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  1. /*
  2. ** $Id: lcode.c,v 2.60 2011/08/30 16:26:41 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 "lstring.h"
  25. #include "ltable.h"
  26. #include "lvm.h"
  27.  
  28.  
  29. #define hasjumps(e)     ((e)->t != (e)->f)
  30.  
  31.  
  32. static int isnumeral(expdesc *e) {
  33.   return (e->k == VKNUM && e->t == NO_JUMP && e->f == NO_JUMP);
  34. }
  35.  
  36.  
  37. void luaK_nil (FuncState *fs, int from, int n) {
  38.   Instruction *previous;
  39.   int l = from + n - 1;  /* last register to set nil */
  40.   if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
  41.     previous = &fs->f->code[fs->pc-1];
  42.     if (GET_OPCODE(*previous) == OP_LOADNIL) {
  43.       int pfrom = GETARG_A(*previous);
  44.       int pl = pfrom + GETARG_B(*previous);
  45.       if ((pfrom <= from && from <= pl + 1) ||
  46.           (from <= pfrom && pfrom <= l + 1)) {  /* can connect both? */
  47.         if (pfrom < from) from = pfrom;  /* from = min(from, pfrom) */
  48.         if (pl > l) l = pl;  /* l = max(l, pl) */
  49.         SETARG_A(*previous, from);
  50.         SETARG_B(*previous, l - from);
  51.         return;
  52.       }
  53.     }  /* else go through */
  54.   }
  55.   luaK_codeABC(fs, OP_LOADNIL, 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. LUAI_FUNC void luaK_patchclose (FuncState *fs, int list, int level) {
  180.   level++;  /* argument is +1 to reserve 0 as non-op */
  181.   while (list != NO_JUMP) {
  182.     int next = getjump(fs, list);
  183.     lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP &&
  184.                 (GETARG_A(fs->f->code[list]) == 0 ||
  185.                  GETARG_A(fs->f->code[list]) >= level));
  186.     SETARG_A(fs->f->code[list], level);
  187.     list = next;
  188.   }
  189. }
  190.  
  191.  
  192. void luaK_patchtohere (FuncState *fs, int list) {
  193.   luaK_getlabel(fs);
  194.   luaK_concat(fs, &fs->jpc, list);
  195. }
  196.  
  197.  
  198. void luaK_concat (FuncState *fs, int *l1, int l2) {
  199.   if (l2 == NO_JUMP) return;
  200.   else if (*l1 == NO_JUMP)
  201.     *l1 = l2;
  202.   else {
  203.     int list = *l1;
  204.     int next;
  205.     while ((next = getjump(fs, list)) != NO_JUMP)  /* find last element */
  206.       list = next;
  207.     fixjump(fs, list, l2);
  208.   }
  209. }
  210.  
  211.  
  212. static int luaK_code (FuncState *fs, Instruction i) {
  213.   Proto *f = fs->f;
  214.   dischargejpc(fs);  /* `pc' will change */
  215.   /* put new instruction in code array */
  216.   luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,
  217.                   MAX_INT, "opcodes");
  218.   f->code[fs->pc] = i;
  219.   /* save corresponding line information */
  220.   luaM_growvector(fs->ls->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
  221.                   MAX_INT, "opcodes");
  222.   f->lineinfo[fs->pc] = fs->ls->lastline;
  223.   return fs->pc++;
  224. }
  225.  
  226.  
  227. int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
  228.   lua_assert(getOpMode(o) == iABC);
  229.   lua_assert(getBMode(o) != OpArgN || b == 0);
  230.   lua_assert(getCMode(o) != OpArgN || c == 0);
  231.   lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);
  232.   return luaK_code(fs, CREATE_ABC(o, a, b, c));
  233. }
  234.  
  235.  
  236. int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
  237.   lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
  238.   lua_assert(getCMode(o) == OpArgN);
  239.   lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
  240.   return luaK_code(fs, CREATE_ABx(o, a, bc));
  241. }
  242.  
