src/lj_carith.c

   1 /*
   2 ** C data arithmetic.
   3 ** Copyright (C) 2005-2012 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_ctype.h"
  15 #include "lj_cconv.h"
  16 #include "lj_cdata.h"
  17 #include "lj_carith.h"
  18
  19 /* -- C data arithmetic --------------------------------------------------- */
  20
  21 /* Binary operands of an operator converted to ctypes. */
  22 typedef struct CDArith {
  23   uint8_t *p[2];
  24   CType *ct[2];
  25 } CDArith;
  26
  27 /* Check arguments for arithmetic metamethods. */
  28 static int carith_checkarg(lua_State *L, CTState *cts, CDArith *ca)
  29 {
  30   TValue *o = L->base;
  31   int ok = 1;
  32   MSize i;
  33   if (o+1 >= L->top)
  34     lj_err_argt(L, 1, LUA_TCDATA);
  35   for (i = 0; i < 2; i++, o++) {
  36     if (tviscdata(o)) {
  37       GCcdata *cd = cdataV(o);
  38       CTypeID id = (CTypeID)cd->ctypeid;
  39       CType *ct = ctype_raw(cts, id);
  40       uint8_t *p = (uint8_t *)cdataptr(cd);
  41       if (ctype_isptr(ct->info)) {
  42         p = (uint8_t *)cdata_getptr(p, ct->size);
  43         if (ctype_isref(ct->info)) ct = ctype_rawchild(cts, ct);
  44       } else if (ctype_isfunc(ct->info)) {
  45         p = (uint8_t *)*(void **)p;
  46         ct = ctype_get(cts,
  47           lj_ctype_intern(cts, CTINFO(CT_PTR, CTALIGN_PTR|id), CTSIZE_PTR));
  48       }
  49       if (ctype_isenum(ct->info)) ct = ctype_child(cts, ct);
  50       ca->ct[i] = ct;
  51       ca->p[i] = p;
  52     } else if (tvisint(o)) {
  53       ca->ct[i] = ctype_get(cts, CTID_INT32);
  54       ca->p[i] = (uint8_t *)&o->i;
  55     } else if (tvisnum(o)) {
  56       ca->ct[i] = ctype_get(cts, CTID_DOUBLE);
  57       ca->p[i] = (uint8_t *)&o->n;
  58     } else if (tvisnil(o)) {
  59       ca->ct[i] = ctype_get(cts, CTID_P_VOID);
  60       ca->p[i] = (uint8_t *)0;
  61     } else if (tvisstr(o)) {
  62       TValue *o2 = i == 0 ? o+1 : o-1;
  63       CType *ct = ctype_raw(cts, cdataV(o2)->ctypeid);
  64       ca->ct[i] = NULL;
  65       ca->p[i] = NULL;
  66       ok = 0;
  67       if (ctype_isenum(ct->info)) {
  68         CTSize ofs;
  69         CType *cct = lj_ctype_getfield(cts, ct, strV(o), &ofs);
  70         if (cct && ctype_isconstval(cct->info)) {
  71           ca->ct[i] = ctype_child(cts, cct);
  72           ca->p[i] = (uint8_t *)&cct->size;  /* Assumes ct does not grow. */
  73           ok = 1;
  74         } else {
  75           ca->ct[1-i] = ct;  /* Use enum to improve error message. */
  76           ca->p[1-i] = NULL;
  77           break;
  78         }
  79       }
  80     } else {
  81       ca->ct[i] = NULL;
  82       ca->p[i] = NULL;
  83       ok = 0;
  84     }
  85   }
  86   return ok;
  87 }
  88
  89 /* Pointer arithmetic. */
  90 static int carith_ptr(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
  91 {
  92   CType *ctp = ca->ct[0];
  93   uint8_t *pp = ca->p[0];
  94   ptrdiff_t idx;
  95   CTSize sz;
  96   CTypeID id;
  97   GCcdata *cd;
