src/lj_ir.c

   1 /*
   2 ** SSA IR (Intermediate Representation) emitter.
   3 ** Copyright (C) 2005-2011 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #define lj_ir_c
   7 #define LUA_CORE
   8
   9 /* For pointers to libc/libm functions. */
  10 #include <stdio.h>
  11 #include <math.h>
  12
  13 #include "lj_obj.h"
  14
  15 #if LJ_HASJIT
  16
  17 #include "lj_gc.h"
  18 #include "lj_str.h"
  19 #include "lj_tab.h"
  20 #include "lj_ir.h"
  21 #include "lj_jit.h"
  22 #include "lj_ircall.h"
  23 #include "lj_iropt.h"
  24 #include "lj_trace.h"
  25 #if LJ_HASFFI
  26 #include "lj_ctype.h"
  27 #include "lj_cdata.h"
  28 #include "lj_carith.h"
  29 #endif
  30 #include "lj_vm.h"
  31 #include "lj_lib.h"
  32
  33 /* Some local macros to save typing. Undef'd at the end. */
  34 #define IR(ref)                 (&J->cur.ir[(ref)])
  35 #define fins                    (&J->fold.ins)
  36
  37 /* Pass IR on to next optimization in chain (FOLD). */
  38 #define emitir(ot, a, b)        (lj_ir_set(J, (ot), (a), (b)), lj_opt_fold(J))
  39
  40 /* -- IR tables ----------------------------------------------------------- */
  41
  42 /* IR instruction modes. */
  43 LJ_DATADEF const uint8_t lj_ir_mode[IR__MAX+1] = {
  44 IRDEF(IRMODE)
  45   0
  46 };
  47
  48 /* C call info for CALL* instructions. */
  49 LJ_DATADEF const CCallInfo lj_ir_callinfo[] = {
  50 #define IRCALLCI(cond, name, nargs, kind, type, flags) \
  51   { (ASMFunction)IRCALLCOND_##cond(name), \
  52     (nargs)|(CCI_CALL_##kind)|(IRT_##type<<CCI_OTSHIFT)|(flags) },
  53 IRCALLDEF(IRCALLCI)
  54 #undef IRCALLCI
  55   { NULL, 0 }
  56 };
  57
  58 /* -- IR emitter ---------------------------------------------------------- */
  59
  60 /* Grow IR buffer at the top. */
  61 void LJ_FASTCALL lj_ir_growtop(jit_State *J)
  62 {
  63   IRIns *baseir = J->irbuf + J->irbotlim;
  64   MSize szins = J->irtoplim - J->irbotlim;
  65   if (szins) {
  66     baseir = (IRIns *)lj_mem_realloc(J->L, baseir, szins*sizeof(IRIns),
  67                                      2*szins*sizeof(IRIns));
  68     J->irtoplim = J->irbotlim + 2*szins;
  69   } else {
  70     baseir = (IRIns *)lj_mem_realloc(J->L, NULL, 0, LJ_MIN_IRSZ*sizeof(IRIns));
  71     J->irbotlim = REF_BASE - LJ_MIN_IRSZ/4;
  72     J->irtoplim = J->irbotlim + LJ_MIN_IRSZ;
  73   }
  74   J->cur.ir = J->irbuf = baseir - J->irbotlim;
  75 }
  76
  77 /* Grow IR buffer at the bottom or shift it up. */
  78 static void lj_ir_growbot(jit_State *J)
  79 {
  80   IRIns *baseir = J->irbuf + J->irbotlim;
  81   MSize szins = J->irtoplim - J->irbotlim;
  82   lua_assert(szins != 0);
  83   lua_assert(J->cur.nk == J->irbotlim);
  84   if (J->cur.nins + (szins >> 1) < J->irtoplim) {
  85     /* More than half of the buffer is free on top: shift up by a quarter. */
  86     MSize ofs = szins >> 2;
  87     memmove(baseir + ofs, baseir, (J->cur.nins - J->irbotlim)*sizeof(IRIns));
  88     J->irbotlim -= ofs;
  89     J->irtoplim -= ofs;
  90     J->cur.ir = J->irbuf = baseir - J->irbotlim;
  91   } else {
  92     /* Double the buffer size, but split the growth amongst top/bottom. */
  93     IRIns *newbase = lj_mem_newt(J->L, 2*szins*sizeof(IRIns), IRIns);