  243.  
  244. static int codeextraarg (FuncState *fs, int a) {
  245.   lua_assert(a <= MAXARG_Ax);
  246.   return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a));
  247. }
  248.  
  249.  
  250. int luaK_codek (FuncState *fs, int reg, int k) {
  251.   if (k <= MAXARG_Bx)
  252.     return luaK_codeABx(fs, OP_LOADK, reg, k);
  253.   else {
  254.     int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);
  255.     codeextraarg(fs, k);
  256.     return p;
  257.   }
  258. }
  259.  
  260.  
  261. void luaK_checkstack (FuncState *fs, int n) {
  262.   int newstack = fs->freereg + n;
  263.   if (newstack > fs->f->maxstacksize) {
  264.     if (newstack >= MAXSTACK)
  265.       luaX_syntaxerror(fs->ls, "function or expression too complex");
  266.     fs->f->maxstacksize = cast_byte(newstack);
  267.   }
  268. }
  269.  
  270.  
  271. void luaK_reserveregs (FuncState *fs, int n) {
  272.   luaK_checkstack(fs, n);
  273.   fs->freereg += n;
  274. }
  275.  
  276.  
  277. static void freereg (FuncState *fs, int reg) {
  278.   if (!ISK(reg) && reg >= fs->nactvar) {
  279.     fs->freereg--;
  280.     lua_assert(reg == fs->freereg);
  281.   }
  282. }
  283.  
  284.  
  285. static void freeexp (FuncState *fs, expdesc *e) {
  286.   if (e->k == VNONRELOC)
  287.     freereg(fs, e->u.info);
  288. }
  289.  
  290.  
  291. static int addk (FuncState *fs, TValue *key, TValue *v) {
  292.   lua_State *L = fs->ls->L;
  293.   TValue *idx = luaH_set(L, fs->h, key);
  294.   Proto *f = fs->f;
  295.   int k, oldsize;
  296.   if (ttisnumber(idx)) {
  297.     lua_Number n = nvalue(idx);
  298.     lua_number2int(k, n);
  299.     if (luaV_rawequalobj(&f->k[k], v))
  300.       return k;
  301.     /* else may be a collision (e.g., between 0.0 and "\0\0\0\0\0\0\0\0");
  302.        go through and create a new entry for this value */
  303.   }
  304.   /* constant not found; create a new entry */
  305.   oldsize = f->sizek;
  306.   k = fs->nk;
  307.   /* numerical value does not need GC barrier;
  308.      table has no metatable, so it does not need to invalidate cache */
  309.   setnvalue(idx, cast_num(k));
  310.   luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");
  311.   while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
  312.   setobj(L, &f->k[k], v);
  313.   fs->nk++;
  314.   luaC_barrier(L, f, v);
  315.   return k;
  316. }
  317.  
  318.  
  319. int luaK_stringK (FuncState *fs, TString *s) {
  320.   TValue o;
  321.   setsvalue(fs->ls->L, &o, s);
  322.   return addk(fs, &o, &o);
  323. }
  324.  
  325.  
  326. int luaK_numberK (FuncState *fs, lua_Number r) {
  327.   int n;
  328.   lua_State *L = fs->ls->L;
  329.   TValue o;
  330.   setnvalue(&o, r);
  331.   if (r == 0 || luai_numisnan(NULL, r)) {  /* handle -0 and NaN */
  332.     /* use raw representation as key to avoid numeric problems */
  333.     setsvalue(L, L->top, luaS_newlstr(L, (char *)&r, sizeof(r)));
  334.      incr_top(L);
  335.      n = addk(fs, L->top - 1, &o);
  336.      L->top--;
  337.   }
  338.   else
  339.     n = addk(fs, &o, &o);  /* regular case */
  340.   return n;
  341. }
  342.  
  343.  
