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  1. /*
  2. ** $Id: lcode.c,v 2.62.1.1 2013/04/12 18:48:47 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.     n = addk(fs, L->top - 1, &o);
  335.     L->top--;
  336.   }
  337.   else
  338.     n = addk(fs, &o, &o);  /* regular case */
  339.   return n;
  340. }
  341.  
  342.  
  343. static int boolK (FuncState *fs, int b) {
  344.   TValue o;
  345.   setbvalue(&o, b);
  346.   return addk(fs, &o, &o);
  347. }
  348.  
  349.  
  350. static int nilK (FuncState *fs) {
  351.   TValue k, v;
  352.   setnilvalue(&v);
  353.   /* cannot use nil as key; instead use table itself to represent nil */
  354.   sethvalue(fs->ls->L, &k, fs->h);
  355.   return addk(fs, &k, &v);
  356. }
  357.  
  358.  
  359. void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
  360.   if (e->k == VCALL) {  /* expression is an open function call? */
  361.     SETARG_C(getcode(fs, e), nresults+1);
  362.   }
  363.   else if (e->k == VVARARG) {
  364.     SETARG_B(getcode(fs, e), nresults+1);
  365.     SETARG_A(getcode(fs, e), fs->freereg);
  366.     luaK_reserveregs(fs, 1);
  367.   }
  368. }
  369.  
  370.  
  371. void luaK_setoneret (FuncState *fs, expdesc *e) {
  372.   if (e->k == VCALL) {  /* expression is an open function call? */
  373.     e->k = VNONRELOC;
  374.     e->u.info = GETARG_A(getcode(fs, e));
  375.   }
  376.   else if (e->k == VVARARG) {
  377.     SETARG_B(getcode(fs, e), 2);
  378.     e->k = VRELOCABLE;  /* can relocate its simple result */
  379.   }
  380. }
  381.  
  382.  
  383. void luaK_dischargevars (FuncState *fs, expdesc *e) {
  384.   switch (e->k) {
  385.     case VLOCAL: {
  386.       e->k = VNONRELOC;
  387.       break;
  388.     }
  389.     case VUPVAL: {
  390.       e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
  391.       e->k = VRELOCABLE;
  392.       break;
  393.     }
  394.     case VINDEXED: {
  395.       OpCode op = OP_GETTABUP;  /* assume 't' is in an upvalue */
  396.       freereg(fs, e->u.ind.idx);
  397.       if (e->u.ind.vt == VLOCAL) {  /* 't' is in a register? */
  398.         freereg(fs, e->u.ind.t);
  399.         op = OP_GETTABLE;
  400.       }
  401.       e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx);
  402.       e->k = VRELOCABLE;
  403.       break;
  404.     }
  405.     case VVARARG:
  406.     case VCALL: {
  407.       luaK_setoneret(fs, e);
  408.       break;
  409.     }
  410.     default: break;  /* there is one value available (somewhere) */
  411.   }
  412. }
  413.  
  414.  
  415. static int code_label (FuncState *fs, int A, int b, int jump) {
  416.   luaK_getlabel(fs);  /* those instructions may be jump targets */
  417.   return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
  418. }
  419.  
  420.  
  421. static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
  422.   luaK_dischargevars(fs, e);
  423.   switch (e->k) {
  424.     case VNIL: {
  425.       luaK_nil(fs, reg, 1);
  426.       break;
  427.     }
  428.     case VFALSE: case VTRUE: {
  429.       luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
  430.       break;
  431.     }
  432.     case VK: {
  433.       luaK_codek(fs, reg, e->u.info);
  434.       break;
  435.     }
  436.     case VKNUM: {
  437.       luaK_codek(fs, reg, luaK_numberK(fs, e->u.nval));
  438.       break;
  439.     }
  440.     case VRELOCABLE: {
  441.       Instruction *pc = &getcode(fs, e);
  442.       SETARG_A(*pc, reg);
  443.       break;
  444.     }
  445.     case VNONRELOC: {
  446.       if (reg != e->u.info)
  447.         luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
  448.       break;
  449.     }
  450.     default: {
  451.       lua_assert(e->k == VVOID || e->k == VJMP);
  452.       return;  /* nothing to do... */
  453.     }
  454.   }
  455.   e->u.info = reg;
  456.   e->k = VNONRELOC;
  457. }
  458.  
