1 /* $NetBSD: lcode.c,v 1.14 2023/06/08 21:12:08 nikita Exp $ */
2
3 /*
4 ** Id: lcode.c
5 ** Code generator for Lua
6 ** See Copyright Notice in lua.h
7 */
8
9 #define lcode_c
10 #define LUA_CORE
11
12 #include "lprefix.h"
13
14
15 #ifndef _KERNEL
16 #include <float.h>
17 #include <limits.h>
18 #include <math.h>
19 #include <stdlib.h>
20 #endif /* _KERNEL */
21
22 #include "lua.h"
23
24 #include "lcode.h"
25 #include "ldebug.h"
26 #include "ldo.h"
27 #include "lgc.h"
28 #include "llex.h"
29 #include "lmem.h"
30 #include "lobject.h"
31 #include "lopcodes.h"
32 #include "lparser.h"
33 #include "lstring.h"
34 #include "ltable.h"
35 #include "lvm.h"
36
37
38 /* Maximum number of registers in a Lua function (must fit in 8 bits) */
39 #define MAXREGS 255
40
41
42 #define hasjumps(e) ((e)->t != (e)->f)
43
44
45 static int codesJ (FuncState *fs, OpCode o, int sj, int k);
46
47
48
49 /* semantic error */
luaK_semerror(LexState * ls,const char * msg)50 l_noret luaK_semerror (LexState *ls, const char *msg) {
51 ls->t.token = 0; /* remove "near <token>" from final message */
52 luaX_syntaxerror(ls, msg);
53 }
54
55
56 /*
57 ** If expression is a numeric constant, fills 'v' with its value
58 ** and returns 1. Otherwise, returns 0.
59 */
tonumeral(const expdesc * e,TValue * v)60 static int tonumeral (const expdesc *e, TValue *v) {
61 if (hasjumps(e))
62 return 0; /* not a numeral */
63 switch (e->k) {
64 case VKINT:
65 if (v) setivalue(v, e->u.ival);
66 return 1;
67 #ifndef _KERNEL
68 case VKFLT:
69 if (v) setfltvalue(v, e->u.nval);
70 return 1;
71 #endif /* _KERNEL */
72 default: return 0;
73 }
74 }
75
76
77 /*
78 ** Get the constant value from a constant expression
79 */
const2val(FuncState * fs,const expdesc * e)80 static TValue *const2val (FuncState *fs, const expdesc *e) {
81 lua_assert(e->k == VCONST);
82 return &fs->ls->dyd->actvar.arr[e->u.info].k;
83 }
84
85
86 /*
87 ** If expression is a constant, fills 'v' with its value
88 ** and returns 1. Otherwise, returns 0.
89 */
luaK_exp2const(FuncState * fs,const expdesc * e,TValue * v)90 int luaK_exp2const (FuncState *fs, const expdesc *e, TValue *v) {
91 if (hasjumps(e))
92 return 0; /* not a constant */
93 switch (e->k) {
94 case VFALSE:
95 setbfvalue(v);
96 return 1;
97 case VTRUE:
98 setbtvalue(v);
99 return 1;
100 case VNIL:
101 setnilvalue(v);
102 return 1;
103 case VKSTR: {
104 setsvalue(fs->ls->L, v, e->u.strval);
105 return 1;
106 }
107 case VCONST: {
108 setobj(fs->ls->L, v, const2val(fs, e));
109 return 1;
110 }
111 default: return tonumeral(e, v);
112 }
113 }
114
115
116 /*
117 ** Return the previous instruction of the current code. If there
118 ** may be a jump target between the current instruction and the
119 ** previous one, return an invalid instruction (to avoid wrong
120 ** optimizations).
121 */
previousinstruction(FuncState * fs)122 static Instruction *previousinstruction (FuncState *fs) {
123 static const Instruction invalidinstruction = ~(Instruction)0;
124 if (fs->pc > fs->lasttarget)
125 return &fs->f->code[fs->pc - 1]; /* previous instruction */
126 else
127 return cast(Instruction*, &invalidinstruction);
128 }
129
130
131 /*
132 ** Create a OP_LOADNIL instruction, but try to optimize: if the previous
133 ** instruction is also OP_LOADNIL and ranges are compatible, adjust
134 ** range of previous instruction instead of emitting a new one. (For
135 ** instance, 'local a; local b' will generate a single opcode.)
136 */
luaK_nil(FuncState * fs,int from,int n)137 void luaK_nil (FuncState *fs, int from, int n) {
138 int l = from + n - 1; /* last register to set nil */
139 Instruction *previous = previousinstruction(fs);
140 if (GET_OPCODE(*previous) == OP_LOADNIL) { /* previous is LOADNIL? */
141 int pfrom = GETARG_A(*previous); /* get previous range */
142 int pl = pfrom + GETARG_B(*previous);
143 if ((pfrom <= from && from <= pl + 1) ||
144 (from <= pfrom && pfrom <= l + 1)) { /* can connect both? */
145 if (pfrom < from) from = pfrom; /* from = min(from, pfrom) */
146 if (pl > l) l = pl; /* l = max(l, pl) */
147 SETARG_A(*previous, from);
148 SETARG_B(*previous, l - from);
149 return;
150 } /* else go through */
151 }
152 luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0); /* else no optimization */
153 }
154
155
156 /*
157 ** Gets the destination address of a jump instruction. Used to traverse
158 ** a list of jumps.
159 */
getjump(FuncState * fs,int pc)160 static int getjump (FuncState *fs, int pc) {
161 int offset = GETARG_sJ(fs->f->code[pc]);
162 if (offset == NO_JUMP) /* point to itself represents end of list */
163 return NO_JUMP; /* end of list */
164 else
165 return (pc+1)+offset; /* turn offset into absolute position */
166 }
167
168
169 /*
170 ** Fix jump instruction at position 'pc' to jump to 'dest'.
171 ** (Jump addresses are relative in Lua)
172 */
fixjump(FuncState * fs,int pc,int dest)173 static void fixjump (FuncState *fs, int pc, int dest) {
174 Instruction *jmp = &fs->f->code[pc];
175 int offset = dest - (pc + 1);
176 lua_assert(dest != NO_JUMP);
177 if (!(-OFFSET_sJ <= offset && offset <= MAXARG_sJ - OFFSET_sJ))
178 luaX_syntaxerror(fs->ls, "control structure too long");
179 lua_assert(GET_OPCODE(*jmp) == OP_JMP);
180 SETARG_sJ(*jmp, offset);
181 }
182
183
184 /*
185 ** Concatenate jump-list 'l2' into jump-list 'l1'
186 */
luaK_concat(FuncState * fs,int * l1,int l2)187 void luaK_concat (FuncState *fs, int *l1, int l2) {
188 if (l2 == NO_JUMP) return; /* nothing to concatenate? */
189 else if (*l1 == NO_JUMP) /* no original list? */
190 *l1 = l2; /* 'l1' points to 'l2' */
191 else {
192 int list = *l1;
193 int next;
194 while ((next = getjump(fs, list)) != NO_JUMP) /* find last element */
195 list = next;
196 fixjump(fs, list, l2); /* last element links to 'l2' */
197 }
198 }
199
200
201 /*
202 ** Create a jump instruction and return its position, so its destination
203 ** can be fixed later (with 'fixjump').
204 */
luaK_jump(FuncState * fs)205 int luaK_jump (FuncState *fs) {
206 return codesJ(fs, OP_JMP, NO_JUMP, 0);
207 }
208
209
210 /*
211 ** Code a 'return' instruction
212 */
luaK_ret(FuncState * fs,int first,int nret)213 void luaK_ret (FuncState *fs, int first, int nret) {
214 OpCode op;
215 switch (nret) {
216 case 0: op = OP_RETURN0; break;
217 case 1: op = OP_RETURN1; break;
218 default: op = OP_RETURN; break;
219 }
220 luaK_codeABC(fs, op, first, nret + 1, 0);
221 }
222
223
224 /*
225 ** Code a "conditional jump", that is, a test or comparison opcode
226 ** followed by a jump. Return jump position.
227 */
condjump(FuncState * fs,OpCode op,int A,int B,int C,int k)228 static int condjump (FuncState *fs, OpCode op, int A, int B, int C, int k) {
229 luaK_codeABCk(fs, op, A, B, C, k);
230 return luaK_jump(fs);
231 }
232
233
234 /*
235 ** returns current 'pc' and marks it as a jump target (to avoid wrong
236 ** optimizations with consecutive instructions not in the same basic block).
237 */
luaK_getlabel(FuncState * fs)238 int luaK_getlabel (FuncState *fs) {
239 fs->lasttarget = fs->pc;
240 return fs->pc;
241 }
242
243
244 /*
245 ** Returns the position of the instruction "controlling" a given
246 ** jump (that is, its condition), or the jump itself if it is
247 ** unconditional.
248 */
getjumpcontrol(FuncState * fs,int pc)249 static Instruction *getjumpcontrol (FuncState *fs, int pc) {
250 Instruction *pi = &fs->f->code[pc];
251 if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
252 return pi-1;
253 else
254 return pi;
255 }
256
257
258 /*
259 ** Patch destination register for a TESTSET instruction.
260 ** If instruction in position 'node' is not a TESTSET, return 0 ("fails").
