1 /*
2 ** $Id: lcode.c,v 2.103 2015/11/19 19:16:22 roberto Exp $
3 ** Code generator for Lua
4 ** See Copyright Notice in lua.h
5 */
6
7 #define lcode_c
8 #define LUA_CORE
9
10 #include "lprefix.h"
11
12
13 #include <math.h>
14 #include <stdlib.h>
15
16 #include "lua.h"
17
18 #include "lcode.h"
19 #include "ldebug.h"
20 #include "ldo.h"
21 #include "lgc.h"
22 #include "llex.h"
23 #include "lmem.h"
24 #include "lobject.h"
25 #include "lopcodes.h"
26 #include "lparser.h"
27 #include "lstring.h"
28 #include "ltable.h"
29 #include "lvm.h"
30
31
32 /* Maximum number of registers in a Lua function (must fit in 8 bits) */
33 #define MAXREGS 255
34
35
36 #define hasjumps(e) ((e)->t != (e)->f)
37
38
39 static int tonumeral(expdesc *e, TValue *v) {
40 if (hasjumps(e))
41 return 0; /* not a numeral */
42 switch (e->k) {
43 case VKINT:
44 if (v) setivalue(v, e->u.ival);
45 return 1;
46 case VKFLT:
47 if (v) setfltvalue(v, e->u.nval);
48 return 1;
49 default: return 0;
50 }
51 }
52
53
54 void luaK_nil (FuncState *fs, int from, int n) {
55 Instruction *previous;
56 int l = from + n - 1; /* last register to set nil */
57 if (fs->pc > fs->lasttarget) { /* no jumps to current position? */
58 previous = &fs->f->code[fs->pc-1];
59 if (GET_OPCODE(*previous) == OP_LOADNIL) {
60 int pfrom = GETARG_A(*previous);
61 int pl = pfrom + GETARG_B(*previous);
62 if ((pfrom <= from && from <= pl + 1) ||
63 (from <= pfrom && pfrom <= l + 1)) { /* can connect both? */
64 if (pfrom < from) from = pfrom; /* from = min(from, pfrom) */
65 if (pl > l) l = pl; /* l = max(l, pl) */
66 SETARG_A(*previous, from);
67 SETARG_B(*previous, l - from);
68 return;
69 }
70 } /* else go through */
71 }
72 luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0); /* else no optimization */
73 }
74
75
76 int luaK_jump (FuncState *fs) {
77 int jpc = fs->jpc; /* save list of jumps to here */
78 int j;
79 fs->jpc = NO_JUMP;
80 j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
81 luaK_concat(fs, &j, jpc); /* keep them on hold */
82 return j;
83 }
84
85
86 void luaK_ret (FuncState *fs, int first, int nret) {
87 luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
88 }
89
90
91 static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
92 luaK_codeABC(fs, op, A, B, C);
93 return luaK_jump(fs);
94 }
95
96
97 static void fixjump (FuncState *fs, int pc, int dest) {
98 Instruction *jmp = &fs->f->code[pc];
99 int offset = dest-(pc+1);
100 lua_assert(dest != NO_JUMP);
101 if (abs(offset) > MAXARG_sBx)
102 luaX_syntaxerror(fs->ls, "control structure too long");
103 SETARG_sBx(*jmp, offset);
104 }
105
106
107 /*
108 ** returns current 'pc' and marks it as a jump target (to avoid wrong
109 ** optimizations with consecutive instructions not in the same basic block).
