src/lj_ir.c

   1 /*
   2 ** SSA IR (Intermediate Representation) emitter.
   3 ** Copyright (C) 2005-2014 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_buf.h"
  19 #include "lj_str.h"
  20 #include "lj_tab.h"
  21 #include "lj_ir.h"
  22 #include "lj_jit.h"
  23 #include "lj_ircall.h"
  24 #include "lj_iropt.h"
  25 #include "lj_trace.h"
  26 #if LJ_HASFFI
  27 #include "lj_ctype.h"
  28 #include "lj_cdata.h"
  29 #include "lj_carith.h"
  30 #endif
  31 #include "lj_vm.h"
  32 #include "lj_strscan.h"
  33 #include "lj_strfmt.h"
  34 #include "lj_lib.h"
  35
  36 /* Some local macros to save typing. Undef'd at the end. */
  37 #define IR(ref)                 (&J->cur.ir[(ref)])
  38 #define fins                    (&J->fold.ins)
  39
  40 /* Pass IR on to next optimization in chain (FOLD). */
  41 #define emitir(ot, a, b)        (lj_ir_set(J, (ot), (a), (b)), lj_opt_fold(J))
  42
  43 /* -- IR tables ----------------------------------------------------------- */
  44
  45 /* IR instruction modes. */
  46 LJ_DATADEF const uint8_t lj_ir_mode[IR__MAX+1] = {
  47 IRDEF(IRMODE)
  48   0
  49 };
  50
  51 /* IR type sizes. */
  52 LJ_DATADEF const uint8_t lj_ir_type_size[IRT__MAX+1] = {
  53 #define IRTSIZE(name, size)     size,
  54 IRTDEF(IRTSIZE)
  55 #undef IRTSIZE
  56   0
  57 };
  58
  59 /* C call info for CALL* instructions. */
  60 LJ_DATADEF const CCallInfo lj_ir_callinfo[] = {
  61 #define IRCALLCI(cond, name, nargs, kind, type, flags) \
  62   { (ASMFunction)IRCALLCOND_##cond(name), \
  63     (nargs)|(CCI_CALL_##kind)|(IRT_##type<<CCI_OTSHIFT)|(flags) },
  64 IRCALLDEF(IRCALLCI)
  65 #undef IRCALLCI
  66   { NULL, 0 }
  67 };
  68
  69 /* -- IR emitter ---------------------------------------------------------- */
  70
  71 /* Grow IR buffer at the top. */
  72 void LJ_FASTCALL lj_ir_growtop(jit_State *J)
  73 {
  74   IRIns *baseir = J->irbuf + J->irbotlim;
  75   MSize szins = J->irtoplim - J->irbotlim;
  76   if (szins) {
  77     baseir = (IRIns *)lj_mem_realloc(J->L, baseir, szins*sizeof(IRIns),
  78                                      2*szins*sizeof(IRIns));
  79     J->irtoplim = J->irbotlim + 2*szins;
  80   } else {
  81     baseir = (IRIns *)lj_mem_realloc(J->L, NULL, 0, LJ_MIN_IRSZ*sizeof(IRIns));
  82     J->irbotlim = REF_BASE - LJ_MIN_IRSZ/4;
  83     J->irtoplim = J->irbotlim + LJ_MIN_IRSZ;
  84   }
  85   J->cur.ir = J->irbuf = baseir - J->irbotlim;
  86 }
  87
  88 /* Grow IR buffer at the bottom or shift it up. */
  89 static void lj_ir_growbot(jit_State *J)
  90 {
  91   IRIns *baseir = J->irbuf + J->irbotlim;
  92   MSize szins = J->irtoplim - J->irbotlim;
  93   lua_assert(szins != 0);
  94   lua_assert(J->cur.nk == J->irbotlim);
  95   if (J->cur.nins + (szins >> 1) < J->irtoplim) {
  96     /* More than half of the buffer is free on top: shift up by a quarter. */
  97     MSize ofs = szins >> 2;
  98     memmove(baseir + ofs, baseir, (J->cur.nins - J->irbotlim)*sizeof(IRIns));
  99     J->irbotlim -= ofs;
 100     J->irtoplim -= ofs;
 101     J->cur.ir = J->irbuf = baseir - J->irbotlim;
 102   } else {
 103     /* Double the buffer size, but split the growth amongst top/bottom. */
 104     IRIns *newbase = lj_mem_newt(J->L, 2*szins*sizeof(IRIns), IRIns);
 105     MSize ofs = szins >= 256 ? 128 : (szins >> 1);  /* Limit bottom growth. */
 106     memcpy(newbase + ofs, baseir, (J->cur.nins - J->irbotlim)*sizeof(IRIns));
 107     lj_mem_free(G(J->L), baseir, szins*sizeof(IRIns));
 108     J->irbotlim -= ofs;
 109     J->irtoplim = J->irbotlim + 2*szins;
 110     J->cur.ir = J->irbuf = newbase - J->irbotlim;
 111   }
 112 }
 113
 114 /* Emit IR without any optimizations. */
 115 TRef LJ_FASTCALL lj_ir_emit(jit_State *J)
 116 {
 117   IRRef ref = lj_ir_nextins(J);
 118   IRIns *ir = IR(ref);
 119   IROp op = fins->o;
 120   ir->prev = J->chain[op];
 121   J->chain[op] = (IRRef1)ref;
 122   ir->o = op;
 123   ir->op1 = fins->op1;
 124   ir->op2 = fins->op2;
 125   J->guardemit.irt |= fins->t.irt;
 126   return TREF(ref, irt_t((ir->t = fins->t)));