  94     MSize ofs = szins >= 256 ? 128 : (szins >> 1);  /* Limit bottom growth. */
  95     memcpy(newbase + ofs, baseir, (J->cur.nins - J->irbotlim)*sizeof(IRIns));
  96     lj_mem_free(G(J->L), baseir, szins*sizeof(IRIns));
  97     J->irbotlim -= ofs;
  98     J->irtoplim = J->irbotlim + 2*szins;
  99     J->cur.ir = J->irbuf = newbase - J->irbotlim;
 100   }
 101 }
 102
 103 /* Emit IR without any optimizations. */
 104 TRef LJ_FASTCALL lj_ir_emit(jit_State *J)
 105 {
 106   IRRef ref = lj_ir_nextins(J);
 107   IRIns *ir = IR(ref);
 108   IROp op = fins->o;
 109   ir->prev = J->chain[op];
 110   J->chain[op] = (IRRef1)ref;
 111   ir->o = op;
 112   ir->op1 = fins->op1;
 113   ir->op2 = fins->op2;
 114   J->guardemit.irt |= fins->t.irt;
 115   return TREF(ref, irt_t((ir->t = fins->t)));
 116 }
 117
 118 /* Emit call to a C function. */
 119 TRef lj_ir_call(jit_State *J, IRCallID id, ...)
 120 {
 121   const CCallInfo *ci = &lj_ir_callinfo[id];
 122   uint32_t n = CCI_NARGS(ci);
 123   TRef tr = TREF_NIL;
 124   va_list argp;
 125   va_start(argp, id);
 126   if ((ci->flags & CCI_L)) n--;
 127   if (n > 0)
 128     tr = va_arg(argp, IRRef);
 129   while (n-- > 1)
 130     tr = emitir(IRT(IR_CARG, IRT_NIL), tr, va_arg(argp, IRRef));
 131   va_end(argp);
 132   if (CCI_OP(ci) == IR_CALLS)
 133     J->needsnap = 1;  /* Need snapshot after call with side effect. */
 134   return emitir(CCI_OPTYPE(ci), tr, id);
 135 }
 136
 137 /* -- Interning of constants ---------------------------------------------- */
 138
 139 /*
 140 ** IR instructions for constants are kept between J->cur.nk >= ref < REF_BIAS.
 141 ** They are chained like all other instructions, but grow downwards.
 142 ** The are interned (like strings in the VM) to facilitate reference
 143 ** comparisons. The same constant must get the same reference.
 144 */
 145
 146 /* Get ref of next IR constant and optionally grow IR.
 147 ** Note: this may invalidate all IRIns *!
 148 */
 149 static LJ_AINLINE IRRef ir_nextk(jit_State *J)
 150 {
 151   IRRef ref = J->cur.nk;
 152   if (LJ_UNLIKELY(ref <= J->irbotlim)) lj_ir_growbot(J);
 153   J->cur.nk = --ref;
 154   return ref;
 155 }
 156
 157 /* Intern int32_t constant. */
 158 TRef LJ_FASTCALL lj_ir_kint(jit_State *J, int32_t k)
 159 {
 160   IRIns *ir, *cir = J->cur.ir;
 161   IRRef ref;
 162   for (ref = J->chain[IR_KINT]; ref; ref = cir[ref].prev)
 163     if (cir[ref].i == k)
 164       goto found;
 165   ref = ir_nextk(J);
 166   ir = IR(ref);
 167   ir->i = k;
 168   ir->t.irt = IRT_INT;
 169   ir->o = IR_KINT;
 170   ir->prev = J->chain[IR_KINT];
 171   J->chain[IR_KINT] = (IRRef1)ref;
 172 found:
 173   return TREF(ref, IRT_INT);
 174 }
 175
 176 /* The MRef inside the KNUM/KINT64 IR instructions holds the address of the
 177 ** 64 bit constant. The constants themselves are stored in a chained array
 178 ** and shared across traces.
 179 **
 180 ** Rationale for choosing this data structure:
 181 ** - The address of the constants is embedded in the generated machine code
 182 **   and must never move. A resizable array or hash table wouldn't work.
 183 ** - Most apps need very few non-32 bit integer constants (less than a dozen).
 184 ** - Linear search is hard to beat in terms of speed and low complexity.
