/* ** $Id: lcode.c,v 2.152 2018/01/28 15:13:26 roberto Exp roberto $ ** Code generator for Lua ** See Copyright Notice in lua.h */ #define lcode_c #define LUA_CORE #include "lprefix.h" #include #include #include #include "lua.h" #include "lcode.h" #include "ldebug.h" #include "ldo.h" #include "lgc.h" #include "llex.h" #include "lmem.h" #include "lobject.h" #include "lopcodes.h" #include "lparser.h" #include "lstring.h" #include "ltable.h" #include "lvm.h" /* Maximum number of registers in a Lua function (must fit in 8 bits) */ #define MAXREGS 254 #define hasjumps(e) ((e)->t != (e)->f) static int codesJ (FuncState *fs, OpCode o, int sj, int k); /* ** If expression is a numeric constant, fills 'v' with its value ** and returns 1. Otherwise, returns 0. */ static int tonumeral(const expdesc *e, TValue *v) { if (hasjumps(e)) return 0; /* not a numeral */ switch (e->k) { case VKINT: if (v) setivalue(v, e->u.ival); return 1; case VKFLT: if (v) setfltvalue(v, e->u.nval); return 1; default: return 0; } } /* ** Return the previous instruction of the current code. If there ** may be a jump target between the current instruction and the ** previous one, return an invalid instruction (to avoid wrong ** optimizations). */ static Instruction *previousinstruction (FuncState *fs) { static const Instruction invalidinstruction = -1; if (fs->pc > fs->lasttarget) return &fs->f->code[fs->pc - 1]; /* previous instruction */ else return cast(Instruction*, &invalidinstruction); } /* ** Create a OP_LOADNIL instruction, but try to optimize: if the previous ** instruction is also OP_LOADNIL and ranges are compatible, adjust ** range of previous instruction instead of emitting a new one. (For ** instance, 'local a; local b' will generate a single opcode.) */ void luaK_nil (FuncState *fs, int from, int n) { int l = from + n - 1; /* last register to set nil */ Instruction *previous = previousinstruction(fs); if (GET_OPCODE(*previous) == OP_LOADNIL) { /* previous is LOADNIL? */ int pfrom = GETARG_A(*previous); /* get previous range */ int pl = pfrom + GETARG_B(*previous); if ((pfrom <= from && from <= pl + 1) || (from <= pfrom && pfrom <= l + 1)) { /* can connect both? */ if (pfrom < from) from = pfrom; /* from = min(from, pfrom) */ if (pl > l) l = pl; /* l = max(l, pl) */ SETARG_A(*previous, from); SETARG_B(*previous, l - from); return; } /* else go through */ } luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0); /* else no optimization */ } /* ** Gets the destination address of a jump instruction. Used to traverse ** a list of jumps. */ static int getjump (FuncState *fs, int pc) { int offset = GETARG_sJ(fs->f->code[pc]); if (offset == NO_JUMP) /* point to itself represents end of list */ return NO_JUMP; /* end of list */ else return (pc+1)+offset; /* turn offset into absolute position */ } /* ** Fix jump instruction at position 'pc' to jump to 'dest'. ** (Jump addresses are relative in Lua) */ static void fixjump (FuncState *fs, int pc, int dest) { Instruction *jmp = &fs->f->code[pc]; int offset = dest - (pc + 1); lua_assert(dest != NO_JUMP); if (!(-OFFSET_sJ <= offset && offset <= MAXARG_sJ - OFFSET_sJ)) luaX_syntaxerror(fs->ls, "control structure too long"); lua_assert(GET_OPCODE(*jmp) == OP_JMP); SETARG_sJ(*jmp, offset); } /* ** Concatenate jump-list 'l2' into jump-list 'l1' */ void luaK_concat (FuncState *fs, int *l1, int l2) { if (l2 == NO_JUMP) return; /* nothing to concatenate? */ else if (*l1 == NO_JUMP) /* no original list? */ *l1 = l2; /* 'l1' points to 'l2' */ else { int list = *l1; int next; while ((next = getjump(fs, list)) != NO_JUMP) /* find last element */ list = next; fixjump(fs, list, l2); /* last element links to 'l2' */ } } /* ** Create a jump instruction and return its position, so its destination ** can be fixed later (with 'fixjump'). */ int luaK_jump (FuncState *fs) { return codesJ(fs, OP_JMP, NO_JUMP, 0); } /* ** Code a 'return' instruction */ void luaK_ret (FuncState *fs, int first, int nret) { OpCode op; if (fs->f->is_vararg) op = OP_RETVARARG; else { switch (nret) { case 0: op = OP_RETURN0; break; case 1: op = OP_RETURN1; break; default: op = OP_RETURN; break; } } luaK_codeABC(fs, op, first, nret + 1, fs->f->numparams); } /* ** Code a "conditional jump", that is, a test or comparison opcode ** followed by a jump. Return jump position. */ static int condjump (FuncState *fs, OpCode op, int A, int B, int C, int k) { luaK_codeABCk(fs, op, A, B, C, k); return luaK_jump(fs); } /* ** returns current 'pc' and marks it as a jump target (to avoid wrong ** optimizations with consecutive instructions not in the same basic block). */ int luaK_getlabel (FuncState *fs) { fs->lasttarget = fs->pc; return fs->pc; } /* ** Returns the position of the instruction "controlling" a given ** jump (that is, its condition), or the jump itself if it is ** unconditional. */ static Instruction *getjumpcontrol (FuncState *fs, int pc) { Instruction *pi = &fs->f->code[pc]; if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1)))) return pi-1; else return pi; } /* ** Patch destination register for a TESTSET instruction. ** If instruction in position 'node' is not a TESTSET, return 0 ("fails"). ** Otherwise, if 'reg' is not 'NO_REG', set it as the destination ** register. Otherwise, change instruction to a simple 'TEST' (produces ** no register value) */ static int patchtestreg (FuncState *fs, int node, int