261 ** Otherwise, if 'reg' is not 'NO_REG', set it as the destination
262 ** register. Otherwise, change instruction to a simple 'TEST' (produces
263 ** no register value)
264 */
patchtestreg(FuncState * fs,int node,int reg)265 static int patchtestreg (FuncState *fs, int node, int reg) {
266 Instruction *i = getjumpcontrol(fs, node);
267 if (GET_OPCODE(*i) != OP_TESTSET)
268 return 0; /* cannot patch other instructions */
269 if (reg != NO_REG && reg != GETARG_B(*i))
270 SETARG_A(*i, reg);
271 else {
272 /* no register to put value or register already has the value;
273 change instruction to simple test */
274 *i = CREATE_ABCk(OP_TEST, GETARG_B(*i), 0, 0, GETARG_k(*i));
275 }
276 return 1;
277 }
278
279
280 /*
281 ** Traverse a list of tests ensuring no one produces a value
282 */
removevalues(FuncState * fs,int list)283 static void removevalues (FuncState *fs, int list) {
284 for (; list != NO_JUMP; list = getjump(fs, list))
285 patchtestreg(fs, list, NO_REG);
286 }
287
288
289 /*
290 ** Traverse a list of tests, patching their destination address and
291 ** registers: tests producing values jump to 'vtarget' (and put their
292 ** values in 'reg'), other tests jump to 'dtarget'.
293 */
patchlistaux(FuncState * fs,int list,int vtarget,int reg,int dtarget)294 static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
295 int dtarget) {
296 while (list != NO_JUMP) {
297 int next = getjump(fs, list);
298 if (patchtestreg(fs, list, reg))
299 fixjump(fs, list, vtarget);
300 else
301 fixjump(fs, list, dtarget); /* jump to default target */
302 list = next;
303 }
304 }
305
306
307 /*
308 ** Path all jumps in 'list' to jump to 'target'.
309 ** (The assert means that we cannot fix a jump to a forward address
310 ** because we only know addresses once code is generated.)
311 */
luaK_patchlist(FuncState * fs,int list,int target)312 void luaK_patchlist (FuncState *fs, int list, int target) {
313 lua_assert(target <= fs->pc);
314 patchlistaux(fs, list, target, NO_REG, target);
315 }
316
317
luaK_patchtohere(FuncState * fs,int list)318 void luaK_patchtohere (FuncState *fs, int list) {
319 int hr = luaK_getlabel(fs); /* mark "here" as a jump target */
320 luaK_patchlist(fs, list, hr);
321 }
322
323
324 /* limit for difference between lines in relative line info. */
325 #define LIMLINEDIFF 0x80
326
327
328 /*
329 ** Save line info for a new instruction. If difference from last line
330 ** does not fit in a byte, of after that many instructions, save a new
331 ** absolute line info; (in that case, the special value 'ABSLINEINFO'
332 ** in 'lineinfo' signals the existence of this absolute information.)
333 ** Otherwise, store the difference from last line in 'lineinfo'.
334 */
savelineinfo(FuncState * fs,Proto * f,int line)335 static void savelineinfo (FuncState *fs, Proto *f, int line) {
336 int linedif = line - fs->previousline;
337 int pc = fs->pc - 1; /* last instruction coded */
338 if (abs(linedif) >= LIMLINEDIFF || fs->iwthabs++ >= MAXIWTHABS) {
339 luaM_growvector(fs->ls->L, f->abslineinfo, fs->nabslineinfo,
340 f->sizeabslineinfo, AbsLineInfo, MAX_INT, "lines");
341 f->abslineinfo[fs->nabslineinfo].pc = pc;
342 f->abslineinfo[fs->nabslineinfo++].line = line;
343 linedif = ABSLINEINFO; /* signal that there is absolute information */
344 fs->iwthabs = 1; /* restart counter */
345 }
346 luaM_growvector(fs->ls->L, f->lineinfo, pc, f->sizelineinfo, ls_byte,
347 MAX_INT, "opcodes");
348 f->lineinfo[pc] = linedif;
349 fs->previousline = line; /* last line saved */
350 }
351
352
353 /*
354 ** Remove line information from the last instruction.
355 ** If line information for that instruction is absolute, set 'iwthabs'
356 ** above its max to force the new (replacing) instruction to have
357 ** absolute line info, too.
358 */
removelastlineinfo(FuncState * fs)359 static void removelastlineinfo (FuncState *fs) {
360 Proto *f = fs->f;
361 int pc = fs->pc - 1; /* last instruction coded */
362 if (f->lineinfo[pc] != ABSLINEINFO) { /* relative line info? */
363 fs->previousline -= f->lineinfo[pc]; /* correct last line saved */
364 fs->iwthabs--; /* undo previous increment */
365 }
366 else { /* absolute line information */
367 lua_assert(f->abslineinfo[fs->nabslineinfo - 1].pc == pc);
368 fs->nabslineinfo--; /* remove it */
369 fs->iwthabs = MAXIWTHABS + 1; /* force next line info to be absolute */
370 }
371 }
372
373
374 /*
375 ** Remove the last instruction created, correcting line information
376 ** accordingly.
377 */
removelastinstruction(FuncState * fs)378 static void removelastinstruction (FuncState *fs) {
379 removelastlineinfo(fs);
380 fs->pc--;
381 }
382
383
384 /*
385 ** Emit instruction 'i', checking for array sizes and saving also its
386 ** line information. Return 'i' position.
387 */
luaK_code(FuncState * fs,Instruction i)388 int luaK_code (FuncState *fs, Instruction i) {
389 Proto *f = fs->f;
390 /* put new instruction in code array */
391 luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,
392 MAX_INT, "opcodes");
393 f->code[fs->pc++] = i;
394 savelineinfo(fs, f, fs->ls->lastline);
395 return fs->pc - 1; /* index of new instruction */
396 }
397
398
399 /*
400 ** Format and emit an 'iABC' instruction. (Assertions check consistency
401 ** of parameters versus opcode.)
402 */
luaK_codeABCk(FuncState * fs,OpCode o,int a,int b,int c,int k)403 int luaK_codeABCk (FuncState *fs, OpCode o, int a, int b, int c, int k) {
404 lua_assert(getOpMode(o) == iABC);
405 lua_assert(a <= MAXARG_A && b <= MAXARG_B &&
406 c <= MAXARG_C && (k & ~1) == 0);
407 return luaK_code(fs, CREATE_ABCk(o, a, b, c, k));
408 }
409
410
411 /*
412 ** Format and emit an 'iABx' instruction.
413 */
luaK_codeABx(FuncState * fs,OpCode o,int a,unsigned int bc)414 int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
415 lua_assert(getOpMode(o) == iABx);
416 lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
417 return luaK_code(fs, CREATE_ABx(o, a, bc));
418 }
419
420
421 /*
422 ** Format and emit an 'iAsBx' instruction.
423 */
luaK_codeAsBx(FuncState * fs,OpCode o,int a,int bc)424 int luaK_codeAsBx (FuncState *fs, OpCode o, int a, int bc) {
425 unsigned int b = bc + OFFSET_sBx;
426 lua_assert(getOpMode(o) == iAsBx);
427 lua_assert(a <= MAXARG_A && b <= MAXARG_Bx);
428 return luaK_code(fs, CREATE_ABx(o, a, b));
429 }
430
431
432 /*
433 ** Format and emit an 'isJ' instruction.
434 */
codesJ(FuncState * fs,OpCode o,int sj,int k)435 static int codesJ (FuncState *fs, OpCode o, int sj, int k) {
436 unsigned int j = sj + OFFSET_sJ;
437 lua_assert(getOpMode(o) == isJ);
438 lua_assert(j <= MAXARG_sJ && (k & ~1) == 0);
439 return luaK_code(fs, CREATE_sJ(o, j, k));
440 }
441
442
443 /*
444 ** Emit an "extra argument" instruction (format 'iAx')
445 */
codeextraarg(FuncState * fs,int a)446 static int codeextraarg (FuncState *fs, int a) {
447 lua_assert(a <= MAXARG_Ax);
448 return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a));
449 }
450
451
452 /*
453 ** Emit a "load constant" instruction, using either 'OP_LOADK'
454 ** (if constant index 'k' fits in 18 bits) or an 'OP_LOADKX'
455 ** instruction with "extra argument".
456 */
luaK_codek(FuncState * fs,int reg,int k)457 static int luaK_codek (FuncState *fs, int reg, int k) {
458 if (k <= MAXARG_Bx)
459 return luaK_codeABx(fs, OP_LOADK, reg, k);
460 else {
461 int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);
462 codeextraarg(fs, k);
463 return p;
464 }
465 }
466
467
468 /*
469 ** Check register-stack level, keeping track of its maximum size
470 ** in field 'maxstacksize'
471 */
luaK_checkstack(FuncState * fs,int n)472 void luaK_checkstack (FuncState *fs, int n) {
473 int newstack = fs->freereg + n;
474 if (newstack > fs->f->maxstacksize) {
475 if (newstack >= MAXREGS)
476 luaX_syntaxerror(fs->ls,
477 "function or expression needs too many registers");
478 fs->f->maxstacksize = cast_byte(newstack);
479 }
480 }
481
482
483 /*
484 ** Reserve 'n' registers in register stack
485 */
luaK_reserveregs(FuncState * fs,int n)486 void luaK_reserveregs (FuncState *fs, int n) {
487 luaK_checkstack(fs, n);
488 fs->freereg += n;
489 }
490
491
492 /*
493 ** Free register 'reg', if it is neither a constant index nor
494 ** a local variable.