110 */
111 int luaK_getlabel (FuncState *fs) {
112 fs->lasttarget = fs->pc;
113 return fs->pc;
114 }
115
116
117 static int getjump (FuncState *fs, int pc) {
118 int offset = GETARG_sBx(fs->f->code[pc]);
119 if (offset == NO_JUMP) /* point to itself represents end of list */
120 return NO_JUMP; /* end of list */
121 else
122 return (pc+1)+offset; /* turn offset into absolute position */
123 }
124
125
126 static Instruction *getjumpcontrol (FuncState *fs, int pc) {
127 Instruction *pi = &fs->f->code[pc];
128 if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
129 return pi-1;
130 else
131 return pi;
132 }
133
134
135 /*
136 ** check whether list has any jump that do not produce a value
137 ** (or produce an inverted value)
138 */
139 static int need_value (FuncState *fs, int list) {
140 for (; list != NO_JUMP; list = getjump(fs, list)) {
141 Instruction i = *getjumpcontrol(fs, list);
142 if (GET_OPCODE(i) != OP_TESTSET) return 1;
143 }
144 return 0; /* not found */
145 }
146
147
148 static int patchtestreg (FuncState *fs, int node, int reg) {
149 Instruction *i = getjumpcontrol(fs, node);
150 if (GET_OPCODE(*i) != OP_TESTSET)
151 return 0; /* cannot patch other instructions */
152 if (reg != NO_REG && reg != GETARG_B(*i))
153 SETARG_A(*i, reg);
154 else /* no register to put value or register already has the value */
155 *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
156
157 return 1;
158 }
159
160
161 static void removevalues (FuncState *fs, int list) {
162 for (; list != NO_JUMP; list = getjump(fs, list))
163 patchtestreg(fs, list, NO_REG);
164 }
165
166
167 static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
168 int dtarget) {
169 while (list != NO_JUMP) {
170 int next = getjump(fs, list);
171 if (patchtestreg(fs, list, reg))
172 fixjump(fs, list, vtarget);
173 else
174 fixjump(fs, list, dtarget); /* jump to default target */
175 list = next;
176 }
177 }
178
179
180 static void dischargejpc (FuncState *fs) {
181 patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
182 fs->jpc = NO_JUMP;
183 }
184
185
186 void luaK_patchlist (FuncState *fs, int list, int target) {
187 if (target == fs->pc)
188 luaK_patchtohere(fs, list);
189 else {
190 lua_assert(target < fs->pc);
191 patchlistaux(fs, list, target, NO_REG, target);
192 }
193 }
194
195
196 void luaK_patchclose (FuncState *fs, int list, int level) {
197 level++; /* argument is +1 to reserve 0 as non-op */
198 while (list != NO_JUMP) {
199 int next = getjump(fs, list);
200 lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP &&
201 (GETARG_A(fs->f->code[list]) == 0 ||
202 GETARG_A(fs->f->code[list]) >= level));
203 SETARG_A(fs->f->code[list], level);
204 list = next;
205 }
206 }
207
208
209 void luaK_patchtohere (FuncState *fs, int list) {
210 luaK_getlabel(fs);
211 luaK_concat(fs, &fs->jpc, list);
212 }
213
214
215 void luaK_concat (FuncState *fs, int *l1, int l2) {
216 if (l2 == NO_JUMP) return;
217 else if (*l1 == NO_JUMP)
218 *l1 = l2;
219 else {
220 int list = *l1;
221 int next;
222 while ((next = getjump(fs, list)) != NO_JUMP) /* find last element */
223 list = next;
224 fixjump(fs, list, l2);
225 }
226 }
227
228
229 static int luaK_code (FuncState *fs, Instruction i) {
230 Proto *f = fs->f;
231 dischargejpc(fs); /* 'pc' will change */
232 /* put new instruction in code array */