reg) { Instruction *i = getjumpcontrol(fs, node); if (GET_OPCODE(*i) != OP_TESTSET) return 0; /* cannot patch other instructions */ if (reg != NO_REG && reg != GETARG_B(*i)) SETARG_A(*i, reg); else { /* no register to put value or register already has the value; change instruction to simple test */ *i = CREATE_ABCk(OP_TEST, GETARG_B(*i), 0, 0, GETARG_k(*i)); } return 1; } /* ** Traverse a list of tests ensuring no one produces a value */ static void removevalues (FuncState *fs, int list) { for (; list != NO_JUMP; list = getjump(fs, list)) patchtestreg(fs, list, NO_REG); } /* ** Traverse a list of tests, patching their destination address and ** registers: tests producing values jump to 'vtarget' (and put their ** values in 'reg'), other tests jump to 'dtarget'. */ static void patchlistaux (FuncState *fs, int list, int vtarget, int reg, int dtarget) { while (list != NO_JUMP) { int next = getjump(fs, list); if (patchtestreg(fs, list, reg)) fixjump(fs, list, vtarget); else fixjump(fs, list, dtarget); /* jump to default target */ list = next; } } /* ** Path all jumps in 'list' to jump to 'target'. ** (The assert means that we cannot fix a jump to a forward address ** because we only know addresses once code is generated.) */ void luaK_patchlist (FuncState *fs, int list, int target) { lua_assert(target <= fs->pc); patchlistaux(fs, list, target, NO_REG, target); } void luaK_patchtohere (FuncState *fs, int list) { int hr = luaK_getlabel(fs); /* mark "here" as a jump target */ luaK_patchlist(fs, list, hr); } /* ** Correct a jump list to jump to 'target'. If 'hasclose' is true, ** 'target' contains an OP_CLOSE instruction (see first assert). ** Only the jumps with ('m' == true) need that close; other jumps ** avoid it jumping to the next instruction. */ void luaK_patchgoto (FuncState *fs, int list, int target, int hasclose) { lua_assert(!hasclose || GET_OPCODE(fs->f->code[target]) == OP_CLOSE); while (list != NO_JUMP) { int next = getjump(fs, list); lua_assert(!GETARG_m(fs->f->code[list]) || hasclose); patchtestreg(fs, list, NO_REG); /* do not generate values */ if (!hasclose || GETARG_m(fs->f->code[list])) fixjump(fs, list, target); else /* there is a CLOSE instruction but jump does not need it */ fixjump(fs, list, target + 1); /* avoid CLOSE instruction */ list = next; } } /* ** Mark (using the 'm' arg) all jumps in 'list' to close upvalues. Mark ** will instruct 'luaK_patchgoto' to make these jumps go to OP_CLOSE ** instructions. */ void luaK_patchclose (FuncState *fs, int list) { for (; list != NO_JUMP; list = getjump(fs, list)) { lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP); SETARG_m(fs->f->code[list], 1); } } #if !defined(MAXIWTHABS) #define MAXIWTHABS 120 #endif /* ** Save line info for a new instruction. If difference from last line ** does not fit in a byte, of after that many instructions, save a new ** absolute line info; (in that case, the special value 'ABSLINEINFO' ** in 'lineinfo' signals the existence of this absolute information.) ** Otherwise, store the difference from last line in 'lineinfo'. */ static void savelineinfo (FuncState *fs, Proto *f, int pc, int line) { int linedif = line - fs->previousline; if (abs(linedif) >= 0x80 || fs->iwthabs++ > MAXIWTHABS) { luaM_growvector(fs->ls->L, f->abslineinfo, fs->nabslineinfo, f->sizeabslineinfo, AbsLineInfo, MAX_INT, "lines"); f->abslineinfo[fs->nabslineinfo].pc = pc; f->abslineinfo[fs->nabslineinfo++].line = line; linedif = ABSLINEINFO; /* signal there is absolute information */ fs->iwthabs = 0; /* restart counter */ } luaM_growvector(fs->ls->L, f->lineinfo, pc, f->sizelineinfo, ls_byte, MAX_INT, "opcodes"); f->lineinfo[pc] = linedif; fs->previousline = line; /* last line saved */ } /* ** Emit instruction 'i', checking for array sizes and saving also its ** line information. Return 'i' position. */ static int luaK_code (FuncState *fs, Instruction i) { Proto *f = fs->f; /* put new instruction in code array */ luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction, MAX_INT, "opcodes"); f->code[fs->pc] = i; savelineinfo(fs, f, fs->pc, fs->ls->lastline); return fs->pc++; } /* ** Format and emit an 'iABC' instruction. (Assertions check consistency ** of parameters versus opcode.) */ int luaK_codeABCk (FuncState *fs, OpCode o, int a, int b, int c, int k) { lua_assert(getOpMode(o) == iABC); lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C && (k & ~1) == 0); return luaK_code(fs, CREATE_ABCk(o, a, b, c, k)); } #define codeABsC(fs,o,a,b,c,k) luaK_codeABCk(fs,o,a,b,((c) + OFFSET_sC),k) /* ** Format and emit an 'iABx' instruction. */ int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) { lua_assert(getOpMode(o) == iABx); lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx); return luaK_code(fs, CREATE_ABx(o, a, bc)); } /* ** Format and emit an 'iAsBx' instruction. */ int luaK_codeAsBx (FuncState *fs, OpCode o, int a, int bc) { unsigned int b = bc + OFFSET_sBx; lua_assert(getOpMode(o) == iAsBx); lua_assert(a <= MAXARG_A && b <= MAXARG_Bx); return luaK_code(fs, CREATE_ABx(o, a, b)); } /* ** Format and emit an 'isJ' instruction. */ static int codesJ (FuncState *fs, OpCode o, int sj, int k) { unsigned int j = sj + OFFSET_sJ; lua_assert(getOpMode(o) == isJ); lua_assert(j <= MAXARG_sJ && (k & ~1) == 0); return luaK_code(fs, CREATE_sJ(o, j, k)); } /* ** Emit an "extra argument" instruction (format 'iAx') */ static int