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  1. /*
  2. ** $Id: lcode.c,v 2.25.1.5 2011/01/31 14:53:16 roberto Exp $
  3. ** Code generator for Lua
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7.  
  8. #include <stdlib.h>
  9.  
  10. #define lcode_c
  11. #define LUA_CORE
  12.  
  13. #include "lua.h"
  14.  
  15. #include "lcode.h"
  16. #include "ldebug.h"
  17. #include "ldo.h"
  18. #include "lgc.h"
  19. #include "llex.h"
  20. #include "lmem.h"
  21. #include "lobject.h"
  22. #include "lopcodes.h"
  23. #include "lparser.h"
  24. #include "ltable.h"
  25.  
  26.  
  27. #define hasjumps(e)     ((e)->t != (e)->f)
  28.  
  29.  
  30. static int isnumeral(expdesc *e) {
  31.   return (e->k == VKNUM && e->t == NO_JUMP && e->f == NO_JUMP);
  32. }
  33.  
  34.  
  35. void luaK_nil (FuncState *fs, int from, int n) {
  36.   Instruction *previous;
  37.   if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
  38.     if (fs->pc == 0) {  /* function start? */
  39.       if (from >= fs->nactvar)
  40.         return;  /* positions are already clean */
  41.     }
  42.     else {
  43.       previous = &fs->f->code[fs->pc-1];
  44.       if (GET_OPCODE(*previous) == OP_LOADNIL) {
  45.         int pfrom = GETARG_A(*previous);
  46.         int pto = GETARG_B(*previous);
  47.         if (pfrom <= from && from <= pto+1) {  /* can connect both? */
  48.           if (from+n-1 > pto)
  49.             SETARG_B(*previous, from+n-1);
  50.           return;
  51.         }
  52.       }
  53.     }
  54.   }
  55.   luaK_codeABC(fs, OP_LOADNIL, from, from+n-1, 0);  /* else no optimization */
  56. }
  57.  
  58.  
  59. int luaK_jump (FuncState *fs) {
  60.   int jpc = fs->jpc;  /* save list of jumps to here */
  61.   int j;
  62.   fs->jpc = NO_JUMP;
  63.   j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
  64.   luaK_concat(fs, &j, jpc);  /* keep them on hold */
  65.   return j;
  66. }
  67.  
  68.  
  69. void luaK_ret (FuncState *fs, int first, int nret) {
  70.   luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
  71. }
  72.  
  73.  
  74. static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
  75.   luaK_codeABC(fs, op, A, B, C);
  76.   return luaK_jump(fs);
  77. }
  78.  
  79.  
  80. static void fixjump (FuncState *fs, int pc, int dest) {
  81.   Instruction *jmp = &fs->f->code[pc];
  82.   int offset = dest-(pc+1);
  83.   lua_assert(dest != NO_JUMP);
  84.   if (abs(offset) > MAXARG_sBx)
  85.     luaX_syntaxerror(fs->ls, "control structure too long");
  86.   SETARG_sBx(*jmp, offset);
  87. }
  88.  
  89.  
  90. /*
  91. ** returns current `pc' and marks it as a jump target (to avoid wrong
  92. ** optimizations with consecutive instructions not in the same basic block).
  93. */
  94. int luaK_getlabel (FuncState *fs) {
  95.   fs->lasttarget = fs->pc;
  96.   return fs->pc;
  97. }
  98.  
  99.  
  100. static int getjump (FuncState *fs, int pc) {
  101.   int offset = GETARG_sBx(fs->f->code[pc]);
  102.   if (offset == NO_JUMP)  /* point to itself represents end of list */
  103.     return NO_JUMP;  /* end of list */
  104.   else
  105.     return (pc+1)+offset;  /* turn offset into absolute position */
  106. }
  107.  
  108.  
  109. static Instruction *getjumpcontrol (FuncState *fs, int pc) {
  110.   Instruction *pi = &fs->f->code[pc];
  111.   if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
  112.     return pi-1;
  113.   else
  114.     return pi;
  115. }
  116.  
