src/lj_carith.c

   1 /*
   2 ** C data arithmetic.
   3 ** Copyright (C) 2005-2014 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #include "lj_obj.h"
   7
   8 #if LJ_HASFFI
   9
  10 #include "lj_gc.h"
  11 #include "lj_err.h"
  12 #include "lj_tab.h"
  13 #include "lj_meta.h"
  14 #include "lj_ir.h"
  15 #include "lj_ctype.h"
  16 #include "lj_cconv.h"
  17 #include "lj_cdata.h"
  18 #include "lj_carith.h"
  19 #include "lj_strscan.h"
  20
  21 /* -- C data arithmetic --------------------------------------------------- */
  22
  23 /* Binary operands of an operator converted to ctypes. */
  24 typedef struct CDArith {
  25   uint8_t *p[2];
  26   CType *ct[2];
  27 } CDArith;
  28
  29 /* Check arguments for arithmetic metamethods. */
  30 static int carith_checkarg(lua_State *L, CTState *cts, CDArith *ca)
  31 {
  32   TValue *o = L->base;
  33   int ok = 1;
  34   MSize i;
  35   if (o+1 >= L->top)
  36     lj_err_argt(L, 1, LUA_TCDATA);
  37   for (i = 0; i < 2; i++, o++) {
  38     if (tviscdata(o)) {
  39       GCcdata *cd = cdataV(o);
  40       CTypeID id = (CTypeID)cd->ctypeid;
  41       CType *ct = ctype_raw(cts, id);
  42       uint8_t *p = (uint8_t *)cdataptr(cd);
  43       if (ctype_isptr(ct->info)) {
  44         p = (uint8_t *)cdata_getptr(p, ct->size);
  45         if (ctype_isref(ct->info)) ct = ctype_rawchild(cts, ct);
  46       } else if (ctype_isfunc(ct->info)) {
  47         p = (uint8_t *)*(void **)p;
  48         ct = ctype_get(cts,
  49           lj_ctype_intern(cts, CTINFO(CT_PTR, CTALIGN_PTR|id), CTSIZE_PTR));
  50       }
  51       if (ctype_isenum(ct->info)) ct = ctype_child(cts, ct);
  52       ca->ct[i] = ct;
  53       ca->p[i] = p;
  54     } else if (tvisint(o)) {
  55       ca->ct[i] = ctype_get(cts, CTID_INT32);
  56       ca->p[i] = (uint8_t *)&o->i;
  57     } else if (tvisnum(o)) {
  58       ca->ct[i] = ctype_get(cts, CTID_DOUBLE);
  59       ca->p[i] = (uint8_t *)&o->n;
  60     } else if (tvisnil(o)) {
  61       ca->ct[i] = ctype_get(cts, CTID_P_VOID);
  62       ca->p[i] = (uint8_t *)0;
  63     } else if (tvisstr(o)) {
  64       TValue *o2 = i == 0 ? o+1 : o-1;
  65       CType *ct = ctype_raw(cts, cdataV(o2)->ctypeid);
  66       ca->ct[i] = NULL;
  67       ca->p[i] = (uint8_t *)strVdata(o);
  68       ok = 0;
  69       if (ctype_isenum(ct->info)) {
  70         CTSize ofs;
  71         CType *cct = lj_ctype_getfield(cts, ct, strV(o), &ofs);
  72         if (cct && ctype_isconstval(cct->info)) {
  73           ca->ct[i] = ctype_child(cts, cct);
  74           ca->p[i] = (uint8_t *)&cct->size;  /* Assumes ct does not grow. */
  75           ok = 1;
  76         } else {
  77           ca->ct[1-i] = ct;  /* Use enum to improve error message. */
  78           ca->p[1-i] = NULL;
  79           break;
  80         }
  81       }
  82     } else {
  83       ca->ct[i] = NULL;
  84       ca->p[i] = (void *)(intptr_t)1;  /* To make it unequal. */
  85       ok = 0;
  86     }
  87   }
  88   return ok;
  89 }
  90
  91 /* Pointer arithmetic. */
  92 static int carith_ptr(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
