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_WASM_INTERPRETER_H_ |
| 6 | #define V8_WASM_INTERPRETER_H_ |
| 7 | |
| 8 | #include "src/wasm/wasm-opcodes.h" |
| 9 | #include "src/zone-containers.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace base { |
| 13 | class AccountingAllocator; |
| 14 | } |
| 15 | |
| 16 | namespace internal { |
| 17 | namespace wasm { |
| 18 | |
| 19 | // forward declarations. |
| 20 | struct WasmFunction; |
| 21 | struct WasmModuleInstance; |
| 22 | class WasmInterpreterInternals; |
| 23 | |
| 24 | typedef size_t pc_t; |
| 25 | typedef size_t sp_t; |
| 26 | typedef int32_t pcdiff_t; |
| 27 | typedef uint32_t spdiff_t; |
| 28 | |
| 29 | const pc_t kInvalidPc = 0x80000000; |
| 30 | |
| 31 | // Visible for testing. A {ControlTransfer} helps the interpreter figure out |
| 32 | // the target program counter and stack manipulations for a branch. |
| 33 | struct ControlTransfer { |
| 34 | enum StackAction { kNoAction, kPopAndRepush, kPushVoid }; |
| 35 | pcdiff_t pcdiff; // adjustment to the program counter (positive or negative). |
| 36 | spdiff_t spdiff; // number of elements to pop off the stack. |
| 37 | StackAction action; // action to perform on the stack. |
| 38 | }; |
| 39 | typedef ZoneMap<pc_t, ControlTransfer> ControlTransferMap; |
| 40 | |
| 41 | // Macro for defining union members. |
| 42 | #define FOREACH_UNION_MEMBER(V) \ |
| 43 | V(i32, kAstI32, int32_t) \ |
| 44 | V(u32, kAstI32, uint32_t) \ |
| 45 | V(i64, kAstI64, int64_t) \ |
| 46 | V(u64, kAstI64, uint64_t) \ |
| 47 | V(f32, kAstF32, float) \ |
| 48 | V(f64, kAstF64, double) |
| 49 | |
| 50 | // Representation of values within the interpreter. |
| 51 | struct WasmVal { |
| 52 | LocalType type; |
| 53 | union { |
| 54 | #define DECLARE_FIELD(field, localtype, ctype) ctype field; |
| 55 | FOREACH_UNION_MEMBER(DECLARE_FIELD) |
| 56 | #undef DECLARE_FIELD |
| 57 | } val; |
| 58 | |
| 59 | WasmVal() : type(kAstStmt) {} |
| 60 | |
| 61 | #define DECLARE_CONSTRUCTOR(field, localtype, ctype) \ |
| 62 | explicit WasmVal(ctype v) : type(localtype) { val.field = v; } |
| 63 | FOREACH_UNION_MEMBER(DECLARE_CONSTRUCTOR) |
| 64 | #undef DECLARE_CONSTRUCTOR |
| 65 | |
| 66 | template <typename T> |
| 67 | T to() { |
| 68 | UNREACHABLE(); |
| 69 | } |
| 70 | }; |
| 71 | |
| 72 | #define DECLARE_CAST(field, localtype, ctype) \ |
| 73 | template <> \ |
| 74 | inline ctype WasmVal::to() { \ |
| 75 | CHECK_EQ(localtype, type); \ |
| 76 | return val.field; \ |
| 77 | } |
| 78 | FOREACH_UNION_MEMBER(DECLARE_CAST) |
| 79 | #undef DECLARE_CAST |
| 80 | |
| 81 | template <> |
| 82 | inline void WasmVal::to() { |
| 83 | CHECK_EQ(kAstStmt, type); |
| 84 | } |
| 85 | |
| 86 | // Representation of frames within the interpreter. |
| 87 | class WasmFrame { |
| 88 | public: |
| 89 | const WasmFunction* function() const { return function_; } |
| 90 | int pc() const { return pc_; } |
| 91 | |
| 92 | private: |
| 93 | friend class WasmInterpreter; |
| 94 | |
| 95 | WasmFrame(const WasmFunction* function, int pc, int fp, int sp) |
| 96 | : function_(function), pc_(pc), fp_(fp), sp_(sp) {} |
| 97 | |
| 98 | const WasmFunction* function_; |
| 99 | int pc_; |
| 100 | int fp_; |
| 101 | int sp_; |
| 102 | }; |
| 103 | |
| 104 | // An interpreter capable of executing WASM. |
| 105 | class WasmInterpreter { |
| 106 | public: |
| 107 | // State machine for a Thread: |
| 108 | // +---------------Run()-----------+ |
| 109 | // V | |
| 110 | // STOPPED ---Run()--> RUNNING ------Pause()-----+-> PAUSED <------+ |
| 111 | // | | | / | | |
| 112 | // | | +---- Breakpoint ---+ +-- Step() --+ |
| 113 | // | | |
| 114 | // | +------------ Trap --------------> TRAPPED |
| 115 | // +------------- Finish -------------> FINISHED |
| 116 | enum State { STOPPED, RUNNING, PAUSED, FINISHED, TRAPPED }; |
| 117 | |
| 118 | // Representation of a thread in the interpreter. |
| 119 | class Thread { |
| 120 | public: |
| 121 | // Execution control. |
| 122 | virtual State state() = 0; |