 185 */
 186 typedef struct K64Array {
 187   MRef next;                    /* Pointer to next list. */
 188   MSize numk;                   /* Number of used elements in this array. */
 189   TValue k[LJ_MIN_K64SZ];       /* Array of constants. */
 190 } K64Array;
 191
 192 /* Free all chained arrays. */
 193 void lj_ir_k64_freeall(jit_State *J)
 194 {
 195   K64Array *k;
 196   for (k = mref(J->k64, K64Array); k; ) {
 197     K64Array *next = mref(k->next, K64Array);
 198     lj_mem_free(J2G(J), k, sizeof(K64Array));
 199     k = next;
 200   }
 201 }
 202
 203 /* Find 64 bit constant in chained array or add it. */
 204 cTValue *lj_ir_k64_find(jit_State *J, uint64_t u64)
 205 {
 206   K64Array *k, *kp = NULL;
 207   TValue *ntv;
 208   MSize idx;
 209   /* Search for the constant in the whole chain of arrays. */
 210   for (k = mref(J->k64, K64Array); k; k = mref(k->next, K64Array)) {
 211     kp = k;  /* Remember previous element in list. */
 212     for (idx = 0; idx < k->numk; idx++) {  /* Search one array. */
 213       TValue *tv = &k->k[idx];
 214       if (tv->u64 == u64)  /* Needed for +-0/NaN/absmask. */
 215         return tv;
 216     }
 217   }
 218   /* Constant was not found, need to add it. */
 219   if (!(kp && kp->numk < LJ_MIN_K64SZ)) {  /* Allocate a new array. */
 220     K64Array *kn = lj_mem_newt(J->L, sizeof(K64Array), K64Array);
 221     setmref(kn->next, NULL);
 222     kn->numk = 0;
 223     if (kp)
 224       setmref(kp->next, kn);  /* Chain to the end of the list. */
 225     else
 226       setmref(J->k64, kn);  /* Link first array. */
 227     kp = kn;
 228   }
 229   ntv = &kp->k[kp->numk++];  /* Add to current array. */
 230   ntv->u64 = u64;
 231   return ntv;
 232 }
 233
 234 /* Intern 64 bit constant, given by its address. */
 235 TRef lj_ir_k64(jit_State *J, IROp op, cTValue *tv)
 236 {
 237   IRIns *ir, *cir = J->cur.ir;
 238   IRRef ref;
 239   IRType t = op == IR_KNUM ? IRT_NUM : IRT_I64;
 240   for (ref = J->chain[op]; ref; ref = cir[ref].prev)
 241     if (ir_k64(&cir[ref]) == tv)
 242       goto found;
 243   ref = ir_nextk(J);
 244   ir = IR(ref);
 245   lua_assert(checkptr32(tv));
 246   setmref(ir->ptr, tv);
 247   ir->t.irt = t;
 248   ir->o = op;
 249   ir->prev = J->chain[op];
 250   J->chain[op] = (IRRef1)ref;
 251 found:
 252   return TREF(ref, t);
 253 }
 254
 255 /* Intern FP constant, given by its 64 bit pattern. */
 256 TRef lj_ir_knum_u64(jit_State *J, uint64_t u64)
 257 {
 258   return lj_ir_k64(J, IR_KNUM, lj_ir_k64_find(J, u64));
 259 }
 260
 261 /* Intern 64 bit integer constant. */
 262 TRef lj_ir_kint64(jit_State *J, uint64_t u64)
 263 {
 264   return lj_ir_k64(J, IR_KINT64, lj_ir_k64_find(J, u64));
 265 }
 266
 267 /* Check whether a number is int and return it. -0 is NOT considered an int. */
 268 static int numistrueint(lua_Number n, int32_t *kp)
 269 {
 270   int32_t k = lj_num2int(n);
 271   if (n == (lua_Number)k) {
 272     if (kp) *kp = k;
 273     if (k == 0) {  /* Special check for -0. */
 274       TValue tv;
 275       setnumV(&tv, n);
 276       if (tv.u32.hi != 0)
 277         return 0;
 278     }
 279     return 1;