495 )
496 */
freereg(FuncState * fs,int reg)497 static void freereg (FuncState *fs, int reg) {
498 if (reg >= luaY_nvarstack(fs)) {
499 fs->freereg--;
500 lua_assert(reg == fs->freereg);
501 }
502 }
503
504
505 /*
506 ** Free two registers in proper order
507 */
freeregs(FuncState * fs,int r1,int r2)508 static void freeregs (FuncState *fs, int r1, int r2) {
509 if (r1 > r2) {
510 freereg(fs, r1);
511 freereg(fs, r2);
512 }
513 else {
514 freereg(fs, r2);
515 freereg(fs, r1);
516 }
517 }
518
519
520 /*
521 ** Free register used by expression 'e' (if any)
522 */
freeexp(FuncState * fs,expdesc * e)523 static void freeexp (FuncState *fs, expdesc *e) {
524 if (e->k == VNONRELOC)
525 freereg(fs, e->u.info);
526 }
527
528
529 /*
530 ** Free registers used by expressions 'e1' and 'e2' (if any) in proper
531 ** order.
532 */
freeexps(FuncState * fs,expdesc * e1,expdesc * e2)533 static void freeexps (FuncState *fs, expdesc *e1, expdesc *e2) {
534 int r1 = (e1->k == VNONRELOC) ? e1->u.info : -1;
535 int r2 = (e2->k == VNONRELOC) ? e2->u.info : -1;
536 freeregs(fs, r1, r2);
537 }
538
539
540 /*
541 ** Add constant 'v' to prototype's list of constants (field 'k').
542 ** Use scanner's table to cache position of constants in constant list
543 ** and try to reuse constants. Because some values should not be used
544 ** as keys (nil cannot be a key, integer keys can collapse with float
545 ** keys), the caller must provide a useful 'key' for indexing the cache.
546 ** Note that all functions share the same table, so entering or exiting
547 ** a function can make some indices wrong.
548 */
addk(FuncState * fs,TValue * key,TValue * v)549 static int addk (FuncState *fs, TValue *key, TValue *v) {
550 TValue val;
551 lua_State *L = fs->ls->L;
552 Proto *f = fs->f;
553 const TValue *idx = luaH_get(fs->ls->h, key); /* query scanner table */
554 int k, oldsize;
555 if (ttisinteger(idx)) { /* is there an index there? */
556 k = cast_int(ivalue(idx));
557 /* correct value? (warning: must distinguish floats from integers!) */
558 if (k < fs->nk && ttypetag(&f->k[k]) == ttypetag(v) &&
559 luaV_rawequalobj(&f->k[k], v))
560 return k; /* reuse index */
561 }
562 /* constant not found; create a new entry */
563 oldsize = f->sizek;
564 k = fs->nk;
565 /* numerical value does not need GC barrier;
566 table has no metatable, so it does not need to invalidate cache */
567 setivalue(&val, k);
568 luaH_finishset(L, fs->ls->h, key, idx, &val);
569 luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");
570 while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
571 setobj(L, &f->k[k], v);
572 fs->nk++;
573 luaC_barrier(L, f, v);
574 return k;
575 }
576
577
578 /*
579 ** Add a string to list of constants and return its index.
580 */
stringK(FuncState * fs,TString * s)581 static int stringK (FuncState *fs, TString *s) {
582 TValue o;
583 setsvalue(fs->ls->L, &o, s);
584 return addk(fs, &o, &o); /* use string itself as key */
585 }
586
587
588 /*
589 ** Add an integer to list of constants and return its index.
590 */
luaK_intK(FuncState * fs,lua_Integer n)591 static int luaK_intK (FuncState *fs, lua_Integer n) {
592 TValue o;
593 setivalue(&o, n);
594 return addk(fs, &o, &o); /* use integer itself as key */
595 }
596
597
598 #ifndef _KERNEL
599 /*
600 ** Add a float to list of constants and return its index. Floats
601 ** with integral values need a different key, to avoid collision
602 ** with actual integers. To that, we add to the number its smaller
603 ** power-of-two fraction that is still significant in its scale.
604 ** For doubles, that would be 1/2^52.
605 ** (This method is not bulletproof: there may be another float
606 ** with that value, and for floats larger than 2^53 the result is
607 ** still an integer. At worst, this only wastes an entry with
608 ** a duplicate.)
609 */
luaK_numberK(FuncState * fs,lua_Number r)610 static int luaK_numberK (FuncState *fs, lua_Number r) {
611 TValue o;
612 lua_Integer ik;
613 setfltvalue(&o, r);
614 if (!luaV_flttointeger(r, &ik, F2Ieq)) /* not an integral value? */
615 return addk(fs, &o, &o); /* use number itself as key */
616 else { /* must build an alternative key */
617 const int nbm = l_floatatt(MANT_DIG);
618 const lua_Number q = l_mathop(ldexp)(l_mathop(1.0), -nbm + 1);
619 const lua_Number k = (ik == 0) ? q : r + r*q; /* new key */
620 TValue kv;
621 setfltvalue(&kv, k);
622 /* result is not an integral value, unless value is too large */
623 lua_assert(!luaV_flttointeger(k, &ik, F2Ieq) ||
624 l_mathop(fabs)(r) >= l_mathop(1e6));
625 return addk(fs, &kv, &o);
626 }
627 }
628 #endif /* _KERNEL */
629
630
631 /*
632 ** Add a false to list of constants and return its index.
633 */
boolF(FuncState * fs)634 static int boolF (FuncState *fs) {
635 TValue o;
636 setbfvalue(&o);
637 return addk(fs, &o, &o); /* use boolean itself as key */
638 }
639
640
641 /*
642 ** Add a true to list of constants and return its index.
643 */
boolT(FuncState * fs)644 static int boolT (FuncState *fs) {
645 TValue o;
646 setbtvalue(&o);
647 return addk(fs, &o, &o); /* use boolean itself as key */
648 }
649
650
651 /*
652 ** Add nil to list of constants and return its index.
653 */
nilK(FuncState * fs)654 static int nilK (FuncState *fs) {
655 TValue k, v;
656 setnilvalue(&v);
657 /* cannot use nil as key; instead use table itself to represent nil */
658 sethvalue(fs->ls->L, &k, fs->ls->h);
659 return addk(fs, &k, &v);
660 }
661
662
663 /*
664 ** Check whether 'i' can be stored in an 'sC' operand. Equivalent to
665 ** (0 <= int2sC(i) && int2sC(i) <= MAXARG_C) but without risk of
666 ** overflows in the hidden addition inside 'int2sC'.
667 */
fitsC(lua_Integer i)668 static int fitsC (lua_Integer i) {
669 return (l_castS2U(i) + OFFSET_sC <= cast_uint(MAXARG_C));
670 }
671
672
673 /*
674 ** Check whether 'i' can be stored in an 'sBx' operand.
675 */
fitsBx(lua_Integer i)676 static int fitsBx (lua_Integer i) {
677 return (-OFFSET_sBx <= i && i <= MAXARG_Bx - OFFSET_sBx);
678 }
679
680
luaK_int(FuncState * fs,int reg,lua_Integer i)681 void luaK_int (FuncState *fs, int reg, lua_Integer i) {
682 if (fitsBx(i))
683 luaK_codeAsBx(fs, OP_LOADI, reg, cast_int(i));
684 else
685 luaK_codek(fs, reg, luaK_intK(fs, i));
686 }
687
688
689 #ifndef _KERNEL
luaK_float(FuncState * fs,int reg,lua_Number f)690 static void luaK_float (FuncState *fs, int reg, lua_Number f) {
691 lua_Integer fi;
692 if (luaV_flttointeger(f, &fi, F2Ieq) && fitsBx(fi))
693 luaK_codeAsBx(fs, OP_LOADF, reg, cast_int(fi));
694 else
695 luaK_codek(fs, reg, luaK_numberK(fs, f));
696 }
697 #endif /* _KERNEL */
698
699
700 /*
701 ** Convert a constant in 'v' into an expression description 'e'
702 */
const2exp(TValue * v,expdesc * e)703 static void const2exp (TValue *v, expdesc *e) {
704 switch (ttypetag(v)) {
705 case LUA_VNUMINT:
706 e->k = VKINT; e->u.ival = ivalue(v);
707 break;
708 #ifndef _KERNEL
709 case LUA_VNUMFLT:
710 e->k = VKFLT; e->u.nval = fltvalue(v);
711 break;
712 #endif /* _KERNEL */
713 case LUA_VFALSE:
714 e->k = VFALSE;
715 break;
716 case LUA_VTRUE:
717 e->k = VTRUE;
718 break;
719 case LUA_VNIL:
720 e->k = VNIL;
721 break;
722 case LUA_VSHRSTR: case LUA_VLNGSTR:
723 e->k = VKSTR; e->u.strval = tsvalue(v);
724 break;
725 default: lua_assert(0);
726 }
727 }
728
729
730 /*
731 ** Fix an expression to return the number of results 'nresults'.
732 ** 'e' must be a multi-ret expression (function call or vararg).
733 */
luaK_setreturns(FuncState * fs,expdesc * e,int nresults)734 void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
735 Instruction *pc = &getinstruction(fs, e);
736 if (e->k == VCALL) /* expression is an open function call? */
737 SETARG_C(*pc, nresults + 1);
738 else {
739 lua_assert(e->k == VVARARG);
740 SETARG_C(*pc, nresults + 1);
741 SETARG_A(*pc, fs->freereg);
742 luaK_reserveregs(fs, 1);
743 }
744 }
745
746
747 /*
748 ** Convert a VKSTR to a VK
749 */
str2K(FuncState * fs,expdesc * e)750 static void str2K (FuncState *fs, expdesc *e) {
751 lua_assert(e->k == VKSTR);
752 e->u.info = stringK(fs, e->u.strval);
753 e->k = VK;
754 }
755
756
757 /*
758 ** Fix an expression to return one result.