  98   if (ctype_isptr(ctp->info) || ctype_isrefarray(ctp->info)) {
  99     if ((mm == MM_sub || mm == MM_eq || mm == MM_lt || mm == MM_le) &&
 100         (ctype_isptr(ca->ct[1]->info) || ctype_isrefarray(ca->ct[1]->info))) {
 101       uint8_t *pp2 = ca->p[1];
 102       if (mm == MM_eq) {  /* Pointer equality. Incompatible pointers are ok. */
 103         setboolV(L->top-1, (pp == pp2));
 104         return 1;
 105       }
 106       if (!lj_cconv_compatptr(cts, ctp, ca->ct[1], CCF_IGNQUAL))
 107         return 0;
 108       if (mm == MM_sub) {  /* Pointer difference. */
 109         intptr_t diff;
 110         sz = lj_ctype_size(cts, ctype_cid(ctp->info));  /* Element size. */
 111         if (sz == 0 || sz == CTSIZE_INVALID)
 112           return 0;
 113         diff = ((intptr_t)pp - (intptr_t)pp2) / (int32_t)sz;
 114         /* All valid pointer differences on x64 are in (-2^47, +2^47),
 115         ** which fits into a double without loss of precision.
 116         */
 117         setintptrV(L->top-1, (int32_t)diff);
 118         return 1;
 119       } else if (mm == MM_lt) {  /* Pointer comparison (unsigned). */
 120         setboolV(L->top-1, ((uintptr_t)pp < (uintptr_t)pp2));
 121         return 1;
 122       } else {
 123         lua_assert(mm == MM_le);
 124         setboolV(L->top-1, ((uintptr_t)pp <= (uintptr_t)pp2));
 125         return 1;
 126       }
 127     }
 128     if (!((mm == MM_add || mm == MM_sub) && ctype_isnum(ca->ct[1]->info)))
 129       return 0;
 130     lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ca->ct[1],
 131                    (uint8_t *)&idx, ca->p[1], 0);
 132     if (mm == MM_sub) idx = -idx;
 133   } else if (mm == MM_add && ctype_isnum(ctp->info) &&
 134       (ctype_isptr(ca->ct[1]->info) || ctype_isrefarray(ca->ct[1]->info))) {
 135     /* Swap pointer and index. */
 136     ctp = ca->ct[1]; pp = ca->p[1];
 137     lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ca->ct[0],
 138                    (uint8_t *)&idx, ca->p[0], 0);
 139   } else {
 140     return 0;
 141   }
 142   sz = lj_ctype_size(cts, ctype_cid(ctp->info));  /* Element size. */
 143   if (sz == CTSIZE_INVALID)
 144     return 0;
 145   pp += idx*(int32_t)sz;  /* Compute pointer + index. */
 146   id = lj_ctype_intern(cts, CTINFO(CT_PTR, CTALIGN_PTR|ctype_cid(ctp->info)),
 147                        CTSIZE_PTR);
 148   cd = lj_cdata_new(cts, id, CTSIZE_PTR);
 149   *(uint8_t **)cdataptr(cd) = pp;
 150   setcdataV(L, L->top-1, cd);
 151   lj_gc_check(L);
 152   return 1;
 153 }
 154
 155 /* 64 bit integer arithmetic. */
 156 static int carith_int64(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
 157 {
 158   if (ctype_isnum(ca->ct[0]->info) && ca->ct[0]->size <= 8 &&
 159       ctype_isnum(ca->ct[1]->info) && ca->ct[1]->size <= 8) {
 160     CTypeID id = (((ca->ct[0]->info & CTF_UNSIGNED) && ca->ct[0]->size == 8) ||
 161                   ((ca->ct[1]->info & CTF_UNSIGNED) && ca->ct[1]->size == 8)) ?
