	return GetKind() == kUnallocated;
	}

	static Location UnallocatedLocation(Policy policy) {
	return Location(kUnallocated, PolicyField::Encode(policy));
	}

	// Any free register is suitable to replace this unallocated location.
	static Location Any() {
	return UnallocatedLocation(kAny);
	}

	static Location RequiresRegister() {
	return UnallocatedLocation(kRequiresRegister);
	}

	static Location RequiresFpuRegister() {
	return UnallocatedLocation(kRequiresFpuRegister);
	}

	static Location RegisterOrConstant(HInstruction* instruction);
	static Location RegisterOrInt32Constant(HInstruction* instruction);
	static Location ByteRegisterOrConstant(int reg, HInstruction* instruction);
	static Location FpuRegisterOrConstant(HInstruction* instruction);
	static Location FpuRegisterOrInt32Constant(HInstruction* instruction);

	// The location of the first input to the instruction will be
	// used to replace this unallocated location.
	static Location SameAsFirstInput() {
	return UnallocatedLocation(kSameAsFirstInput);
	}

	Policy GetPolicy() const {
	DCHECK(IsUnallocated());
	return PolicyField::Decode(GetPayload());
	}

	bool RequiresRegisterKind() const {
	return GetPolicy() == kRequiresRegister \|\| GetPolicy() == kRequiresFpuRegister;
	}

	uintptr_t GetEncoding() const {
	return GetPayload();
	}

	private:
	// Number of bits required to encode Kind value.
	static constexpr uint32_t kBitsForKind = 4;
	static constexpr uint32_t kBitsForPayload = kBitsPerIntPtrT - kBitsForKind;
	static constexpr uintptr_t kLocationConstantMask = 0x3;

	explicit Location(uintptr_t value) : value_(value) {}

	constexpr Location(Kind kind, uintptr_t payload)
	: value_(KindField::Encode(kind) \| PayloadField::Encode(payload)) {}

	uintptr_t GetPayload() const {
	return PayloadField::Decode(value_);
	}

	static void DCheckInstructionIsConstant(HInstruction* instruction);

	using KindField = BitField<Kind, 0, kBitsForKind>;
	using PayloadField = BitField<uintptr_t, kBitsForKind, kBitsForPayload>;

	// Layout for kUnallocated locations payload.
	using PolicyField = BitField<Policy, 0, 3>;

	// Layout for stack slots.
	static const intptr_t kStackIndexBias =
	static_cast<intptr_t>(1) << (kBitsForPayload - 1);

	// Location either contains kind and payload fields or a tagged handle for
	// a constant locations. Values of enumeration Kind are selected in such a
	// way that none of them can be interpreted as a kConstant tag.
	uintptr_t value_;
	};
	std::ostream& operator<<(std::ostream& os, Location::Kind rhs);
	std::ostream& operator<<(std::ostream& os, Location::Policy rhs);

	class RegisterSet : public ValueObject {
	public:
	static RegisterSet Empty() { return RegisterSet(); }
	static RegisterSet AllFpu() { return RegisterSet(0, -1); }

	void Add(Location loc) {
	if (loc.IsRegister()) {
	core_registers_ \|= (1 << loc.reg());
	} else {
	DCHECK(loc.IsFpuRegister());
	floating_point_registers_ \|= (1 << loc.reg());
	}
	}

	void Remove(Location loc) {
	if (loc.IsRegister()) {
	core_registers_ &= ~(1 << loc.reg());
	} else {
	DCHECK(loc.IsFpuRegister()) << loc;
	floating_point_registers_ &= ~(1 << loc.reg());
	}
	}

	bool ContainsCoreRegister(uint32_t id) const {
	return Contains(core_registers_, id);
	}

	bool ContainsFloatingPointRegister(uint32_t id) const {
	return Contains(floating_point_registers_, id);
	}

	static bool Contains(uint32_t register_set, uint32_t reg) {
	return (register_set & (1 << reg)) != 0;
	}