233 luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,
234 MAX_INT, "opcodes");
235 f->code[fs->pc] = i;
236 /* save corresponding line information */
237 luaM_growvector(fs->ls->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
238 MAX_INT, "opcodes");
239 f->lineinfo[fs->pc] = fs->ls->lastline;
240 return fs->pc++;
241 }
242
243
244 int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
245 lua_assert(getOpMode(o) == iABC);
246 lua_assert(getBMode(o) != OpArgN || b == 0);
247 lua_assert(getCMode(o) != OpArgN || c == 0);
248 lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);
249 return luaK_code(fs, CREATE_ABC(o, a, b, c));
250 }
251
252
253 int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
254 lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
255 lua_assert(getCMode(o) == OpArgN);
256 lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
257 return luaK_code(fs, CREATE_ABx(o, a, bc));
258 }
259
260
261 static int codeextraarg (FuncState *fs, int a) {
262 lua_assert(a <= MAXARG_Ax);
263 return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a));
264 }
265
266
267 int luaK_codek (FuncState *fs, int reg, int k) {
268 if (k <= MAXARG_Bx)
269 return luaK_codeABx(fs, OP_LOADK, reg, k);
270 else {
271 int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);
272 codeextraarg(fs, k);
273 return p;
274 }
275 }
276
277
278 void luaK_checkstack (FuncState *fs, int n) {
279 int newstack = fs->freereg + n;
280 if (newstack > fs->f->maxstacksize) {
281 if (newstack >= MAXREGS)
282 luaX_syntaxerror(fs->ls,
283 "function or expression needs too many registers");
284 fs->f->maxstacksize = cast_byte(newstack);
285 }
286 }
287
288
289 void luaK_reserveregs (FuncState *fs, int n) {
290 luaK_checkstack(fs, n);
291 fs->freereg += n;
292 }
293
294
295 static void freereg (FuncState *fs, int reg) {
296 if (!ISK(reg) && reg >= fs->nactvar) {
297 fs->freereg--;
298 lua_assert(reg == fs->freereg);
299 }
300 }
301
302
303 static void freeexp (FuncState *fs, expdesc *e) {
304 if (e->k == VNONRELOC)
305 freereg(fs, e->u.info);
306 }
307
308
309 /*
310 ** Use scanner's table to cache position of constants in constant list
311 ** and try to reuse constants
312 */
313 static int addk (FuncState *fs, TValue *key, TValue *v) {
314 lua_State *L = fs->ls->L;
315 Proto *f = fs->f;
316 TValue *idx = luaH_set(L, fs->ls->h, key); /* index scanner table */
317 int k, oldsize;
318 if (ttisinteger(idx)) { /* is there an index there? */
319 k = cast_int(ivalue(idx));
320 /* correct value? (warning: must distinguish floats from integers!) */
321 if (k < fs->nk && ttype(&f->k[k]) == ttype(v) &&
322 luaV_rawequalobj(&f->k[k], v))
323 return k; /* reuse index */
324 }
325 /* constant not found; create a new entry */
326 oldsize = f->sizek;
327 k = fs->nk;
328 /* numerical value does not need GC barrier;
329 table has no metatable, so it does not need to invalidate cache */
330 setivalue(idx, k);
331 luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");
332 while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
333 setobj(L, &f->k[k], v);
334 fs->nk++;
335 luaC_barrier(L, f, v);
336 return k;
337 }
338
339
340 int luaK_stringK (FuncState *fs, TString *s) {
341 TValue o;
342 setsvalue(fs->ls->L, &o, s);
343 return addk(fs, &o, &o);