759 ** If expression is not a multi-ret expression (function call or
760 ** vararg), it already returns one result, so nothing needs to be done.
761 ** Function calls become VNONRELOC expressions (as its result comes
762 ** fixed in the base register of the call), while vararg expressions
763 ** become VRELOC (as OP_VARARG puts its results where it wants).
764 ** (Calls are created returning one result, so that does not need
765 ** to be fixed.)
766 */
luaK_setoneret(FuncState * fs,expdesc * e)767 void luaK_setoneret (FuncState *fs, expdesc *e) {
768 if (e->k == VCALL) { /* expression is an open function call? */
769 /* already returns 1 value */
770 lua_assert(GETARG_C(getinstruction(fs, e)) == 2);
771 e->k = VNONRELOC; /* result has fixed position */
772 e->u.info = GETARG_A(getinstruction(fs, e));
773 }
774 else if (e->k == VVARARG) {
775 SETARG_C(getinstruction(fs, e), 2);
776 e->k = VRELOC; /* can relocate its simple result */
777 }
778 }
779
780
781 /*
782 ** Ensure that expression 'e' is not a variable (nor a <const>).
783 ** (Expression still may have jump lists.)
784 */
luaK_dischargevars(FuncState * fs,expdesc * e)785 void luaK_dischargevars (FuncState *fs, expdesc *e) {
786 switch (e->k) {
787 case VCONST: {
788 const2exp(const2val(fs, e), e);
789 break;
790 }
791 case VLOCAL: { /* already in a register */
792 e->u.info = e->u.var.ridx;
793 e->k = VNONRELOC; /* becomes a non-relocatable value */
794 break;
795 }
796 case VUPVAL: { /* move value to some (pending) register */
797 e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
798 e->k = VRELOC;
799 break;
800 }
801 case VINDEXUP: {
802 e->u.info = luaK_codeABC(fs, OP_GETTABUP, 0, e->u.ind.t, e->u.ind.idx);
803 e->k = VRELOC;
804 break;
805 }
806 case VINDEXI: {
807 freereg(fs, e->u.ind.t);
808 e->u.info = luaK_codeABC(fs, OP_GETI, 0, e->u.ind.t, e->u.ind.idx);
809 e->k = VRELOC;
810 break;
811 }
812 case VINDEXSTR: {
813 freereg(fs, e->u.ind.t);
814 e->u.info = luaK_codeABC(fs, OP_GETFIELD, 0, e->u.ind.t, e->u.ind.idx);
815 e->k = VRELOC;
816 break;
817 }
818 case VINDEXED: {
819 freeregs(fs, e->u.ind.t, e->u.ind.idx);
820 e->u.info = luaK_codeABC(fs, OP_GETTABLE, 0, e->u.ind.t, e->u.ind.idx);
821 e->k = VRELOC;
822 break;
823 }
824 case VVARARG: case VCALL: {
825 luaK_setoneret(fs, e);
826 break;
827 }
828 default: break; /* there is one value available (somewhere) */
829 }
830 }
831
832
833 /*
834 ** Ensure expression value is in register 'reg', making 'e' a
835 ** non-relocatable expression.
836 ** (Expression still may have jump lists.)
837 */
discharge2reg(FuncState * fs,expdesc * e,int reg)838 static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
839 luaK_dischargevars(fs, e);
840 switch (e->k) {
841 case VNIL: {
842 luaK_nil(fs, reg, 1);
843 break;
844 }
845 case VFALSE: {
846 luaK_codeABC(fs, OP_LOADFALSE, reg, 0, 0);
847 break;
848 }
849 case VTRUE: {
850 luaK_codeABC(fs, OP_LOADTRUE, reg, 0, 0);
851 break;
852 }
853 case VKSTR: {
854 str2K(fs, e);
855 } /* FALLTHROUGH */
856 case VK: {
857 luaK_codek(fs, reg, e->u.info);
858 break;
859 }
860 #ifndef _KERNEL
861 case VKFLT: {
862 luaK_float(fs, reg, e->u.nval);
863 break;
864 }
865 #endif /* _KERNEL */
866 case VKINT: {
867 luaK_int(fs, reg, e->u.ival);
868 break;
869 }
870 case VRELOC: {
871 Instruction *pc = &getinstruction(fs, e);
872 SETARG_A(*pc, reg); /* instruction will put result in 'reg' */
873 break;
874 }
875 case VNONRELOC: {
876 if (reg != e->u.info)
877 luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
878 break;
879 }
880 default: {
881 lua_assert(e->k == VJMP);
882 return; /* nothing to do... */
883 }
884 }
885 e->u.info = reg;
886 e->k = VNONRELOC;
887 }
888
889
890 /*
891 ** Ensure expression value is in a register, making 'e' a
892 ** non-relocatable expression.
893 ** (Expression still may have jump lists.)
894 */
discharge2anyreg(FuncState * fs,expdesc * e)895 static void discharge2anyreg (FuncState *fs, expdesc *e) {
896 if (e->k != VNONRELOC) { /* no fixed register yet? */
897 luaK_reserveregs(fs, 1); /* get a register */
898 discharge2reg(fs, e, fs->freereg-1); /* put value there */
899 }
900 }
901
902
code_loadbool(FuncState * fs,int A,OpCode op)903 static int code_loadbool (FuncState *fs, int A, OpCode op) {
904 luaK_getlabel(fs); /* those instructions may be jump targets */
905 return luaK_codeABC(fs, op, A, 0, 0);
906 }
907
908
909 /*
910 ** check whether list has any jump that do not produce a value
911 ** or produce an inverted value
912 */
need_value(FuncState * fs,int list)913 static int need_value (FuncState *fs, int list) {
914 for (; list != NO_JUMP; list = getjump(fs, list)) {
915 Instruction i = *getjumpcontrol(fs, list);
916 if (GET_OPCODE(i) != OP_TESTSET) return 1;
917 }
918 return 0; /* not found */
919 }
920
921
922 /*
923 ** Ensures final expression result (which includes results from its
924 ** jump lists) is in register 'reg'.
925 ** If expression has jumps, need to patch these jumps either to
926 ** its final position or to "load" instructions (for those tests
927 ** that do not produce values).
928 */
exp2reg(FuncState * fs,expdesc * e,int reg)929 static void exp2reg (FuncState *fs, expdesc *e, int reg) {
930 discharge2reg(fs, e, reg);
931 if (e->k == VJMP) /* expression itself is a test? */
932 luaK_concat(fs, &e->t, e->u.info); /* put this jump in 't' list */
933 if (hasjumps(e)) {
934 int final; /* position after whole expression */
935 int p_f = NO_JUMP; /* position of an eventual LOAD false */
936 int p_t = NO_JUMP; /* position of an eventual LOAD true */
937 if (need_value(fs, e->t) || need_value(fs, e->f)) {
938 int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
939 p_f = code_loadbool(fs, reg, OP_LFALSESKIP); /* skip next inst. */
940 p_t = code_loadbool(fs, reg, OP_LOADTRUE);
941 /* jump around these booleans if 'e' is not a test */
942 luaK_patchtohere(fs, fj);
943 }
944 final = luaK_getlabel(fs);
945 patchlistaux(fs, e->f, final, reg, p_f);
946 patchlistaux(fs, e->t, final, reg, p_t);
947 }
948 e->f = e->t = NO_JUMP;
949 e->u.info = reg;
950 e->k = VNONRELOC;
951 }
952
953
954 /*
955 ** Ensures final expression result is in next available register.
956 */
luaK_exp2nextreg(FuncState * fs,expdesc * e)957 void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
958 luaK_dischargevars(fs, e);
959 freeexp(fs, e);
960 luaK_reserveregs(fs, 1);
961 exp2reg(fs, e, fs->freereg - 1);
962 }
963
964
965 /*
966 ** Ensures final expression result is in some (any) register
967 ** and return that register.
968 */
luaK_exp2anyreg(FuncState * fs,expdesc * e)969 int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
970 luaK_dischargevars(fs, e);
971 if (e->k == VNONRELOC) { /* expression already has a register? */
972 if (!hasjumps(e)) /* no jumps? */
973 return e->u.info; /* result is already in a register */
974 if (e->u.info >= luaY_nvarstack(fs)) { /* reg. is not a local? */
975 exp2reg(fs, e, e->u.info); /* put final result in it */
976 return e->u.info;
977 }
978 /* else expression has jumps and cannot change its register
979 to hold the jump values, because it is a local variable.
980 Go through to the default case. */
981 }
982 luaK_exp2nextreg(fs, e); /* default: use next available register */
983 return e->u.info;
984 }
985
986
987 /*
988 ** Ensures final expression result is either in a register
989 ** or in an upvalue.
990 */
luaK_exp2anyregup(FuncState * fs,expdesc * e)991 void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
992 if (e->k != VUPVAL || hasjumps(e))
993 luaK_exp2anyreg(fs, e);
994 }
995
996
997 /*
998 ** Ensures final expression result is either in a register
999 ** or it is a constant.