codeextraarg (FuncState *fs, int a) { lua_assert(a <= MAXARG_Ax); return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a)); } /* ** Emit a "load constant" instruction, using either 'OP_LOADK' ** (if constant index 'k' fits in 18 bits) or an 'OP_LOADKX' ** instruction with "extra argument". */ static int luaK_codek (FuncState *fs, int reg, int k) { if (k <= MAXARG_Bx) return luaK_codeABx(fs, OP_LOADK, reg, k); else { int p = luaK_codeABx(fs, OP_LOADKX, reg, 0); codeextraarg(fs, k); return p; } } /* ** Check register-stack level, keeping track of its maximum size ** in field 'maxstacksize' */ void luaK_checkstack (FuncState *fs, int n) { int newstack = fs->freereg + n; if (newstack > fs->f->maxstacksize) { if (newstack >= MAXREGS) luaX_syntaxerror(fs->ls, "function or expression needs too many registers"); fs->f->maxstacksize = cast_byte(newstack); } } /* ** Reserve 'n' registers in register stack */ void luaK_reserveregs (FuncState *fs, int n) { luaK_checkstack(fs, n); fs->freereg += n; } /* ** Free register 'reg', if it is neither a constant index nor ** a local variable. ) */ static void freereg (FuncState *fs, int reg) { if (reg >= fs->nactvar) { fs->freereg--; lua_assert(reg == fs->freereg); } } /* ** Free two registers in proper order */ static void freeregs (FuncState *fs, int r1, int r2) { if (r1 > r2) { freereg(fs, r1); freereg(fs, r2); } else { freereg(fs, r2); freereg(fs, r1); } } /* ** Free register used by expression 'e' (if any) */ static void freeexp (FuncState *fs, expdesc *e) { if (e->k == VNONRELOC) freereg(fs, e->u.info); } /* ** Free registers used by expressions 'e1' and 'e2' (if any) in proper ** order. */ static void freeexps (FuncState *fs, expdesc *e1, expdesc *e2) { int r1 = (e1->k == VNONRELOC) ? e1->u.info : -1; int r2 = (e2->k == VNONRELOC) ? e2->u.info : -1; freeregs(fs, r1, r2); } /* ** Add constant 'v' to prototype's list of constants (field 'k'). ** Use scanner's table to cache position of constants in constant list ** and try to reuse constants. Because some values should not be used ** as keys (nil cannot be a key, integer keys can collapse with float ** keys), the caller must provide a useful 'key' for indexing the cache. */ static int addk (FuncState *fs, TValue *key, TValue *v) { lua_State *L = fs->ls->L; Proto *f = fs->f; TValue *idx = luaH_set(L, fs->ls->h, key); /* index scanner table */ int k, oldsize; if (ttisinteger(idx)) { /* is there an index there? */ k = cast_int(ivalue(idx)); /* correct value? (warning: must distinguish floats from integers!) */ if (k < fs->nk && ttype(&f->k[k]) == ttype(v) && luaV_rawequalobj(&f->k[k], v)) return k; /* reuse index */ } /* constant not found; create a new entry */ oldsize = f->sizek; k = fs->nk; /* numerical value does not need GC barrier; table has no metatable, so it does not need to invalidate cache */ setivalue(idx, k); luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants"); while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]); setobj(L, &f->k[k], v); fs->nk++; luaC_barrier(L, f, v); return k; } /* ** Add a string to list of constants and return its index. */ int luaK_stringK (FuncState *fs, TString *s) { TValue o; setsvalue(fs->ls->L, &o, s); return addk(fs, &o, &o); /* use string itself as key */ } /* ** Add an integer to list of constants and return its index. ** Integers use userdata as keys to avoid collision with floats with ** same value; conversion to 'void*' is used only for hashing, so there ** are no "precision" problems. */ static int luaK_intK (FuncState *fs, lua_Integer n) { TValue k, o; setpvalue(&k, cast_voidp(cast_sizet(n))); setivalue(&o, n); return addk(fs, &k, &o); } /* ** Add a float to list of constants and return its index. */ static int luaK_numberK (FuncState *fs, lua_Number r) { TValue o; setfltvalue(&o, r); return addk(fs, &o, &o); /* use number itself as key */ } /* ** Add a boolean to list of constants and return its index. */ static int boolK (FuncState *fs, int b) { TValue o; setbvalue(&o, b); return addk(fs, &o, &o); /* use boolean itself as key */ } /* ** Add nil to list of constants and return its index. */ static int nilK (FuncState *fs) { TValue k, v; setnilvalue(&v); /* cannot use nil as key; instead use table itself to represent nil */ sethvalue(fs->ls->L, &k, fs->ls->h); return addk(fs, &k, &v); } /* ** Check whether 'i' can be stored in an 'sC' operand. ** Equivalent to (0 <= i + OFFSET_sC && i + OFFSET_sC <= MAXARG_C) ** but without risk of overflows in the addition. */ static int fitsC (lua_Integer i) { return (-OFFSET_sC <= i && i <= MAXARG_C - OFFSET_sC); } /* ** Check whether 'i' can be stored in an 'sBx' operand. */ static int fitsBx (lua_Integer i) { return (-OFFSET_sBx <= i && i <= MAXARG_Bx - OFFSET_sBx); } void luaK_int (FuncState *fs, int reg, lua_Integer i) { if (fitsBx(i)) luaK_codeAsBx(fs, OP_LOADI, reg, cast_int(i)); else luaK_codek(fs, reg, luaK_intK(fs, i)); } static int floatI (lua_Number f, lua_Integer *fi) { TValue v; setfltvalue(&v, f); return (luaV_flttointeger(&v, fi, 0) && fitsBx(*fi)); } static void luaK_float (FuncState *fs, int reg, lua_Number f) { lua_Integer fi; if (floatI(f, &fi)) luaK_codeAsBx(fs, OP_LOADF, reg, cast_int(fi)); else luaK_codek(fs, reg, luaK_numberK(fs, f)); } /* ** Fix an expression to return the number of results 'nresults'. ** Either 'e' is a multi-ret expression (function call or vararg) ** or 