Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame] | 1 | // Copyright 2016 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef V8_INTERPRETER_BYTECODE_REGISTER_OPTIMIZER_H_ |
| 6 | #define V8_INTERPRETER_BYTECODE_REGISTER_OPTIMIZER_H_ |
| 7 | |
| 8 | #include "src/interpreter/bytecode-pipeline.h" |
| 9 | |
| 10 | namespace v8 { |
| 11 | namespace internal { |
| 12 | namespace interpreter { |
| 13 | |
| 14 | // An optimization stage for eliminating unnecessary transfers between |
| 15 | // registers. The bytecode generator uses temporary registers |
| 16 | // liberally for correctness and convenience and this stage removes |
| 17 | // transfers that are not required and preserves correctness. |
| 18 | class BytecodeRegisterOptimizer final : public BytecodePipelineStage, |
| 19 | public TemporaryRegisterObserver, |
| 20 | public ZoneObject { |
| 21 | public: |
| 22 | BytecodeRegisterOptimizer(Zone* zone, |
| 23 | TemporaryRegisterAllocator* register_allocator, |
| 24 | int parameter_count, |
| 25 | BytecodePipelineStage* next_stage); |
| 26 | virtual ~BytecodeRegisterOptimizer() {} |
| 27 | |
| 28 | // BytecodePipelineStage interface. |
| 29 | void Write(BytecodeNode* node) override; |
| 30 | void WriteJump(BytecodeNode* node, BytecodeLabel* label) override; |
| 31 | void BindLabel(BytecodeLabel* label) override; |
| 32 | void BindLabel(const BytecodeLabel& target, BytecodeLabel* label) override; |
| 33 | Handle<BytecodeArray> ToBytecodeArray( |
| 34 | int fixed_register_count, int parameter_count, |
| 35 | Handle<FixedArray> handler_table) override; |
| 36 | |
| 37 | private: |
| 38 | static const uint32_t kInvalidEquivalenceId = kMaxUInt32; |
| 39 | |
| 40 | class RegisterInfo; |
| 41 | |
| 42 | // TemporaryRegisterObserver interface. |
| 43 | void TemporaryRegisterFreeEvent(Register reg) override; |
| 44 | |
| 45 | // Helpers for BytecodePipelineStage interface. |
| 46 | void FlushState(); |
| 47 | void WriteToNextStage(BytecodeNode* node) const; |
| 48 | void WriteToNextStage(BytecodeNode* node, |
| 49 | const BytecodeSourceInfo& output_info) const; |
| 50 | |
| 51 | // Update internal state for register transfer from |input| to |
| 52 | // |output| using |source_info| as source position information if |
| 53 | // any bytecodes are emitted due to transfer. |
| 54 | void RegisterTransfer(RegisterInfo* input, RegisterInfo* output, |
| 55 | const BytecodeSourceInfo& source_info); |
| 56 | |
| 57 | // Emit a register transfer bytecode from |input| to |output|. |
| 58 | void OutputRegisterTransfer( |
| 59 | RegisterInfo* input, RegisterInfo* output, |
| 60 | const BytecodeSourceInfo& source_info = BytecodeSourceInfo()); |
| 61 | |
| 62 | // Emits a Nop to preserve source position information in the |
| 63 | // bytecode pipeline. |
| 64 | void EmitNopForSourceInfo(const BytecodeSourceInfo& source_info) const; |
| 65 | |
| 66 | // Handlers for bytecode nodes for register to register transfers. |
| 67 | void DoLdar(const BytecodeNode* const node); |
| 68 | void DoMov(const BytecodeNode* const node); |
| 69 | void DoStar(const BytecodeNode* const node); |
| 70 | |
| 71 | // Operand processing methods for bytecodes other than those |
| 72 | // performing register to register transfers. |
| 73 | void PrepareOperands(BytecodeNode* const node); |