344 }
345
346
347 /*
348 ** Integers use userdata as keys to avoid collision with floats with same
349 ** value; conversion to 'void*' used only for hashing, no "precision"
350 ** problems
351 */
352 int luaK_intK (FuncState *fs, lua_Integer n) {
353 TValue k, o;
354 setpvalue(&k, cast(void*, cast(size_t, n)));
355 setivalue(&o, n);
356 return addk(fs, &k, &o);
357 }
358
359
360 static int luaK_numberK (FuncState *fs, lua_Number r) {
361 TValue o;
362 setfltvalue(&o, r);
363 return addk(fs, &o, &o);
364 }
365
366
367 static int boolK (FuncState *fs, int b) {
368 TValue o;
369 setbvalue(&o, b);
370 return addk(fs, &o, &o);
371 }
372
373
374 static int nilK (FuncState *fs) {
375 TValue k, v;
376 setnilvalue(&v);
377 /* cannot use nil as key; instead use table itself to represent nil */
378 sethvalue(fs->ls->L, &k, fs->ls->h);
379 return addk(fs, &k, &v);
380 }
381
382
383 void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
384 if (e->k == VCALL) { /* expression is an open function call? */
385 SETARG_C(getcode(fs, e), nresults+1);
386 }
387 else if (e->k == VVARARG) {
388 SETARG_B(getcode(fs, e), nresults+1);
389 SETARG_A(getcode(fs, e), fs->freereg);
390 luaK_reserveregs(fs, 1);
391 }
392 }
393
394
395 void luaK_setoneret (FuncState *fs, expdesc *e) {
396 if (e->k == VCALL) { /* expression is an open function call? */
397 e->k = VNONRELOC;
398 e->u.info = GETARG_A(getcode(fs, e));
399 }
400 else if (e->k == VVARARG) {
401 SETARG_B(getcode(fs, e), 2);
402 e->k = VRELOCABLE; /* can relocate its simple result */
403 }
404 }
405
406
407 void luaK_dischargevars (FuncState *fs, expdesc *e) {
408 switch (e->k) {
409 case VLOCAL: {
410 e->k = VNONRELOC;
411 break;
412 }
413 case VUPVAL: {
414 e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
415 e->k = VRELOCABLE;
416 break;
417 }
418 case VINDEXED: {
419 OpCode op = OP_GETTABUP; /* assume 't' is in an upvalue */
420 freereg(fs, e->u.ind.idx);
421 if (e->u.ind.vt == VLOCAL) { /* 't' is in a register? */
422 freereg(fs, e->u.ind.t);
423 op = OP_GETTABLE;
424 }
425 e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx);
426 e->k = VRELOCABLE;
427 break;
428 }
429 case VVARARG:
430 case VCALL: {
431 luaK_setoneret(fs, e);
432 break;
433 }
434 default: break; /* there is one value available (somewhere) */
435 }
436 }
437
438
439 static int code_label (FuncState *fs, int A, int b, int jump) {
440 luaK_getlabel(fs); /* those instructions may be jump targets */
441 return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
442 }
443
444
445 static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
446 luaK_dischargevars(fs, e);
447 switch (e->k) {
448 case VNIL: {
449 luaK_nil(fs, reg, 1);
450 break;
451 }
452 case VFALSE: case VTRUE: {
453 luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
454 break;
455 }
456 case VK: {
457 luaK_codek(fs, reg, e->u.info);
458 break;
459 }
460 case VKFLT: {
461 luaK_codek(fs, reg, luaK_numberK(fs, e->u.nval));
462 break;
463 }
464 case VKINT: {
465 luaK_codek(fs, reg, luaK_intK(fs, e->u.ival));
466 break;
467 }
468 case VRELOCABLE: {
469 Instruction *pc = &getcode(fs, e);
470 SETARG_A(*pc, reg);
471 break;
472 }
473 case VNONRELOC: {
474 if (reg != e->u.info)
475 luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
476 break;
477 }
478 default: {