  93 {
  94   CType *ctp = ca->ct[0];
  95   uint8_t *pp = ca->p[0];
  96   ptrdiff_t idx;
  97   CTSize sz;
  98   CTypeID id;
  99   GCcdata *cd;
 100   if (ctype_isptr(ctp->info) || ctype_isrefarray(ctp->info)) {
 101     if ((mm == MM_sub || mm == MM_eq || mm == MM_lt || mm == MM_le) &&
 102         (ctype_isptr(ca->ct[1]->info) || ctype_isrefarray(ca->ct[1]->info))) {
 103       uint8_t *pp2 = ca->p[1];
 104       if (mm == MM_eq) {  /* Pointer equality. Incompatible pointers are ok. */
 105         setboolV(L->top-1, (pp == pp2));
 106         return 1;
 107       }
 108       if (!lj_cconv_compatptr(cts, ctp, ca->ct[1], CCF_IGNQUAL))
 109         return 0;
 110       if (mm == MM_sub) {  /* Pointer difference. */
 111         intptr_t diff;
 112         sz = lj_ctype_size(cts, ctype_cid(ctp->info));  /* Element size. */
 113         if (sz == 0 || sz == CTSIZE_INVALID)
 114           return 0;
 115         diff = ((intptr_t)pp - (intptr_t)pp2) / (int32_t)sz;
 116         /* All valid pointer differences on x64 are in (-2^47, +2^47),
 117         ** which fits into a double without loss of precision.
 118         */
 119         setintptrV(L->top-1, (int32_t)diff);
 120         return 1;
 121       } else if (mm == MM_lt) {  /* Pointer comparison (unsigned). */
 122         setboolV(L->top-1, ((uintptr_t)pp < (uintptr_t)pp2));
 123         return 1;
 124       } else {
 125         lua_assert(mm == MM_le);
 126         setboolV(L->top-1, ((uintptr_t)pp <= (uintptr_t)pp2));
 127         return 1;
 128       }
 129     }
 130     if (!((mm == MM_add || mm == MM_sub) && ctype_isnum(ca->ct[1]->info)))
 131       return 0;
 132     lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ca->ct[1],
 133                    (uint8_t *)&idx, ca->p[1], 0);
 134     if (mm == MM_sub) idx = -idx;
 135   } else if (mm == MM_add && ctype_isnum(ctp->info) &&
 136       (ctype_isptr(ca->ct[1]->info) || ctype_isrefarray(ca->ct[1]->info))) {
 137     /* Swap pointer and index. */
 138     ctp = ca->ct[1]; pp = ca->p[1];
 139     lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ca->ct[0],
 140                    (uint8_t *)&idx, ca->p[0], 0);
 141   } else {
 142     return 0;
 143   }
 144   sz = lj_ctype_size(cts, ctype_cid(ctp->info));  /* Element size. */
 145   if (sz == CTSIZE_INVALID)
 146     return 0;
 147   pp += idx*(int32_t)sz;  /* Compute pointer + index. */
 148   id = lj_ctype_intern(cts, CTINFO(CT_PTR, CTALIGN_PTR|ctype_cid(ctp->info)),
 149                        CTSIZE_PTR);
 150   cd = lj_cdata_new(cts, id, CTSIZE_PTR);
 151   *(uint8_t **)cdataptr(cd) = pp;
 152   setcdataV(L, L->top-1, cd);
 153   lj_gc_check(L);
 154   return 1;
 155 }
 156
 157 /* 64 bit integer arithmetic. */
 158 static int carith_int64(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
 159 {
 160   if (ctype_isnum(ca->ct[0]->info) && ca->ct[0]->size <= 8 &&
 161       ctype_isnum(ca->ct[1]->info) && ca->ct[1]->size <= 8) {
 162     CTypeID id = (((ca->ct[0]->info & CTF_UNSIGNED) && ca->ct[0]->size == 8) ||
 163                   ((ca->ct[1]->info & CTF_UNSIGNED) && ca->ct[1]->size == 8)) ?