| 74 | void PrepareAccumulator(BytecodeNode* const node); |
| 75 | void PrepareRegisterOperands(BytecodeNode* const node); |
| 76 | |
| 77 | void PrepareRegisterOutputOperand(RegisterInfo* reg_info); |
| 78 | void PrepareRegisterRangeOutputOperand(Register start, int count); |
| 79 | void PrepareRegisterInputOperand(BytecodeNode* const node, Register reg, |
| 80 | int operand_index); |
| 81 | void PrepareRegisterRangeInputOperand(Register start, int count); |
| 82 | |
| 83 | Register GetEquivalentRegisterForInputOperand(Register reg); |
| 84 | |
| 85 | static Register GetRegisterInputOperand(int index, Bytecode bytecode, |
| 86 | const uint32_t* operands, |
| 87 | int operand_count); |
| 88 | static Register GetRegisterOutputOperand(int index, Bytecode bytecode, |
| 89 | const uint32_t* operands, |
| 90 | int operand_count); |
| 91 | |
| 92 | void CreateMaterializedEquivalent(RegisterInfo* info); |
| 93 | RegisterInfo* GetMaterializedEquivalent(RegisterInfo* info); |
| 94 | RegisterInfo* GetMaterializedEquivalentNotAccumulator(RegisterInfo* info); |
| 95 | void Materialize(RegisterInfo* info); |
| 96 | void AddToEquivalenceSet(RegisterInfo* set_member, |
| 97 | RegisterInfo* non_set_member); |
| 98 | |
| 99 | // Methods for finding and creating metadata for each register. |
| 100 | RegisterInfo* GetOrCreateRegisterInfo(Register reg); |
| 101 | RegisterInfo* GetRegisterInfo(Register reg); |
| 102 | RegisterInfo* NewRegisterInfo(Register reg); |
| 103 | void GrowRegisterMap(Register reg); |
| 104 | |
| 105 | bool RegisterIsTemporary(Register reg) const { |
| 106 | return reg >= temporary_base_; |
| 107 | } |
| 108 | |
| 109 | bool RegisterIsObservable(Register reg) const { |
| 110 | return reg != accumulator_ && !RegisterIsTemporary(reg); |
| 111 | } |
| 112 | |
| 113 | static Register OperandToRegister(uint32_t operand) { |
| 114 | return Register::FromOperand(static_cast<int32_t>(operand)); |
| 115 | } |
| 116 | |
| 117 | size_t GetRegisterInfoTableIndex(Register reg) const { |
| 118 | return static_cast<size_t>(reg.index() + register_info_table_offset_); |
| 119 | } |
| 120 | |
| 121 | Register RegisterFromRegisterInfoTableIndex(size_t index) const { |
| 122 | return Register(static_cast<int>(index) - register_info_table_offset_); |
| 123 | } |
| 124 | |
| 125 | uint32_t NextEquivalenceId() { |
| 126 | equivalence_id_++; |
| 127 | CHECK_NE(equivalence_id_, kInvalidEquivalenceId); |
| 128 | return equivalence_id_; |
| 129 | } |
| 130 | |
| 131 | Zone* zone() { return zone_; } |
| 132 | |
| 133 | const Register accumulator_; |
| 134 | RegisterInfo* accumulator_info_; |
| 135 | const Register temporary_base_; |
| 136 | |
| 137 | // Direct mapping to register info. |
| 138 | ZoneVector<RegisterInfo*> register_info_table_; |
| 139 | int register_info_table_offset_; |
| 140 | |
| 141 | // Counter for equivalence sets identifiers. |
| 142 | int equivalence_id_; |
| 143 | |
| 144 | BytecodePipelineStage* next_stage_; |
| 145 | bool flush_required_; |
| 146 | Zone* zone_; |
| 147 | |
| 148 | DISALLOW_COPY_AND_ASSIGN(BytecodeRegisterOptimizer); |
| 149 | }; |
| 150 | |
| 151 | } // namespace interpreter |
| 152 | } // namespace internal |
| 153 | } // namespace v8 |
| 154 | |
| 155 | #endif // V8_INTERPRETER_BYTECODE_REGISTER_OPTIMIZER_H_ |