/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef jsopcode_h #define jsopcode_h /* * JS bytecode definitions. */ #include "mozilla/Attributes.h" #include "jsbytecode.h" #include "jstypes.h" #include "NamespaceImports.h" #include "frontend/SourceNotes.h" #include "js/UniquePtr.h" #include "vm/Opcodes.h" #include "vm/Printer.h" /* * JS operation bytecodes. */ typedef enum JSOp { #define ENUMERATE_OPCODE(op, val, ...) op = val, FOR_EACH_OPCODE(ENUMERATE_OPCODE) #undef ENUMERATE_OPCODE JSOP_LIMIT } JSOp; /* * JS bytecode formats. */ enum { JOF_BYTE = 0, /* single bytecode, no immediates */ JOF_JUMP = 1, /* signed 16-bit jump offset immediate */ JOF_ATOM = 2, /* unsigned 16-bit constant index */ JOF_UINT16 = 3, /* unsigned 16-bit immediate operand */ JOF_TABLESWITCH = 4, /* table switch */ /* 5 is unused */ JOF_QARG = 6, /* quickened get/set function argument ops */ JOF_LOCAL = 7, /* var or block-local variable */ JOF_DOUBLE = 8, /* uint32_t index for double value */ JOF_UINT24 = 12, /* extended unsigned 24-bit literal (index) */ JOF_UINT8 = 13, /* uint8_t immediate, e.g. top 8 bits of 24-bit atom index */ JOF_INT32 = 14, /* int32_t immediate operand */ JOF_UINT32 = 15, /* uint32_t immediate operand */ JOF_OBJECT = 16, /* unsigned 32-bit object index */ JOF_REGEXP = 17, /* unsigned 32-bit regexp index */ JOF_INT8 = 18, /* int8_t immediate operand */ JOF_ATOMOBJECT = 19, /* uint16_t constant index + object index */ JOF_SCOPE = 20, /* unsigned 32-bit scope index */ JOF_ENVCOORD = 21, /* embedded ScopeCoordinate immediate */ JOF_TYPEMASK = 0x001f, /* mask for above immediate types */ JOF_NAME = 1 << 5, /* name operation */ JOF_PROP = 2 << 5, /* obj.prop operation */ JOF_ELEM = 3 << 5, /* obj[index] operation */ JOF_MODEMASK = 7 << 5, /* mask for above addressing modes */ JOF_SET = 1 << 8, /* set (i.e., assignment) operation */ /* 1 << 9 is unused */ /* 1 << 10 is unused */ /* 1 << 11 is unused */ /* 1 << 12 is unused */ /* 1 << 13 is unused */ JOF_DETECTING = 1 << 14, /* object detection for warning-quelling */ /* 1 << 15 is unused */ JOF_LEFTASSOC = 1 << 16, /* left-associative operator */ /* 1 << 17 is unused */ /* 1 << 18 is unused */ JOF_CHECKSLOPPY = 1 << 19, /* Op can only be generated in sloppy mode */ JOF_CHECKSTRICT = 1 << 20, /* Op can only be generated in strict mode */ JOF_INVOKE = 1 << 21, /* JSOP_CALL, JSOP_FUNCALL, JSOP_FUNAPPLY, JSOP_NEW, JSOP_EVAL, JSOP_CALLITER */ /* 1 << 22 is unused */ /* 1 << 23 is unused */ /* 1 << 24 is unused */ JOF_GNAME = 1 << 25, /* predicted global name */ JOF_TYPESET = 1 << 26, /* has an entry in a script's type sets */ JOF_ARITH = 1 << 27 /* unary or binary arithmetic opcode */ }; /* Shorthand for type from format. */ static inline uint32_t JOF_TYPE(uint32_t fmt) { return fmt & JOF_TYPEMASK; } /* Shorthand for mode from format. */ static inline uint32_t JOF_MODE(uint32_t fmt) { return fmt & JOF_MODEMASK; } /* * Immediate operand getters, setters, and bounds. */ static MOZ_ALWAYS_INLINE uint8_t GET_UINT8(jsbytecode* pc) { return uint8_t(pc[1]); } static MOZ_ALWAYS_INLINE void SET_UINT8(jsbytecode* pc, uint8_t u) { pc[1] = jsbytecode(u); } /* Common