2 ** $Id: lcode.c,v 2.109 2016/05/13 19:09:21 roberto Exp $
3 ** Code generator for Lua
4 ** See Copyright Notice in lua.h
32 /* Maximum number of registers in a Lua function (must fit in 8 bits) */
36 #define hasjumps(e) ((e)->t != (e)->f)
40 ** If expression is a numeric constant, fills 'v' with its value
41 ** and returns 1. Otherwise, returns 0.
43 static int tonumeral(expdesc *e, TValue *v) {
45 return 0; /* not a numeral */
48 if (v) setivalue(v, e->u.ival);
51 if (v) setfltvalue(v, e->u.nval);
59 ** Create a OP_LOADNIL instruction, but try to optimize: if the previous
60 ** instruction is also OP_LOADNIL and ranges are compatible, adjust
61 ** range of previous instruction instead of emitting a new one. (For
62 ** instance, 'local a; local b' will generate a single opcode.)
64 void luaK_nil (FuncState *fs, int from, int n) {
65 Instruction *previous;
66 int l = from + n - 1; /* last register to set nil */
67 if (fs->pc > fs->lasttarget) { /* no jumps to current position? */
68 previous = &fs->f->code[fs->pc-1];
69 if (GET_OPCODE(*previous) == OP_LOADNIL) { /* previous is LOADNIL? */
70 int pfrom = GETARG_A(*previous); /* get previous range */
71 int pl = pfrom + GETARG_B(*previous);
72 if ((pfrom <= from && from <= pl + 1) ||
73 (from <= pfrom && pfrom <= l + 1)) { /* can connect both? */
74 if (pfrom < from) from = pfrom; /* from = min(from, pfrom) */
75 if (pl > l) l = pl; /* l = max(l, pl) */
76 SETARG_A(*previous, from);
77 SETARG_B(*previous, l - from);
80 } /* else go through */
82 luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0); /* else no optimization */
87 ** Gets the destination address of a jump instruction. Used to traverse
90 static int getjump (FuncState *fs, int pc) {
91 int offset = GETARG_sBx(fs->f->code[pc]);
92 if (offset == NO_JUMP) /* point to itself represents end of list */
93 return NO_JUMP; /* end of list */
95 return (pc+1)+offset; /* turn offset into absolute position */
100 ** Fix jump instruction at position 'pc' to jump to 'dest'.
101 ** (Jump addresses are relative in Lua)
103 static void fixjump (FuncState *fs, int pc, int dest) {
104 Instruction *jmp = &fs->f->code[pc];
105 int offset = dest - (pc + 1);
106 lua_assert(dest != NO_JUMP);
107 if (abs(offset) > MAXARG_sBx)
108 luaX_syntaxerror(fs->ls, "control structure too long");
109 SETARG_sBx(*jmp, offset);
114 ** Concatenate jump-list 'l2' into jump-list 'l1'
116 void luaK_concat (FuncState *fs, int *l1, int l2) {
117 if (l2 == NO_JUMP) return; /* nothing to concatenate? */
118 else if (*l1 == NO_JUMP) /* no original list? */
119 *l1 = l2; /* 'l1' points to 'l2' */
123 while ((next = getjump(fs, list)) != NO_JUMP) /* find last element */
125 fixjump(fs, list, l2); /* last element links to 'l2' */
131 ** Create a jump instruction and return its position, so its destination
132 ** can be fixed later (with 'fixjump'). If there are jumps to
133 ** this position (kept in 'jpc'), link them all together so that
134 ** 'patchlistaux' will fix all them directly to the final destination.
136 int luaK_jump (FuncState *fs) {
137 int jpc = fs->jpc; /* save list of jumps to here */
139 fs->jpc = NO_JUMP; /* no more jumps to here */
140 j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
141 luaK_concat(fs, &j, jpc); /* keep them on hold */
147 ** Code a 'return' instruction
149 void luaK_ret (FuncState *fs, int first, int nret) {
150 luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
155 ** Code a "conditional jump", that is, a test or comparison opcode
156 ** followed by a jump. Return jump position.