 162                  CTID_UINT64 : CTID_INT64;
 163     CType *ct = ctype_get(cts, id);
 164     GCcdata *cd;
 165     uint64_t u0, u1, *up;
 166     lj_cconv_ct_ct(cts, ct, ca->ct[0], (uint8_t *)&u0, ca->p[0], 0);
 167     if (mm != MM_unm)
 168       lj_cconv_ct_ct(cts, ct, ca->ct[1], (uint8_t *)&u1, ca->p[1], 0);
 169     switch (mm) {
 170     case MM_eq:
 171       setboolV(L->top-1, (u0 == u1));
 172       return 1;
 173     case MM_lt:
 174       setboolV(L->top-1,
 175                id == CTID_INT64 ? ((int64_t)u0 < (int64_t)u1) : (u0 < u1));
 176       return 1;
 177     case MM_le:
 178       setboolV(L->top-1,
 179                id == CTID_INT64 ? ((int64_t)u0 <= (int64_t)u1) : (u0 <= u1));
 180       return 1;
 181     default: break;
 182     }
 183     cd = lj_cdata_new(cts, id, 8);
 184     up = (uint64_t *)cdataptr(cd);
 185     setcdataV(L, L->top-1, cd);
 186     switch (mm) {
 187     case MM_add: *up = u0 + u1; break;
 188     case MM_sub: *up = u0 - u1; break;
 189     case MM_mul: *up = u0 * u1; break;
 190     case MM_div:
 191       if (id == CTID_INT64)
 192         *up = (uint64_t)lj_carith_divi64((int64_t)u0, (int64_t)u1);
 193       else
 194         *up = lj_carith_divu64(u0, u1);
 195       break;
 196     case MM_mod:
 197       if (id == CTID_INT64)
 198         *up = (uint64_t)lj_carith_modi64((int64_t)u0, (int64_t)u1);
 199       else
 200         *up = lj_carith_modu64(u0, u1);
 201       break;
 202     case MM_pow:
 203       if (id == CTID_INT64)
 204         *up = (uint64_t)lj_carith_powi64((int64_t)u0, (int64_t)u1);
 205       else
 206         *up = lj_carith_powu64(u0, u1);
 207       break;
 208     case MM_unm: *up = (uint64_t)-(int64_t)u0; break;
 209     default: lua_assert(0); break;
 210     }
 211     lj_gc_check(L);
 212     return 1;
 213   }
 214   return 0;
 215 }
 216
 217 /* Handle ctype arithmetic metamethods. */
 218 static int lj_carith_meta(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
 219 {
 220   cTValue *tv = NULL;
 221   if (tviscdata(L->base)) {
 222     CTypeID id = cdataV(L->base)->ctypeid;
 223     CType *ct = ctype_raw(cts, id);
 224     if (ctype_isptr(ct->info)) id = ctype_cid(ct->info);
 225     tv = lj_ctype_meta(cts, id, mm);
 226   }
 227   if (!tv && L->base+1 < L->top && tviscdata(L->base+1)) {
 228     CTypeID id = cdataV(L->base+1)->ctypeid;
 229     CType *ct = ctype_raw(cts, id);
 230     if (ctype_isptr(ct->info)) id = ctype_cid(ct->info);
 231     tv = lj_ctype_meta(cts, id, mm);
 232   }
 233   if (!tv) {
 234     const char *repr[2];
 235     int i, isenum = -1, isstr = -1;
 236     if (mm == MM_eq) {  /* Equality checks never raise an error. */
 237       setboolV(L->top-1, 0);
 238       return 1;
 239     }
 240     for (i = 0; i < 2; i++) {
 241       if (ca->ct[i]) {
 242         if (ctype_isenum(ca->ct[i]->info)) isenum = i;
 243         repr[i] = strdata(lj_ctype_repr(L, ctype_typeid(cts, ca->ct[i]), NULL));
 244       } else {