1000 */
luaK_exp2val(FuncState * fs,expdesc * e)1001 void luaK_exp2val (FuncState *fs, expdesc *e) {
1002 if (hasjumps(e))
1003 luaK_exp2anyreg(fs, e);
1004 else
1005 luaK_dischargevars(fs, e);
1006 }
1007
1008
1009 /*
1010 ** Try to make 'e' a K expression with an index in the range of R/K
1011 ** indices. Return true iff succeeded.
1012 */
luaK_exp2K(FuncState * fs,expdesc * e)1013 static int luaK_exp2K (FuncState *fs, expdesc *e) {
1014 if (!hasjumps(e)) {
1015 int info;
1016 switch (e->k) { /* move constants to 'k' */
1017 case VTRUE: info = boolT(fs); break;
1018 case VFALSE: info = boolF(fs); break;
1019 case VNIL: info = nilK(fs); break;
1020 case VKINT: info = luaK_intK(fs, e->u.ival); break;
1021 #ifndef _KERNEL
1022 case VKFLT: info = luaK_numberK(fs, e->u.nval); break;
1023 #endif /* _KERNEL */
1024 case VKSTR: info = stringK(fs, e->u.strval); break;
1025 case VK: info = e->u.info; break;
1026 default: return 0; /* not a constant */
1027 }
1028 if (info <= MAXINDEXRK) { /* does constant fit in 'argC'? */
1029 e->k = VK; /* make expression a 'K' expression */
1030 e->u.info = info;
1031 return 1;
1032 }
1033 }
1034 /* else, expression doesn't fit; leave it unchanged */
1035 return 0;
1036 }
1037
1038
1039 /*
1040 ** Ensures final expression result is in a valid R/K index
1041 ** (that is, it is either in a register or in 'k' with an index
1042 ** in the range of R/K indices).
1043 ** Returns 1 iff expression is K.
1044 */
luaK_exp2RK(FuncState * fs,expdesc * e)1045 int luaK_exp2RK (FuncState *fs, expdesc *e) {
1046 if (luaK_exp2K(fs, e))
1047 return 1;
1048 else { /* not a constant in the right range: put it in a register */
1049 luaK_exp2anyreg(fs, e);
1050 return 0;
1051 }
1052 }
1053
1054
codeABRK(FuncState * fs,OpCode o,int a,int b,expdesc * ec)1055 static void codeABRK (FuncState *fs, OpCode o, int a, int b,
1056 expdesc *ec) {
1057 int k = luaK_exp2RK(fs, ec);
1058 luaK_codeABCk(fs, o, a, b, ec->u.info, k);
1059 }
1060
1061
1062 /*
1063 ** Generate code to store result of expression 'ex' into variable 'var'.
1064 */
luaK_storevar(FuncState * fs,expdesc * var,expdesc * ex)1065 void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
1066 switch (var->k) {
1067 case VLOCAL: {
1068 freeexp(fs, ex);
1069 exp2reg(fs, ex, var->u.var.ridx); /* compute 'ex' into proper place */
1070 return;
1071 }
1072 case VUPVAL: {
1073 int e = luaK_exp2anyreg(fs, ex);
1074 luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
1075 break;
1076 }
1077 case VINDEXUP: {
1078 codeABRK(fs, OP_SETTABUP, var->u.ind.t, var->u.ind.idx, ex);
1079 break;
1080 }
1081 case VINDEXI: {
1082 codeABRK(fs, OP_SETI, var->u.ind.t, var->u.ind.idx, ex);
1083 break;
1084 }
1085 case VINDEXSTR: {
1086 codeABRK(fs, OP_SETFIELD, var->u.ind.t, var->u.ind.idx, ex);
1087 break;
1088 }
1089 case VINDEXED: {
1090 codeABRK(fs, OP_SETTABLE, var->u.ind.t, var->u.ind.idx, ex);
1091 break;
1092 }
1093 default: lua_assert(0); /* invalid var kind to store */
1094 }
1095 freeexp(fs, ex);
1096 }
1097
1098
1099 /*
1100 ** Emit SELF instruction (convert expression 'e' into 'e:key(e,').
1101 */
luaK_self(FuncState * fs,expdesc * e,expdesc * key)1102 void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
1103 int ereg;
1104 luaK_exp2anyreg(fs, e);
1105 ereg = e->u.info; /* register where 'e' was placed */
1106 freeexp(fs, e);
1107 e->u.info = fs->freereg; /* base register for op_self */
1108 e->k = VNONRELOC; /* self expression has a fixed register */
1109 luaK_reserveregs(fs, 2); /* function and 'self' produced by op_self */
1110 codeABRK(fs, OP_SELF, e->u.info, ereg, key);
1111 freeexp(fs, key);
1112 }
1113
1114
1115 /*
1116 ** Negate condition 'e' (where 'e' is a comparison).
1117 */
negatecondition(FuncState * fs,expdesc * e)1118 static void negatecondition (FuncState *fs, expdesc *e) {
1119 Instruction *pc = getjumpcontrol(fs, e->u.info);
1120 lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
1121 GET_OPCODE(*pc) != OP_TEST);
1122 SETARG_k(*pc, (GETARG_k(*pc) ^ 1));
1123 }
1124
1125
1126 /*
1127 ** Emit instruction to jump if 'e' is 'cond' (that is, if 'cond'
1128 ** is true, code will jump if 'e' is true.) Return jump position.
1129 ** Optimize when 'e' is 'not' something, inverting the condition
1130 ** and removing the 'not'.
1131 */
jumponcond(FuncState * fs,expdesc * e,int cond)1132 static int jumponcond (FuncState *fs, expdesc *e, int cond) {
1133 if (e->k == VRELOC) {
1134 Instruction ie = getinstruction(fs, e);
1135 if (GET_OPCODE(ie) == OP_NOT) {
1136 removelastinstruction(fs); /* remove previous OP_NOT */
1137 return condjump(fs, OP_TEST, GETARG_B(ie), 0, 0, !cond);
1138 }
1139 /* else go through */
1140 }
1141 discharge2anyreg(fs, e);
1142 freeexp(fs, e);
1143 return condjump(fs, OP_TESTSET, NO_REG, e->u.info, 0, cond);
1144 }
1145
1146
1147 /*
1148 ** Emit code to go through if 'e' is true, jump otherwise.
1149 */
luaK_goiftrue(FuncState * fs,expdesc * e)1150 void luaK_goiftrue (FuncState *fs, expdesc *e) {
1151 int pc; /* pc of new jump */
1152 luaK_dischargevars(fs, e);
1153 switch (e->k) {
1154 case VJMP: { /* condition? */
1155 negatecondition(fs, e); /* jump when it is false */
1156 pc = e->u.info; /* save jump position */
1157 break;
1158 }
1159 #ifndef _KERNEL
1160 case VK: case VKFLT: case VKINT: case VKSTR: case VTRUE: {
1161 #else /* _KERNEL */
1162 case VK: case VKINT: case VKSTR: case VTRUE: {
1163 #endif /* _KERNEL */
1164 pc = NO_JUMP; /* always true; do nothing */
1165 break;
1166 }
1167 default: {
1168 pc = jumponcond(fs, e, 0); /* jump when false */
1169 break;
1170 }
1171 }
1172 luaK_concat(fs, &e->f, pc); /* insert new jump in false list */
1173 luaK_patchtohere(fs, e->t); /* true list jumps to here (to go through) */
1174 e->t = NO_JUMP;
1175 }
1176
1177
1178 /*
1179 ** Emit code to go through if 'e' is false, jump otherwise.
1180 */
1181 void luaK_goiffalse (FuncState *fs, expdesc *e) {
1182 int pc; /* pc of new jump */
1183 luaK_dischargevars(fs, e);
1184 switch (e->k) {
1185 case VJMP: {
1186 pc = e->u.info; /* already jump if true */
1187 break;
1188 }
1189 case VNIL: case VFALSE: {
1190 pc = NO_JUMP; /* always false; do nothing */
1191 break;
1192 }
1193 default: {
1194 pc = jumponcond(fs, e, 1); /* jump if true */
1195 break;
1196 }
1197 }
1198 luaK_concat(fs, &e->t, pc); /* insert new jump in 't' list */
1199 luaK_patchtohere(fs, e->f); /* false list jumps to here (to go through) */
1200 e->f = NO_JUMP;
1201 }
1202
1203
1204 /*
1205 ** Code 'not e', doing constant folding.
1206 */
1207 static void codenot (FuncState *fs, expdesc *e) {
1208 switch (e->k) {
1209 case VNIL: case VFALSE: {
1210 e->k = VTRUE; /* true == not nil == not false */
1211 break;
1212 }
1213 #ifndef _KERNEL
1214 case VK: case VKFLT: case VKINT: case VKSTR: case VTRUE: {
1215 #else /* _KERNEL */
1216 case VK: case VKINT: case VKSTR: case VTRUE: {
1217 #endif /* _KERNEL */
1218 e->k = VFALSE; /* false == not "x" == not 0.5 == not 1 == not true */
1219 break;
1220 }
1221 case VJMP: {
1222 negatecondition(fs, e);
1223 break;
1224 }
1225 case VRELOC:
1226 case VNONRELOC: {
1227 discharge2anyreg(fs, e);
1228 freeexp(fs, e);
1229 e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0);
1230 e->k = VRELOC;
1231 break;
1232 }
1233 default: lua_assert(0); /* cannot happen */
1234 }
1235 /* interchange true and false lists */
1236 { int temp = e->f; e->f = e->t; e->t = temp; }
1237 removevalues(fs, e->f); /* values are useless when negated */
1238 removevalues(fs, e->t);
1239 }
1240
1241
1242 /*
1243 ** Check whether expression 'e' is a small literal string
1244 */
1245 static int isKstr (FuncState *fs, expdesc *e) {
1246 return (e->k == VK && !hasjumps(e) && e->u.info <= MAXARG_B &&
1247 ttisshrstring(&fs->f->k[e->u.info]));
1248 }
1249
1250 /*
1251 ** Check whether expression 'e' is a literal integer.