479 lua_assert(e->k == VVOID || e->k == VJMP);
480 return; /* nothing to do... */
481 }
482 }
483 e->u.info = reg;
484 e->k = VNONRELOC;
485 }
486
487
488 static void discharge2anyreg (FuncState *fs, expdesc *e) {
489 if (e->k != VNONRELOC) {
490 luaK_reserveregs(fs, 1);
491 discharge2reg(fs, e, fs->freereg-1);
492 }
493 }
494
495
496 static void exp2reg (FuncState *fs, expdesc *e, int reg) {
497 discharge2reg(fs, e, reg);
498 if (e->k == VJMP)
499 luaK_concat(fs, &e->t, e->u.info); /* put this jump in 't' list */
500 if (hasjumps(e)) {
501 int final; /* position after whole expression */
502 int p_f = NO_JUMP; /* position of an eventual LOAD false */
503 int p_t = NO_JUMP; /* position of an eventual LOAD true */
504 if (need_value(fs, e->t) || need_value(fs, e->f)) {
505 int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
506 p_f = code_label(fs, reg, 0, 1);
507 p_t = code_label(fs, reg, 1, 0);
508 luaK_patchtohere(fs, fj);
509 }
510 final = luaK_getlabel(fs);
511 patchlistaux(fs, e->f, final, reg, p_f);
512 patchlistaux(fs, e->t, final, reg, p_t);
513 }
514 e->f = e->t = NO_JUMP;
515 e->u.info = reg;
516 e->k = VNONRELOC;
517 }
518
519
520 void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
521 luaK_dischargevars(fs, e);
522 freeexp(fs, e);
523 luaK_reserveregs(fs, 1);
524 exp2reg(fs, e, fs->freereg - 1);
525 }
526
527
528 int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
529 luaK_dischargevars(fs, e);
530 if (e->k == VNONRELOC) {
531 if (!hasjumps(e)) return e->u.info; /* exp is already in a register */
532 if (e->u.info >= fs->nactvar) { /* reg. is not a local? */
533 exp2reg(fs, e, e->u.info); /* put value on it */
534 return e->u.info;
535 }
536 }
537 luaK_exp2nextreg(fs, e); /* default */
538 return e->u.info;
539 }
540
541
542 void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
543 if (e->k != VUPVAL || hasjumps(e))
544 luaK_exp2anyreg(fs, e);
545 }
546
547
548 void luaK_exp2val (FuncState *fs, expdesc *e) {
549 if (hasjumps(e))
550 luaK_exp2anyreg(fs, e);
551 else
552 luaK_dischargevars(fs, e);
553 }
554
555
556 int luaK_exp2RK (FuncState *fs, expdesc *e) {
557 luaK_exp2val(fs, e);
558 switch (e->k) {
559 case VTRUE:
560 case VFALSE:
561 case VNIL: {
562 if (fs->nk <= MAXINDEXRK) { /* constant fits in RK operand? */
563 e->u.info = (e->k == VNIL) ? nilK(fs) : boolK(fs, (e->k == VTRUE));
564 e->k = VK;
565 return RKASK(e->u.info);
566 }
567 else break;
568 }
569 case VKINT: {
570 e->u.info = luaK_intK(fs, e->u.ival);
571 e->k = VK;
572 goto vk;
573 }
574 case VKFLT: {
575 e->u.info = luaK_numberK(fs, e->u.nval);
576 e->k = VK;
577 }
578 /* FALLTHROUGH */
579 case VK: {
580 vk:
581 if (e->u.info <= MAXINDEXRK) /* constant fits in 'argC'? */
582 return RKASK(e->u.info);
583 else break;
584 }
585 default: break;
586 }
587 /* not a constant in the right range: put it in a register */
588 return luaK_exp2anyreg(fs, e);
589 }
590
591
592 void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
593 switch (var->k) {
594 case VLOCAL: {
595 freeexp(fs, ex);
596 exp2reg(fs, ex, var->u.info);
597 return;
598 }
599 case VUPVAL: {
600 int e = luaK_exp2anyreg(fs, ex);
601 luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
602 break;
603 }
604 case VINDEXED: {
605 OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;