  344. static int boolK (FuncState *fs, int b) {
  345.   TValue o;
  346.   setbvalue(&o, b);
  347.   return addk(fs, &o, &o);
  348. }
  349.  
  350.  
  351. static int nilK (FuncState *fs) {
  352.   TValue k, v;
  353.   setnilvalue(&v);
  354.   /* cannot use nil as key; instead use table itself to represent nil */
  355.   sethvalue(fs->ls->L, &k, fs->h);
  356.   return addk(fs, &k, &v);
  357. }
  358.  
  359.  
  360. void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
  361.   if (e->k == VCALL) {  /* expression is an open function call? */
  362.     SETARG_C(getcode(fs, e), nresults+1);
  363.   }
  364.   else if (e->k == VVARARG) {
  365.     SETARG_B(getcode(fs, e), nresults+1);
  366.     SETARG_A(getcode(fs, e), fs->freereg);
  367.     luaK_reserveregs(fs, 1);
  368.   }
  369. }
  370.  
  371.  
  372. void luaK_setoneret (FuncState *fs, expdesc *e) {
  373.   if (e->k == VCALL) {  /* expression is an open function call? */
  374.     e->k = VNONRELOC;
  375.     e->u.info = GETARG_A(getcode(fs, e));
  376.   }
  377.   else if (e->k == VVARARG) {
  378.     SETARG_B(getcode(fs, e), 2);
  379.     e->k = VRELOCABLE;  /* can relocate its simple result */
  380.   }
  381. }
  382.  
  383.  
  384. void luaK_dischargevars (FuncState *fs, expdesc *e) {
  385.   switch (e->k) {
  386.     case VLOCAL: {
  387.       e->k = VNONRELOC;
  388.       break;
  389.     }
  390.     case VUPVAL: {
  391.       e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
  392.       e->k = VRELOCABLE;
  393.       break;
  394.     }
  395.     case VINDEXED: {
  396.       OpCode op = OP_GETTABUP;  /* assume 't' is in an upvalue */
  397.       freereg(fs, e->u.ind.idx);
  398.       if (e->u.ind.vt == VLOCAL) {  /* 't' is in a register? */
  399.         freereg(fs, e->u.ind.t);
  400.         op = OP_GETTABLE;
  401.       }
  402.       e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx);
  403.       e->k = VRELOCABLE;
  404.       break;
  405.     }
  406.     case VVARARG:
  407.     case VCALL: {
  408.       luaK_setoneret(fs, e);
  409.       break;
  410.     }
  411.     default: break;  /* there is one value available (somewhere) */
  412.   }
  413. }
  414.  
  415.  
  416. static int code_label (FuncState *fs, int A, int b, int jump) {
  417.   luaK_getlabel(fs);  /* those instructions may be jump targets */
  418.   return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
  419. }
  420.  
  421.  
  422. static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
  423.   luaK_dischargevars(fs, e);
  424.   switch (e->k) {
  425.     case VNIL: {
  426.       luaK_nil(fs, reg, 1);
  427.       break;
  428.     }
  429.     case VFALSE:  case VTRUE: {
  430.       luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
  431.       break;
  432.     }
  433.     case VK: {
  434.       luaK_codek(fs, reg, e->u.info);
  435.       break;
  436.     }
  437.     case VKNUM: {
  438.       luaK_codek(fs, reg, luaK_numberK(fs, e->u.nval));
  439.       break;
  440.     }
  441.     case VRELOCABLE: {
  442.       Instruction *pc = &getcode(fs, e);
  443.       SETARG_A(*pc, reg);
  444.       break;
  445.     }
  446.     case VNONRELOC: {
  447.       if (reg != e->u.info)
  448.         luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
  449.       break;
  450.     }
  451.     default: {
  452.       lua_assert(e->k == VVOID || e->k == VJMP);
  453.       return;  /* nothing to do... */
  454.     }
  455.   }
  456.   e->u.info = reg;
  457.   e->k = VNONRELOC;
  458. }
  459.  
  460.  