1252 */
1253 int luaK_isKint (expdesc *e) {
1254 return (e->k == VKINT && !hasjumps(e));
1255 }
1256
1257
1258 /*
1259 ** Check whether expression 'e' is a literal integer in
1260 ** proper range to fit in register C
1261 */
1262 static int isCint (expdesc *e) {
1263 return luaK_isKint(e) && (l_castS2U(e->u.ival) <= l_castS2U(MAXARG_C));
1264 }
1265
1266
1267 /*
1268 ** Check whether expression 'e' is a literal integer in
1269 ** proper range to fit in register sC
1270 */
1271 static int isSCint (expdesc *e) {
1272 return luaK_isKint(e) && fitsC(e->u.ival);
1273 }
1274
1275
1276 /*
1277 ** Check whether expression 'e' is a literal integer or float in
1278 ** proper range to fit in a register (sB or sC).
1279 */
1280 static int isSCnumber (expdesc *e, int *pi, int *isfloat) {
1281 lua_Integer i;
1282 if (e->k == VKINT)
1283 i = e->u.ival;
1284 #ifndef _KERNEL
1285 else if (e->k == VKFLT && luaV_flttointeger(e->u.nval, &i, F2Ieq))
1286 *isfloat = 1;
1287 #endif /* _KERNEL */
1288 else
1289 return 0; /* not a number */
1290 if (!hasjumps(e) && fitsC(i)) {
1291 *pi = int2sC(cast_int(i));
1292 return 1;
1293 }
1294 else
1295 return 0;
1296 }
1297
1298
1299 /*
1300 ** Create expression 't[k]'. 't' must have its final result already in a
1301 ** register or upvalue. Upvalues can only be indexed by literal strings.
1302 ** Keys can be literal strings in the constant table or arbitrary
1303 ** values in registers.
1304 */
1305 void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
1306 if (k->k == VKSTR)
1307 str2K(fs, k);
1308 lua_assert(!hasjumps(t) &&
1309 (t->k == VLOCAL || t->k == VNONRELOC || t->k == VUPVAL));
1310 if (t->k == VUPVAL && !isKstr(fs, k)) /* upvalue indexed by non 'Kstr'? */
1311 luaK_exp2anyreg(fs, t); /* put it in a register */
1312 if (t->k == VUPVAL) {
1313 t->u.ind.t = t->u.info; /* upvalue index */
1314 t->u.ind.idx = k->u.info; /* literal string */
1315 t->k = VINDEXUP;
1316 }
1317 else {
1318 /* register index of the table */
1319 t->u.ind.t = (t->k == VLOCAL) ? t->u.var.ridx: t->u.info;
1320 if (isKstr(fs, k)) {
1321 t->u.ind.idx = k->u.info; /* literal string */
1322 t->k = VINDEXSTR;
1323 }
1324 else if (isCint(k)) {
1325 t->u.ind.idx = cast_int(k->u.ival); /* int. constant in proper range */
1326 t->k = VINDEXI;
1327 }
1328 else {
1329 t->u.ind.idx = luaK_exp2anyreg(fs, k); /* register */
1330 t->k = VINDEXED;
1331 }
1332 }
1333 }
1334
1335
1336 /*
1337 ** Return false if folding can raise an error.
1338 ** Bitwise operations need operands convertible to integers; division
1339 ** operations cannot have 0 as divisor.
1340 */
1341 static int validop (int op, TValue *v1, TValue *v2) {
1342 switch (op) {
1343 case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
1344 case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT: { /* conversion errors */
1345 lua_Integer i;
1346 return (luaV_tointegerns(v1, &i, LUA_FLOORN2I) &&
1347 luaV_tointegerns(v2, &i, LUA_FLOORN2I));
1348 }
1349 #ifndef _KERNEL
1350 case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD: /* division by 0 */
1351 #else /* _KERNEL */
1352 case LUA_OPIDIV: case LUA_OPMOD: /* division by 0 */
1353 #endif /* _KERNEL */
1354 return (nvalue(v2) != 0);
1355 default: return 1; /* everything else is valid */
1356 }
1357 }
1358
1359
1360 /*
1361 ** Try to "constant-fold" an operation; return 1 iff successful.
1362 ** (In this case, 'e1' has the final result.)
1363 */
1364 static int constfolding (FuncState *fs, int op, expdesc *e1,
1365 const expdesc *e2) {
1366 TValue v1, v2, res;
1367 if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2))
1368 return 0; /* non-numeric operands or not safe to fold */
1369 luaO_rawarith(fs->ls->L, op, &v1, &v2, &res); /* does operation */
1370 if (ttisinteger(&res)) {
1371 e1->k = VKINT;
1372 e1->u.ival = ivalue(&res);
1373 }
1374 else { /* folds neither NaN nor 0.0 (to avoid problems with -0.0) */
1375 #ifndef _KERNEL
1376 lua_Number n = fltvalue(&res);
1377 if (luai_numisnan(n) || n == 0)
1378 return 0;
1379 e1->k = VKFLT;
1380 e1->u.nval = n;
1381 #else /* _KERNEL */
1382 return 0; /* if it is not integer, we must fail */
1383 #endif /* _KERNEL */
1384 }
1385 return 1;
1386 }
1387
1388
1389 /*
1390 ** Convert a BinOpr to an OpCode (ORDER OPR - ORDER OP)
1391 */
1392 l_sinline OpCode binopr2op (BinOpr opr, BinOpr baser, OpCode base) {
1393 lua_assert(baser <= opr &&
1394 ((baser == OPR_ADD && opr <= OPR_SHR) ||
1395 (baser == OPR_LT && opr <= OPR_LE)));
1396 return cast(OpCode, (cast_int(opr) - cast_int(baser)) + cast_int(base));
1397 }
1398
1399
1400 /*
1401 ** Convert a UnOpr to an OpCode (ORDER OPR - ORDER OP)
1402 */
1403 l_sinline OpCode unopr2op (UnOpr opr) {
1404 return cast(OpCode, (cast_int(opr) - cast_int(OPR_MINUS)) +
1405 cast_int(OP_UNM));
1406 }
1407
1408
1409 /*
1410 ** Convert a BinOpr to a tag method (ORDER OPR - ORDER TM)
1411 */
1412 l_sinline TMS binopr2TM (BinOpr opr) {
1413 lua_assert(OPR_ADD <= opr && opr <= OPR_SHR);
1414 return cast(TMS, (cast_int(opr) - cast_int(OPR_ADD)) + cast_int(TM_ADD));
1415 }
1416
1417
1418 /*
1419 ** Emit code for unary expressions that "produce values"
1420 ** (everything but 'not').
1421 ** Expression to produce final result will be encoded in 'e'.
1422 */
1423 static void codeunexpval (FuncState *fs, OpCode op, expdesc *e, int line) {
1424 int r = luaK_exp2anyreg(fs, e); /* opcodes operate only on registers */
1425 freeexp(fs, e);
1426 e->u.info = luaK_codeABC(fs, op, 0, r, 0); /* generate opcode */
1427 e->k = VRELOC; /* all those operations are relocatable */
1428 luaK_fixline(fs, line);
1429 }
1430
1431
1432 /*
1433 ** Emit code for binary expressions that "produce values"
1434 ** (everything but logical operators 'and'/'or' and comparison
1435 ** operators).
1436 ** Expression to produce final result will be encoded in 'e1'.
1437 */
1438 static void finishbinexpval (FuncState *fs, expdesc *e1, expdesc *e2,
1439 OpCode op, int v2, int flip, int line,
1440 OpCode mmop, TMS event) {
1441 int v1 = luaK_exp2anyreg(fs, e1);
1442 int pc = luaK_codeABCk(fs, op, 0, v1, v2, 0);
1443 freeexps(fs, e1, e2);
1444 e1->u.info = pc;
1445 e1->k = VRELOC; /* all those operations are relocatable */
1446 luaK_fixline(fs, line);
1447 luaK_codeABCk(fs, mmop, v1, v2, event, flip); /* to call metamethod */
1448 luaK_fixline(fs, line);
1449 }
1450
1451
1452 /*
1453 ** Emit code for binary expressions that "produce values" over
1454 ** two registers.
1455 */
1456 static void codebinexpval (FuncState *fs, BinOpr opr,
1457 expdesc *e1, expdesc *e2, int line) {
1458 OpCode op = binopr2op(opr, OPR_ADD, OP_ADD);
1459 int v2 = luaK_exp2anyreg(fs, e2); /* make sure 'e2' is in a register */
1460 /* 'e1' must be already in a register or it is a constant */
1461 lua_assert((VNIL <= e1->k && e1->k <= VKSTR) ||
1462 e1->k == VNONRELOC || e1->k == VRELOC);
1463 lua_assert(OP_ADD <= op && op <= OP_SHR);
1464 finishbinexpval(fs, e1, e2, op, v2, 0, line, OP_MMBIN, binopr2TM(opr));
1465 }
1466
1467
1468 /*
1469 ** Code binary operators with immediate operands.