uint16_t immediate format helpers. */ static inline jsbytecode UINT16_HI(uint16_t i) { return jsbytecode(i >> 8); } static inline jsbytecode UINT16_LO(uint16_t i) { return jsbytecode(i); } static MOZ_ALWAYS_INLINE uint16_t GET_UINT16(const jsbytecode* pc) { return uint16_t((pc[1] << 8) | pc[2]); } static MOZ_ALWAYS_INLINE void SET_UINT16(jsbytecode* pc, uint16_t i) { pc[1] = UINT16_HI(i); pc[2] = UINT16_LO(i); } static const unsigned UINT16_LEN = 2; static const unsigned UINT16_LIMIT = 1 << 16; /* Helpers for accessing the offsets of jump opcodes. */ static const unsigned JUMP_OFFSET_LEN = 4; static const int32_t JUMP_OFFSET_MIN = INT32_MIN; static const int32_t JUMP_OFFSET_MAX = INT32_MAX; static MOZ_ALWAYS_INLINE int32_t GET_JUMP_OFFSET(jsbytecode* pc) { return (pc[1] << 24) | (pc[2] << 16) | (pc[3] << 8) | pc[4]; } static MOZ_ALWAYS_INLINE void SET_JUMP_OFFSET(jsbytecode* pc, int32_t off) { pc[1] = jsbytecode(off >> 24); pc[2] = jsbytecode(off >> 16); pc[3] = jsbytecode(off >> 8); pc[4] = jsbytecode(off); } static const unsigned UINT32_INDEX_LEN = 4; static MOZ_ALWAYS_INLINE uint32_t GET_UINT32_INDEX(const jsbytecode* pc) { return (pc[1] << 24) | (pc[2] << 16) | (pc[3] << 8) | pc[4]; } static MOZ_ALWAYS_INLINE void SET_UINT32_INDEX(jsbytecode* pc, uint32_t index) { pc[1] = jsbytecode(index >> 24); pc[2] = jsbytecode(index >> 16); pc[3] = jsbytecode(index >> 8); pc[4] = jsbytecode(index); } static inline jsbytecode UINT24_HI(unsigned i) { return jsbytecode(i >> 16); } static inline jsbytecode UINT24_MID(unsigned i) { return jsbytecode(i >> 8); } static inline jsbytecode UINT24_LO(unsigned i) { return jsbytecode(i); } static MOZ_ALWAYS_INLINE unsigned GET_UINT24(const jsbytecode* pc) { return unsigned((pc[1] << 16) | (pc[2] << 8) | pc[3]); } static MOZ_ALWAYS_INLINE void SET_UINT24(jsbytecode* pc, unsigned i) { MOZ_ASSERT(i < (1 << 24)); pc[1] = UINT24_HI(i); pc[2] = UINT24_MID(i); pc[3] = UINT24_LO(i); } static MOZ_ALWAYS_INLINE int8_t GET_INT8(const jsbytecode* pc) { return int8_t(pc[1]); } static MOZ_ALWAYS_INLINE uint32_t GET_UINT32(const jsbytecode* pc) { return (uint32_t(pc[1]) << 24) | (uint32_t(pc[2]) << 16) | (uint32_t(pc[3]) << 8) | uint32_t(pc[4]); } static MOZ_ALWAYS_INLINE void SET_UINT32(jsbytecode* pc, uint32_t u) { pc[1] = jsbytecode(u >> 24); pc[2] = jsbytecode(u >> 16); pc[3] = jsbytecode(u >> 8); pc[4] = jsbytecode(u); } static MOZ_ALWAYS_INLINE int32_t GET_INT32(const jsbytecode* pc) { return static_cast(GET_UINT32(pc)); } static MOZ_ALWAYS_INLINE void SET_INT32(jsbytecode* pc, int32_t i) { SET_UINT32(pc, static_cast(i)); } /* Index limit is determined by SN_4BYTE_OFFSET_FLAG, see frontend/BytecodeEmitter.h. */ static const unsigned INDEX_LIMIT_LOG2 = 31; static const uint32_t INDEX_LIMIT = uint32_t(1) << INDEX_LIMIT_LOG2; static inline jsbytecode ARGC_HI(uint16_t argc) { return UINT16_HI(argc); } static inline jsbytecode ARGC_LO(uint16_t argc) { return UINT16_LO(argc); } static inline uint16_t GET_ARGC(const jsbytecode* pc) { return GET_UINT16(pc); } static const unsigned ARGC_LIMIT = UINT16_LIMIT; static inline uint16_t GET_ARGNO(const jsbytecode* pc) { return