606 int e = luaK_exp2RK(fs, ex);
607 luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e);
608 break;
609 }
610 default: {
611 lua_assert(0); /* invalid var kind to store */
612 break;
613 }
614 }
615 freeexp(fs, ex);
616 }
617
618
619 void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
620 int ereg;
621 luaK_exp2anyreg(fs, e);
622 ereg = e->u.info; /* register where 'e' was placed */
623 freeexp(fs, e);
624 e->u.info = fs->freereg; /* base register for op_self */
625 e->k = VNONRELOC;
626 luaK_reserveregs(fs, 2); /* function and 'self' produced by op_self */
627 luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));
628 freeexp(fs, key);
629 }
630
631
632 static void invertjump (FuncState *fs, expdesc *e) {
633 Instruction *pc = getjumpcontrol(fs, e->u.info);
634 lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
635 GET_OPCODE(*pc) != OP_TEST);
636 SETARG_A(*pc, !(GETARG_A(*pc)));
637 }
638
639
640 static int jumponcond (FuncState *fs, expdesc *e, int cond) {
641 if (e->k == VRELOCABLE) {
642 Instruction ie = getcode(fs, e);
643 if (GET_OPCODE(ie) == OP_NOT) {
644 fs->pc--; /* remove previous OP_NOT */
645 return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
646 }
647 /* else go through */
648 }
649 discharge2anyreg(fs, e);
650 freeexp(fs, e);
651 return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond);
652 }
653
654
655 void luaK_goiftrue (FuncState *fs, expdesc *e) {
656 int pc; /* pc of last jump */
657 luaK_dischargevars(fs, e);
658 switch (e->k) {
659 case VJMP: {
660 invertjump(fs, e);
661 pc = e->u.info;
662 break;
663 }
664 case VK: case VKFLT: case VKINT: case VTRUE: {
665 pc = NO_JUMP; /* always true; do nothing */
666 break;
667 }
668 default: {
669 pc = jumponcond(fs, e, 0);
670 break;
671 }
672 }
673 luaK_concat(fs, &e->f, pc); /* insert last jump in 'f' list */
674 luaK_patchtohere(fs, e->t);
675 e->t = NO_JUMP;
676 }
677
678
679 void luaK_goiffalse (FuncState *fs, expdesc *e) {
680 int pc; /* pc of last jump */
681 luaK_dischargevars(fs, e);
682 switch (e->k) {
683 case VJMP: {
684 pc = e->u.info;
685 break;
686 }
687 case VNIL: case VFALSE: {
688 pc = NO_JUMP; /* always false; do nothing */
689 break;
690 }
691 default: {
692 pc = jumponcond(fs, e, 1);
693 break;
694 }
695 }
696 luaK_concat(fs, &e->t, pc); /* insert last jump in 't' list */
697 luaK_patchtohere(fs, e->f);
698 e->f = NO_JUMP;
699 }
700
701
702 static void codenot (FuncState *fs, expdesc *e) {
703 luaK_dischargevars(fs, e);
704 switch (e->k) {
705 case VNIL: case VFALSE: {
706 e->k = VTRUE;
707 break;
708 }
709 case VK: case VKFLT: case VKINT: case VTRUE: {
710 e->k = VFALSE;
711 break;
712 }
713 case VJMP: {
714 invertjump(fs, e);
715 break;
716 }
717 case VRELOCABLE:
718 case VNONRELOC: {
719 discharge2anyreg(fs, e);
720 freeexp(fs, e);
721 e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0);
722 e->k = VRELOCABLE;
723 break;
724 }
725 default: {
726 lua_assert(0); /* cannot happen */
727 break;
728 }
729 }
730 /* interchange true and false lists */
731 { int temp = e->f; e->f = e->t; e->t = temp; }
732 removevalues(fs, e->f);
733 removevalues(fs, e->t);
734 }
735
736
737 void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
738 lua_assert(!hasjumps(t));
|
(1) Event offset: |
The address of "t->u.ind.t" is 10 bytes off of "t". |