158 static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
159 luaK_codeABC(fs, op, A, B, C);
160 return luaK_jump(fs);
165 ** returns current 'pc' and marks it as a jump target (to avoid wrong
166 ** optimizations with consecutive instructions not in the same basic block).
168 int luaK_getlabel (FuncState *fs) {
169 fs->lasttarget = fs->pc;
175 ** Returns the position of the instruction "controlling" a given
176 ** jump (that is, its condition), or the jump itself if it is
179 static Instruction *getjumpcontrol (FuncState *fs, int pc) {
180 Instruction *pi = &fs->f->code[pc];
181 if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
189 ** Patch destination register for a TESTSET instruction.
190 ** If instruction in position 'node' is not a TESTSET, return 0 ("fails").
191 ** Otherwise, if 'reg' is not 'NO_REG', set it as the destination
192 ** register. Otherwise, change instruction to a simple 'TEST' (produces
193 ** no register value)
195 static int patchtestreg (FuncState *fs, int node, int reg) {
196 Instruction *i = getjumpcontrol(fs, node);
197 if (GET_OPCODE(*i) != OP_TESTSET)
198 return 0; /* cannot patch other instructions */
199 if (reg != NO_REG && reg != GETARG_B(*i))
202 /* no register to put value or register already has the value;
203 change instruction to simple test */
204 *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
211 ** Traverse a list of tests ensuring no one produces a value
213 static void removevalues (FuncState *fs, int list) {
214 for (; list != NO_JUMP; list = getjump(fs, list))
215 patchtestreg(fs, list, NO_REG);
220 ** Traverse a list of tests, patching their destination address and
221 ** registers: tests producing values jump to 'vtarget' (and put their
222 ** values in 'reg'), other tests jump to 'dtarget'.
224 static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
226 while (list != NO_JUMP) {
227 int next = getjump(fs, list);
228 if (patchtestreg(fs, list, reg))
229 fixjump(fs, list, vtarget);
231 fixjump(fs, list, dtarget); /* jump to default target */
238 ** Ensure all pending jumps to current position are fixed (jumping
239 ** to current position with no values) and reset list of pending
242 static void dischargejpc (FuncState *fs) {
243 patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
249 ** Add elements in 'list' to list of pending jumps to "here"
250 ** (current position)
252 void luaK_patchtohere (FuncState *fs, int list) {
253 luaK_getlabel(fs); /* mark "here" as a jump target */
254 luaK_concat(fs, &fs->jpc, list);
259 ** Path all jumps in 'list' to jump to 'target'.
260 ** (The assert means that we cannot fix a jump to a forward address
261 ** because we only know addresses once code is generated.)
263 void luaK_patchlist (FuncState *fs, int list, int target) {
264 if (target == fs->pc) /* 'target' is current position? */
265 luaK_patchtohere(fs, list); /* add list to pending jumps */
267 lua_assert(target < fs->pc);
268 patchlistaux(fs, list, target, NO_REG, target);
274 ** Path all jumps in 'list' to close upvalues up to given 'level'
275 ** (The assertion checks that jumps either were closing nothing
276 ** or were closing higher levels, from inner blocks.)
278 void luaK_patchclose (FuncState *fs, int list, int level) {
279 level++; /* argument is +1 to reserve 0 as non-op */
280 for (; list != NO_JUMP; list = getjump(fs, list)) {
281 lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP &&
282 (GETARG_A(fs->f->code[list]) == 0 ||
283 GETARG_A(fs->f->code[list]) >= level));
284 SETARG_A(fs->f->code[list], level);
290 ** Emit instruction 'i', checking for array sizes and saving also its
291 ** line information. Return 'i' position.
293 static int luaK_code (FuncState *fs, Instruction i) {
295 dischargejpc(fs); /* 'pc' will change */
296 /* put new instruction in code array */
297 luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,
300 /* save corresponding line information */
301 luaM_growvector(fs->ls->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
303 f->lineinfo[fs->pc] = fs->ls->lastline;
309 ** Format and emit an 'iABC' instruction. (Assertions check consistency
310 ** of parameters versus opcode.)