  459.  
  460. static void discharge2anyreg (FuncState *fs, expdesc *e) {
  461.   if (e->k != VNONRELOC) {
  462.     luaK_reserveregs(fs, 1);
  463.     discharge2reg(fs, e, fs->freereg-1);
  464.   }
  465. }
  466.  
  467.  
  468. static void exp2reg (FuncState *fs, expdesc *e, int reg) {
  469.   discharge2reg(fs, e, reg);
  470.   if (e->k == VJMP)
  471.     luaK_concat(fs, &e->t, e->u.info);  /* put this jump in `t' list */
  472.   if (hasjumps(e)) {
  473.     int final;  /* position after whole expression */
  474.     int p_f = NO_JUMP;  /* position of an eventual LOAD false */
  475.     int p_t = NO_JUMP;  /* position of an eventual LOAD true */
  476.     if (need_value(fs, e->t) || need_value(fs, e->f)) {
  477.       int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
  478.       p_f = code_label(fs, reg, 0, 1);
  479.       p_t = code_label(fs, reg, 1, 0);
  480.       luaK_patchtohere(fs, fj);
  481.     }
  482.     final = luaK_getlabel(fs);
  483.     patchlistaux(fs, e->f, final, reg, p_f);
  484.     patchlistaux(fs, e->t, final, reg, p_t);
  485.   }
  486.   e->f = e->t = NO_JUMP;
  487.   e->u.info = reg;
  488.   e->k = VNONRELOC;
  489. }
  490.  
  491.  
  492. void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
  493.   luaK_dischargevars(fs, e);
  494.   freeexp(fs, e);
  495.   luaK_reserveregs(fs, 1);
  496.   exp2reg(fs, e, fs->freereg - 1);
  497. }
  498.  
  499.  
  500. int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
  501.   luaK_dischargevars(fs, e);
  502.   if (e->k == VNONRELOC) {
  503.     if (!hasjumps(e)) return e->u.info;  /* exp is already in a register */
  504.     if (e->u.info >= fs->nactvar) {  /* reg. is not a local? */
  505.       exp2reg(fs, e, e->u.info);  /* put value on it */
  506.       return e->u.info;
  507.     }
  508.   }
  509.   luaK_exp2nextreg(fs, e);  /* default */
  510.   return e->u.info;
  511. }
  512.  
  513.  
  514. void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
  515.   if (e->k != VUPVAL || hasjumps(e))
  516.     luaK_exp2anyreg(fs, e);
  517. }
  518.  
  519.  
  520. void luaK_exp2val (FuncState *fs, expdesc *e) {
  521.   if (hasjumps(e))
  522.     luaK_exp2anyreg(fs, e);
  523.   else
  524.     luaK_dischargevars(fs, e);
  525. }
  526.  
  527.  
  528. int luaK_exp2RK (FuncState *fs, expdesc *e) {
  529.   luaK_exp2val(fs, e);
  530.   switch (e->k) {
  531.     case VTRUE:
  532.     case VFALSE:
  533.     case VNIL: {
  534.       if (fs->nk <= MAXINDEXRK) {  /* constant fits in RK operand? */
  535.         e->u.info = (e->k == VNIL) ? nilK(fs) : boolK(fs, (e->k == VTRUE));
  536.         e->k = VK;
  537.         return RKASK(e->u.info);
  538.       }
  539.       else break;
  540.     }
  541.     case VKNUM: {
  542.       e->u.info = luaK_numberK(fs, e->u.nval);
  543.       e->k = VK;
  544.       /* go through */
  545.     }
  546.     case VK: {
  547.       if (e->u.info <= MAXINDEXRK)  /* constant fits in argC? */
  548.         return RKASK(e->u.info);
  549.       else break;
  550.     }
  551.     default: break;
  552.   }
  553.   /* not a constant in the right range: put it in a register */
  554.   return luaK_exp2anyreg(fs, e);
  555. }
  556.  