  461. static void discharge2anyreg (FuncState *fs, expdesc *e) {
  462.   if (e->k != VNONRELOC) {
  463.     luaK_reserveregs(fs, 1);
  464.     discharge2reg(fs, e, fs->freereg-1);
  465.   }
  466. }
  467.  
  468.  
  469. static void exp2reg (FuncState *fs, expdesc *e, int reg) {
  470.   discharge2reg(fs, e, reg);
  471.   if (e->k == VJMP)
  472.     luaK_concat(fs, &e->t, e->u.info);  /* put this jump in `t' list */
  473.   if (hasjumps(e)) {
  474.     int final;  /* position after whole expression */
  475.     int p_f = NO_JUMP;  /* position of an eventual LOAD false */
  476.     int p_t = NO_JUMP;  /* position of an eventual LOAD true */
  477.     if (need_value(fs, e->t) || need_value(fs, e->f)) {
  478.       int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
  479.       p_f = code_label(fs, reg, 0, 1);
  480.       p_t = code_label(fs, reg, 1, 0);
  481.       luaK_patchtohere(fs, fj);
  482.     }
  483.     final = luaK_getlabel(fs);
  484.     patchlistaux(fs, e->f, final, reg, p_f);
  485.     patchlistaux(fs, e->t, final, reg, p_t);
  486.   }
  487.   e->f = e->t = NO_JUMP;
  488.   e->u.info = reg;
  489.   e->k = VNONRELOC;
  490. }
  491.  
  492.  
  493. void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
  494.   luaK_dischargevars(fs, e);
  495.   freeexp(fs, e);
  496.   luaK_reserveregs(fs, 1);
  497.   exp2reg(fs, e, fs->freereg - 1);
  498. }
  499.  
  500.  
  501. int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
  502.   luaK_dischargevars(fs, e);
  503.   if (e->k == VNONRELOC) {
  504.     if (!hasjumps(e)) return e->u.info;  /* exp is already in a register */
  505.     if (e->u.info >= fs->nactvar) {  /* reg. is not a local? */
  506.       exp2reg(fs, e, e->u.info);  /* put value on it */
  507.       return e->u.info;
  508.     }
  509.   }
  510.   luaK_exp2nextreg(fs, e);  /* default */
  511.   return e->u.info;
  512. }
  513.  
  514.  
  515. void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
  516.   if (e->k != VUPVAL || hasjumps(e))
  517.     luaK_exp2anyreg(fs, e);
  518. }
  519.  
  520.  
  521. void luaK_exp2val (FuncState *fs, expdesc *e) {
  522.   if (hasjumps(e))
  523.     luaK_exp2anyreg(fs, e);
  524.   else
  525.     luaK_dischargevars(fs, e);
  526. }
  527.  
  528.  
  529. int luaK_exp2RK (FuncState *fs, expdesc *e) {
  530.   luaK_exp2val(fs, e);
  531.   switch (e->k) {
  532.     case VTRUE:
  533.     case VFALSE:
  534.     case VNIL: {
  535.       if (fs->nk <= MAXINDEXRK) {  /* constant fits in RK operand? */
  536.         e->u.info = (e->k == VNIL) ? nilK(fs) : boolK(fs, (e->k == VTRUE));
  537.         e->k = VK;
  538.         return RKASK(e->u.info);
  539.       }
  540.       else break;
  541.     }
  542.     case VKNUM: {
  543.       e->u.info = luaK_numberK(fs, e->u.nval);
  544.       e->k = VK;
  545.       /* go through */
  546.     }
  547.     case VK: {
  548.       if (e->u.info <= MAXINDEXRK)  /* constant fits in argC? */
  549.         return RKASK(e->u.info);
  550.       else break;
  551.     }
  552.     default: break;
  553.   }
  554.   /* not a constant in the right range: put it in a register */
  555.   return luaK_exp2anyreg(fs, e);
  556. }
  557.  
  558.  