312 int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
313 lua_assert(getOpMode(o) == iABC);
314 lua_assert(getBMode(o) != OpArgN || b == 0);
315 lua_assert(getCMode(o) != OpArgN || c == 0);
316 lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);
317 return luaK_code(fs, CREATE_ABC(o, a, b, c));
322 ** Format and emit an 'iABx' instruction.
324 int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
325 lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
326 lua_assert(getCMode(o) == OpArgN);
327 lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
328 return luaK_code(fs, CREATE_ABx(o, a, bc));
333 ** Emit an "extra argument" instruction (format 'iAx')
335 static int codeextraarg (FuncState *fs, int a) {
336 lua_assert(a <= MAXARG_Ax);
337 return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a));
342 ** Emit a "load constant" instruction, using either 'OP_LOADK'
343 ** (if constant index 'k' fits in 18 bits) or an 'OP_LOADKX'
344 ** instruction with "extra argument".
346 int luaK_codek (FuncState *fs, int reg, int k) {
348 return luaK_codeABx(fs, OP_LOADK, reg, k);
350 int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);
358 ** Check register-stack level, keeping track of its maximum size
359 ** in field 'maxstacksize'
361 void luaK_checkstack (FuncState *fs, int n) {
362 int newstack = fs->freereg + n;
363 if (newstack > fs->f->maxstacksize) {
364 if (newstack >= MAXREGS)
365 luaX_syntaxerror(fs->ls,
366 "function or expression needs too many registers");
367 fs->f->maxstacksize = cast_byte(newstack);
373 ** Reserve 'n' registers in register stack
375 void luaK_reserveregs (FuncState *fs, int n) {
376 luaK_checkstack(fs, n);
382 ** Free register 'reg', if it is neither a constant index nor
386 static void freereg (FuncState *fs, int reg) {
387 if (!ISK(reg) && reg >= fs->nactvar) {
389 lua_assert(reg == fs->freereg);
395 ** Free register used by expression 'e' (if any)
397 static void freeexp (FuncState *fs, expdesc *e) {
398 if (e->k == VNONRELOC)
399 freereg(fs, e->u.info);
404 ** Free registers used by expressions 'e1' and 'e2' (if any) in proper
407 static void freeexps (FuncState *fs, expdesc *e1, expdesc *e2) {
408 int r1 = (e1->k == VNONRELOC) ? e1->u.info : -1;
409 int r2 = (e2->k == VNONRELOC) ? e2->u.info : -1;
422 ** Add constant 'v' to prototype's list of constants (field 'k').
423 ** Use scanner's table to cache position of constants in constant list
424 ** and try to reuse constants. Because some values should not be used
425 ** as keys (nil cannot be a key, integer keys can collapse with float
426 ** keys), the caller must provide a useful 'key' for indexing the cache.
428 static int addk (FuncState *fs, TValue *key, TValue *v) {
429 lua_State *L = fs->ls->L;
431 TValue *idx = luaH_set(L, fs->ls->h, key); /* index scanner table */
433 if (ttisinteger(idx)) { /* is there an index there? */
434 k = cast_int(ivalue(idx));
435 /* correct value? (warning: must distinguish floats from integers!) */
436 if (k < fs->nk && ttype(&f->k[k]) == ttype(v) &&
437 luaV_rawequalobj(&f->k[k], v))
438 return k; /* reuse index */
440 /* constant not found; create a new entry */
443 /* numerical value does not need GC barrier;
444 table has no metatable, so it does not need to invalidate cache */
446 luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");
447 while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
448 setobj(L, &f->k[k], v);
450 luaC_barrier(L, f, v);
456 ** Add a string to list of constants and return its index.
458 int luaK_stringK (FuncState *fs, TString *s) {
460 setsvalue(fs->ls->L, &o, s);
461 return addk(fs, &o, &o); /* use string itself as key */
466 ** Add an integer to list of constants and return its index.
467 ** Integers use userdata as keys to avoid collision with floats with
468 ** same value; conversion to 'void*' is used only for hashing, so there
469 ** are no "precision" problems.
471 int luaK_intK (FuncState *fs, lua_Integer n) {
473 setpvalue(&k, cast(void*, cast(size_t, n)));
475 return addk(fs, &k, &o);
479 ** Add a float to list of constants and return its index.