1470 */
1471 static void codebini (FuncState *fs, OpCode op,
1472 expdesc *e1, expdesc *e2, int flip, int line,
1473 TMS event) {
1474 int v2 = int2sC(cast_int(e2->u.ival)); /* immediate operand */
1475 lua_assert(e2->k == VKINT);
1476 finishbinexpval(fs, e1, e2, op, v2, flip, line, OP_MMBINI, event);
1477 }
1478
1479
1480 /*
1481 ** Code binary operators with K operand.
1482 */
1483 static void codebinK (FuncState *fs, BinOpr opr,
1484 expdesc *e1, expdesc *e2, int flip, int line) {
1485 TMS event = binopr2TM(opr);
1486 int v2 = e2->u.info; /* K index */
1487 OpCode op = binopr2op(opr, OPR_ADD, OP_ADDK);
1488 finishbinexpval(fs, e1, e2, op, v2, flip, line, OP_MMBINK, event);
1489 }
1490
1491
1492 /* Try to code a binary operator negating its second operand.
1493 ** For the metamethod, 2nd operand must keep its original value.
1494 */
1495 static int finishbinexpneg (FuncState *fs, expdesc *e1, expdesc *e2,
1496 OpCode op, int line, TMS event) {
1497 if (!luaK_isKint(e2))
1498 return 0; /* not an integer constant */
1499 else {
1500 lua_Integer i2 = e2->u.ival;
1501 if (!(fitsC(i2) && fitsC(-i2)))
1502 return 0; /* not in the proper range */
1503 else { /* operating a small integer constant */
1504 int v2 = cast_int(i2);
1505 finishbinexpval(fs, e1, e2, op, int2sC(-v2), 0, line, OP_MMBINI, event);
1506 /* correct metamethod argument */
1507 SETARG_B(fs->f->code[fs->pc - 1], int2sC(v2));
1508 return 1; /* successfully coded */
1509 }
1510 }
1511 }
1512
1513
1514 static void swapexps (expdesc *e1, expdesc *e2) {
1515 expdesc temp = *e1; *e1 = *e2; *e2 = temp; /* swap 'e1' and 'e2' */
1516 }
1517
1518
1519 /*
1520 ** Code binary operators with no constant operand.
1521 */
1522 static void codebinNoK (FuncState *fs, BinOpr opr,
1523 expdesc *e1, expdesc *e2, int flip, int line) {
1524 if (flip)
1525 swapexps(e1, e2); /* back to original order */
1526 codebinexpval(fs, opr, e1, e2, line); /* use standard operators */
1527 }
1528
1529
1530 /*
1531 ** Code arithmetic operators ('+', '-', ...). If second operand is a
1532 ** constant in the proper range, use variant opcodes with K operands.
1533 */
1534 static void codearith (FuncState *fs, BinOpr opr,
1535 expdesc *e1, expdesc *e2, int flip, int line) {
1536 if (tonumeral(e2, NULL) && luaK_exp2K(fs, e2)) /* K operand? */
1537 codebinK(fs, opr, e1, e2, flip, line);
1538 else /* 'e2' is neither an immediate nor a K operand */
1539 codebinNoK(fs, opr, e1, e2, flip, line);
1540 }
1541
1542
1543 /*
1544 ** Code commutative operators ('+', '*'). If first operand is a
1545 ** numeric constant, change order of operands to try to use an
1546 ** immediate or K operator.
1547 */
1548 static void codecommutative (FuncState *fs, BinOpr op,
1549 expdesc *e1, expdesc *e2, int line) {
1550 int flip = 0;
1551 if (tonumeral(e1, NULL)) { /* is first operand a numeric constant? */
1552 swapexps(e1, e2); /* change order */
1553 flip = 1;
1554 }
1555 if (op == OPR_ADD && isSCint(e2)) /* immediate operand? */
1556 codebini(fs, OP_ADDI, e1, e2, flip, line, TM_ADD);
1557 else
1558 codearith(fs, op, e1, e2, flip, line);
1559 }
1560
1561
1562 /*
1563 ** Code bitwise operations; they are all commutative, so the function
1564 ** tries to put an integer constant as the 2nd operand (a K operand).
1565 */
1566 static void codebitwise (FuncState *fs, BinOpr opr,
1567 expdesc *e1, expdesc *e2, int line) {
1568 int flip = 0;
1569 if (e1->k == VKINT) {
1570 swapexps(e1, e2); /* 'e2' will be the constant operand */
1571 flip = 1;
1572 }
1573 if (e2->k == VKINT && luaK_exp2K(fs, e2)) /* K operand? */
1574 codebinK(fs, opr, e1, e2, flip, line);
1575 else /* no constants */
1576 codebinNoK(fs, opr, e1, e2, flip, line);
1577 }
1578
1579
1580 /*
1581 ** Emit code for order comparisons. When using an immediate operand,
1582 ** 'isfloat' tells whether the original value was a float.
1583 */
1584 static void codeorder (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2) {
1585 int r1, r2;
1586 int im;
1587 int isfloat = 0;
1588 OpCode op;
1589 if (isSCnumber(e2, &im, &isfloat)) {
1590 /* use immediate operand */
1591 r1 = luaK_exp2anyreg(fs, e1);
1592 r2 = im;
1593 op = binopr2op(opr, OPR_LT, OP_LTI);
1594 }
1595 else if (isSCnumber(e1, &im, &isfloat)) {
1596 /* transform (A < B) to (B > A) and (A <= B) to (B >= A) */
1597 r1 = luaK_exp2anyreg(fs, e2);
1598 r2 = im;
1599 op = binopr2op(opr, OPR_LT, OP_GTI);
1600 }
1601 else { /* regular case, compare two registers */
1602 r1 = luaK_exp2anyreg(fs, e1);
1603 r2 = luaK_exp2anyreg(fs, e2);
1604 op = binopr2op(opr, OPR_LT, OP_LT);
1605 }
1606 freeexps(fs, e1, e2);
1607 e1->u.info = condjump(fs, op, r1, r2, isfloat, 1);
1608 e1->k = VJMP;
1609 }
1610
1611
1612 /*
1613 ** Emit code for equality comparisons ('==', '~=').
1614 ** 'e1' was already put as RK by 'luaK_infix'.
1615 */
1616 static void codeeq (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2) {
1617 int r1, r2;
1618 int im;
1619 int isfloat = 0; /* not needed here, but kept for symmetry */
1620 OpCode op;
1621 if (e1->k != VNONRELOC) {
1622 lua_assert(e1->k == VK || e1->k == VKINT || e1->k == VKFLT);
1623 swapexps(e1, e2);
1624 }
1625 r1 = luaK_exp2anyreg(fs, e1); /* 1st expression must be in register */
1626 if (isSCnumber(e2, &im, &isfloat)) {
1627 op = OP_EQI;
1628 r2 = im; /* immediate operand */
1629 }
1630 else if (luaK_exp2RK(fs, e2)) { /* 2nd expression is constant? */
1631 op = OP_EQK;
1632 r2 = e2->u.info; /* constant index */
1633 }
1634 else {
1635 op = OP_EQ; /* will compare two registers */
1636 r2 = luaK_exp2anyreg(fs, e2);
1637 }
1638 freeexps(fs, e1, e2);
1639 e1->u.info = condjump(fs, op, r1, r2, isfloat, (opr == OPR_EQ));
1640 e1->k = VJMP;
1641 }
1642
1643
1644 /*
1645 ** Apply prefix operation 'op' to expression 'e'.
1646 */
1647 void luaK_prefix (FuncState *fs, UnOpr opr, expdesc *e, int line) {
1648 static const expdesc ef = {VKINT, {0}, NO_JUMP, NO_JUMP};
1649 luaK_dischargevars(fs, e);
1650 switch (opr) {
1651 case OPR_MINUS: case OPR_BNOT: /* use 'ef' as fake 2nd operand */
1652 if (constfolding(fs, opr + LUA_OPUNM, e, &ef))
1653 break;
1654 /* else */ /* FALLTHROUGH */
1655 case OPR_LEN:
1656 codeunexpval(fs, unopr2op(opr), e, line);
1657 break;
1658 case OPR_NOT: codenot(fs, e); break;
1659 default: lua_assert(0);
1660 }
1661 }
1662
1663
1664 /*
1665 ** Process 1st operand 'v' of binary operation 'op' before reading
1666 ** 2nd operand.
1667 */
1668 void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
1669 luaK_dischargevars(fs, v);
1670 switch (op) {
1671 case OPR_AND: {
1672 luaK_goiftrue(fs, v); /* go ahead only if 'v' is true */
1673 break;
1674 }
1675 case OPR_OR: {
1676 luaK_goiffalse(fs, v); /* go ahead only if 'v' is false */
1677 break;
1678 }
1679 case OPR_CONCAT: {
1680 luaK_exp2nextreg(fs, v); /* operand must be on the stack */
1681 break;
1682 }
1683 case OPR_ADD: case OPR_SUB:
1684 #ifndef _KERNEL
1685 case OPR_MUL: case OPR_DIV: case OPR_IDIV:
1686 case OPR_MOD: case OPR_POW:
1687 #else /* _KERNEL */
1688 case OPR_MUL: case OPR_IDIV:
1689 case OPR_MOD:
1690 #endif /* _KERNEL */
1691 case OPR_BAND: case OPR_BOR: case OPR_BXOR:
1692 case OPR_SHL: case OPR_SHR: {
1693 if (!tonumeral(v, NULL))
1694 luaK_exp2anyreg(fs, v);
1695 /* else keep numeral, which may be folded or used as an immediate
1696 operand */
1697 break;
1698 }
1699 case OPR_EQ: case OPR_NE: {
1700 if (!tonumeral(v, NULL))
1701 luaK_exp2RK(fs, v);
1702 /* else keep numeral, which may be an immediate operand */
1703 break;
1704 }
1705 case OPR_LT: case OPR_LE:
1706 case OPR_GT: case OPR_GE: {
1707 int dummy, dummy2;
1708 if (!isSCnumber(v, &dummy, &dummy2))
1709 luaK_exp2anyreg(fs, v);
1710 /* else keep numeral, which may be an immediate operand */
1711 break;
1712 }
1713 default: lua_assert(0);
1714 }
1715 }
1716
1717 /*
1718 ** Create code for '(e1 .. e2)'.