|
(2) Event offset: |
The address of "t->u.info" is 8 bytes off of "t". |
|
(3) Event overlapping_assignment: |
Assigning "t->u.info" to "t->u.ind.t", which have overlapping memory locations. |
739 t->u.ind.t = t->u.info;
740 t->u.ind.idx = luaK_exp2RK(fs, k);
741 t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL
742 : check_exp(vkisinreg(t->k), VLOCAL);
743 t->k = VINDEXED;
744 }
745
746
747 /*
748 ** return false if folding can raise an error
749 */
750 static int validop (int op, TValue *v1, TValue *v2) {
751 switch (op) {
752 case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
753 case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT: { /* conversion errors */
754 lua_Integer i;
755 return (tointeger(v1, &i) && tointeger(v2, &i));
756 }
757 case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD: /* division by 0 */
758 return (nvalue(v2) != 0);
759 default: return 1; /* everything else is valid */
760 }
761 }
762
763
764 /*
765 ** Try to "constant-fold" an operation; return 1 iff successful
766 */
767 static int constfolding (FuncState *fs, int op, expdesc *e1, expdesc *e2) {
768 TValue v1, v2, res;
769 if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2))
770 return 0; /* non-numeric operands or not safe to fold */
771 luaO_arith(fs->ls->L, op, &v1, &v2, &res); /* does operation */
772 if (ttisinteger(&res)) {
773 e1->k = VKINT;
774 e1->u.ival = ivalue(&res);
775 }
776 else { /* folds neither NaN nor 0.0 (to avoid collapsing with -0.0) */
777 lua_Number n = fltvalue(&res);
778 if (luai_numisnan(n) || n == 0)
779 return 0;
780 e1->k = VKFLT;
781 e1->u.nval = n;
782 }
783 return 1;
784 }
785
786
787 /*
788 ** Code for binary and unary expressions that "produce values"
789 ** (arithmetic operations, bitwise operations, concat, length). First
790 ** try to do constant folding (only for numeric [arithmetic and
791 ** bitwise] operations, which is what 'lua_arith' accepts).
792 ** Expression to produce final result will be encoded in 'e1'.
793 */
794 static void codeexpval (FuncState *fs, OpCode op,
795 expdesc *e1, expdesc *e2, int line) {
796 lua_assert(op >= OP_ADD);
797 if (op <= OP_BNOT && constfolding(fs, (op - OP_ADD) + LUA_OPADD, e1, e2))
798 return; /* result has been folded */
799 else {
800 int o1, o2;
801 /* move operands to registers (if needed) */
802 if (op == OP_UNM || op == OP_BNOT || op == OP_LEN) { /* unary op? */
803 o2 = 0; /* no second expression */
804 o1 = luaK_exp2anyreg(fs, e1); /* cannot operate on constants */
805 }
806 else { /* regular case (binary operators) */
807 o2 = luaK_exp2RK(fs, e2); /* both operands are "RK" */
808 o1 = luaK_exp2RK(fs, e1);
809 }
810 if (o1 > o2) { /* free registers in proper order */
811 freeexp(fs, e1);
812 freeexp(fs, e2);
813 }
814 else {
815 freeexp(fs, e2);
816 freeexp(fs, e1);
817 }
818 e1->u.info = luaK_codeABC(fs, op, 0, o1, o2); /* generate opcode */
819 e1->k = VRELOCABLE; /* all those operations are relocatable */
820 luaK_fixline(fs, line);
821 }
822 }
823
824
825 static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
826 expdesc *e2) {
827 int o1 = luaK_exp2RK(fs, e1);
828 int o2 = luaK_exp2RK(fs, e2);
829 freeexp(fs, e2);
830 freeexp(fs, e1);
831 if (cond == 0 && op != OP_EQ) {
832 int temp; /* exchange args to replace by '<' or '<=' */