481 static int luaK_numberK (FuncState *fs, lua_Number r) {
484 return addk(fs, &o, &o); /* use number itself as key */
489 ** Add a boolean to list of constants and return its index.
491 static int boolK (FuncState *fs, int b) {
494 return addk(fs, &o, &o); /* use boolean itself as key */
499 ** Add nil to list of constants and return its index.
501 static int nilK (FuncState *fs) {
504 /* cannot use nil as key; instead use table itself to represent nil */
505 sethvalue(fs->ls->L, &k, fs->ls->h);
506 return addk(fs, &k, &v);
511 ** Fix an expression to return the number of results 'nresults'.
512 ** Either 'e' is a multi-ret expression (function call or vararg)
513 ** or 'nresults' is LUA_MULTRET (as any expression can satisfy that).
515 void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
516 if (e->k == VCALL) { /* expression is an open function call? */
517 SETARG_C(getinstruction(fs, e), nresults + 1);
519 else if (e->k == VVARARG) {
520 Instruction *pc = &getinstruction(fs, e);
521 SETARG_B(*pc, nresults + 1);
522 SETARG_A(*pc, fs->freereg);
523 luaK_reserveregs(fs, 1);
525 else lua_assert(nresults == LUA_MULTRET);
530 ** Fix an expression to return one result.
531 ** If expression is not a multi-ret expression (function call or
532 ** vararg), it already returns one result, so nothing needs to be done.
533 ** Function calls become VNONRELOC expressions (as its result comes
534 ** fixed in the base register of the call), while vararg expressions
535 ** become VRELOCABLE (as OP_VARARG puts its results where it wants).
536 ** (Calls are created returning one result, so that does not need
539 void luaK_setoneret (FuncState *fs, expdesc *e) {
540 if (e->k == VCALL) { /* expression is an open function call? */
541 /* already returns 1 value */
542 lua_assert(GETARG_C(getinstruction(fs, e)) == 2);
543 e->k = VNONRELOC; /* result has fixed position */
544 e->u.info = GETARG_A(getinstruction(fs, e));
546 else if (e->k == VVARARG) {
547 SETARG_B(getinstruction(fs, e), 2);
548 e->k = VRELOCABLE; /* can relocate its simple result */
554 ** Ensure that expression 'e' is not a variable.
556 void luaK_dischargevars (FuncState *fs, expdesc *e) {
558 case VLOCAL: { /* already in a register */
559 e->k = VNONRELOC; /* becomes a non-relocatable value */
562 case VUPVAL: { /* move value to some (pending) register */
563 e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
569 freereg(fs, e->u.ind.idx);
570 if (e->u.ind.vt == VLOCAL) { /* is 't' in a register? */
571 freereg(fs, e->u.ind.t);
575 lua_assert(e->u.ind.vt == VUPVAL);
576 op = OP_GETTABUP; /* 't' is in an upvalue */
578 e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx);
582 case VVARARG: case VCALL: {
583 luaK_setoneret(fs, e);
586 default: break; /* there is one value available (somewhere) */
592 ** Ensures expression value is in register 'reg' (and therefore
593 ** 'e' will become a non-relocatable expression).
595 static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
596 luaK_dischargevars(fs, e);
599 luaK_nil(fs, reg, 1);
602 case VFALSE: case VTRUE: {
603 luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
607 luaK_codek(fs, reg, e->u.info);
611 luaK_codek(fs, reg, luaK_numberK(fs, e->u.nval));
615 luaK_codek(fs, reg, luaK_intK(fs, e->u.ival));
619 Instruction *pc = &getinstruction(fs, e);
620 SETARG_A(*pc, reg); /* instruction will put result in 'reg' */
624 if (reg != e->u.info)
625 luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
629 lua_assert(e->k == VJMP);
630 return; /* nothing to do... */
639 ** Ensures expression value is in any register.