'nresults' is LUA_MULTRET (as any expression can satisfy that). */ void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) { Instruction *pc = &getinstruction(fs, e); if (e->k == VCALL) /* expression is an open function call? */ SETARG_C(*pc, nresults + 1); else if (e->k == VVARARG) { SETARG_C(*pc, nresults + 1); SETARG_A(*pc, fs->freereg); luaK_reserveregs(fs, 1); } else lua_assert(nresults == LUA_MULTRET); } /* ** Fix an expression to return one result. ** If expression is not a multi-ret expression (function call or ** vararg), it already returns one result, so nothing needs to be done. ** Function calls become VNONRELOC expressions (as its result comes ** fixed in the base register of the call), while vararg expressions ** become VRELOC (as OP_VARARG puts its results where it wants). ** (Calls are created returning one result, so that does not need ** to be fixed.) */ void luaK_setoneret (FuncState *fs, expdesc *e) { if (e->k == VCALL) { /* expression is an open function call? */ /* already returns 1 value */ lua_assert(GETARG_C(getinstruction(fs, e)) == 2); e->k = VNONRELOC; /* result has fixed position */ e->u.info = GETARG_A(getinstruction(fs, e)); } else if (e->k == VVARARG) { SETARG_C(getinstruction(fs, e), 2); e->k = VRELOC; /* can relocate its simple result */ } } /* ** Ensure that expression 'e' is not a variable. ** (Expression still may have jump lists.) */ void luaK_dischargevars (FuncState *fs, expdesc *e) { switch (e->k) { case VLOCAL: { /* already in a register */ e->k = VNONRELOC; /* becomes a non-relocatable value */ break; } case VUPVAL: { /* move value to some (pending) register */ e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0); e->k = VRELOC; break; } case VINDEXUP: { e->u.info = luaK_codeABC(fs, OP_GETTABUP, 0, e->u.ind.t, e->u.ind.idx); e->k = VRELOC; break; } case VINDEXI: { freereg(fs, e->u.ind.t); e->u.info = luaK_codeABC(fs, OP_GETI, 0, e->u.ind.t, e->u.ind.idx); e->k = VRELOC; break; } case VINDEXSTR: { freereg(fs, e->u.ind.t); e->u.info = luaK_codeABC(fs, OP_GETFIELD, 0, e->u.ind.t, e->u.ind.idx); e->k = VRELOC; break; } case VINDEXED: { freeregs(fs, e->u.ind.t, e->u.ind.idx); e->u.info = luaK_codeABC(fs, OP_GETTABLE, 0, e->u.ind.t, e->u.ind.idx); e->k = VRELOC; break; } case VVARARG: case VCALL: { luaK_setoneret(fs, e); break; } default: break; /* there is one value available (somewhere) */ } } /* ** Ensures expression value is in register 'reg' (and therefore ** 'e' will become a non-relocatable expression). ** (Expression still may have jump lists.) */ static void discharge2reg (FuncState *fs, expdesc *e, int reg) { luaK_dischargevars(fs, e); switch (e->k) { case VNIL: { luaK_nil(fs, reg, 1); break; } case VFALSE: case VTRUE: { luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0); break; } case VK: { luaK_codek(fs, reg, e->u.info); break; } case VKFLT: { luaK_float(fs, reg, e->u.nval); break; } case VKINT: { luaK_int(fs, reg, e->u.ival); break; } case VRELOC: { Instruction *pc = &getinstruction(fs, e); SETARG_A(*pc, reg); /* instruction will put result in 'reg' */ break; } case VNONRELOC: { if (reg != e->u.info) luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0); break; } default: { lua_assert(e->k == VJMP); return; /* nothing to do... */ } } e->u.info = reg; e->k = VNONRELOC; } /* ** Ensures expression value is in any register. ** (Expression still may have jump lists.) */ static void discharge2anyreg (FuncState *fs, expdesc *e) { if (e->k != VNONRELOC) { /* no fixed register yet? */ luaK_reserveregs(fs, 1); /* get a register */ discharge2reg(fs, e, fs->freereg-1); /* put value there */ } } static int code_loadbool (FuncState *fs, int A, int b, int jump) { luaK_getlabel(fs); /* those instructions may be jump targets */ return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump); } /* ** check whether list has any jump that do not produce a value ** or produce an inverted value */ static int need_value (FuncState *fs, int list) { for (; list != NO_JUMP; list = getjump(fs, list)) { Instruction i = *getjumpcontrol(fs, list); if (GET_OPCODE(i) != OP_TESTSET) return 1; } return 0; /* not found */ } /* ** Ensures final expression result (which includes results from its ** jump ** lists) is in register 'reg'. ** If expression has jumps, need to patch these jumps either to ** its final position or to "load" instructions (for those tests ** that do not produce values). */ static void exp2reg (FuncState *fs, expdesc *e, int reg) { discharge2reg(fs, e, reg); if (e->k == VJMP) /* expression itself is a test? */ luaK_concat(fs, &e->t, e->u.info); /* put this jump in 't' list */ if (hasjumps(e)) { int final; /* position after whole expression */ int p_f = NO_JUMP; /* position of an eventual LOAD false */ int p_t = NO_JUMP; /* position of an eventual LOAD true */ if (need_value(fs, e->t) || need_value(fs, e->f)) { int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs); p_f = code_loadbool(fs, reg, 0, 1); p_t = code_loadbool(fs, reg, 1, 0); luaK_patchtohere(fs, fj); } final = luaK_getlabel(fs); patchlistaux(fs, e->f, final, reg, p_f); patchlistaux(fs, e->t, final, reg, p_t); } e->f = e->t = NO_JUMP; e->u.info = reg; e->k = VNONRELOC; } /* ** Ensures final expression result is in next available register. */ void luaK_exp2nextreg (FuncState *fs, expdesc *e) { luaK_dischargevars(fs, e); freeexp(fs, e); luaK_reserveregs(fs, 