GET_UINT16(pc); } static inline void SET_ARGNO(jsbytecode* pc, uint16_t argno) { SET_UINT16(pc, argno); } static const unsigned ARGNO_LEN = 2; static const unsigned ARGNO_LIMIT = UINT16_LIMIT; static inline uint32_t GET_LOCALNO(const jsbytecode* pc) { return GET_UINT24(pc); } static inline void SET_LOCALNO(jsbytecode* pc, uint32_t varno) { SET_UINT24(pc, varno); } static const unsigned LOCALNO_LEN = 3; static const unsigned LOCALNO_BITS = 24; static const uint32_t LOCALNO_LIMIT = 1 << LOCALNO_BITS; static inline unsigned LoopEntryDepthHint(jsbytecode* pc) { MOZ_ASSERT(*pc == JSOP_LOOPENTRY); return GET_UINT8(pc) & 0x7f; } static inline bool LoopEntryCanIonOsr(jsbytecode* pc) { MOZ_ASSERT(*pc == JSOP_LOOPENTRY); return GET_UINT8(pc) & 0x80; } static inline uint8_t PackLoopEntryDepthHintAndFlags(unsigned loopDepth, bool canIonOsr) { return (loopDepth < 0x80 ? uint8_t(loopDepth) : 0x7f) | (canIonOsr ? 0x80 : 0); } /* * Describes the 'hops' component of a JOF_ENVCOORD opcode. * * Note: this component is only 8 bits wide, limiting the maximum number of * scopes between a use and def to roughly 255. This is a pretty small limit but * note that SpiderMonkey's recursive descent parser can only parse about this * many functions before hitting the C-stack recursion limit so this shouldn't * be a significant limitation in practice. */ static inline uint8_t GET_ENVCOORD_HOPS(jsbytecode* pc) { return GET_UINT8(pc); } static inline void SET_ENVCOORD_HOPS(jsbytecode* pc, uint8_t hops) { SET_UINT8(pc, hops); } static const unsigned ENVCOORD_HOPS_LEN = 1; static const unsigned ENVCOORD_HOPS_BITS = 8; static const unsigned ENVCOORD_HOPS_LIMIT = 1 << ENVCOORD_HOPS_BITS; /* Describes the 'slot' component of a JOF_ENVCOORD opcode. */ static inline uint32_t GET_ENVCOORD_SLOT(const jsbytecode* pc) { return GET_UINT24(pc); } static inline void SET_ENVCOORD_SLOT(jsbytecode* pc, uint32_t slot) { SET_UINT24(pc, slot); } static const unsigned ENVCOORD_SLOT_LEN = 3; static const unsigned ENVCOORD_SLOT_BITS = 24; static const uint32_t ENVCOORD_SLOT_LIMIT = 1 << ENVCOORD_SLOT_BITS; struct JSCodeSpec { int8_t length; /* length including opcode byte */ int8_t nuses; /* arity, -1 if variadic */ int8_t ndefs; /* number of stack results */ uint32_t format; /* immediate operand format */ uint32_t type() const { return JOF_TYPE(format); } }; /* Silence unreferenced formal parameter warnings */ #ifdef _MSC_VER #pragma warning(push) #pragma warning(disable:4100) #endif namespace js { extern const JSCodeSpec CodeSpec[]; extern const unsigned NumCodeSpecs; extern const char * const CodeName[]; /* Shorthand for type from opcode. */ static inline uint32_t JOF_OPTYPE(JSOp op) { return JOF_TYPE(CodeSpec[op].format); } static inline bool IsJumpOpcode(JSOp op) { uint32_t type = JOF_TYPE(CodeSpec[op].format); /* * LABEL opcodes have type JOF_JUMP but are no-ops, don't treat them as * jumps to avoid degrading precision. */ return type == JOF_JUMP && op != JSOP_LABEL; } static inline bool BytecodeFallsThrough(JSOp op) { switch (op) { case JSOP_GOTO: case JSOP_DEFAULT: case JSOP_RETURN: case JSOP_RETRVAL: case JSOP_FINALYIELDRVAL: case JSOP_THROW: case JSOP_THROWMSG: case JSOP_TABLESWITCH: return false; case JSOP_GOSUB: /* These fall through indirectly, after executing a 'finally'. */ return true; default: return true; } } static inline bool BytecodeIsJumpTarget(JSOp op) { switch (op) { case JSOP_JUMPTARGET: case JSOP_LOOPHEAD: case JSOP_LOOPENTRY: case JSOP_ENDITER: case JSOP_TRY: return true; default: return false; } } class SrcNoteLineScanner { /* offset of the current JSOp in the bytecode */ ptrdiff_t offset; /* next src note to process */ jssrcnote* sn; /* line number of the current JSOp */ uint32_t lineno; /* * Is the current op the first one after a line change directive? Note that * multiple ops may be "first" if a line directive is used to return to a * previous line (eg, with a for loop increment expression.) */ bool lineHeader; public: SrcNoteLineScanner(jssrcnote* sn, uint32_t lineno) : offset(0), sn(sn), lineno(lineno) { } /* * This is called repeatedly with always-advancing relpc values. The src * notes are tuples of . Scan * through, updating the lineno, until the next src note is for a later * bytecode. * * When looking at the desired PC offset ('relpc'), the op is first in that * line iff there is a SRC_SETLINE or SRC_NEWLINE src note for that exact * bytecode. * * Note that a single bytecode may have multiple line-modifying notes (even * though only one should ever be needed.) */ void advanceTo(ptrdiff_t relpc) { // Must always advance! If the same or an earlier PC is erroneously // passed in, we will already be past the relevant src notes MOZ_ASSERT_IF(offset > 0, relpc > offset); // Next src note should be for after the current offset MOZ_ASSERT_IF(offset > 0, SN_IS_TERMINATOR(sn) || SN_DELTA(sn) > 0); // The first PC requested is always considered to be a line header lineHeader = (offset == 0); if (SN_IS_TERMINATOR(sn)) return; ptrdiff_t nextOffset; while ((nextOffset = offset + SN_DELTA(sn)) <= relpc && !SN_IS_TERMINATOR(sn)) { offset = nextOffset; SrcNoteType type = (SrcNoteType) SN_TYPE(sn); if (type == SRC_SETLINE || type == SRC_NEWLINE) { if (type == SRC_SETLINE) lineno = GetSrcNoteOffset(sn, 0); else lineno++; if (offset == relpc) lineHeader = true; } sn = SN_NEXT(sn); } } bool isLineHeader() const { return lineHeader; } uint32_t getLine() const { return lineno; } }; extern unsigned StackUses(JSScript* script, jsbytecode* pc); extern unsigned StackDefs(JSScript* script, jsbytecode* pc); #ifdef DEBUG /* * Given bytecode address pc in script's main program code, compute the operand * stack depth just before (JSOp) *pc executes. If *pc is not reachable, return * false. */ extern bool ReconstructStackDepth(JSContext* cx, JSScript* script, jsbytecode* pc, uint32_t* depth, bool* reachablePC); #endif } /* namespace js */ #ifdef _MSC_VER #pragma warning(pop) #endif #define JSDVG_IGNORE_STACK 0 #define JSDVG_SEARCH_STACK 1 namespace js { /* * Get the length of variable-length bytecode like JSOP_TABLESWITCH. */ extern size_t GetVariableBytecodeLength(jsbytecode* pc); /* * Find the source expression that resulted in v, and return a newly allocated * C-string containing it. Fall back on v's string conversion (fallback) if