641 static void discharge2anyreg (FuncState *fs, expdesc *e) {
642 if (e->k != VNONRELOC) { /* no fixed register yet? */
643 luaK_reserveregs(fs, 1); /* get a register */
644 discharge2reg(fs, e, fs->freereg-1); /* put value there */
649 static int code_loadbool (FuncState *fs, int A, int b, int jump) {
650 luaK_getlabel(fs); /* those instructions may be jump targets */
651 return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
656 ** check whether list has any jump that do not produce a value
657 ** or produce an inverted value
659 static int need_value (FuncState *fs, int list) {
660 for (; list != NO_JUMP; list = getjump(fs, list)) {
661 Instruction i = *getjumpcontrol(fs, list);
662 if (GET_OPCODE(i) != OP_TESTSET) return 1;
664 return 0; /* not found */
669 ** Ensures final expression result (including results from its jump
670 ** lists) is in register 'reg'.
671 ** If expression has jumps, need to patch these jumps either to
672 ** its final position or to "load" instructions (for those tests
673 ** that do not produce values).
675 static void exp2reg (FuncState *fs, expdesc *e, int reg) {
676 discharge2reg(fs, e, reg);
677 if (e->k == VJMP) /* expression itself is a test? */
678 luaK_concat(fs, &e->t, e->u.info); /* put this jump in 't' list */
680 int final; /* position after whole expression */
681 int p_f = NO_JUMP; /* position of an eventual LOAD false */
682 int p_t = NO_JUMP; /* position of an eventual LOAD true */
683 if (need_value(fs, e->t) || need_value(fs, e->f)) {
684 int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
685 p_f = code_loadbool(fs, reg, 0, 1);
686 p_t = code_loadbool(fs, reg, 1, 0);
687 luaK_patchtohere(fs, fj);
689 final = luaK_getlabel(fs);
690 patchlistaux(fs, e->f, final, reg, p_f);
691 patchlistaux(fs, e->t, final, reg, p_t);
693 e->f = e->t = NO_JUMP;
700 ** Ensures final expression result (including results from its jump
701 ** lists) is in next available register.
703 void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
704 luaK_dischargevars(fs, e);
706 luaK_reserveregs(fs, 1);
707 exp2reg(fs, e, fs->freereg - 1);
712 ** Ensures final expression result (including results from its jump
713 ** lists) is in some (any) register and return that register.
715 int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
716 luaK_dischargevars(fs, e);
717 if (e->k == VNONRELOC) { /* expression already has a register? */
718 if (!hasjumps(e)) /* no jumps? */
719 return e->u.info; /* result is already in a register */
720 if (e->u.info >= fs->nactvar) { /* reg. is not a local? */
721 exp2reg(fs, e, e->u.info); /* put final result in it */
725 luaK_exp2nextreg(fs, e); /* otherwise, use next available register */
731 ** Ensures final expression result is either in a register or in an
734 void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
735 if (e->k != VUPVAL || hasjumps(e))
736 luaK_exp2anyreg(fs, e);
741 ** Ensures final expression result is either in a register or it is
744 void luaK_exp2val (FuncState *fs, expdesc *e) {
746 luaK_exp2anyreg(fs, e);
748 luaK_dischargevars(fs, e);
753 ** Ensures final expression result is in a valid R/K index
754 ** (that is, it is either in a register or in 'k' with an index
755 ** in the range of R/K indices).
756 ** Returns R/K index.
758 int luaK_exp2RK (FuncState *fs, expdesc *e) {
760 switch (e->k) { /* move constants to 'k' */
761 case VTRUE: e->u.info = boolK(fs, 1); goto vk;
762 case VFALSE: e->u.info = boolK(fs, 0); goto vk;
763 case VNIL: e->u.info = nilK(fs); goto vk;
764 case VKINT: e->u.info = luaK_intK(fs, e->u.ival); goto vk;
765 case VKFLT: e->u.info = luaK_numberK(fs, e->u.nval); goto vk;
769 if (e->u.info <= MAXINDEXRK) /* constant fits in 'argC'? */
770 return RKASK(e->u.info);
774 /* not a constant in the right range: put it in a register */
775 return luaK_exp2anyreg(fs, e);
780 ** Generate code to store result of expression 'ex' into variable 'var'.