  557.  
  558. void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
  559.   switch (var->k) {
  560.     case VLOCAL: {
  561.       freeexp(fs, ex);
  562.       exp2reg(fs, ex, var->u.info);
  563.       return;
  564.     }
  565.     case VUPVAL: {
  566.       int e = luaK_exp2anyreg(fs, ex);
  567.       luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
  568.       break;
  569.     }
  570.     case VINDEXED: {
  571.       OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;
  572.       int e = luaK_exp2RK(fs, ex);
  573.       luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e);
  574.       break;
  575.     }
  576.     default: {
  577.       lua_assert(0);  /* invalid var kind to store */
  578.       break;
  579.     }
  580.   }
  581.   freeexp(fs, ex);
  582. }
  583.  
  584.  
  585. void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
  586.   int ereg;
  587.   luaK_exp2anyreg(fs, e);
  588.   ereg = e->u.info;  /* register where 'e' was placed */
  589.   freeexp(fs, e);
  590.   e->u.info = fs->freereg;  /* base register for op_self */
  591.   e->k = VNONRELOC;
  592.   luaK_reserveregs(fs, 2);  /* function and 'self' produced by op_self */
  593.   luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));
  594.   freeexp(fs, key);
  595. }
  596.  
  597.  
  598. static void invertjump (FuncState *fs, expdesc *e) {
  599.   Instruction *pc = getjumpcontrol(fs, e->u.info);
  600.   lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
  601.                                            GET_OPCODE(*pc) != OP_TEST);
  602.   SETARG_A(*pc, !(GETARG_A(*pc)));
  603. }
  604.  
  605.  
  606. static int jumponcond (FuncState *fs, expdesc *e, int cond) {
  607.   if (e->k == VRELOCABLE) {
  608.     Instruction ie = getcode(fs, e);
  609.     if (GET_OPCODE(ie) == OP_NOT) {
  610.       fs->pc--;  /* remove previous OP_NOT */
  611.       return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
  612.     }
  613.     /* else go through */
  614.   }
  615.   discharge2anyreg(fs, e);
  616.   freeexp(fs, e);
  617.   return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond);
  618. }
  619.  
  620.  
  621. void luaK_goiftrue (FuncState *fs, expdesc *e) {
  622.   int pc;  /* pc of last jump */
  623.   luaK_dischargevars(fs, e);
  624.   switch (e->k) {
  625.     case VJMP: {
  626.       invertjump(fs, e);
  627.       pc = e->u.info;
  628.       break;
  629.     }
  630.     case VK: case VKNUM: case VTRUE: {
  631.       pc = NO_JUMP;  /* always true; do nothing */
  632.       break;
  633.     }
  634.     default: {
  635.       pc = jumponcond(fs, e, 0);
  636.       break;
  637.     }
  638.   }
  639.   luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
  640.   luaK_patchtohere(fs, e->t);
  641.   e->t = NO_JUMP;
  642. }
  643.  
  644.  
  645. void luaK_goiffalse (FuncState *fs, expdesc *e) {
  646.   int pc;  /* pc of last jump */
  647.   luaK_dischargevars(fs, e);
  648.   switch (e->k) {
  649.     case VJMP: {
  650.       pc = e->u.info;
  651.       break;
  652.     }
  653.     case VNIL: case VFALSE: {
  654.       pc = NO_JUMP;  /* always false; do nothing */
  655.       break;
  656.     }
  657.     default: {
  658.       pc = jumponcond(fs, e, 1);
  659.       break;
  660.     }
  661.   }
  662.   luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
  663.   luaK_patchtohere(fs, e->f);
  664.   e->f = NO_JUMP;
  665. }
  666.  
  667.  