1); exp2reg(fs, e, fs->freereg - 1); } /* ** Ensures final expression result is in some (any) register ** and return that register. */ int luaK_exp2anyreg (FuncState *fs, expdesc *e) { luaK_dischargevars(fs, e); if (e->k == VNONRELOC) { /* expression already has a register? */ if (!hasjumps(e)) /* no jumps? */ return e->u.info; /* result is already in a register */ if (e->u.info >= fs->nactvar) { /* reg. is not a local? */ exp2reg(fs, e, e->u.info); /* put final result in it */ return e->u.info; } } luaK_exp2nextreg(fs, e); /* otherwise, use next available register */ return e->u.info; } /* ** Ensures final expression result is either in a register ** or in an upvalue. */ void luaK_exp2anyregup (FuncState *fs, expdesc *e) { if (e->k != VUPVAL || hasjumps(e)) luaK_exp2anyreg(fs, e); } /* ** Ensures final expression result is either in a register ** or it is a constant. */ void luaK_exp2val (FuncState *fs, expdesc *e) { if (hasjumps(e)) luaK_exp2anyreg(fs, e); else luaK_dischargevars(fs, e); } /* ** Ensures final expression result is in a valid R/K index ** (that is, it is either in a register or in 'k' with an index ** in the range of R/K indices). ** Returns 1 if expression is K, 0 otherwise. */ int luaK_exp2RK (FuncState *fs, expdesc *e) { luaK_exp2val(fs, e); switch (e->k) { /* move constants to 'k' */ case VTRUE: e->u.info = boolK(fs, 1); goto vk; case VFALSE: e->u.info = boolK(fs, 0); goto vk; case VNIL: e->u.info = nilK(fs); goto vk; case VKINT: e->u.info = luaK_intK(fs, e->u.ival); goto vk; case VKFLT: e->u.info = luaK_numberK(fs, e->u.nval); goto vk; case VK: vk: e->k = VK; if (e->u.info <= MAXINDEXRK) /* constant fits in 'argC'? */ return 1; else break; default: break; } /* not a constant in the right range: put it in a register */ luaK_exp2anyreg(fs, e); return 0; } static void codeABRK (FuncState *fs, OpCode o, int a, int b, expdesc *ec) { int k = luaK_exp2RK(fs, ec); luaK_codeABCk(fs, o, a, b, ec->u.info, k); } /* ** Generate code to store result of expression 'ex' into variable 'var'. */ void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) { switch (var->k) { case VLOCAL: { freeexp(fs, ex); exp2reg(fs, ex, var->u.info); /* compute 'ex' into proper place */ return; } case VUPVAL: { int e = luaK_exp2anyreg(fs, ex); luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0); break; } case VINDEXUP: { codeABRK(fs, OP_SETTABUP, var->u.ind.t, var->u.ind.idx, ex); break; } case VINDEXI: { codeABRK(fs, OP_SETI, var->u.ind.t, var->u.ind.idx, ex); break; } case VINDEXSTR: { codeABRK(fs, OP_SETFIELD, var->u.ind.t, var->u.ind.idx, ex); break; } case VINDEXED: { codeABRK(fs, OP_SETTABLE, var->u.ind.t, var->u.ind.idx, ex); break; } default: lua_assert(0); /* invalid var kind to store */ } freeexp(fs, ex); } /* ** Emit SELF instruction (convert expression 'e' into 'e:key(e,'). */ void luaK_self (FuncState *fs, expdesc *e, expdesc *key) { int ereg; luaK_exp2anyreg(fs, e); ereg = e->u.info; /* register where 'e' was placed */ freeexp(fs, e); e->u.info = fs->freereg; /* base register for op_self */ e->k = VNONRELOC; /* self expression has a fixed register */ luaK_reserveregs(fs, 2); /* function and 'self' produced by op_self */ codeABRK(fs, OP_SELF, e->u.info, ereg, key); freeexp(fs, key); } /* ** Negate condition 'e' (where 'e' is a comparison). */ static void negatecondition (FuncState *fs, expdesc *e) { Instruction *pc = getjumpcontrol(fs, e->u.info); lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET && GET_OPCODE(*pc) != OP_TEST); SETARG_k(*pc, (GETARG_k(*pc) ^ 1)); } /* ** Emit instruction to jump if 'e' is 'cond' (that is, if 'cond' ** is true, code will jump if 'e' is true.) Return jump position. ** Optimize when 'e' is 'not' something, inverting the condition ** and removing the 'not'. */ static int jumponcond (FuncState *fs, expdesc *e, int cond) { if (e->k == VRELOC) { Instruction ie = getinstruction(fs, e); if (GET_OPCODE(ie) == OP_NOT) { fs->pc--; /* remove previous OP_NOT */ return condjump(fs, OP_TEST, GETARG_B(ie), 0, 0, !cond); } /* else go through */ } discharge2anyreg(fs, e); freeexp(fs, e); return condjump(fs, OP_TESTSET, NO_REG, e->u.info, 0, cond); } /* ** Emit code to go through if 'e' is true, jump otherwise. */ void luaK_goiftrue (FuncState *fs, expdesc *e) { int pc; /* pc of new jump */ luaK_dischargevars(fs, e); switch (e->k) { case VJMP: { /* condition? */ negatecondition(fs, e); /* jump when it is false */ pc = e->u.info; /* save jump position */ break; } case VK: case VKFLT: case VKINT: case VTRUE: { pc = NO_JUMP; /* always true; do nothing */ break; } default: { pc = jumponcond(fs, e, 0); /* jump when false */ break; } } luaK_concat(fs, &e->f, pc); /* insert new jump in false list */ luaK_patchtohere(fs, e->t); /* true list jumps to here (to go through) */ e->t = NO_JUMP; } /* ** Emit code to go through if 'e' is false, jump otherwise. */ void luaK_goiffalse (FuncState *fs, expdesc *e) { int pc; /* pc of new jump */ luaK_dischargevars(fs, e); switch (e->k) { case VJMP: { pc = e->u.info; /* already jump if true */ break; } case VNIL: case VFALSE: { pc = NO_JUMP; /* always false; do nothing */ break; } default: { pc = jumponcond(fs, e, 1); /* jump if true */ break; } } luaK_concat(fs, &e->t, pc); /* insert new jump in 't' list */ luaK_patchtohere(fs, e->f); /* false list jumps to here (to go through) */ e->f = NO_JUMP; } /* ** Code 'not e', doing constant