782 void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
786 exp2reg(fs, ex, var->u.info); /* compute 'ex' into proper place */
790 int e = luaK_exp2anyreg(fs, ex);
791 luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
795 OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;
796 int e = luaK_exp2RK(fs, ex);
797 luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e);
800 default: lua_assert(0); /* invalid var kind to store */
807 ** Emit SELF instruction (convert expression 'e' into 'e:key(e,').
809 void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
811 luaK_exp2anyreg(fs, e);
812 ereg = e->u.info; /* register where 'e' was placed */
814 e->u.info = fs->freereg; /* base register for op_self */
815 e->k = VNONRELOC; /* self expression has a fixed register */
816 luaK_reserveregs(fs, 2); /* function and 'self' produced by op_self */
817 luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));
823 ** Negate condition 'e' (where 'e' is a comparison).
825 static void negatecondition (FuncState *fs, expdesc *e) {
826 Instruction *pc = getjumpcontrol(fs, e->u.info);
827 lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
828 GET_OPCODE(*pc) != OP_TEST);
829 SETARG_A(*pc, !(GETARG_A(*pc)));
834 ** Emit instruction to jump if 'e' is 'cond' (that is, if 'cond'
835 ** is true, code will jump if 'e' is true.) Return jump position.
836 ** Optimize when 'e' is 'not' something, inverting the condition
837 ** and removing the 'not'.
839 static int jumponcond (FuncState *fs, expdesc *e, int cond) {
840 if (e->k == VRELOCABLE) {
841 Instruction ie = getinstruction(fs, e);
842 if (GET_OPCODE(ie) == OP_NOT) {
843 fs->pc--; /* remove previous OP_NOT */
844 return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
846 /* else go through */
848 discharge2anyreg(fs, e);
850 return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond);
855 ** Emit code to go through if 'e' is true, jump otherwise.
857 void luaK_goiftrue (FuncState *fs, expdesc *e) {
858 int pc; /* pc of new jump */
859 luaK_dischargevars(fs, e);
861 case VJMP: { /* condition? */
862 negatecondition(fs, e); /* jump when it is false */
863 pc = e->u.info; /* save jump position */
866 case VK: case VKFLT: case VKINT: case VTRUE: {
867 pc = NO_JUMP; /* always true; do nothing */
871 pc = jumponcond(fs, e, 0); /* jump when false */
875 luaK_concat(fs, &e->f, pc); /* insert new jump in false list */
876 luaK_patchtohere(fs, e->t); /* true list jumps to here (to go through) */
882 ** Emit code to go through if 'e' is false, jump otherwise.
884 void luaK_goiffalse (FuncState *fs, expdesc *e) {
885 int pc; /* pc of new jump */
886 luaK_dischargevars(fs, e);
889 pc = e->u.info; /* already jump if true */
892 case VNIL: case VFALSE: {
893 pc = NO_JUMP; /* always false; do nothing */
897 pc = jumponcond(fs, e, 1); /* jump if true */
901 luaK_concat(fs, &e->t, pc); /* insert new jump in 't' list */
902 luaK_patchtohere(fs, e->f); /* false list jumps to here (to go through) */
908 ** Code 'not e', doing constant folding.
910 static void codenot (FuncState *fs, expdesc *e) {
911 luaK_dischargevars(fs, e);
913 case VNIL: case VFALSE: {
914 e->k = VTRUE; /* true == not nil == not false */
917 case VK: case VKFLT: case VKINT: case VTRUE: {
918 e->k = VFALSE; /* false == not "x" == not 0.5 == not 1 == not true */
922 negatecondition(fs, e);
927 discharge2anyreg(fs, e);
929 e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0);
933 default: lua_assert(0); /* cannot happen */
935 /* interchange true and false lists */
936 { int temp = e->f; e->f = e->t; e->t = temp; }
937 removevalues(fs, e->f); /* values are useless when negated */
938 removevalues(fs, e->t);
943 ** Create expression 't[k]'. 't' must have its final result already in a
944 ** register or upvalue.
946 void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
947 lua_assert(!hasjumps(t) && (vkisinreg(t->k) || t->k == VUPVAL));
948 t->u.ind.t = t->u.info; /* register or upvalue index */
949 t->u.ind.idx = luaK_exp2RK(fs, k); /* R/K index for key */
950 t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL : VLOCAL;
956 ** Return false if folding can raise an error.