  668. static void codenot (FuncState *fs, expdesc *e) {
  669.   luaK_dischargevars(fs, e);
  670.   switch (e->k) {
  671.     case VNIL: case VFALSE: {
  672.       e->k = VTRUE;
  673.       break;
  674.     }
  675.     case VK: case VKNUM: case VTRUE: {
  676.       e->k = VFALSE;
  677.       break;
  678.     }
  679.     case VJMP: {
  680.       invertjump(fs, e);
  681.       break;
  682.     }
  683.     case VRELOCABLE:
  684.     case VNONRELOC: {
  685.       discharge2anyreg(fs, e);
  686.       freeexp(fs, e);
  687.       e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0);
  688.       e->k = VRELOCABLE;
  689.       break;
  690.     }
  691.     default: {
  692.       lua_assert(0);  /* cannot happen */
  693.       break;
  694.     }
  695.   }
  696.   /* interchange true and false lists */
  697.   { int temp = e->f; e->f = e->t; e->t = temp; }
  698.   removevalues(fs, e->f);
  699.   removevalues(fs, e->t);
  700. }
  701.  
  702.  
  703. void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
  704.   lua_assert(!hasjumps(t));
  705.   t->u.ind.t = t->u.info;
  706.   t->u.ind.idx = luaK_exp2RK(fs, k);
  707.   t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL
  708.                                  : check_exp(vkisinreg(t->k), VLOCAL);
  709.   t->k = VINDEXED;
  710. }
  711.  
  712.  
  713. static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
  714.   lua_Number r;
  715.   if (!isnumeral(e1) || !isnumeral(e2)) return 0;
  716.   if ((op == OP_DIV || op == OP_MOD) && e2->u.nval == 0)
  717.     return 0;  /* do not attempt to divide by 0 */
  718.   r = luaO_arith(op - OP_ADD + LUA_OPADD, e1->u.nval, e2->u.nval);
  719.   e1->u.nval = r;
  720.   return 1;
  721. }
  722.  
  723.  
  724. static void codearith (FuncState *fs, OpCode op,
  725.                        expdesc *e1, expdesc *e2, int line) {
  726.   if (constfolding(op, e1, e2))
  727.     return;
  728.   else {
  729.     int o2 = (op != OP_UNM && op != OP_LEN) ? luaK_exp2RK(fs, e2) : 0;
  730.     int o1 = luaK_exp2RK(fs, e1);
  731.     if (o1 > o2) {
  732.       freeexp(fs, e1);
  733.       freeexp(fs, e2);
  734.     }
  735.     else {
  736.       freeexp(fs, e2);
  737.       freeexp(fs, e1);
  738.     }
  739.     e1->u.info = luaK_codeABC(fs, op, 0, o1, o2);
  740.     e1->k = VRELOCABLE;
  741.     luaK_fixline(fs, line);
  742.   }
  743. }
  744.  
  745.  
  746. static void codecomp (FuncState *fs, OpCode op, int cond, expdesc *e1,
  747.                                                           expdesc *e2) {
  748.   int o1 = luaK_exp2RK(fs, e1);
  749.   int o2 = luaK_exp2RK(fs, e2);
  750.   freeexp(fs, e2);
  751.   freeexp(fs, e1);
  752.   if (cond == 0 && op != OP_EQ) {
  753.     int temp;  /* exchange args to replace by `<' or `<=' */
  754.     temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
  755.     cond = 1;
  756.   }
  757.   e1->u.info = condjump(fs, op, cond, o1, o2);
  758.   e1->k = VJMP;
  759. }
  760.  
  761.  
  762. void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) {
  763.   expdesc e2;
  764.   e2.t = e2.f = NO_JUMP; e2.k = VKNUM; e2.u.nval = 0;
  765.   switch (op) {
  766.     case OPR_MINUS: {
  767.       if (isnumeral(e))  /* minus constant? */
  768.         e->u.nval = luai_numunm(NULL, e->u.nval);  /* fold it */
  769.       else {
  770.         luaK_exp2anyreg(fs, e);
  771.         codearith(fs, OP_UNM, e, &e2, line);
  772.       }
  773.       break;
  774.     }
  775.     case OPR_NOT: codenot(fs, e); break;
  776.     case OPR_LEN: {
  777.       luaK_exp2anyreg(fs, e);  /* cannot operate on constants */
  778.       codearith(fs, OP_LEN, e, &e2, line);
  779.       break;
  780.     }
  781.     default: lua_assert(0);
  782.   }
  783. }
  784.  