 164                  CTID_UINT64 : CTID_INT64;
 165     CType *ct = ctype_get(cts, id);
 166     GCcdata *cd;
 167     uint64_t u0, u1, *up;
 168     lj_cconv_ct_ct(cts, ct, ca->ct[0], (uint8_t *)&u0, ca->p[0], 0);
 169     if (mm != MM_unm)
 170       lj_cconv_ct_ct(cts, ct, ca->ct[1], (uint8_t *)&u1, ca->p[1], 0);
 171     switch (mm) {
 172     case MM_eq:
 173       setboolV(L->top-1, (u0 == u1));
 174       return 1;
 175     case MM_lt:
 176       setboolV(L->top-1,
 177                id == CTID_INT64 ? ((int64_t)u0 < (int64_t)u1) : (u0 < u1));
 178       return 1;
 179     case MM_le:
 180       setboolV(L->top-1,
 181                id == CTID_INT64 ? ((int64_t)u0 <= (int64_t)u1) : (u0 <= u1));
 182       return 1;
 183     default: break;
 184     }
 185     cd = lj_cdata_new(cts, id, 8);
 186     up = (uint64_t *)cdataptr(cd);
 187     setcdataV(L, L->top-1, cd);
 188     switch (mm) {
 189     case MM_add: *up = u0 + u1; break;
 190     case MM_sub: *up = u0 - u1; break;
 191     case MM_mul: *up = u0 * u1; break;
 192     case MM_div:
 193       if (id == CTID_INT64)
 194         *up = (uint64_t)lj_carith_divi64((int64_t)u0, (int64_t)u1);
 195       else
 196         *up = lj_carith_divu64(u0, u1);
 197       break;
 198     case MM_mod:
 199       if (id == CTID_INT64)
 200         *up = (uint64_t)lj_carith_modi64((int64_t)u0, (int64_t)u1);
 201       else
 202         *up = lj_carith_modu64(u0, u1);
 203       break;
 204     case MM_pow:
 205       if (id == CTID_INT64)
 206         *up = (uint64_t)lj_carith_powi64((int64_t)u0, (int64_t)u1);
 207       else
 208         *up = lj_carith_powu64(u0, u1);
 209       break;
 210     case MM_unm: *up = (uint64_t)-(int64_t)u0; break;
 211     default: lua_assert(0); break;
 212     }
 213     lj_gc_check(L);
 214     return 1;
 215   }
 216   return 0;
 217 }
 218
 219 /* Handle ctype arithmetic metamethods. */
 220 static int lj_carith_meta(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
 221 {
 222   cTValue *tv = NULL;
 223   if (tviscdata(L->base)) {
 224     CTypeID id = cdataV(L->base)->ctypeid;
 225     CType *ct = ctype_raw(cts, id);
 226     if (ctype_isptr(ct->info)) id = ctype_cid(ct->info);
 227     tv = lj_ctype_meta(cts, id, mm);
 228   }
 229   if (!tv && L->base+1 < L->top && tviscdata(L->base+1)) {
 230     CTypeID id = cdataV(L->base+1)->ctypeid;
 231     CType *ct = ctype_raw(cts, id);
 232     if (ctype_isptr(ct->info)) id = ctype_cid(ct->info);
 233     tv = lj_ctype_meta(cts, id, mm);
 234   }
 235   if (!tv) {
 236     const char *repr[2];
 237     int i, isenum = -1, isstr = -1;
 238     if (mm == MM_eq) {  /* Equality checks never raise an error. */
 239       int eq = ca->p[0] == ca->p[1];
 240       setboolV(L->top-1, eq);
 241       setboolV(&G(L)->tmptv2, eq);  /* Remember for trace recorder. */
 242       return 1;
 243     }
 244     for (i = 0; i < 2; i++) {
 245       if (ca->ct[i] && tviscdata(L->base+i)) {
