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// Copyright 2016 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.
#ifndef V8_WASM_INTERPRETER_H_
#define V8_WASM_INTERPRETER_H_
#include "src/wasm/wasm-opcodes.h"
#include "src/zone/zone-containers.h"
namespace v8 {
namespace base {
class AccountingAllocator;
}
namespace internal {
namespace wasm {
// forward declarations.
struct WasmFunction;
struct WasmModuleInstance;
class WasmInterpreterInternals;
typedef size_t pc_t;
typedef size_t sp_t;
typedef int32_t pcdiff_t;
typedef uint32_t spdiff_t;
const pc_t kInvalidPc = 0x80000000;
typedef ZoneMap<pc_t, pcdiff_t> ControlTransferMap;
// Macro for defining union members.
#define FOREACH_UNION_MEMBER(V) \
V(i32, kAstI32, int32_t) \
V(u32, kAstI32, uint32_t) \
V(i64, kAstI64, int64_t) \
V(u64, kAstI64, uint64_t) \
V(f32, kAstF32, float) \
V(f64, kAstF64, double)
// Representation of values within the interpreter.
struct WasmVal {
LocalType type;
union {
#define DECLARE_FIELD(field, localtype, ctype) ctype field;
FOREACH_UNION_MEMBER(DECLARE_FIELD)
#undef DECLARE_FIELD
} val;
WasmVal() : type(kAstStmt) {}
#define DECLARE_CONSTRUCTOR(field, localtype, ctype) \
explicit WasmVal(ctype v) : type(localtype) { val.field = v; }
FOREACH_UNION_MEMBER(DECLARE_CONSTRUCTOR)
#undef DECLARE_CONSTRUCTOR
template <typename T>
T to() {
UNREACHABLE();
}
};
#define DECLARE_CAST(field, localtype, ctype) \
template <> \
inline ctype WasmVal::to() { \
CHECK_EQ(localtype, type); \
return val.field; \
}
FOREACH_UNION_MEMBER(DECLARE_CAST)
#undef DECLARE_CAST
template <>
inline void WasmVal::to() {
CHECK_EQ(kAstStmt, type);
}
// Representation of frames within the interpreter.
class WasmFrame {
public:
const WasmFunction* function() const { return function_; }
int pc() const { return pc_; }
private:
friend class WasmInterpreter;
WasmFrame(const WasmFunction* function, int pc, int fp, int sp)
: function_(function), pc_(pc), fp_(fp), sp_(sp) {}
const WasmFunction* function_;
int pc_;
int fp_;
int sp_;
};
// An interpreter capable of executing WASM.
class V8_EXPORT_PRIVATE WasmInterpreter {
public:
// State machine for a Thread:
// +---------------Run()-----------+
// V |
// STOPPED ---Run()--> RUNNING ------Pause()-----+-> PAUSED <------+
// | | | / | |
// | | +---- Breakpoint ---+ +-- Step() --+
// | |
// | +------------ Trap --------------> TRAPPED
// +------------- Finish -------------> FINISHED
enum State { STOPPED, RUNNING, PAUSED, FINISHED, TRAPPED };
// Representation of a thread in the interpreter.
class Thread {
public:
// Execution control.
virtual State state() = 0;
virtual void PushFrame(const WasmFunction* function, WasmVal* args) = 0;
virtual State Run() = 0;
virtual State Step() = 0;
virtual void Pause() = 0;
virtual void Reset() = 0;
virtual ~Thread() {}
// Stack inspection and modification.
virtual pc_t GetBreakpointPc() = 0;
virtual int GetFrameCount() = 0;
virtual const WasmFrame* GetFrame(int index) = 0;
virtual WasmFrame* GetMutableFrame(int index) = 0;
virtual WasmVal GetReturnValue(int index = 0) = 0;
// Thread-specific breakpoints.
bool SetBreakpoint(const WasmFunction* function, int pc, bool enabled);
bool GetBreakpoint(const WasmFunction* function, int pc);
};
WasmInterpreter(WasmModuleInstance* instance, AccountingAllocator* allocator);
~WasmInterpreter();
//==========================================================================
// Execution controls.
//==========================================================================
void Run();
void Pause();
// Set a breakpoint at {pc} in {function} to be {enabled}. Returns the
// previous state of the breakpoint at {pc}.
bool SetBreakpoint(const WasmFunction* function, pc_t pc, bool enabled);
// Gets the current state of the breakpoint at {function}.
bool GetBreakpoint(const WasmFunction* function, pc_t pc);
// Enable or disable tracing for {function}. Return the previous state.
bool SetTracing(const WasmFunction* function, bool enabled);
//==========================================================================
// Thread iteration and inspection.
//==========================================================================
int GetThreadCount();
Thread* GetThread(int id);
//==========================================================================
// Stack frame inspection.
//==========================================================================
WasmVal GetLocalVal(const WasmFrame* frame, int index);
WasmVal GetExprVal(const WasmFrame* frame, int pc);
void SetLocalVal(WasmFrame* frame, int index, WasmVal val);
void SetExprVal(WasmFrame* frame, int pc, WasmVal val);
//==========================================================================
// Memory access.
//==========================================================================
size_t GetMemorySize();
WasmVal ReadMemory(size_t offset);
void WriteMemory(size_t offset, WasmVal val);
//==========================================================================
// Testing functionality.
//==========================================================================
// Manually adds a function to this interpreter, returning the index of the
// function.
int AddFunctionForTesting(const WasmFunction* function);
// Manually adds code to the interpreter for the given function.
bool SetFunctionCodeForTesting(const WasmFunction* function,
const byte* start, const byte* end);
// Computes the control transfers for the given bytecode. Used internally in
// the interpreter, but exposed for testing.
static ControlTransferMap ComputeControlTransfersForTesting(Zone* zone,
const byte* start,
const byte* end);
private:
Zone zone_;
WasmInterpreterInternals* internals_;
};
} // namespace wasm
} // namespace internal
} // namespace v8
#endif // V8_WASM_INTERPRETER_H_
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