957 ** Bitwise operations need operands convertible to integers; division
958 ** operations cannot have 0 as divisor.
960 static int validop (int op, TValue *v1, TValue *v2) {
962 case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
963 case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT: { /* conversion errors */
965 return (tointeger(v1, &i) && tointeger(v2, &i));
967 case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD: /* division by 0 */
968 return (nvalue(v2) != 0);
969 default: return 1; /* everything else is valid */
975 ** Try to "constant-fold" an operation; return 1 iff successful.
976 ** (In this case, 'e1' has the final result.)
978 static int constfolding (FuncState *fs, int op, expdesc *e1, expdesc *e2) {
980 if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2))
981 return 0; /* non-numeric operands or not safe to fold */
982 luaO_arith(fs->ls->L, op, &v1, &v2, &res); /* does operation */
983 if (ttisinteger(&res)) {
985 e1->u.ival = ivalue(&res);
987 else { /* folds neither NaN nor 0.0 (to avoid problems with -0.0) */
988 lua_Number n = fltvalue(&res);
989 if (luai_numisnan(n) || n == 0)
999 ** Emit code for unary expressions that "produce values"
1000 ** (everything but 'not').
1001 ** Expression to produce final result will be encoded in 'e'.
1003 static void codeunexpval (FuncState *fs, OpCode op, expdesc *e, int line) {
1004 int r = luaK_exp2anyreg(fs, e); /* opcodes operate only on registers */
1006 e->u.info = luaK_codeABC(fs, op, 0, r, 0); /* generate opcode */
1007 e->k = VRELOCABLE; /* all those operations are relocatable */
1008 luaK_fixline(fs, line);
1013 ** Emit code for binary expressions that "produce values"
1014 ** (everything but logical operators 'and'/'or' and comparison
1016 ** Expression to produce final result will be encoded in 'e1'.
1018 static void codebinexpval (FuncState *fs, OpCode op,
1019 expdesc *e1, expdesc *e2, int line) {
1020 int rk1 = luaK_exp2RK(fs, e1); /* both operands are "RK" */
1021 int rk2 = luaK_exp2RK(fs, e2);
1022 freeexps(fs, e1, e2);
1023 e1->u.info = luaK_codeABC(fs, op, 0, rk1, rk2); /* generate opcode */
1024 e1->k = VRELOCABLE; /* all those operations are relocatable */
1025 luaK_fixline(fs, line);
1030 ** Emit code for comparisons.
1031 ** 'e1' was already put in R/K form by 'luaK_infix'.
1033 static void codecomp (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2) {
1034 int rk1 = (e1->k == VK) ? RKASK(e1->u.info)
1035 : check_exp(e1->k == VNONRELOC, e1->u.info);
1036 int rk2 = luaK_exp2RK(fs, e2);
1037 freeexps(fs, e1, e2);
1039 case OPR_NE: { /* '(a ~= b)' ==> 'not (a == b)' */
1040 e1->u.info = condjump(fs, OP_EQ, 0, rk1, rk2);
1043 case OPR_GT: case OPR_GE: {
1044 /* '(a > b)' ==> '(b < a)'; '(a >= b)' ==> '(b <= a)' */
1045 OpCode op = cast(OpCode, (opr - OPR_NE) + OP_EQ);
1046 e1->u.info = condjump(fs, op, 1, rk2, rk1); /* invert operands */
1049 default: { /* '==', '<', '<=' use their own opcodes */
1050 OpCode op = cast(OpCode, (opr - OPR_EQ) + OP_EQ);
1051 e1->u.info = condjump(fs, op, 1, rk1, rk2);
1060 ** Aplly prefix operation 'op' to expression 'e'.