folding. */ static void codenot (FuncState *fs, expdesc *e) { luaK_dischargevars(fs, e); switch (e->k) { case VNIL: case VFALSE: { e->k = VTRUE; /* true == not nil == not false */ break; } case VK: case VKFLT: case VKINT: case VTRUE: { e->k = VFALSE; /* false == not "x" == not 0.5 == not 1 == not true */ break; } case VJMP: { negatecondition(fs, e); break; } case VRELOC: case VNONRELOC: { discharge2anyreg(fs, e); freeexp(fs, e); e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0); e->k = VRELOC; break; } default: lua_assert(0); /* cannot happen */ } /* interchange true and false lists */ { int temp = e->f; e->f = e->t; e->t = temp; } removevalues(fs, e->f); /* values are useless when negated */ removevalues(fs, e->t); } /* ** Check whether expression 'e' is a small literal string */ static int isKstr (FuncState *fs, expdesc *e) { return (e->k == VK && !hasjumps(e) && e->u.info <= MAXARG_B && ttisshrstring(&fs->f->k[e->u.info])); } /* ** Check whether expression 'e' is a literal integer. */ int luaK_isKint (expdesc *e) { return (e->k == VKINT && !hasjumps(e)); } /* ** Check whether expression 'e' is a literal integer in ** proper range to fit in register C */ static int isCint (expdesc *e) { return luaK_isKint(e) && (l_castS2U(e->u.ival) <= l_castS2U(MAXARG_C)); } /* ** Check whether expression 'e' is a literal integer in ** proper range to fit in register sC */ static int isSCint (expdesc *e) { return luaK_isKint(e) && fitsC(e->u.ival); } /* ** Check whether expression 'e' is a literal integer or float in ** proper range to fit in register sC */ static int isSCnumber (expdesc *e, lua_Integer *i) { if (e->k == VKINT) *i = e->u.ival; else if (!(e->k == VKFLT && floatI(e->u.nval, i))) return 0; /* not a number */ if (!hasjumps(e) && fitsC(*i)) { *i += OFFSET_sC; return 1; } else return 0; } /* ** Create expression 't[k]'. 't' must have its final result already in a ** register or upvalue. Upvalues can only be indexed by literal strings. ** Keys can be literal strings in the constant table or arbitrary ** values in registers. */ void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) { lua_assert(!hasjumps(t) && (vkisinreg(t->k) || t->k == VUPVAL)); if (t->k == VUPVAL && !isKstr(fs, k)) /* upvalue indexed by non string? */ luaK_exp2anyreg(fs, t); /* put it in a register */ t->u.ind.t = t->u.info; /* register or upvalue index */ if (t->k == VUPVAL) { t->u.ind.idx = k->u.info; /* literal string */ t->k = VINDEXUP; } else if (isKstr(fs, k)) { t->u.ind.idx = k->u.info; /* literal string */ t->k = VINDEXSTR; } else if (isCint(k)) { t->u.ind.idx = cast_int(k->u.ival); /* integer constant in proper range */ t->k = VINDEXI; } else { t->u.ind.idx = luaK_exp2anyreg(fs, k); /* register */ t->k = VINDEXED; } } /* ** Return false if folding can raise an error. ** Bitwise operations need operands convertible to integers; division ** operations cannot have 0 as divisor. */ static int validop (int op, TValue *v1, TValue *v2) { switch (op) { case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR: case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT: { /* conversion errors */ lua_Integer i; return (tointegerns(v1, &i) && tointegerns(v2, &i)); } case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD: /* division by 0 */ return (nvalue(v2) != 0); default: return 1; /* everything else is valid */ } } /* ** Try to "constant-fold" an operation; return 1 iff successful. ** (In this case, 'e1' has the final result.) */ static int constfolding (FuncState *fs, int op, expdesc *e1, const expdesc *e2) { TValue v1, v2, res; if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2)) return 0; /* non-numeric operands or not safe to fold */ luaO_rawarith(fs->ls->L, op, &v1, &v2, &res); /* does operation */ if (ttisinteger(&res)) { e1->k = VKINT; e1->u.ival = ivalue(&res); } else { /* folds neither NaN nor 0.0 (to avoid problems with -0.0) */ lua_Number n = fltvalue(&res); if (luai_numisnan(n) || n == 0) return 0; e1->k = VKFLT; e1->u.nval = n; } return 1; } /* ** Emit code for unary expressions that "produce values" ** (everything but 'not'). ** Expression to produce final result will be encoded in 'e'. */ static void codeunexpval (FuncState *fs, OpCode op, expdesc *e, int line) { int r = luaK_exp2anyreg(fs, e); /* opcodes operate only on registers */ freeexp(fs, e); e->u.info = luaK_codeABC(fs, op, 0, r, 0); /* generate opcode */ e->k = VRELOC; /* all those operations are relocatable */ luaK_fixline(fs, line); } static void finishbinexpval (FuncState *fs, expdesc *e1, expdesc *e2, int pc, int line) { freeexps(fs, e1, e2); e1->u.info = pc; e1->k = VRELOC; /* all those operations are relocatable */ luaK_fixline(fs, line); } /* ** Emit code for binary expressions that "produce values" ** (everything but logical operators 'and'/'or' and comparison ** operators). ** Expression to produce final result will be encoded in 'e1'. ** Because 'luaK_exp2anyreg' can free registers, its calls must be ** in "stack order" (that is, first on 'e2', which may have more ** recent registers to be released). */ static void codebinexpval (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2, int line) { int v2 = luaK_exp2anyreg(fs, e2); /* both operands are in registers */ int v1 = luaK_exp2anyreg(fs, e1); int pc = luaK_codeABC(fs, op, 0, v1, v2); /* generate opcode */ finishbinexpval(fs, e1, e2, pc, line); } /* ** Code