 246         if (ctype_isenum(ca->ct[i]->info)) isenum = i;
 247         repr[i] = strdata(lj_ctype_repr(L, ctype_typeid(cts, ca->ct[i]), NULL));
 248       } else {
 249         if (tvisstr(&L->base[i])) isstr = i;
 250         repr[i] = lj_typename(&L->base[i]);
 251       }
 252     }
 253     if ((isenum ^ isstr) == 1)
 254       lj_err_callerv(L, LJ_ERR_FFI_BADCONV, repr[isstr], repr[isenum]);
 255     lj_err_callerv(L, mm == MM_len ? LJ_ERR_FFI_BADLEN :
 256                       mm == MM_concat ? LJ_ERR_FFI_BADCONCAT :
 257                       mm < MM_add ? LJ_ERR_FFI_BADCOMP : LJ_ERR_FFI_BADARITH,
 258                    repr[0], repr[1]);
 259   }
 260   return lj_meta_tailcall(L, tv);
 261 }
 262
 263 /* Arithmetic operators for cdata. */
 264 int lj_carith_op(lua_State *L, MMS mm)
 265 {
 266   CTState *cts = ctype_cts(L);
 267   CDArith ca;
 268   if (carith_checkarg(L, cts, &ca)) {
 269     if (carith_int64(L, cts, &ca, mm) || carith_ptr(L, cts, &ca, mm)) {
 270       copyTV(L, &G(L)->tmptv2, L->top-1);  /* Remember for trace recorder. */
 271       return 1;
 272     }
 273   }
 274   return lj_carith_meta(L, cts, &ca, mm);
 275 }
 276
 277 /* -- 64 bit bit operations helpers --------------------------------------- */
 278
 279 #if LJ_64
 280 #define B64DEF(name) \
 281   static LJ_AINLINE uint64_t lj_carith_##name(uint64_t x, int32_t sh)
 282 #else
 283 /* Not inlined on 32 bit archs, since some of these are quite lengthy. */
 284 #define B64DEF(name) \
 285   uint64_t LJ_NOINLINE lj_carith_##name(uint64_t x, int32_t sh)
 286 #endif
 287
 288 B64DEF(shl64) { return x << (sh&63); }
 289 B64DEF(shr64) { return x >> (sh&63); }
 290 B64DEF(sar64) { return (uint64_t)((int64_t)x >> (sh&63)); }
 291 B64DEF(rol64) { return lj_rol(x, (sh&63)); }
 292 B64DEF(ror64) { return lj_ror(x, (sh&63)); }
 293
 294 #undef B64DEF
 295
 296 uint64_t lj_carith_shift64(uint64_t x, int32_t sh, int op)
 297 {
 298   switch (op) {
 299   case IR_BSHL-IR_BSHL: x = lj_carith_shl64(x, sh); break;
 300   case IR_BSHR-IR_BSHL: x = lj_carith_shr64(x, sh); break;
 301   case IR_BSAR-IR_BSHL: x = lj_carith_sar64(x, sh); break;
 302   case IR_BROL-IR_BSHL: x = lj_carith_rol64(x, sh); break;
 303   case IR_BROR-IR_BSHL: x = lj_carith_ror64(x, sh); break;
 304   default: lua_assert(0); break;
 305   }
 306   return x;
 307 }
 308
 309 /* Equivalent to lj_lib_checkbit(), but handles cdata. */
 310 uint64_t lj_carith_check64(lua_State *L, int narg, CTypeID *id)
 311 {
 312   TValue *o = L->base + narg-1;
 313   if (o >= L->top) {
 314   err:
 315     lj_err_argt(L, narg, LUA_TNUMBER);
 316   } else if (LJ_LIKELY(tvisnumber(o))) {
 317     /* Handled below. */
 318   } else if (tviscdata(o)) {
 319     CTState *cts = ctype_cts(L);
 320     uint8_t *sp = (uint8_t *)cdataptr(cdataV(o));
 321     CTypeID sid = cdataV(o)->ctypeid;
 322     CType *s = ctype_get(cts, sid);
 323     uint64_t x;