833 temp = o1; o1 = o2; o2 = temp; /* o1 <==> o2 */
834 cond = 1;
835 }
836 e1->u.info = condjump(fs, op, cond, o1, o2);
837 e1->k = VJMP;
838 }
839
840
841 void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) {
842 expdesc e2;
843 e2.t = e2.f = NO_JUMP; e2.k = VKINT; e2.u.ival = 0;
844 switch (op) {
845 case OPR_MINUS: case OPR_BNOT: case OPR_LEN: {
846 codeexpval(fs, cast(OpCode, (op - OPR_MINUS) + OP_UNM), e, &e2, line);
847 break;
848 }
849 case OPR_NOT: codenot(fs, e); break;
850 default: lua_assert(0);
851 }
852 }
853
854
855 void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
856 switch (op) {
857 case OPR_AND: {
858 luaK_goiftrue(fs, v);
859 break;
860 }
861 case OPR_OR: {
862 luaK_goiffalse(fs, v);
863 break;
864 }
865 case OPR_CONCAT: {
866 luaK_exp2nextreg(fs, v); /* operand must be on the 'stack' */
867 break;
868 }
869 case OPR_ADD: case OPR_SUB:
870 case OPR_MUL: case OPR_DIV: case OPR_IDIV:
871 case OPR_MOD: case OPR_POW:
872 case OPR_BAND: case OPR_BOR: case OPR_BXOR:
873 case OPR_SHL: case OPR_SHR: {
874 if (!tonumeral(v, NULL)) luaK_exp2RK(fs, v);
875 break;
876 }
877 default: {
878 luaK_exp2RK(fs, v);
879 break;
880 }
881 }
882 }
883
884
885 void luaK_posfix (FuncState *fs, BinOpr op,
886 expdesc *e1, expdesc *e2, int line) {
887 switch (op) {
888 case OPR_AND: {
889 lua_assert(e1->t == NO_JUMP); /* list must be closed */
890 luaK_dischargevars(fs, e2);
891 luaK_concat(fs, &e2->f, e1->f);
892 *e1 = *e2;
893 break;
894 }
895 case OPR_OR: {
896 lua_assert(e1->f == NO_JUMP); /* list must be closed */
897 luaK_dischargevars(fs, e2);
898 luaK_concat(fs, &e2->t, e1->t);
899 *e1 = *e2;
900 break;
901 }
902 case OPR_CONCAT: {
903 luaK_exp2val(fs, e2);
904 if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
905 lua_assert(e1->u.info == GETARG_B(getcode(fs, e2))-1);
906 freeexp(fs, e1);
907 SETARG_B(getcode(fs, e2), e1->u.info);
908 e1->k = VRELOCABLE; e1->u.info = e2->u.info;
909 }
910 else {
911 luaK_exp2nextreg(fs, e2); /* operand must be on the 'stack' */
912 codeexpval(fs, OP_CONCAT, e1, e2, line);
913 }
914 break;
915 }
916 case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
917 case OPR_IDIV: case OPR_MOD: case OPR_POW:
918 case OPR_BAND: case OPR_BOR: case OPR_BXOR:
919 case OPR_SHL: case OPR_SHR: {
920 codeexpval(fs, cast(OpCode, (op - OPR_ADD) + OP_ADD), e1, e2, line);
921 break;
922 }
923 case OPR_EQ: case OPR_LT: case OPR_LE: {
924 codecomp(fs, cast(OpCode, (op - OPR_EQ) + OP_EQ), 1, e1, e2);
925 break;
926 }
927 case OPR_NE: case OPR_GT: case OPR_GE: {
928 codecomp(fs, cast(OpCode, (op - OPR_NE) + OP_EQ), 0, e1, e2);
929 break;
930 }
931 default: lua_assert(0);
932 }
933 }
934
935
936 void luaK_fixline (FuncState *fs, int line) {
937 fs->f->lineinfo[fs->pc - 1] = line;
938 }
939
940
941 void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
942 int c = (nelems - 1)/LFIELDS_PER_FLUSH + 1;
943 int b = (tostore == LUA_MULTRET) ? 0 : tostore;
944 lua_assert(tostore != 0);
945 if (c <= MAXARG_C)
946 luaK_codeABC(fs, OP_SETLIST, base, b, c);
947 else if (c <= MAXARG_Ax) {
948 luaK_codeABC(fs, OP_SETLIST, base, b, 0);
949 codeextraarg(fs, c);
950 }
951 else
952 luaX_syntaxerror(fs->ls, "constructor too long");
953 fs->freereg = base + 1; /* free registers with list values */
954 }
955
956