  559. void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
  560.   switch (var->k) {
  561.     case VLOCAL: {
  562.       freeexp(fs, ex);
  563.       exp2reg(fs, ex, var->u.info);
  564.       return;
  565.     }
  566.     case VUPVAL: {
  567.       int e = luaK_exp2anyreg(fs, ex);
  568.       luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
  569.       break;
  570.     }
  571.     case VINDEXED: {
  572.       OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;
  573.       int e = luaK_exp2RK(fs, ex);
  574.       luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e);
  575.       break;
  576.     }
  577.     default: {
  578.       lua_assert(0);  /* invalid var kind to store */
  579.       break;
  580.     }
  581.   }
  582.   freeexp(fs, ex);
  583. }
  584.  
  585.  
  586. void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
  587.   int ereg;
  588.   luaK_exp2anyreg(fs, e);
  589.   ereg = e->u.info;  /* register where 'e' was placed */
  590.   freeexp(fs, e);
  591.   e->u.info = fs->freereg;  /* base register for op_self */
  592.   e->k = VNONRELOC;
  593.   luaK_reserveregs(fs, 2);  /* function and 'self' produced by op_self */
  594.   luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));
  595.   freeexp(fs, key);
  596. }
  597.  
  598.  
  599. static void invertjump (FuncState *fs, expdesc *e) {
  600.   Instruction *pc = getjumpcontrol(fs, e->u.info);
  601.   lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
  602.                                            GET_OPCODE(*pc) != OP_TEST);
  603.   SETARG_A(*pc, !(GETARG_A(*pc)));
  604. }
  605.  
  606.  
  607. static int jumponcond (FuncState *fs, expdesc *e, int cond) {
  608.   if (e->k == VRELOCABLE) {
  609.     Instruction ie = getcode(fs, e);
  610.     if (GET_OPCODE(ie) == OP_NOT) {
  611.       fs->pc--;  /* remove previous OP_NOT */
  612.       return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
  613.     }
  614.     /* else go through */
  615.   }
  616.   discharge2anyreg(fs, e);
  617.   freeexp(fs, e);
  618.   return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond);
  619. }
  620.  
  621.  
  622. void luaK_goiftrue (FuncState *fs, expdesc *e) {
  623.   int pc;  /* pc of last jump */
  624.   luaK_dischargevars(fs, e);
  625.   switch (e->k) {
  626.     case VJMP: {
  627.       invertjump(fs, e);
  628.       pc = e->u.info;
  629.       break;
  630.     }
  631.     case VK: case VKNUM: case VTRUE: {
  632.       pc = NO_JUMP;  /* always true; do nothing */
  633.       break;
  634.     }
  635.     default: {
  636.       pc = jumponcond(fs, e, 0);
  637.       break;
  638.     }
  639.   }
  640.   luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
  641.   luaK_patchtohere(fs, e->t);
  642.   e->t = NO_JUMP;
  643. }
  644.  
  645.  
  646. void luaK_goiffalse (FuncState *fs, expdesc *e) {
  647.   int pc;  /* pc of last jump */
  648.   luaK_dischargevars(fs, e);
  649.   switch (e->k) {
  650.     case VJMP: {
  651.       pc = e->u.info;
  652.       break;
  653.     }
  654.     case VNIL: case VFALSE: {
  655.       pc = NO_JUMP;  /* always false; do nothing */
  656.       break;
  657.     }
  658.     default: {
  659.       pc = jumponcond(fs, e, 1);
  660.       break;
  661.     }
  662.   }
  663.   luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
  664.   luaK_patchtohere(fs, e->f);
  665.   e->f = NO_JUMP;
  666. }
  667.  
  668.  