  785.  
  786. void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
  787.   switch (op) {
  788.     case OPR_AND: {
  789.       luaK_goiftrue(fs, v);
  790.       break;
  791.     }
  792.     case OPR_OR: {
  793.       luaK_goiffalse(fs, v);
  794.       break;
  795.     }
  796.     case OPR_CONCAT: {
  797.       luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
  798.       break;
  799.     }
  800.     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
  801.     case OPR_MOD: case OPR_POW: {
  802.       if (!isnumeral(v)) luaK_exp2RK(fs, v);
  803.       break;
  804.     }
  805.     default: {
  806.       luaK_exp2RK(fs, v);
  807.       break;
  808.     }
  809.   }
  810. }
  811.  
  812.  
  813. void luaK_posfix (FuncState *fs, BinOpr op,
  814.                   expdesc *e1, expdesc *e2, int line) {
  815.   switch (op) {
  816.     case OPR_AND: {
  817.       lua_assert(e1->t == NO_JUMP);  /* list must be closed */
  818.       luaK_dischargevars(fs, e2);
  819.       luaK_concat(fs, &e2->f, e1->f);
  820.       *e1 = *e2;
  821.       break;
  822.     }
  823.     case OPR_OR: {
  824.       lua_assert(e1->f == NO_JUMP);  /* list must be closed */
  825.       luaK_dischargevars(fs, e2);
  826.       luaK_concat(fs, &e2->t, e1->t);
  827.       *e1 = *e2;
  828.       break;
  829.     }
  830.     case OPR_CONCAT: {
  831.       luaK_exp2val(fs, e2);
  832.       if (e2->k == VRELOCABLE && GET_OPCODE(getcode(fs, e2)) == OP_CONCAT) {
  833.         lua_assert(e1->u.info == GETARG_B(getcode(fs, e2))-1);
  834.         freeexp(fs, e1);
  835.         SETARG_B(getcode(fs, e2), e1->u.info);
  836.         e1->k = VRELOCABLE; e1->u.info = e2->u.info;
  837.       }
  838.       else {
  839.         luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
  840.         codearith(fs, OP_CONCAT, e1, e2, line);
  841.       }
  842.       break;
  843.     }
  844.     case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
  845.     case OPR_MOD: case OPR_POW: {
  846.       codearith(fs, cast(OpCode, op - OPR_ADD + OP_ADD), e1, e2, line);
  847.       break;
  848.     }
  849.     case OPR_EQ: case OPR_LT: case OPR_LE: {
  850.       codecomp(fs, cast(OpCode, op - OPR_EQ + OP_EQ), 1, e1, e2);
  851.       break;
  852.     }
  853.     case OPR_NE: case OPR_GT: case OPR_GE: {
  854.       codecomp(fs, cast(OpCode, op - OPR_NE + OP_EQ), 0, e1, e2);
  855.       break;
  856.     }
  857.     default: lua_assert(0);
  858.   }
  859. }
  860.  
  861.  
  862. void luaK_fixline (FuncState *fs, int line) {
  863.   fs->f->lineinfo[fs->pc - 1] = line;
  864. }
  865.  
  866.  
  867. void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
  868.   int c =  (nelems - 1)/LFIELDS_PER_FLUSH + 1;
  869.   int b = (tostore == LUA_MULTRET) ? 0 : tostore;
  870.   lua_assert(tostore != 0);
  871.   if (c <= MAXARG_C)
  872.     luaK_codeABC(fs, OP_SETLIST, base, b, c);
  873.   else if (c <= MAXARG_Ax) {
  874.     luaK_codeABC(fs, OP_SETLIST, base, b, 0);
  875.     codeextraarg(fs, c);
  876.   }
  877.   else
  878.     luaX_syntaxerror(fs->ls, "constructor too long");
  879.   fs->freereg = base + 1;  /* free registers with list values */
  880. }
  881.  
  882.