  117.  
  118. /*
  119. ** check whether list has any jump that do not produce a value
  120. ** (or produce an inverted value)
  121. */
  122. static int need_value (FuncState *fs, int list) {
  123.   for (; list != NO_JUMP; list = getjump(fs, list)) {
  124.     Instruction i = *getjumpcontrol(fs, list);
  125.     if (GET_OPCODE(i) != OP_TESTSET) return 1;
  126.   }
  127.   return 0;  /* not found */
  128. }
  129.  
  130.  
  131. static int patchtestreg (FuncState *fs, int node, int reg) {
  132.   Instruction *i = getjumpcontrol(fs, node);
  133.   if (GET_OPCODE(*i) != OP_TESTSET)
  134.     return 0;  /* cannot patch other instructions */
  135.   if (reg != NO_REG && reg != GETARG_B(*i))
  136.     SETARG_A(*i, reg);
  137.   else  /* no register to put value or register already has the value */
  138.     *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
  139.  
  140.   return 1;
  141. }
  142.  
  143.  
  144. static void removevalues (FuncState *fs, int list) {
  145.   for (; list != NO_JUMP; list = getjump(fs, list))
  146.       patchtestreg(fs, list, NO_REG);
  147. }
  148.  
  149.  
  150. static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
  151.                           int dtarget) {
  152.   while (list != NO_JUMP) {
  153.     int next = getjump(fs, list);
  154.     if (patchtestreg(fs, list, reg))
  155.       fixjump(fs, list, vtarget);
  156.     else
  157.       fixjump(fs, list, dtarget);  /* jump to default target */
  158.     list = next;
  159.   }
  160. }
  161.  
  162.  
  163. static void dischargejpc (FuncState *fs) {
  164.   patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
  165.   fs->jpc = NO_JUMP;
  166. }
  167.  
  168.  
  169. void luaK_patchlist (FuncState *fs, int list, int target) {
  170.   if (target == fs->pc)
  171.     luaK_patchtohere(fs, list);
  172.   else {
  173.     lua_assert(target < fs->pc);
  174.     patchlistaux(fs, list, target, NO_REG, target);
  175.   }
  176. }
  177.  
  178.  
  179. void luaK_patchtohere (FuncState *fs, int list) {
  180.   luaK_getlabel(fs);
  181.   luaK_concat(fs, &fs->jpc, list);
  182. }
  183.  
  184.  
  185. void luaK_concat (FuncState *fs, int *l1, int l2) {
  186.   if (l2 == NO_JUMP) return;
  187.   else if (*l1 == NO_JUMP)
  188.     *l1 = l2;
  189.   else {
  190.     int list = *l1;
  191.     int next;
  192.     while ((next = getjump(fs, list)) != NO_JUMP)  /* find last element */
  193.       list = next;
  194.     fixjump(fs, list, l2);
  195.   }
  196. }
  197.  
  198.  
  199. void luaK_checkstack (FuncState *fs, int n) {
  200.   int newstack = fs->freereg + n;
  201.   if (newstack > fs->f->maxstacksize) {
  202.     if (newstack >= MAXSTACK)
  203.       luaX_syntaxerror(fs->ls, "function or expression too complex");
  204.     fs->f->maxstacksize = cast_byte(newstack);
  205.   }
  206. }
  207.  
  208.  
  209. void luaK_reserveregs (FuncState *fs, int n) {
  210.   luaK_checkstack(fs, n);
  211.   fs->freereg += n;
  212. }
  213.  
  214.  
  215. static void freereg (FuncState *fs, int reg) {
  216.   if (!ISK(reg) && reg >= fs->nactvar) {
  217.     fs->freereg--;
  218.     lua_assert(reg == fs->freereg);
  219.   }
  220. }
  221.  
  222.  
  223. static void freeexp (FuncState *fs, expdesc *e) {
  224.   if (e->k == VNONRELOC)
  225.     freereg(fs, e->u.s.info);
  226. }
  227.  