 245         if (tvisstr(&L->base[i])) isstr = i;
 246         repr[i] = lj_typename(&L->base[i]);
 247       }
 248     }
 249     if ((isenum ^ isstr) == 1)
 250       lj_err_callerv(L, LJ_ERR_FFI_BADCONV, repr[isstr], repr[isenum]);
 251     lj_err_callerv(L, mm == MM_len ? LJ_ERR_FFI_BADLEN :
 252                       mm == MM_concat ? LJ_ERR_FFI_BADCONCAT :
 253                       mm < MM_add ? LJ_ERR_FFI_BADCOMP : LJ_ERR_FFI_BADARITH,
 254                    repr[0], repr[1]);
 255   }
 256   return lj_meta_tailcall(L, tv);
 257 }
 258
 259 /* Arithmetic operators for cdata. */
 260 int lj_carith_op(lua_State *L, MMS mm)
 261 {
 262   CTState *cts = ctype_cts(L);
 263   CDArith ca;
 264   if (carith_checkarg(L, cts, &ca)) {
 265     if (carith_int64(L, cts, &ca, mm) || carith_ptr(L, cts, &ca, mm)) {
 266       copyTV(L, &G(L)->tmptv2, L->top-1);  /* Remember for trace recorder. */
 267       return 1;
 268     }
 269   }
 270   return lj_carith_meta(L, cts, &ca, mm);
 271 }
 272
 273 /* -- 64 bit integer arithmetic helpers ----------------------------------- */
 274
 275 #if LJ_32 && LJ_HASJIT
 276 /* Signed/unsigned 64 bit multiplication. */
 277 int64_t lj_carith_mul64(int64_t a, int64_t b)
 278 {
 279   return a * b;
 280 }
 281 #endif
 282
 283 /* Unsigned 64 bit division. */
 284 uint64_t lj_carith_divu64(uint64_t a, uint64_t b)
 285 {
 286   if (b == 0) return U64x(80000000,00000000);
 287   return a / b;
 288 }
 289
 290 /* Signed 64 bit division. */
 291 int64_t lj_carith_divi64(int64_t a, int64_t b)
 292 {
 293   if (b == 0 || (a == (int64_t)U64x(80000000,00000000) && b == -1))
 294     return U64x(80000000,00000000);
 295   return a / b;
 296 }
 297
 298 /* Unsigned 64 bit modulo. */
 299 uint64_t lj_carith_modu64(uint64_t a, uint64_t b)
 300 {
 301   if (b == 0) return U64x(80000000,00000000);
 302   return a % b;
 303 }
 304
 305 /* Signed 64 bit modulo. */
 306 int64_t lj_carith_modi64(int64_t a, int64_t b)
 307 {
 308   if (b == 0) return U64x(80000000,00000000);
 309   if (a == (int64_t)U64x(80000000,00000000) && b == -1) return 0;
 310   return a % b;
 311 }
 312
 313 /* Unsigned 64 bit x^k. */
 314 uint64_t lj_carith_powu64(uint64_t x, uint64_t k)
 315 {
 316   uint64_t y;
 317   if (k == 0)
 318     return 1;
 319   for (; (k & 1) == 0; k >>= 1) x *= x;
 320   y = x;
 321   if ((k >>= 1) != 0) {
 322     for (;;) {
 323       x *= x;
 324       if (k == 1) break;
 325       if (k & 1) y *= x;
 326       k >>= 1;
 327     }
 328     y *= x;
 329   }
 330   return y;
 331 }
 332
 333 /* Signed 64 bit x^k. */
 334 int64_t lj_carith_powi64(int64_t x, int64_t k)
 335 {
 336   if (k == 0)
 337     return 1;
 338   if (k < 0) {
 339     if (x == 0)
 340       return U64x(7fffffff,ffffffff);
 341     else if (x == 1)
 342       return 1;
 343     else if (x == -1)
 344       return (k & 1) ? -1 : 1;
 345     else
 346       return 0;
 347   }
 348   return (int64_t)lj_carith_powu64((uint64_t)x, (uint64_t)k);
 349 }
 350
 351 #endif