  669. static void codenot (FuncState *fs, expdesc *e) {
  670.   luaK_dischargevars(fs, e);
  671.   switch (e->k) {
  672.     case VNIL: case VFALSE: {
  673.       e->k = VTRUE;
  674.       break;
  675.     }
  676.     case VK: case VKNUM: case VTRUE: {
  677.       e->k = VFALSE;
  678.       break;
  679.     }
  680.     case VJMP: {
  681.       invertjump(fs, e);
  682.       break;
  683.     }
  684.     case VRELOCABLE:
  685.     case VNONRELOC: {
  686.       discharge2anyreg(fs, e);
  687.       freeexp(fs, e);
  688.       e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0);
  689.       e->k = VRELOCABLE;
  690.       break;
  691.     }
  692.     default: {
  693.       lua_assert(0);  /* cannot happen */
  694.       break;
  695.     }
  696.   }
  697.   /* interchange true and false lists */
  698.   { int temp = e->f; e->f = e->t; e->t = temp; }
  699.   removevalues(fs, e->f);
  700.   removevalues(fs, e->t);
  701. }
  702.  
  703.  
  704. void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
  705.   lua_assert(!hasjumps(t));
  706.   t->u.ind.t = t->u.info;
  707.   t->u.ind.idx = luaK_exp2RK(fs, k);
  708.   t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL
  709.                                  : check_exp(vkisinreg(t->k), VLOCAL);
  710.   t->k = VINDEXED;
  711. }
  712.  
  713.  
  714. static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
  715.   lua_Number r;
  716.   if (!isnumeral(e1) || !isnumeral(e2)) return 0;
  717.   if ((op == OP_DIV || op == OP_MOD) && e2->u.nval == 0)
  718.     return 0;  /* do not attempt to divide by 0 */
  719.   r = luaO_arith(op - OP_ADD + LUA_OPADD, e1->u.nval, e2->u.nval);
  720.   e1->u.nval = r;
  721.   return 1;
  722. }
  723.  
  724.  
  725. static void codearith (FuncState *fs, OpCode op,
  726.                        expdesc *e1, expdesc *e2, int line) {
  727.   if (constfolding(op, e1, e2))
  728.     return;
  729.   else {
  730.     int o2 = (op != OP_UNM && op != OP_LEN) ? luaK_exp2RK(fs, e2) : 0;
  731.     int o1 = luaK_exp2RK(fs, e1);
  732.     if (o1 > o2) {
  733.       freeexp(fs, e1);
  734.       freeexp(fs, e2);
  735.     }
  736.     else {
  737.       freeexp(fs, e2);
  738.       freeexp(fs, e1);
  739.     }
  740.     e1->u.info = luaK_codeABC(fs, op, 0, o1, o2);
  741.     e1->k = VRELOCABLE;
  742.     luaK_fixline(fs, line);
  743.   }
  744. }
  745.  
  746.  
  747. static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
  748.                                                           expdesc *e2) {
  749.   int o1 = luaK_exp2RK(fs, e1);
  750.   int o2 = luaK_exp2RK(fs, e2);
  751.   freeexp(fs, e2);
  752.   freeexp(fs, e1);
  753.   if (cond == 0 && op != OP_EQ) {
  754.     int temp;  /* exchange args to replace by `<' or `<=' */
  755.     temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
  756.     cond = 1;
  757.   }
  758.   e1->u.info = condjump(fs, op, cond, o1, o2);
  759.   e1->k = VJMP;
  760. }
  761.  
  762.  
  763. void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) {
  764.   expdesc e2;
  765.   e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
  766.   switch (op) {
  767.     case OPR_MINUS: {
  768.       if (isnumeral(e))  /* minus constant? */
  769.         e->u.nval = luai_numunm(NULL, e->u.nval);  /* fold it */
  770.       else {
  771.         luaK_exp2anyreg(fs, e);
  772.         codearith(fs, OP_UNM, e, &e2, line);
  773.       }
  774.       break;
  775.     }
  776.     case OPR_NOT: codenot(fs, e); break;
  777.     case OPR_LEN: {
  778.       luaK_exp2anyreg(fs, e);  /* cannot operate on constants */
  779.       codearith(fs, OP_LEN, e, &e2, line);
  780.       break;
  781.     }
  782.     default: lua_assert(0);
  783.   }
  784. }
  785.  