  228.  
  229. static int addk (FuncState *fs, TValue *k, TValue *v) {
  230.   lua_State *L = fs->L;
  231.   TValue *idx = luaH_set(L, fs->h, k);
  232.   Proto *f = fs->f;
  233.   int oldsize = f->sizek;
  234.   if (ttisnumber(idx)) {
  235.     lua_assert(luaO_rawequalObj(&fs->f->k[cast_int(nvalue(idx))], v));
  236.     return cast_int(nvalue(idx));
  237.   }
  238.   else {  /* constant not found; create a new entry */
  239.     setnvalue(idx, cast_num(fs->nk));
  240.     luaM_growvector(L, f->k, fs->nk, f->sizek, TValue,
  241.                     MAXARG_Bx, "constant table overflow");
  242.     while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
  243.     setobj(L, &f->k[fs->nk], v);
  244.     luaC_barrier(L, f, v);
  245.     return fs->nk++;
  246.   }
  247. }
  248.  
  249.  
  250. int luaK_stringK (FuncState *fs, TString *s) {
  251.   TValue o;
  252.   setsvalue(fs->L, &o, s);
  253.   return addk(fs, &o, &o);
  254. }
  255.  
  256.  
  257. int luaK_numberK (FuncState *fs, lua_Number r) {
  258.   TValue o;
  259.   setnvalue(&o, r);
  260.   return addk(fs, &o, &o);
  261. }
  262.  
  263.  
  264. static int boolK (FuncState *fs, int b) {
  265.   TValue o;
  266.   setbvalue(&o, b);
  267.   return addk(fs, &o, &o);
  268. }
  269.  
  270.  
  271. static int nilK (FuncState *fs) {
  272.   TValue k, v;
  273.   setnilvalue(&v);
  274.   /* cannot use nil as key; instead use table itself to represent nil */
  275.   sethvalue(fs->L, &k, fs->h);
  276.   return addk(fs, &k, &v);
  277. }
  278.  
  279.  
  280. void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
  281.   if (e->k == VCALL) {  /* expression is an open function call? */
  282.     SETARG_C(getcode(fs, e), nresults+1);
  283.   }
  284.   else if (e->k == VVARARG) {
  285.     SETARG_B(getcode(fs, e), nresults+1);
  286.     SETARG_A(getcode(fs, e), fs->freereg);
  287.     luaK_reserveregs(fs, 1);
  288.   }
  289. }
  290.  
  291.  
  292. void luaK_setoneret (FuncState *fs, expdesc *e) {
  293.   if (e->k == VCALL) {  /* expression is an open function call? */
  294.     e->k = VNONRELOC;
  295.     e->u.s.info = GETARG_A(getcode(fs, e));
  296.   }
  297.   else if (e->k == VVARARG) {
  298.     SETARG_B(getcode(fs, e), 2);
  299.     e->k = VRELOCABLE;  /* can relocate its simple result */
  300.   }
  301. }
  302.  
  303.  
  304. void luaK_dischargevars (FuncState *fs, expdesc *e) {
  305.   switch (e->k) {
  306.     case VLOCAL: {
  307.       e->k = VNONRELOC;
  308.       break;
  309.     }
  310.     case VUPVAL: {
  311.       e->u.s.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.s.info, 0);
  312.       e->k = VRELOCABLE;
  313.       break;
  314.     }
  315.     case VGLOBAL: {
  316.       e->u.s.info = luaK_codeABx(fs, OP_GETGLOBAL, 0, e->u.s.info);
  317.       e->k = VRELOCABLE;
  318.       break;
  319.     }
  320.     case VINDEXED: {
  321.       freereg(fs, e->u.s.aux);
  322.       freereg(fs, e->u.s.info);
  323.       e->u.s.info = luaK_codeABC(fs, OP_GETTABLE, 0, e->u.s.info, e->u.s.aux);
  324.       e->k = VRELOCABLE;
  325.       break;
  326.     }
  327.     case VVARARG:
  328.     case VCALL: {
  329.       luaK_setoneret(fs, e);
  330.       break;
  331.     }
  332.     default: break;  /* there is one value available (somewhere) */
  333.   }
  334. }
  335.  