 280   }
 281   return 0;
 282 }
 283
 284 /* Intern number as int32_t constant if possible, otherwise as FP constant. */
 285 TRef lj_ir_knumint(jit_State *J, lua_Number n)
 286 {
 287   int32_t k;
 288   if (numistrueint(n, &k))
 289     return lj_ir_kint(J, k);
 290   else
 291     return lj_ir_knum(J, n);
 292 }
 293
 294 /* Intern GC object "constant". */
 295 TRef lj_ir_kgc(jit_State *J, GCobj *o, IRType t)
 296 {
 297   IRIns *ir, *cir = J->cur.ir;
 298   IRRef ref;
 299   lua_assert(!isdead(J2G(J), o));
 300   for (ref = J->chain[IR_KGC]; ref; ref = cir[ref].prev)
 301     if (ir_kgc(&cir[ref]) == o)
 302       goto found;
 303   ref = ir_nextk(J);
 304   ir = IR(ref);
 305   /* NOBARRIER: Current trace is a GC root. */
 306   setgcref(ir->gcr, o);
 307   ir->t.irt = (uint8_t)t;
 308   ir->o = IR_KGC;
 309   ir->prev = J->chain[IR_KGC];
 310   J->chain[IR_KGC] = (IRRef1)ref;
 311 found:
 312   return TREF(ref, t);
 313 }
 314
 315 /* Intern 32 bit pointer constant. */
 316 TRef lj_ir_kptr_(jit_State *J, IROp op, void *ptr)
 317 {
 318   IRIns *ir, *cir = J->cur.ir;
 319   IRRef ref;
 320   lua_assert((void *)(intptr_t)i32ptr(ptr) == ptr);
 321   for (ref = J->chain[op]; ref; ref = cir[ref].prev)
 322     if (mref(cir[ref].ptr, void) == ptr)
 323       goto found;
 324   ref = ir_nextk(J);
 325   ir = IR(ref);
 326   setmref(ir->ptr, ptr);
 327   ir->t.irt = IRT_P32;
 328   ir->o = op;
 329   ir->prev = J->chain[op];
 330   J->chain[op] = (IRRef1)ref;
 331 found:
 332   return TREF(ref, IRT_P32);
 333 }
 334
 335 /* Intern typed NULL constant. */
 336 TRef lj_ir_knull(jit_State *J, IRType t)
 337 {
 338   IRIns *ir, *cir = J->cur.ir;
 339   IRRef ref;
 340   for (ref = J->chain[IR_KNULL]; ref; ref = cir[ref].prev)
 341     if (irt_t(cir[ref].t) == t)
 342       goto found;
 343   ref = ir_nextk(J);
 344   ir = IR(ref);
 345   ir->i = 0;
 346   ir->t.irt = (uint8_t)t;
 347   ir->o = IR_KNULL;
 348   ir->prev = J->chain[IR_KNULL];
 349   J->chain[IR_KNULL] = (IRRef1)ref;
 350 found:
 351   return TREF(ref, t);
 352 }
 353
 354 /* Intern key slot. */
 355 TRef lj_ir_kslot(jit_State *J, TRef key, IRRef slot)
 356 {
 357   IRIns *ir, *cir = J->cur.ir;
 358   IRRef2 op12 = IRREF2((IRRef1)key, (IRRef1)slot);
 359   IRRef ref;
 360   /* Const part is not touched by CSE/DCE, so 0-65535 is ok for IRMlit here. */
 361   lua_assert(tref_isk(key) && slot == (IRRef)(IRRef1)slot);
 362   for (ref = J->chain[IR_KSLOT]; ref; ref = cir[ref].prev)
 363     if (cir[ref].op12 == op12)
 364       goto found;
 365   ref = ir_nextk(J);
 366   ir = IR(ref);
 367   ir->op12 = op12;
 368   ir->t.irt = IRT_P32;
 369   ir->o = IR_KSLOT;
 370   ir->prev = J->chain[IR_KSLOT];
 371   J->chain[IR_KSLOT] = (IRRef1)ref;
 372 found:
 373   return TREF(ref, IRT_P32);
 374 }
 375
 376 /* -- Access to IR constants ---------------------------------------------- */
 377
 378 /* Copy value of IR constant. */
 379 void lj_ir_kvalue(lua_State *L, TValue *tv, const IRIns *ir)
 380 {
 381   UNUSED(L);
 382   lua_assert(ir->o != IR_KSLOT);  /* Common mistake. */
 383   switch (ir->o) {
 384   case IR_KPRI: setitype(tv, irt_toitype(ir->t)); break;