1719 ** For '(e1 .. e2.1 .. e2.2)' (which is '(e1 .. (e2.1 .. e2.2))',
1720 ** because concatenation is right associative), merge both CONCATs.
1721 */
1722 static void codeconcat (FuncState *fs, expdesc *e1, expdesc *e2, int line) {
1723 Instruction *ie2 = previousinstruction(fs);
1724 if (GET_OPCODE(*ie2) == OP_CONCAT) { /* is 'e2' a concatenation? */
1725 int n = GETARG_B(*ie2); /* # of elements concatenated in 'e2' */
1726 lua_assert(e1->u.info + 1 == GETARG_A(*ie2));
1727 freeexp(fs, e2);
1728 SETARG_A(*ie2, e1->u.info); /* correct first element ('e1') */
1729 SETARG_B(*ie2, n + 1); /* will concatenate one more element */
1730 }
1731 else { /* 'e2' is not a concatenation */
1732 luaK_codeABC(fs, OP_CONCAT, e1->u.info, 2, 0); /* new concat opcode */
1733 freeexp(fs, e2);
1734 luaK_fixline(fs, line);
1735 }
1736 }
1737
1738
1739 /*
1740 ** Finalize code for binary operation, after reading 2nd operand.
1741 */
1742 void luaK_posfix (FuncState *fs, BinOpr opr,
1743 expdesc *e1, expdesc *e2, int line) {
1744 luaK_dischargevars(fs, e2);
1745 if (foldbinop(opr) && constfolding(fs, opr + LUA_OPADD, e1, e2))
1746 return; /* done by folding */
1747 switch (opr) {
1748 case OPR_AND: {
1749 lua_assert(e1->t == NO_JUMP); /* list closed by 'luaK_infix' */
1750 luaK_concat(fs, &e2->f, e1->f);
1751 *e1 = *e2;
1752 break;
1753 }
1754 case OPR_OR: {
1755 lua_assert(e1->f == NO_JUMP); /* list closed by 'luaK_infix' */
1756 luaK_concat(fs, &e2->t, e1->t);
1757 *e1 = *e2;
1758 break;
1759 }
1760 case OPR_CONCAT: { /* e1 .. e2 */
1761 luaK_exp2nextreg(fs, e2);
1762 codeconcat(fs, e1, e2, line);
1763 break;
1764 }
1765 case OPR_ADD: case OPR_MUL: {
1766 codecommutative(fs, opr, e1, e2, line);
1767 break;
1768 }
1769 case OPR_SUB: {
1770 if (finishbinexpneg(fs, e1, e2, OP_ADDI, line, TM_SUB))
1771 break; /* coded as (r1 + -I) */
1772 /* ELSE */
1773 } /* FALLTHROUGH */
1774 #ifndef _KERNEL
1775 case OPR_DIV: case OPR_IDIV: case OPR_MOD: case OPR_POW: {
1776 #else /* _KERNEL */
1777 case OPR_IDIV: case OPR_MOD: {
1778 #endif
1779 codearith(fs, opr, e1, e2, 0, line);
1780 break;
1781 }
1782 case OPR_BAND: case OPR_BOR: case OPR_BXOR: {
1783 codebitwise(fs, opr, e1, e2, line);
1784 break;
1785 }
1786 case OPR_SHL: {
1787 if (isSCint(e1)) {
1788 swapexps(e1, e2);
1789 codebini(fs, OP_SHLI, e1, e2, 1, line, TM_SHL); /* I << r2 */
1790 }
1791 else if (finishbinexpneg(fs, e1, e2, OP_SHRI, line, TM_SHL)) {
1792 /* coded as (r1 >> -I) */;
1793 }
1794 else /* regular case (two registers) */
1795 codebinexpval(fs, opr, e1, e2, line);
1796 break;
1797 }
1798 case OPR_SHR: {
1799 if (isSCint(e2))
1800 codebini(fs, OP_SHRI, e1, e2, 0, line, TM_SHR); /* r1 >> I */
1801 else /* regular case (two registers) */
1802 codebinexpval(fs, opr, e1, e2, line);
1803 break;
1804 }
1805 case OPR_EQ: case OPR_NE: {
1806 codeeq(fs, opr, e1, e2);
1807 break;
1808 }
1809 case OPR_GT: case OPR_GE: {
1810 /* '(a > b)' <=> '(b < a)'; '(a >= b)' <=> '(b <= a)' */
1811 swapexps(e1, e2);
1812 opr = cast(BinOpr, (opr - OPR_GT) + OPR_LT);
1813 } /* FALLTHROUGH */
1814 case OPR_LT: case OPR_LE: {
1815 codeorder(fs, opr, e1, e2);
1816 break;
1817 }
1818 default: lua_assert(0);
1819 }
1820 }
1821
1822
1823 /*
1824 ** Change line information associated with current position, by removing
1825 ** previous info and adding it again with new line.
1826 */
1827 void luaK_fixline (FuncState *fs, int line) {
1828 removelastlineinfo(fs);
1829 savelineinfo(fs, fs->f, line);
1830 }
1831
1832
1833 void luaK_settablesize (FuncState *fs, int pc, int ra, int asize, int hsize) {
1834 Instruction *inst = &fs->f->code[pc];
1835 int rb = (hsize != 0) ? luaO_ceillog2(hsize) + 1 : 0; /* hash size */
1836 int extra = asize / (MAXARG_C + 1); /* higher bits of array size */
1837 int rc = asize % (MAXARG_C + 1); /* lower bits of array size */
1838 int k = (extra > 0); /* true iff needs extra argument */
1839 *inst = CREATE_ABCk(OP_NEWTABLE, ra, rb, rc, k);
1840 *(inst + 1) = CREATE_Ax(OP_EXTRAARG, extra);
1841 }
1842
1843
1844 /*
1845 ** Emit a SETLIST instruction.
1846 ** 'base' is register that keeps table;
1847 ** 'nelems' is #table plus those to be stored now;
1848 ** 'tostore' is number of values (in registers 'base + 1',...) to add to
1849 ** table (or LUA_MULTRET to add up to stack top).
1850 */
1851 void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
1852 lua_assert(tostore != 0 && tostore <= LFIELDS_PER_FLUSH);
1853 if (tostore == LUA_MULTRET)
1854 tostore = 0;
1855 if (nelems <= MAXARG_C)
1856 luaK_codeABC(fs, OP_SETLIST, base, tostore, nelems);
1857 else {
1858 int extra = nelems / (MAXARG_C + 1);
1859 nelems %= (MAXARG_C + 1);
1860 luaK_codeABCk(fs, OP_SETLIST, base, tostore, nelems, 1);
1861 codeextraarg(fs, extra);
1862 }
1863 fs->freereg = base + 1; /* free registers with list values */
1864 }
1865
1866
1867 /*
1868 ** return the final target of a jump (skipping jumps to jumps)
1869 */
1870 static int finaltarget (Instruction *code, int i) {
1871 int count;
1872 for (count = 0; count < 100; count++) { /* avoid infinite loops */
1873 Instruction pc = code[i];
1874 if (GET_OPCODE(pc) != OP_JMP)
1875 break;
1876 else
1877 i += GETARG_sJ(pc) + 1;
1878 }
1879 return i;
1880 }
1881
1882
1883 /*
1884 ** Do a final pass over the code of a function, doing small peephole
1885 ** optimizations and adjustments.
1886 */
1887 void luaK_finish (FuncState *fs) {
1888 int i;
1889 Proto *p = fs->f;
1890 for (i = 0; i < fs->pc; i++) {
1891 Instruction *pc = &p->code[i];
1892 lua_assert(i == 0 || isOT(*(pc - 1)) == isIT(*pc));
1893 switch (GET_OPCODE(*pc)) {
1894 case OP_RETURN0: case OP_RETURN1: {
1895 if (!(fs->needclose || p->is_vararg))
1896 break; /* no extra work */
1897 /* else use OP_RETURN to do the extra work */
1898 SET_OPCODE(*pc, OP_RETURN);
1899 } /* FALLTHROUGH */
1900 case OP_RETURN: case OP_TAILCALL: {
1901 if (fs->needclose)
1902 SETARG_k(*pc, 1); /* signal that it needs to close */
1903 if (p->is_vararg)
1904 SETARG_C(*pc, p->numparams + 1); /* signal that it is vararg */
1905 break;
1906 }
1907 case OP_JMP: {
1908 int target = finaltarget(p->code, i);
1909 fixjump(fs, i, target);
1910 break;
1911 }
1912 default: break;
1913 }
1914 }
1915 }
1916