  336.  
  337. static int code_label (FuncState *fs, int A, int b, int jump) {
  338.   luaK_getlabel(fs);  /* those instructions may be jump targets */
  339.   return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
  340. }
  341.  
  342.  
  343. static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
  344.   luaK_dischargevars(fs, e);
  345.   switch (e->k) {
  346.     case VNIL: {
  347.       luaK_nil(fs, reg, 1);
  348.       break;
  349.     }
  350.     case VFALSE:  case VTRUE: {
  351.       luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
  352.       break;
  353.     }
  354.     case VK: {
  355.       luaK_codeABx(fs, OP_LOADK, reg, e->u.s.info);
  356.       break;
  357.     }
  358.     case VKNUM: {
  359.       luaK_codeABx(fs, OP_LOADK, reg, luaK_numberK(fs, e->u.nval));
  360.       break;
  361.     }
  362.     case VRELOCABLE: {
  363.       Instruction *pc = &getcode(fs, e);
  364.       SETARG_A(*pc, reg);
  365.       break;
  366.     }
  367.     case VNONRELOC: {
  368.       if (reg != e->u.s.info)
  369.         luaK_codeABC(fs, OP_MOVE, reg, e->u.s.info, 0);
  370.       break;
  371.     }
  372.     default: {
  373.       lua_assert(e->k == VVOID || e->k == VJMP);
  374.       return;  /* nothing to do... */
  375.     }
  376.   }
  377.   e->u.s.info = reg;
  378.   e->k = VNONRELOC;
  379. }
  380.  
  381.  
  382. static void discharge2anyreg (FuncState *fs, expdesc *e) {
  383.   if (e->k != VNONRELOC) {
  384.     luaK_reserveregs(fs, 1);
  385.     discharge2reg(fs, e, fs->freereg-1);
  386.   }
  387. }
  388.  
  389.  
  390. static void exp2reg (FuncState *fs, expdesc *e, int reg) {
  391.   discharge2reg(fs, e, reg);
  392.   if (e->k == VJMP)
  393.     luaK_concat(fs, &e->t, e->u.s.info);  /* put this jump in `t' list */
  394.   if (hasjumps(e)) {
  395.     int final;  /* position after whole expression */
  396.     int p_f = NO_JUMP;  /* position of an eventual LOAD false */
  397.     int p_t = NO_JUMP;  /* position of an eventual LOAD true */
  398.     if (need_value(fs, e->t) || need_value(fs, e->f)) {
  399.       int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
  400.       p_f = code_label(fs, reg, 0, 1);
  401.       p_t = code_label(fs, reg, 1, 0);
  402.       luaK_patchtohere(fs, fj);
  403.     }
  404.     final = luaK_getlabel(fs);
  405.     patchlistaux(fs, e->f, final, reg, p_f);
  406.     patchlistaux(fs, e->t, final, reg, p_t);
  407.   }
  408.   e->f = e->t = NO_JUMP;
  409.   e->u.s.info = reg;
  410.   e->k = VNONRELOC;
  411. }
  412.  
  413.  
  414. void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
  415.   luaK_dischargevars(fs, e);
  416.   freeexp(fs, e);
  417.   luaK_reserveregs(fs, 1);
  418.   exp2reg(fs, e, fs->freereg - 1);
  419. }
  420.  
  421.  
  422. int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
  423.   luaK_dischargevars(fs, e);
  424.   if (e->k == VNONRELOC) {
  425.     if (!hasjumps(e)) return e->u.s.info;  /* exp is already in a register */
  426.     if (e->u.s.info >= fs->nactvar) {  /* reg. is not a local? */
  427.       exp2reg(fs, e, e->u.s.info);  /* put value on it */
  428.       return e->u.s.info;
  429.     }
  430.   }
  431.   luaK_exp2nextreg(fs, e);  /* default */
  432.   return e->u.s.info;
  433. }
  434.  