binary operators ('+', '-', ...) with immediate operands. */ static void codebini (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2, int k, int line) { int v2 = cast_int(e2->u.ival); /* immediate operand */ int v1 = luaK_exp2anyreg(fs, e1); int pc = codeABsC(fs, op, 0, v1, v2, k); /* generate opcode */ finishbinexpval(fs, e1, e2, pc, line); } /* ** Code arithmetic operators ('+', '-', ...). If second operand is a ** constant in the proper range, use variant opcodes with immediate ** operands. */ static void codearith (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2, int flip, int line) { if (!isSCint(e2)) codebinexpval(fs, op, e1, e2, line); /* use standard operators */ else /* use immediate operators */ codebini(fs, cast(OpCode, op - OP_ADD + OP_ADDI), e1, e2, flip, line); } static void swapexps (expdesc *e1, expdesc *e2) { expdesc temp = *e1; *e1 = *e2; *e2 = temp; /* swap 'e1' and 'e2' */ } /* ** Code commutative operators ('+', '*'). If first operand is a ** constant, change order of operands to use immediate operator. */ static void codecommutative (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2, int line) { int flip = 0; if (isSCint(e1)) { swapexps(e1, e2); flip = 1; } codearith(fs, op, e1, e2, flip, line); } /* ** Code bitwise operations; they are all associative, so the function ** tries to put an integer constant as the 2nd operand (a K operand). */ static void codebitwise (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2, int line) { int inv = 0; int v1, v2, pc; OpCode op; if (e1->k == VKINT && luaK_exp2RK(fs, e1)) { swapexps(e1, e2); /* 'e2' will be the constant operand */ inv = 1; } else if (!(e2->k == VKINT && luaK_exp2RK(fs, e2))) { /* no constants? */ op = cast(OpCode, opr - OPR_BAND + OP_BAND); codebinexpval(fs, op, e1, e2, line); /* all-register opcodes */ return; } v1 = luaK_exp2anyreg(fs, e1); v2 = e2->u.info; /* index in K array */ op = cast(OpCode, opr - OPR_BAND + OP_BANDK); lua_assert(ttisinteger(&fs->f->k[v2])); pc = luaK_codeABCk(fs, op, 0, v1, v2, inv); finishbinexpval(fs, e1, e2, pc, line); } /* ** Code shift operators. If second operand is constant, use immediate ** operand (negating it if shift is in the other direction). */ static void codeshift (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2, int line) { if (isSCint(e2)) { int changedir = 0; if (op == OP_SHL) { changedir = 1; e2->u.ival = -(e2->u.ival); } codebini(fs, OP_SHRI, e1, e2, changedir, line); } else codebinexpval(fs, op, e1, e2, line); } /* ** Emit code for order comparisons. ** When the first operand is an integral value in the proper range, ** change (A < B) to (!(B <= A)) and (A <= B) to (!(B < A)) so that ** it can use an immediate operand. In this case, C indicates this ** change, for cases that cannot assume a total order (NaN and ** metamethods). */ static void codeorder (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2) { int r1, r2; int cond = 1; int C = 0; lua_Integer im; if (isSCnumber(e2, &im)) { /* use immediate operand */ r1 = luaK_exp2anyreg(fs, e1); r2 = cast_int(im); op = cast(OpCode, (op - OP_LT) + OP_LTI); } else if (isSCnumber(e1, &im)) { /* transform (A < B) to (!(B <= A)) and (A <= B) to (!(B < A)) */ r1 = luaK_exp2anyreg(fs, e2); r2 = cast_int(im); op = (op == OP_LT) ? OP_LEI : OP_LTI; cond = 0; /* negate original test */ C = 1; /* indication that it used the transformations */ } else { /* regular case, compare two registers */ r1 = luaK_exp2anyreg(fs, e1); r2 = luaK_exp2anyreg(fs, e2); } freeexps(fs, e1, e2); e1->u.info = condjump(fs, op, r1, r2, C, cond); e1->k = VJMP; } /* ** Emit code for equality comparisons ('==', '~='). ** 'e1' was already put as RK by 'luaK_infix'. */ static void codeeq (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2) { int r1, r2; lua_Integer im; OpCode op; if (e1->k != VNONRELOC) { lua_assert(e1->k == VK || e1->k == VKINT || e1->k == VKFLT); swapexps(e1, e2); } r1 = luaK_exp2anyreg(fs, e1); /* 1nd expression must be in register */ if (isSCnumber(e2, &im)) { op = OP_EQI; r2 = cast_int(im); /* immediate operand */ } else if (luaK_exp2RK(fs, e2)) { /* 1st expression is constant? */ op = OP_EQK; r2 = e2->u.info; /* constant index */ } else { op = OP_EQ; /* will compare two registers */ r2 = luaK_exp2anyreg(fs, e2); } freeexps(fs, e1, e2); e1->u.info = condjump(fs, op, r1, r2, 0, (opr == OPR_EQ)); e1->k = VJMP; } /* ** Apply prefix operation 'op' to expression 'e'. */ void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) { static const expdesc ef = {VKINT, {0}, NO_JUMP, NO_JUMP}; switch (op) { case OPR_MINUS: case OPR_BNOT: /* use 'ef' as fake 2nd operand */ if (constfolding(fs, op + LUA_OPUNM, e, &ef)) break; /* FALLTHROUGH */ case OPR_LEN: codeunexpval(fs, cast(OpCode, op + OP_UNM), e, line); break; case OPR_NOT: codenot(fs, e); break; default: lua_assert(0); } } /* ** Process 1st operand 'v' of binary operation 'op' before reading ** 2nd operand. */ void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) { switch (op) { case OPR_AND: { luaK_goiftrue(fs, v); /* go ahead only if 'v' is true */ break; } case OPR_OR: { luaK_goiffalse(fs, v); /* go ahead only if 'v' is false */ break; } case OPR_CONCAT: { luaK_exp2nextreg(fs, v); /* operand must be on the stack */ break; } case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV: case OPR_IDIV: case OPR_MOD: case OPR_POW: case OPR_BAND: case