we * can't find the bytecode that generated and pushed v on the operand stack. * * Search the current stack frame if spindex is JSDVG_SEARCH_STACK. Don't * look for v on the stack if spindex is JSDVG_IGNORE_STACK. Otherwise, * spindex is the negative index of v, measured from cx->fp->sp, or from a * lower frame's sp if cx->fp is native. * * The optional argument skipStackHits can be used to skip a hit in the stack * frame. This can be useful in self-hosted code that wants to report value * errors containing decompiled values that are useful for the user, instead of * values used internally by the self-hosted code. * * The caller must call JS_free on the result after a successful call. */ UniqueChars DecompileValueGenerator(JSContext* cx, int spindex, HandleValue v, HandleString fallback, int skipStackHits = 0); /* * Decompile the formal argument at formalIndex in the nearest non-builtin * stack frame, falling back with converting v to source. */ char* DecompileArgument(JSContext* cx, int formalIndex, HandleValue v); extern bool CallResultEscapes(jsbytecode* pc); static inline unsigned GetDecomposeLength(jsbytecode* pc, size_t len) { /* * The last byte of a DECOMPOSE op stores the decomposed length. This is a * constant: perhaps we should just hardcode values instead? */ MOZ_ASSERT(size_t(CodeSpec[*pc].length) == len); return (unsigned) pc[len - 1]; } static inline unsigned GetBytecodeLength(jsbytecode* pc) { JSOp op = (JSOp)*pc; MOZ_ASSERT(op < JSOP_LIMIT); if (CodeSpec[op].length != -1) return CodeSpec[op].length; return GetVariableBytecodeLength(pc); } static inline bool BytecodeIsPopped(jsbytecode* pc) { jsbytecode* next = pc + GetBytecodeLength(pc); return JSOp(*next) == JSOP_POP; } static inline bool BytecodeFlowsToBitop(jsbytecode* pc) { // Look for simple bytecode for integer conversions like (x | 0) or (x & -1). jsbytecode* next = pc + GetBytecodeLength(pc); if (*next == JSOP_BITOR || *next == JSOP_BITAND) return true; if (*next == JSOP_INT8 && GET_INT8(next) == -1) { next += GetBytecodeLength(next); if (*next == JSOP_BITAND) return true; return false; } if (*next == JSOP_ONE) { next += GetBytecodeLength(next); if (*next == JSOP_NEG) { next += GetBytecodeLength(next); if (*next == JSOP_BITAND) return true; } return false; } if (*next == JSOP_ZERO) { next += GetBytecodeLength(next); if (*next == JSOP_BITOR) return true; return false; } return false; } extern bool IsValidBytecodeOffset(JSContext* cx, JSScript* script, size_t offset); inline bool FlowsIntoNext(JSOp op) { // JSOP_YIELD/JSOP_AWAIT is considered to flow into the next instruction, // like JSOP_CALL. switch (op) { case JSOP_RETRVAL: case JSOP_RETURN: case JSOP_THROW: case JSOP_GOTO: case JSOP_RETSUB: case JSOP_FINALYIELDRVAL: return false; default: return true; } } inline bool IsArgOp(JSOp op) { return JOF_OPTYPE(op) == JOF_QARG; } inline bool IsLocalOp(JSOp op) { return JOF_OPTYPE(op) == JOF_LOCAL; } inline bool IsAliasedVarOp(JSOp op) { return JOF_OPTYPE(op) == JOF_ENVCOORD; } inline bool IsGlobalOp(JSOp op) { return CodeSpec[op].format & JOF_GNAME; } inline bool IsEqualityOp(JSOp op) { return op == JSOP_EQ || op == JSOP_NE || op == JSOP_STRICTEQ || op == JSOP_STRICTNE; } inline bool IsCheckStrictOp(JSOp op) { return CodeSpec[op].format & JOF_CHECKSTRICT; } #ifdef DEBUG inline bool IsCheckSloppyOp(JSOp op) { return CodeSpec[op].format & JOF_CHECKSLOPPY; } #endif inline bool IsAtomOp(JSOp op) { return JOF_OPTYPE(op) == JOF_ATOM; } inline bool IsGetPropPC(jsbytecode* pc) { JSOp op = JSOp(*pc); return op == JSOP_LENGTH || op == JSOP_GETPROP || op == JSOP_CALLPROP; } inline bool IsHiddenInitOp(JSOp op) { return op == JSOP_INITHIDDENPROP || op == JSOP_INITHIDDENELEM || op == JSOP_INITHIDDENPROP_GETTER || op == JSOP_INITHIDDENELEM_GETTER || op == JSOP_INITHIDDENPROP_SETTER || op == JSOP_INITHIDDENELEM_SETTER; } inline bool IsStrictSetPC(jsbytecode* pc) { JSOp op = JSOp(*pc); return op == JSOP_STRICTSETPROP || op == JSOP_STRICTSETNAME || op == JSOP_STRICTSETGNAME || op == JSOP_STRICTSETELEM; } inline bool IsSetPropPC(jsbytecode* pc) { JSOp op = JSOp(*pc); return op == JSOP_SETPROP || op == JSOP_STRICTSETPROP || op == JSOP_SETNAME || op == JSOP_STRICTSETNAME || op == JSOP_SETGNAME || op == JSOP_STRICTSETGNAME; } inline bool IsGetElemPC(jsbytecode* pc) { JSOp op = JSOp(*pc); return op == JSOP_GETELEM || op == JSOP_CALLELEM; } inline bool IsSetElemPC(jsbytecode* pc) { JSOp op = JSOp(*pc); return op == JSOP_SETELEM || op == JSOP_STRICTSETELEM; } inline bool IsCallPC(jsbytecode* pc) { return CodeSpec[*pc].format & JOF_INVOKE; } inline bool IsStrictEvalPC(jsbytecode* pc) { JSOp op = JSOp(*pc); return op == JSOP_STRICTEVAL || op == JSOP_STRICTSPREADEVAL; } static inline int32_t GetBytecodeInteger(jsbytecode* pc) { switch (JSOp(*pc)) { case JSOP_ZERO: return 0; case JSOP_ONE: return 1; case JSOP_UINT16: return GET_UINT16(pc); case JSOP_UINT24: return GET_UINT24(pc); case JSOP_INT8: return GET_INT8(pc); case JSOP_INT32: return GET_INT32(pc); default: MOZ_CRASH("Bad op"); } } /* * Counts accumulated for a single opcode in a script. The counts tracked vary * between opcodes, and this structure ensures that counts are accessed in a * coherent fashion. */ class PCCounts { /* * Offset of the pc inside the script. This fields is used to lookup opcode * which have annotations. */ size_t pcOffset_; /* * Record the number of execution of one instruction, or the number of * throws executed. */ uint64_t numExec_; public: explicit PCCounts(size_t off) : pcOffset_(off), numExec_(0) {} size_t pcOffset() const { return pcOffset_; } // Used for sorting and searching. bool operator<(const PCCounts& rhs) const { return pcOffset_ < rhs.pcOffset_; } uint64_t& numExec() { return numExec_; } uint64_t numExec() const { return numExec_; } static const char* numExecName; }; static inline jsbytecode* GetNextPc(jsbytecode* pc) { return pc + GetBytecodeLength(pc); } #if defined(DEBUG) /* * Disassemblers, for debugging only. */ extern MOZ_MUST_USE bool Disassemble(JSContext* cx, JS::Handle script, bool lines, Sprinter* sp); unsigned Disassemble1(JSContext* cx, JS::Handle script, jsbytecode* pc, unsigned loc, bool lines, Sprinter* sp); #endif extern MOZ_MUST_USE bool DumpCompartmentPCCounts(JSContext* cx); } // namespace js #endif /* jsopcode_h */