  435.  
  436. void luaK_exp2val (FuncState *fs, expdesc *e) {
  437.   if (hasjumps(e))
  438.     luaK_exp2anyreg(fs, e);
  439.   else
  440.     luaK_dischargevars(fs, e);
  441. }
  442.  
  443.  
  444. int luaK_exp2RK (FuncState *fs, expdesc *e) {
  445.   luaK_exp2val(fs, e);
  446.   switch (e->k) {
  447.     case VKNUM:
  448.     case VTRUE:
  449.     case VFALSE:
  450.     case VNIL: {
  451.       if (fs->nk <= MAXINDEXRK) {  /* constant fit in RK operand? */
  452.         e->u.s.info = (e->k == VNIL)  ? nilK(fs) :
  453.                       (e->k == VKNUM) ? luaK_numberK(fs, e->u.nval) :
  454.                                         boolK(fs, (e->k == VTRUE));
  455.         e->k = VK;
  456.         return RKASK(e->u.s.info);
  457.       }
  458.       else break;
  459.     }
  460.     case VK: {
  461.       if (e->u.s.info <= MAXINDEXRK)  /* constant fit in argC? */
  462.         return RKASK(e->u.s.info);
  463.       else break;
  464.     }
  465.     default: break;
  466.   }
  467.   /* not a constant in the right range: put it in a register */
  468.   return luaK_exp2anyreg(fs, e);
  469. }
  470.  
  471.  
  472. void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
  473.   switch (var->k) {
  474.     case VLOCAL: {
  475.       freeexp(fs, ex);
  476.       exp2reg(fs, ex, var->u.s.info);
  477.       return;
  478.     }
  479.     case VUPVAL: {
  480.       int e = luaK_exp2anyreg(fs, ex);
  481.       luaK_codeABC(fs, OP_SETUPVAL, e, var->u.s.info, 0);
  482.       break;
  483.     }
  484.     case VGLOBAL: {
  485.       int e = luaK_exp2anyreg(fs, ex);
  486.       luaK_codeABx(fs, OP_SETGLOBAL, e, var->u.s.info);
  487.       break;
  488.     }
  489.     case VINDEXED: {
  490.       int e = luaK_exp2RK(fs, ex);
  491.       luaK_codeABC(fs, OP_SETTABLE, var->u.s.info, var->u.s.aux, e);
  492.       break;
  493.     }
  494.     default: {
  495.       lua_assert(0);  /* invalid var kind to store */
  496.       break;
  497.     }
  498.   }
  499.   freeexp(fs, ex);
  500. }
  501.  
  502.  
  503. void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
  504.   int func;
  505.   luaK_exp2anyreg(fs, e);
  506.   freeexp(fs, e);
  507.   func = fs->freereg;
  508.   luaK_reserveregs(fs, 2);
  509.   luaK_codeABC(fs, OP_SELF, func, e->u.s.info, luaK_exp2RK(fs, key));
  510.   freeexp(fs, key);
  511.   e->u.s.info = func;
  512.   e->k = VNONRELOC;
  513. }
  514.  
  515.  
  516. static void invertjump (FuncState *fs, expdesc *e) {
  517.   Instruction *pc = getjumpcontrol(fs, e->u.s.info);
  518.   lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
  519.                                            GET_OPCODE(*pc) != OP_TEST);
  520.   SETARG_A(*pc, !(GETARG_A(*pc)));
  521. }
  522.  
  523.  
  524. static int jumponcond (FuncState *fs, expdesc *e, int cond) {
  525.   if (e->k == VRELOCABLE) {
  526.     Instruction ie = getcode(fs, e);
  527.     if (GET_OPCODE(ie) == OP_NOT) {
  528.       fs->pc--;  /* remove previous OP_NOT */
  529.       return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
  530.     }
  531.     /* else go through */
  532.   }
  533.   discharge2anyreg(fs, e);
  534.   freeexp(fs, e);
  535.   return condjump(fs, OP_TESTSET, NO_REG, e->u.s.info, cond);
  536. }
  537.  