OPR_BOR: case OPR_BXOR: case OPR_SHL: case OPR_SHR: { if (!tonumeral(v, NULL)) luaK_exp2anyreg(fs, v); /* else keep numeral, which may be folded with 2nd operand */ break; } case OPR_EQ: case OPR_NE: { if (!tonumeral(v, NULL)) luaK_exp2RK(fs, v); /* else keep numeral, which may be an immediate operand */ break; } case OPR_LT: case OPR_LE: case OPR_GT: case OPR_GE: { lua_Integer dummy; if (!isSCnumber(v, &dummy)) luaK_exp2anyreg(fs, v); /* else keep numeral, which may be an immediate operand */ break; } default: lua_assert(0); } } /* ** Create code for '(e1 .. e2)'. ** For '(e1 .. e2.1 .. e2.2)' (which is '(e1 .. (e2.1 .. e2.2))', ** because concatenation is right associative), merge both CONCATs. */ static void codeconcat (FuncState *fs, expdesc *e1, expdesc *e2, int line) { Instruction *ie2 = previousinstruction(fs); if (GET_OPCODE(*ie2) == OP_CONCAT) { /* is 'e2' a concatenation? */ int n = GETARG_B(*ie2); /* # of elements concatenated in 'e2' */ lua_assert(e1->u.info + 1 == GETARG_A(*ie2)); freeexp(fs, e2); SETARG_A(*ie2, e1->u.info); /* correct first element ('e1') */ SETARG_B(*ie2, n + 1); /* will concatenate one more element */ } else { /* 'e2' is not a concatenation */ luaK_codeABC(fs, OP_CONCAT, e1->u.info, 2, 0); /* new concat opcode */ freeexp(fs, e2); luaK_fixline(fs, line); } } /* ** Finalize code for binary operation, after reading 2nd operand. */ void luaK_posfix (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2, int line) { switch (opr) { case OPR_AND: { lua_assert(e1->t == NO_JUMP); /* list closed by 'luK_infix' */ luaK_dischargevars(fs, e2); luaK_concat(fs, &e2->f, e1->f); *e1 = *e2; break; } case OPR_OR: { lua_assert(e1->f == NO_JUMP); /* list closed by 'luK_infix' */ luaK_dischargevars(fs, e2); luaK_concat(fs, &e2->t, e1->t); *e1 = *e2; break; } case OPR_CONCAT: { /* e1 .. e2 */ luaK_exp2nextreg(fs, e2); codeconcat(fs, e1, e2, line); break; } case OPR_ADD: case OPR_MUL: { if (!constfolding(fs, opr + LUA_OPADD, e1, e2)) codecommutative(fs, cast(OpCode, opr + OP_ADD), e1, e2, line); break; } case OPR_SUB: case OPR_DIV: case OPR_IDIV: case OPR_MOD: case OPR_POW: { if (!constfolding(fs, opr + LUA_OPADD, e1, e2)) codearith(fs, cast(OpCode, opr + OP_ADD), e1, e2, 0, line); break; } case OPR_BAND: case OPR_BOR: case OPR_BXOR: { if (!constfolding(fs, opr + LUA_OPADD, e1, e2)) codebitwise(fs, opr, e1, e2, line); break; } case OPR_SHL: { if (!constfolding(fs, LUA_OPSHL, e1, e2)) { if (isSCint(e1)) { swapexps(e1, e2); codebini(fs, OP_SHLI, e1, e2, 1, line); } else codeshift(fs, OP_SHL, e1, e2, line); } break; } case OPR_SHR: { if (!constfolding(fs, LUA_OPSHR, e1, e2)) codeshift(fs, OP_SHR, e1, e2, line); break; } case OPR_EQ: case OPR_NE: { codeeq(fs, opr, e1, e2); break; } case OPR_LT: case OPR_LE: { OpCode op = cast(OpCode, (opr - OPR_EQ) + OP_EQ); codeorder(fs, op, e1, e2); break; } case OPR_GT: case OPR_GE: { /* '(a > b)' <=> '(b < a)'; '(a >= b)' <=> '(b <= a)' */ OpCode op = cast(OpCode, (opr - OPR_NE) + OP_EQ); swapexps(e1, e2); codeorder(fs, op, e1, e2); break; } default: lua_assert(0); } } /* ** Change line information associated with current position. If that ** information is absolute, just change it and correct 'previousline'. ** Otherwise, restore 'previousline' to its value before saving the ** current position and than saves the line information again, with the ** new line. */ void luaK_fixline (FuncState *fs, int line) { Proto *f = fs->f; if (f->lineinfo[fs->pc - 1] == ABSLINEINFO) { lua_assert(f->abslineinfo[fs->nabslineinfo - 1].pc == fs->pc - 1); f->abslineinfo[fs->nabslineinfo - 1].line = line; fs->previousline = line; } else { fs->previousline -= f->lineinfo[fs->pc - 1]; /* undo previous info. */ savelineinfo(fs, f, fs->pc - 1, line); /* redo it */ } } /* ** Emit a SETLIST instruction. ** 'base' is register that keeps table; ** 'nelems' is #table plus those to be stored now; ** 'tostore' is number of values (in registers 'base + 1',...) to add to ** table (or LUA_MULTRET to add up to stack top). */ void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) { int c = (nelems - 1)/LFIELDS_PER_FLUSH + 1; int b = (tostore == LUA_MULTRET) ? 0 : tostore; lua_assert(tostore != 0 && tostore <= LFIELDS_PER_FLUSH); if (c <= MAXARG_C) luaK_codeABC(fs, OP_SETLIST, base, b, c); else if (c <= MAXARG_Ax) { luaK_codeABC(fs, OP_SETLIST, base, b, 0); codeextraarg(fs, c); } else luaX_syntaxerror(fs->ls, "constructor too long"); fs->freereg = base + 1; /* free registers with list values */ } /* ** return the final target of a jump (skipping jumps to jumps) */ static int finaltarget (Instruction *code, int i) { int count; for (count = 0; count < 100; count++) { /* avoid infinite loops */ Instruction pc = code[i]; if (GET_OPCODE(pc) != OP_JMP) break; else i += GETARG_sJ(pc) + 1; } return i; } /* ** Do a final pass over the code of a function, doing small peephole ** optimizations and adjustments. */ void luaK_finish (FuncState *fs) { int i; Proto *p = fs->f; for (i = 0; i < fs->pc; i++) { Instruction *pc = &p->code[i]; lua_assert(i == 0 || isOT(*(pc - 1)) == isIT(*pc)); switch (GET_OPCODE(*pc)) { case OP_RETURN: case OP_RETURN0: case OP_RETURN1: case OP_RETVARARG: case OP_TAILCALL: { if (p->sizep > 0) SETARG_k(*pc, 1); /* signal that they must close upvalues */ break; } case OP_JMP: { int target = finaltarget(p->code, i); fixjump(fs, i, target); break; } default: break; } } }