	bool OverlapsRegisters(Location out) {
	DCHECK(out.IsRegisterKind());
	switch (out.GetKind()) {
	case Location::Kind::kRegister:
	return ContainsCoreRegister(out.reg());
	case Location::Kind::kFpuRegister:
	return ContainsFloatingPointRegister(out.reg());
	case Location::Kind::kRegisterPair:
	return ContainsCoreRegister(out.low()) \|\| ContainsCoreRegister(out.high());
	case Location::Kind::kFpuRegisterPair:
	return ContainsFloatingPointRegister(out.low()) \|\|
	ContainsFloatingPointRegister(out.high());
	default:
	return false;
	}
	}

	size_t GetNumberOfRegisters() const {
	return POPCOUNT(core_registers_) + POPCOUNT(floating_point_registers_);
	}

	uint32_t GetCoreRegisters() const {
	return core_registers_;
	}

	uint32_t GetFloatingPointRegisters() const {
	return floating_point_registers_;
	}

	private:
	RegisterSet() : core_registers_(0), floating_point_registers_(0) {}
	RegisterSet(uint32_t core, uint32_t fp) : core_registers_(core), floating_point_registers_(fp) {}

	uint32_t core_registers_;
	uint32_t floating_point_registers_;
	};

	static constexpr bool kIntrinsified = true;

	/**
	* The code generator computes LocationSummary for each instruction so that
	* the instruction itself knows what code to generate: where to find the inputs
	* and where to place the result.
	*
	* The intent is to have the code for generating the instruction independent of
	* register allocation. A register allocator just has to provide a LocationSummary.
	*/
	class LocationSummary : public ArenaObject<kArenaAllocLocationSummary> {
	public:
	enum CallKind {
	kNoCall,
	kCallOnMainAndSlowPath,
	kCallOnSlowPath,
	kCallOnMainOnly
	};

	explicit LocationSummary(HInstruction* instruction,
	CallKind call_kind = kNoCall,
	bool intrinsified = false);

	void SetInAt(uint32_t at, Location location) {
	inputs_[at] = location;
	}

	Location InAt(uint32_t at) const {
	return inputs_[at];
	}

	size_t GetInputCount() const {
	return inputs_.size();
	}

	// Set the output location. Argument `overlaps` tells whether the
	// output overlaps any of the inputs (if so, it cannot share the
	// same register as one of the inputs); it is set to
	// `Location::kOutputOverlap` by default for safety.
	void SetOut(Location location, Location::OutputOverlap overlaps = Location::kOutputOverlap) {
	DCHECK(output_.IsInvalid());
	output_overlaps_ = overlaps;
	output_ = location;
	}

	void UpdateOut(Location location) {
	// There are two reasons for updating an output:
	// 1) Parameters, where we only know the exact stack slot after
	// doing full register allocation.
	// 2) Unallocated location.
	DCHECK(output_.IsStackSlot() \|\| output_.IsDoubleStackSlot() \|\| output_.IsUnallocated());
	output_ = location;
	}

	void AddTemp(Location location) {
	temps_.push_back(location);
	}

	void AddRegisterTemps(size_t count) {
	for (size_t i = 0; i < count; ++i) {
	AddTemp(Location::RequiresRegister());
	}
	}

	Location GetTemp(uint32_t at) const {
	return temps_[at];
	}

	void SetTempAt(uint32_t at, Location location) {
	DCHECK(temps_[at].IsUnallocated() \|\| temps_[at].IsInvalid());
	temps_[at] = location;
	}

	size_t GetTempCount() const {
	return temps_.size();
	}

	bool HasTemps() const { return !temps_.empty(); }

	Location Out() const { return output_; }

	bool CanCall() const {
	return call_kind_ != kNoCall;
	}

	bool WillCall() const {
	return call_kind_ == kCallOnMainOnly \|\| call_kind_ == kCallOnMainAndSlowPath;
	}