  538.  
  539. void luaK_goiftrue (FuncState *fs, expdesc *e) {
  540.   int pc;  /* pc of last jump */
  541.   luaK_dischargevars(fs, e);
  542.   switch (e->k) {
  543.     case VK: case VKNUM: case VTRUE: {
  544.       pc = NO_JUMP;  /* always true; do nothing */
  545.       break;
  546.     }
  547.     case VJMP: {
  548.       invertjump(fs, e);
  549.       pc = e->u.s.info;
  550.       break;
  551.     }
  552.     default: {
  553.       pc = jumponcond(fs, e, 0);
  554.       break;
  555.     }
  556.   }
  557.   luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
  558.   luaK_patchtohere(fs, e->t);
  559.   e->t = NO_JUMP;
  560. }
  561.  
  562.  
  563. static void luaK_goiffalse (FuncState *fs, expdesc *e) {
  564.   int pc;  /* pc of last jump */
  565.   luaK_dischargevars(fs, e);
  566.   switch (e->k) {
  567.     case VNIL: case VFALSE: {
  568.       pc = NO_JUMP;  /* always false; do nothing */
  569.       break;
  570.     }
  571.     case VJMP: {
  572.       pc = e->u.s.info;
  573.       break;
  574.     }
  575.     default: {
  576.       pc = jumponcond(fs, e, 1);
  577.       break;
  578.     }
  579.   }
  580.   luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
  581.   luaK_patchtohere(fs, e->f);
  582.   e->f = NO_JUMP;
  583. }
  584.  
  585.  
  586. static void codenot (FuncState *fs, expdesc *e) {
  587.   luaK_dischargevars(fs, e);
  588.   switch (e->k) {
  589.     case VNIL: case VFALSE: {
  590.       e->k = VTRUE;
  591.       break;
  592.     }
  593.     case VK: case VKNUM: case VTRUE: {
  594.       e->k = VFALSE;
  595.       break;
  596.     }
  597.     case VJMP: {
  598.       invertjump(fs, e);
  599.       break;
  600.     }
  601.     case VRELOCABLE:
  602.     case VNONRELOC: {
  603.       discharge2anyreg(fs, e);
  604.       freeexp(fs, e);
  605.       e->u.s.info = luaK_codeABC(fs, OP_NOT, 0, e->u.s.info, 0);
  606.       e->k = VRELOCABLE;
  607.       break;
  608.     }
  609.     default: {
  610.       lua_assert(0);  /* cannot happen */
  611.       break;
  612.     }
  613.   }
  614.   /* interchange true and false lists */
  615.   { int temp = e->f; e->f = e->t; e->t = temp; }
  616.   removevalues(fs, e->f);
  617.   removevalues(fs, e->t);
  618. }
  619.  
  620.  
  621. void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
  622.   t->u.s.aux = luaK_exp2RK(fs, k);
  623.   t->k = VINDEXED;
  624. }
  625.  
  626.  
  627. static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
  628.   lua_Number v1, v2, r;
  629.   if (!isnumeral(e1) || !isnumeral(e2)) return 0;
  630.   v1 = e1->u.nval;
  631.   v2 = e2->u.nval;
  632.   switch (op) {
  633.     case OP_ADD: r = luai_numadd(v1, v2); break;
  634.     case OP_SUB: r = luai_numsub(v1, v2); break;
  635.     case OP_MUL: r = luai_nummul(v1, v2); break;
  636.     case OP_DIV:
  637.       if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
  638.       r = luai_numdiv(v1, v2); break;
  639.     case OP_MOD:
  640.       if (v2 == 0) return 0;  /* do not attempt to divide by 0 */
  641.       r = luai_nummod(v1, v2); break;
  642.     case OP_POW: r = luai_numpow(v1, v2); break;
  643.     case OP_UNM: r = luai_numunm(v1); break;
  644.     case OP_LEN: return 0;  /* no constant folding for 'len' */
  645.     default: lua_assert(0); r = 0; break;
  646.   }
  647.   if (luai_numisnan(r)) return 0;  /* do not attempt to produce NaN */
  648.   e1->u.nval = r;
  649.   return 1;
  650. }
  651.  