 385   case IR_KINT: setintV(tv, ir->i); break;
 386   case IR_KGC: setgcV(L, tv, ir_kgc(ir), irt_toitype(ir->t)); break;
 387   case IR_KPTR: case IR_KKPTR: case IR_KNULL:
 388     setlightudV(tv, mref(ir->ptr, void));
 389     break;
 390   case IR_KNUM: setnumV(tv, ir_knum(ir)->n); break;
 391 #if LJ_HASFFI
 392   case IR_KINT64: {
 393     GCcdata *cd = lj_cdata_new_(L, CTID_INT64, 8);
 394     *(uint64_t *)cdataptr(cd) = ir_kint64(ir)->u64;
 395     setcdataV(L, tv, cd);
 396     break;
 397     }
 398 #endif
 399   default: lua_assert(0); break;
 400   }
 401 }
 402
 403 /* -- Convert IR operand types -------------------------------------------- */
 404
 405 /* Convert from string to number. */
 406 TRef LJ_FASTCALL lj_ir_tonumber(jit_State *J, TRef tr)
 407 {
 408   if (!tref_isnumber(tr)) {
 409     if (tref_isstr(tr))
 410       tr = emitir(IRTG(IR_STRTO, IRT_NUM), tr, 0);
 411     else
 412       lj_trace_err(J, LJ_TRERR_BADTYPE);
 413   }
 414   return tr;
 415 }
 416
 417 /* Convert from integer or string to number. */
 418 TRef LJ_FASTCALL lj_ir_tonum(jit_State *J, TRef tr)
 419 {
 420   if (!tref_isnum(tr)) {
 421     if (tref_isinteger(tr))
 422       tr = emitir(IRTN(IR_CONV), tr, IRCONV_NUM_INT);
 423     else if (tref_isstr(tr))
 424       tr = emitir(IRTG(IR_STRTO, IRT_NUM), tr, 0);
 425     else
 426       lj_trace_err(J, LJ_TRERR_BADTYPE);
 427   }
 428   return tr;
 429 }
 430
 431 /* Convert from integer or number to string. */
 432 TRef LJ_FASTCALL lj_ir_tostr(jit_State *J, TRef tr)
 433 {
 434   if (!tref_isstr(tr)) {
 435     if (!tref_isnumber(tr))
 436       lj_trace_err(J, LJ_TRERR_BADTYPE);
 437     tr = emitir(IRT(IR_TOSTR, IRT_STR), tr, 0);
 438   }
 439   return tr;
 440 }
 441
 442 /* -- Miscellaneous IR ops ------------------------------------------------ */
 443
 444 /* Evaluate numeric comparison. */
 445 int lj_ir_numcmp(lua_Number a, lua_Number b, IROp op)
 446 {
 447   switch (op) {
 448   case IR_EQ: return (a == b);
 449   case IR_NE: return (a != b);
 450   case IR_LT: return (a < b);
 451   case IR_GE: return (a >= b);
 452   case IR_LE: return (a <= b);
 453   case IR_GT: return (a > b);
 454   case IR_ULT: return !(a >= b);
 455   case IR_UGE: return !(a < b);
 456   case IR_ULE: return !(a > b);
 457   case IR_UGT: return !(a <= b);
 458   default: lua_assert(0); return 0;
 459   }
 460 }
 461
 462 /* Evaluate string comparison. */
 463 int lj_ir_strcmp(GCstr *a, GCstr *b, IROp op)
 464 {
 465   int res = lj_str_cmp(a, b);
 466   switch (op) {
 467   case IR_LT: return (res < 0);
 468   case IR_GE: return (res >= 0);
 469   case IR_LE: return (res <= 0);
 470   case IR_GT: return (res > 0);
 471   default: lua_assert(0); return 0;
 472   }
 473 }
 474
 475 /* Rollback IR to previous state. */
 476 void lj_ir_rollback(jit_State *J, IRRef ref)
 477 {
 478   IRRef nins = J->cur.nins;
 479   while (nins > ref) {
 480     IRIns *ir;
 481     nins--;
 482     ir = IR(nins);
 483     J->chain[ir->o] = ir->prev;
 484   }
 485   J->cur.nins = nins;
 486 }
 487
 488 #undef IR
 489 #undef fins
 490 #undef emitir
 491
 492 #endif