	bool CallsOnSlowPath() const {
	return OnlyCallsOnSlowPath() \|\| CallsOnMainAndSlowPath();
	}

	bool OnlyCallsOnSlowPath() const {
	return call_kind_ == kCallOnSlowPath;
	}

	bool NeedsSuspendCheckEntry() const {
	// Slow path calls do not need a SuspendCheck at method entry since they go into the runtime,
	// which we expect to either do a suspend check or return quickly.
	return WillCall();
	}

	bool CallsOnMainAndSlowPath() const {
	return call_kind_ == kCallOnMainAndSlowPath;
	}

	bool NeedsSafepoint() const {
	return CanCall();
	}

	void SetCustomSlowPathCallerSaves(const RegisterSet& caller_saves) {
	DCHECK(OnlyCallsOnSlowPath());
	has_custom_slow_path_calling_convention_ = true;
	custom_slow_path_caller_saves_ = caller_saves;
	}

	bool HasCustomSlowPathCallingConvention() const {
	return has_custom_slow_path_calling_convention_;
	}

	const RegisterSet& GetCustomSlowPathCallerSaves() const {
	DCHECK(HasCustomSlowPathCallingConvention());
	return custom_slow_path_caller_saves_;
	}

	void SetStackBit(uint32_t index) {
	stack_mask_->SetBit(index);
	}

	void ClearStackBit(uint32_t index) {
	stack_mask_->ClearBit(index);
	}

	void SetRegisterBit(uint32_t reg_id) {
	register_mask_ \|= (1 << reg_id);
	}

	uint32_t GetRegisterMask() const {
	return register_mask_;
	}

	bool RegisterContainsObject(uint32_t reg_id) {
	return RegisterSet::Contains(register_mask_, reg_id);
	}

	void AddLiveRegister(Location location) {
	live_registers_.Add(location);
	}

	BitVector* GetStackMask() const {
	return stack_mask_;
	}

	RegisterSet* GetLiveRegisters() {
	return &live_registers_;
	}

	size_t GetNumberOfLiveRegisters() const {
	return live_registers_.GetNumberOfRegisters();
	}

	bool OutputUsesSameAs(uint32_t input_index) const {
	return (input_index == 0)
	&& output_.IsUnallocated()
	&& (output_.GetPolicy() == Location::kSameAsFirstInput);
	}

	bool IsFixedInput(uint32_t input_index) const {
	Location input = inputs_[input_index];
	return input.IsRegister()
	\|\| input.IsFpuRegister()
	\|\| input.IsPair()
	\|\| input.IsStackSlot()
	\|\| input.IsDoubleStackSlot();
	}

	bool OutputCanOverlapWithInputs() const {
	return output_overlaps_ == Location::kOutputOverlap;
	}

	bool Intrinsified() const {
	return intrinsified_;
	}

	private:
	LocationSummary(HInstruction* instruction,
	CallKind call_kind,
	bool intrinsified,
	ArenaAllocator* allocator);

	ArenaVector<Location> inputs_;
	ArenaVector<Location> temps_;
	const CallKind call_kind_;
	// Whether these are locations for an intrinsified call.
	const bool intrinsified_;
	// Whether the slow path has default or custom calling convention.
	bool has_custom_slow_path_calling_convention_;
	// Whether the output overlaps with any of the inputs. If it overlaps, then it cannot
	// share the same register as the inputs.
	Location::OutputOverlap output_overlaps_;
	Location output_;

	// Mask of objects that live in the stack.
	BitVector* stack_mask_;

	// Mask of objects that live in register.
	uint32_t register_mask_;

	// Registers that are in use at this position.
	RegisterSet live_registers_;

	// Custom slow path caller saves. Valid only if indicated by slow_path_calling_convention_.
	RegisterSet custom_slow_path_caller_saves_;

	friend class RegisterAllocatorTest;
	DISALLOW_COPY_AND_ASSIGN(LocationSummary);
	};

	} // namespace art

	#endif // ART_COMPILER_OPTIMIZING_LOCATIONS_H_