  652.  
  653. static void codearith (FuncState *fs, OpCode op, expdesc *e1, expdesc *e2) {
  654.   if (constfolding(op, e1, e2))
  655.     return;
  656.   else {
  657.     int o2 = (op != OP_UNM && op != OP_LEN) ? luaK_exp2RK(fs, e2) : 0;
  658.     int o1 = luaK_exp2RK(fs, e1);
  659.     if (o1 > o2) {
  660.       freeexp(fs, e1);
  661.       freeexp(fs, e2);
  662.     }
  663.     else {
  664.       freeexp(fs, e2);
  665.       freeexp(fs, e1);
  666.     }
  667.     e1->u.s.info = luaK_codeABC(fs, op, 0, o1, o2);
  668.     e1->k = VRELOCABLE;
  669.   }
  670. }
  671.  
  672.  
  673. static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
  674.                                                           expdesc *e2) {
  675.   int o1 = luaK_exp2RK(fs, e1);
  676.   int o2 = luaK_exp2RK(fs, e2);
  677.   freeexp(fs, e2);
  678.   freeexp(fs, e1);
  679.   if (cond == 0 && op != OP_EQ) {
  680.     int temp;  /* exchange args to replace by `<' or `<=' */
  681.     temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
  682.     cond = 1;
  683.   }
  684.   e1->u.s.info = condjump(fs, op, cond, o1, o2);
  685.   e1->k = VJMP;
  686. }
  687.  
  688.  
  689. void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e) {
  690.   expdesc e2;
  691.   e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
  692.   switch (op) {
  693.     case OPR_MINUS: {
  694.       if (!isnumeral(e))
  695.         luaK_exp2anyreg(fs, e);  /* cannot operate on non-numeric constants */
  696.       codearith(fs, OP_UNM, e, &e2);
  697.       break;
  698.     }
  699.     case OPR_NOT: codenot(fs, e); break;
  700.     case OPR_LEN: {
  701.       luaK_exp2anyreg(fs, e);  /* cannot operate on constants */
  702.       codearith(fs, OP_LEN, e, &e2);
  703.       break;
  704.     }
  705.     default: lua_assert(0);
  706.   }
  707. }
  708.  
  709.  
  710. void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
  711.   switch (op) {
  712.     case OPR_AND: {
  713.       luaK_goiftrue(fs, v);
  714.       break;
  715.     }
  716.     case OPR_OR: {
  717.       luaK_goiffalse(fs, v);
  718.       break;
  719.     }
  720.     case OPR_CONCAT: {
  721.       luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
  722.       break;
  723.     }
  724.     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
  725.     case OPR_MOD: case OPR_POW: {
  726.       if (!isnumeral(v)) luaK_exp2RK(fs, v);
  727.       break;
  728.     }
  729.     default: {
  730.       luaK_exp2RK(fs, v);
  731.       break;
  732.     }
  733.   }
  734. }
  735.  
  736.  