1062 void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) {
1063 static expdesc ef = {VKINT, {0}, NO_JUMP, NO_JUMP}; /* fake 2nd operand */
1065 case OPR_MINUS: case OPR_BNOT:
1066 if (constfolding(fs, op + LUA_OPUNM, e, &ef))
1070 codeunexpval(fs, cast(OpCode, op + OP_UNM), e, line);
1072 case OPR_NOT: codenot(fs, e); break;
1073 default: lua_assert(0);
1079 ** Process 1st operand 'v' of binary operation 'op' before reading
1082 void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
1085 luaK_goiftrue(fs, v); /* go ahead only if 'v' is true */
1089 luaK_goiffalse(fs, v); /* go ahead only if 'v' is false */
1093 luaK_exp2nextreg(fs, v); /* operand must be on the 'stack' */
1096 case OPR_ADD: case OPR_SUB:
1097 case OPR_MUL: case OPR_DIV: case OPR_IDIV:
1098 case OPR_MOD: case OPR_POW:
1099 case OPR_BAND: case OPR_BOR: case OPR_BXOR:
1100 case OPR_SHL: case OPR_SHR: {
1101 if (!tonumeral(v, NULL))
1103 /* else keep numeral, which may be folded with 2nd operand */
1115 ** Finalize code for binary operation, after reading 2nd operand.
1116 ** For '(a .. b .. c)' (which is '(a .. (b .. c))', because
1117 ** concatenation is right associative), merge second CONCAT into first
1120 void luaK_posfix (FuncState *fs, BinOpr op,
1121 expdesc *e1, expdesc *e2, int line) {
1124 lua_assert(e1->t == NO_JUMP); /* list closed by 'luK_infix' */
1125 luaK_dischargevars(fs, e2);
1126 luaK_concat(fs, &e2->f, e1->f);
1131 lua_assert(e1->f == NO_JUMP); /* list closed by 'luK_infix' */
1132 luaK_dischargevars(fs, e2);
1133 luaK_concat(fs, &e2->t, e1->t);
1138 luaK_exp2val(fs, e2);
1139 if (e2->k == VRELOCABLE &&
1140 GET_OPCODE(getinstruction(fs, e2)) == OP_CONCAT) {
1141 lua_assert(e1->u.info == GETARG_B(getinstruction(fs, e2))-1);
1143 SETARG_B(getinstruction(fs, e2), e1->u.info);
1144 e1->k = VRELOCABLE; e1->u.info = e2->u.info;
1147 luaK_exp2nextreg(fs, e2); /* operand must be on the 'stack' */
1148 codebinexpval(fs, OP_CONCAT, e1, e2, line);
1152 case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
1153 case OPR_IDIV: case OPR_MOD: case OPR_POW:
1154 case OPR_BAND: case OPR_BOR: case OPR_BXOR:
1155 case OPR_SHL: case OPR_SHR: {
1156 if (!constfolding(fs, op + LUA_OPADD, e1, e2))
1157 codebinexpval(fs, cast(OpCode, op + OP_ADD), e1, e2, line);
1160 case OPR_EQ: case OPR_LT: case OPR_LE:
1161 case OPR_NE: case OPR_GT: case OPR_GE: {
1162 codecomp(fs, op, e1, e2);
1165 default: lua_assert(0);
1171 ** Change line information associated with current position.
1173 void luaK_fixline (FuncState *fs, int line) {
1174 fs->f->lineinfo[fs->pc - 1] = line;
1179 ** Emit a SETLIST instruction.
1180 ** 'base' is register that keeps table;
1181 ** 'nelems' is #table plus those to be stored now;
1182 ** 'tostore' is number of values (in registers 'base + 1',...) to add to
1183 ** table (or LUA_MULTRET to add up to stack top).
1185 void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
1186 int c = (nelems - 1)/LFIELDS_PER_FLUSH + 1;
1187 int b = (tostore == LUA_MULTRET) ? 0 : tostore;
1188 lua_assert(tostore != 0 && tostore <= LFIELDS_PER_FLUSH);
1190 luaK_codeABC(fs, OP_SETLIST, base, b, c);
1191 else if (c <= MAXARG_Ax) {
1192 luaK_codeABC(fs, OP_SETLIST, base, b, 0);
1193 codeextraarg(fs, c);
1196 luaX_syntaxerror(fs->ls, "constructor too long");
1197 fs->freereg = base + 1; /* free registers with list values */