  786.  
  787. void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
  788.   switch (op) {
  789.     case OPR_AND: {
  790.       luaK_goiftrue(fs, v);
  791.       break;
  792.     }
  793.     case OPR_OR: {
  794.       luaK_goiffalse(fs, v);
  795.       break;
  796.     }
  797.     case OPR_CONCAT: {
  798.       luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
  799.       break;
  800.     }
  801.     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
  802.     case OPR_MOD: case OPR_POW: {
  803.       if (!isnumeral(v)) luaK_exp2RK(fs, v);
  804.       break;
  805.     }
  806.     default: {
  807.       luaK_exp2RK(fs, v);
  808.       break;
  809.     }
  810.   }
  811. }
  812.  
  813.  
  814. void luaK_posfix (FuncState *fs, BinOpr op,
  815.                   expdesc *e1, expdesc *e2, int line) {
  816.   switch (op) {
  817.     case OPR_AND: {
  818.       lua_assert(e1->t == NO_JUMP);  /* list must be closed */
  819.       luaK_dischargevars(fs, e2);
  820.       luaK_concat(fs, &e2->f, e1->f);
  821.       *e1 = *e2;
  822.       break;
  823.     }
  824.     case OPR_OR: {
  825.       lua_assert(e1->f == NO_JUMP);  /* list must be closed */
  826.       luaK_dischargevars(fs, e2);
  827.       luaK_concat(fs, &e2->t, e1->t);
  828.       *e1 = *e2;
  829.       break;
  830.     }
  831.     case OPR_CONCAT: {
  832.       luaK_exp2val(fs, e2);
  833.       if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
  834.         lua_assert(e1->u.info == GETARG_B(getcode(fs, e2))-1);
  835.         freeexp(fs, e1);
  836.         SETARG_B(getcode(fs, e2), e1->u.info);
  837.         e1->k = VRELOCABLE; e1->u.info = e2->u.info;
  838.       }
  839.       else {
  840.         luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
  841.         codearith(fs, OP_CONCAT, e1, e2, line);
  842.       }
  843.       break;
  844.     }
  845.     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
  846.     case OPR_MOD: case OPR_POW: {
  847.       codearith(fs, cast(OpCode, op - OPR_ADD + OP_ADD), e1, e2, line);
  848.       break;
  849.     }
  850.     case OPR_EQ: case OPR_LT: case OPR_LE: {
  851.       codecomp(fs, cast(OpCode, op - OPR_EQ + OP_EQ), 1, e1, e2);
  852.       break;
  853.     }
  854.     case OPR_NE: case OPR_GT: case OPR_GE: {
  855.       codecomp(fs, cast(OpCode, op - OPR_NE + OP_EQ), 0, e1, e2);
  856.       break;
  857.     }
  858.     default: lua_assert(0);
  859.   }
  860. }
  861.  
  862.  
  863. void luaK_fixline (FuncState *fs, int line) {
  864.   fs->f->lineinfo[fs->pc - 1] = line;
  865. }
  866.  
  867.  
  868. void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
  869.   int c =  (nelems - 1)/LFIELDS_PER_FLUSH + 1;
  870.   int b = (tostore == LUA_MULTRET) ? 0 : tostore;
  871.   lua_assert(tostore != 0);
  872.   if (c <= MAXARG_C)
  873.     luaK_codeABC(fs, OP_SETLIST, base, b, c);
  874.   else if (c <= MAXARG_Ax) {
  875.     luaK_codeABC(fs, OP_SETLIST, base, b, 0);
  876.     codeextraarg(fs, c);
  877.   }
  878.   else
  879.     luaX_syntaxerror(fs->ls, "constructor too long");
  880.   fs->freereg = base + 1;  /* free registers with list values */
  881. }
  882.  
  883.