  737. void luaK_posfix (FuncState *fs, BinOpr op, expdesc *e1, expdesc *e2) {
  738.   switch (op) {
  739.     case OPR_AND: {
  740.       lua_assert(e1->t == NO_JUMP);  /* list must be closed */
  741.       luaK_dischargevars(fs, e2);
  742.       luaK_concat(fs, &e2->f, e1->f);
  743.       *e1 = *e2;
  744.       break;
  745.     }
  746.     case OPR_OR: {
  747.       lua_assert(e1->f == NO_JUMP);  /* list must be closed */
  748.       luaK_dischargevars(fs, e2);
  749.       luaK_concat(fs, &e2->t, e1->t);
  750.       *e1 = *e2;
  751.       break;
  752.     }
  753.     case OPR_CONCAT: {
  754.       luaK_exp2val(fs, e2);
  755.       if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
  756.         lua_assert(e1->u.s.info == GETARG_B(getcode(fs, e2))-1);
  757.         freeexp(fs, e1);
  758.         SETARG_B(getcode(fs, e2), e1->u.s.info);
  759.         e1->k = VRELOCABLE; e1->u.s.info = e2->u.s.info;
  760.       }
  761.       else {
  762.         luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
  763.         codearith(fs, OP_CONCAT, e1, e2);
  764.       }
  765.       break;
  766.     }
  767.     case OPR_ADD: codearith(fs, OP_ADD, e1, e2); break;
  768.     case OPR_SUB: codearith(fs, OP_SUB, e1, e2); break;
  769.     case OPR_MUL: codearith(fs, OP_MUL, e1, e2); break;
  770.     case OPR_DIV: codearith(fs, OP_DIV, e1, e2); break;
  771.     case OPR_MOD: codearith(fs, OP_MOD, e1, e2); break;
  772.     case OPR_POW: codearith(fs, OP_POW, e1, e2); break;
  773.     case OPR_EQ: codecomp(fs, OP_EQ, 1, e1, e2); break;
  774.     case OPR_NE: codecomp(fs, OP_EQ, 0, e1, e2); break;
  775.     case OPR_LT: codecomp(fs, OP_LT, 1, e1, e2); break;
  776.     case OPR_LE: codecomp(fs, OP_LE, 1, e1, e2); break;
  777.     case OPR_GT: codecomp(fs, OP_LT, 0, e1, e2); break;
  778.     case OPR_GE: codecomp(fs, OP_LE, 0, e1, e2); break;
  779.     default: lua_assert(0);
  780.   }
  781. }
  782.  
  783.  
  784. void luaK_fixline (FuncState *fs, int line) {
  785.   fs->f->lineinfo[fs->pc - 1] = line;
  786. }
  787.  
  788.  
  789. static int luaK_code (FuncState *fs, Instruction i, int line) {
  790.   Proto *f = fs->f;
  791.   dischargejpc(fs);  /* `pc' will change */
  792.   /* put new instruction in code array */
  793.   luaM_growvector(fs->L, f->code, fs->pc, f->sizecode, Instruction,
  794.                   MAX_INT, "code size overflow");
  795.   f->code[fs->pc] = i;
  796.   /* save corresponding line information */
  797.   luaM_growvector(fs->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
  798.                   MAX_INT, "code size overflow");
  799.   f->lineinfo[fs->pc] = line;
  800.   return fs->pc++;
  801. }
  802.  
  803.  
  804. int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
  805.   lua_assert(getOpMode(o) == iABC);
  806.   lua_assert(getBMode(o) != OpArgN || b == 0);
  807.   lua_assert(getCMode(o) != OpArgN || c == 0);
  808.   return luaK_code(fs, CREATE_ABC(o, a, b, c), fs->ls->lastline);
  809. }
  810.  
  811.  
  812. int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
  813.   lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
  814.   lua_assert(getCMode(o) == OpArgN);
  815.   return luaK_code(fs, CREATE_ABx(o, a, bc), fs->ls->lastline);
  816. }
  817.  
  818.  
  819. void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
  820.   int c =  (nelems - 1)/LFIELDS_PER_FLUSH + 1;
  821.   int b = (tostore == LUA_MULTRET) ? 0 : tostore;
  822.   lua_assert(tostore != 0);
  823.   if (c <= MAXARG_C)
  824.     luaK_codeABC(fs, OP_SETLIST, base, b, c);
  825.   else {
  826.     luaK_codeABC(fs, OP_SETLIST, base, b, 0);
  827.     luaK_code(fs, cast(Instruction, c), fs->ls->lastline);
  828.   }
  829.   fs->freereg = base + 1;  /* free registers with list values */
  830. }
  831.  
  832.