| 123 | virtual void PushFrame(const WasmFunction* function, WasmVal* args) = 0; |
| 124 | virtual State Run() = 0; |
| 125 | virtual State Step() = 0; |
| 126 | virtual void Pause() = 0; |
| 127 | virtual void Reset() = 0; |
| 128 | virtual ~Thread() {} |
| 129 | |
| 130 | // Stack inspection and modification. |
| 131 | virtual pc_t GetBreakpointPc() = 0; |
| 132 | virtual int GetFrameCount() = 0; |
| 133 | virtual const WasmFrame* GetFrame(int index) = 0; |
| 134 | virtual WasmFrame* GetMutableFrame(int index) = 0; |
| 135 | virtual WasmVal GetReturnValue() = 0; |
| 136 | |
| 137 | // Thread-specific breakpoints. |
| 138 | bool SetBreakpoint(const WasmFunction* function, int pc, bool enabled); |
| 139 | bool GetBreakpoint(const WasmFunction* function, int pc); |
| 140 | }; |
| 141 | |
| 142 | WasmInterpreter(WasmModuleInstance* instance, |
| 143 | base::AccountingAllocator* allocator); |
| 144 | ~WasmInterpreter(); |
| 145 | |
| 146 | //========================================================================== |
| 147 | // Execution controls. |
| 148 | //========================================================================== |
| 149 | void Run(); |
| 150 | void Pause(); |
| 151 | |
| 152 | // Set a breakpoint at {pc} in {function} to be {enabled}. Returns the |
| 153 | // previous state of the breakpoint at {pc}. |
| 154 | bool SetBreakpoint(const WasmFunction* function, pc_t pc, bool enabled); |
| 155 | |
| 156 | // Gets the current state of the breakpoint at {function}. |
| 157 | bool GetBreakpoint(const WasmFunction* function, pc_t pc); |
| 158 | |
| 159 | // Enable or disable tracing for {function}. Return the previous state. |
| 160 | bool SetTracing(const WasmFunction* function, bool enabled); |
| 161 | |
| 162 | //========================================================================== |
| 163 | // Thread iteration and inspection. |
| 164 | //========================================================================== |
| 165 | int GetThreadCount(); |
| 166 | Thread* GetThread(int id); |
| 167 | |
| 168 | //========================================================================== |
| 169 | // Stack frame inspection. |
| 170 | //========================================================================== |
| 171 | WasmVal GetLocalVal(const WasmFrame* frame, int index); |
| 172 | WasmVal GetExprVal(const WasmFrame* frame, int pc); |
| 173 | void SetLocalVal(WasmFrame* frame, int index, WasmVal val); |
| 174 | void SetExprVal(WasmFrame* frame, int pc, WasmVal val); |
| 175 | |
| 176 | //========================================================================== |
| 177 | // Memory access. |
| 178 | //========================================================================== |
| 179 | size_t GetMemorySize(); |
| 180 | WasmVal ReadMemory(size_t offset); |
| 181 | void WriteMemory(size_t offset, WasmVal val); |
| 182 | |
| 183 | //========================================================================== |
| 184 | // Testing functionality. |
| 185 | //========================================================================== |
| 186 | // Manually adds a function to this interpreter, returning the index of the |
| 187 | // function. |
| 188 | int AddFunctionForTesting(const WasmFunction* function); |
| 189 | // Manually adds code to the interpreter for the given function. |
| 190 | bool SetFunctionCodeForTesting(const WasmFunction* function, |
| 191 | const byte* start, const byte* end); |
| 192 | |
| 193 | // Computes the control targets for the given bytecode as {pc offset, sp |
| 194 | // offset} |
| 195 | // pairs. Used internally in the interpreter, but exposed for testing. |
| 196 | static ControlTransferMap ComputeControlTransfersForTesting(Zone* zone, |
| 197 | const byte* start, |
| 198 | const byte* end); |
| 199 | |
| 200 | private: |
| 201 | Zone zone_; |
| 202 | WasmInterpreterInternals* internals_; |
| 203 | }; |
| 204 | |
| 205 | } // namespace wasm |
| 206 | } // namespace internal |
| 207 | } // namespace v8 |
| 208 | |
| 209 | #endif // V8_WASM_INTERPRETER_H_ |