 324     if (ctype_isref(s->info)) {
 325       sp = *(void **)sp;
 326       sid = ctype_cid(s->info);
 327     }
 328     s = ctype_raw(cts, sid);
 329     if (ctype_isenum(s->info)) s = ctype_child(cts, s);
 330     if ((s->info & (CTMASK_NUM|CTF_BOOL|CTF_FP|CTF_UNSIGNED)) ==
 331         CTINFO(CT_NUM, CTF_UNSIGNED) && s->size == 8)
 332       *id = CTID_UINT64;  /* Use uint64_t, since it has the highest rank. */
 333     else if (!*id)
 334       *id = CTID_INT64;  /* Use int64_t, unless already set. */
 335     lj_cconv_ct_ct(cts, ctype_get(cts, *id), s,
 336                    (uint8_t *)&x, sp, CCF_ARG(narg));
 337     return x;
 338   } else if (!(tvisstr(o) && lj_strscan_number(strV(o), o))) {
 339     goto err;
 340   }
 341   if (LJ_LIKELY(tvisint(o))) {
 342     return (uint32_t)intV(o);
 343   } else {
 344     int32_t i = lj_num2bit(numV(o));
 345     if (LJ_DUALNUM) setintV(o, i);
 346     return (uint32_t)i;
 347   }
 348 }
 349
 350
 351 /* -- 64 bit integer arithmetic helpers ----------------------------------- */
 352
 353 #if LJ_32 && LJ_HASJIT
 354 /* Signed/unsigned 64 bit multiplication. */
 355 int64_t lj_carith_mul64(int64_t a, int64_t b)
 356 {
 357   return a * b;
 358 }
 359 #endif
 360
 361 /* Unsigned 64 bit division. */
 362 uint64_t lj_carith_divu64(uint64_t a, uint64_t b)
 363 {
 364   if (b == 0) return U64x(80000000,00000000);
 365   return a / b;
 366 }
 367
 368 /* Signed 64 bit division. */
 369 int64_t lj_carith_divi64(int64_t a, int64_t b)
 370 {
 371   if (b == 0 || (a == (int64_t)U64x(80000000,00000000) && b == -1))
 372     return U64x(80000000,00000000);
 373   return a / b;
 374 }
 375
 376 /* Unsigned 64 bit modulo. */
 377 uint64_t lj_carith_modu64(uint64_t a, uint64_t b)
 378 {
 379   if (b == 0) return U64x(80000000,00000000);
 380   return a % b;
 381 }
 382
 383 /* Signed 64 bit modulo. */
 384 int64_t lj_carith_modi64(int64_t a, int64_t b)
 385 {
 386   if (b == 0) return U64x(80000000,00000000);
 387   if (a == (int64_t)U64x(80000000,00000000) && b == -1) return 0;
 388   return a % b;
 389 }
 390
 391 /* Unsigned 64 bit x^k. */
 392 uint64_t lj_carith_powu64(uint64_t x, uint64_t k)
 393 {
 394   uint64_t y;
 395   if (k == 0)
 396     return 1;
 397   for (; (k & 1) == 0; k >>= 1) x *= x;
 398   y = x;
 399   if ((k >>= 1) != 0) {
 400     for (;;) {
 401       x *= x;
 402       if (k == 1) break;
 403       if (k & 1) y *= x;
 404       k >>= 1;
 405     }
 406     y *= x;
 407   }
 408   return y;
 409 }
 410
 411 /* Signed 64 bit x^k. */
 412 int64_t lj_carith_powi64(int64_t x, int64_t k)
 413 {
 414   if (k == 0)
 415     return 1;
 416   if (k < 0) {
 417     if (x == 0)
 418       return U64x(7fffffff,ffffffff);
 419     else if (x == 1)
 420       return 1;
 421     else if (x == -1)
 422       return (k & 1) ? -1 : 1;
 423     else
 424       return 0;
 425   }
 426   return (int64_t)lj_carith_powu64((uint64_t)x, (uint64_t)k);
 427 }
 428
 429 #endif