 127 }
 128
 129 /* Emit call to a C function. */
 130 TRef lj_ir_call(jit_State *J, IRCallID id, ...)
 131 {
 132   const CCallInfo *ci = &lj_ir_callinfo[id];
 133   uint32_t n = CCI_NARGS(ci);
 134   TRef tr = TREF_NIL;
 135   va_list argp;
 136   va_start(argp, id);
 137   if ((ci->flags & CCI_L)) n--;
 138   if (n > 0)
 139     tr = va_arg(argp, IRRef);
 140   while (n-- > 1)
 141     tr = emitir(IRT(IR_CARG, IRT_NIL), tr, va_arg(argp, IRRef));
 142   va_end(argp);
 143   if (CCI_OP(ci) == IR_CALLS)
 144     J->needsnap = 1;  /* Need snapshot after call with side effect. */
 145   return emitir(CCI_OPTYPE(ci), tr, id);
 146 }
 147
 148 /* -- Interning of constants ---------------------------------------------- */
 149
 150 /*
 151 ** IR instructions for constants are kept between J->cur.nk >= ref < REF_BIAS.
 152 ** They are chained like all other instructions, but grow downwards.
 153 ** The are interned (like strings in the VM) to facilitate reference
 154 ** comparisons. The same constant must get the same reference.
 155 */
 156
 157 /* Get ref of next IR constant and optionally grow IR.
 158 ** Note: this may invalidate all IRIns *!
 159 */
 160 static LJ_AINLINE IRRef ir_nextk(jit_State *J)
 161 {
 162   IRRef ref = J->cur.nk;
 163   if (LJ_UNLIKELY(ref <= J->irbotlim)) lj_ir_growbot(J);
 164   J->cur.nk = --ref;
 165   return ref;
 166 }
 167
 168 /* Intern int32_t constant. */
 169 TRef LJ_FASTCALL lj_ir_kint(jit_State *J, int32_t k)
 170 {
 171   IRIns *ir, *cir = J->cur.ir;
 172   IRRef ref;
 173   for (ref = J->chain[IR_KINT]; ref; ref = cir[ref].prev)
 174     if (cir[ref].i == k)
 175       goto found;
 176   ref = ir_nextk(J);
 177   ir = IR(ref);
 178   ir->i = k;
 179   ir->t.irt = IRT_INT;
 180   ir->o = IR_KINT;
 181   ir->prev = J->chain[IR_KINT];
 182   J->chain[IR_KINT] = (IRRef1)ref;
 183 found:
 184   return TREF(ref, IRT_INT);
 185 }
 186
 187 /* The MRef inside the KNUM/KINT64 IR instructions holds the address of the
 188 ** 64 bit constant. The constants themselves are stored in a chained array
 189 ** and shared across traces.
 190 **
 191 ** Rationale for choosing this data structure:
 192 ** - The address of the constants is embedded in the generated machine code
 193 **   and must never move. A resizable array or hash table wouldn't work.
 194 ** - Most apps need very few non-32 bit integer constants (less than a dozen).
 195 ** - Linear search is hard to beat in terms of speed and low complexity.
 196 */
 197 typedef struct K64Array {
 198   MRef next;                    /* Pointer to next list. */
 199   MSize numk;                   /* Number of used elements in this array. */
 200   TValue k[LJ_MIN_K64SZ];       /* Array of constants. */
 201 } K64Array;
 202
 203 /* Free all chained arrays. */
 204 void lj_ir_k64_freeall(jit_State *J)
 205 {
 206   K64Array *k;
 207   for (k = mref(J->k64, K64Array); k; ) {
 208     K64Array *next = mref(k->next, K64Array);
 209     lj_mem_free(J2G(J), k, sizeof(K64Array));
 210     k = next;
 211   }
 212 }
 213
 214 /* Find 64 bit constant in chained array or add it. */
 215 cTValue *lj_ir_k64_find(jit_State *J, uint64_t u64)
 216 {
 217   K64Array *k, *kp = NULL;
 218   TValue *ntv;
 219   MSize idx;
 220   /* Search for the constant in the whole chain of arrays. */
 221   for (k = mref(J->k64, K64Array); k; k = mref(k->next, K64Array)) {
 222     kp = k;  /* Remember previous element in list. */
 223     for (idx = 0; idx < k->numk; idx++) {  /* Search one array. */
 224       TValue *tv = &k->k[idx];
 225       if (tv->u64 == u64)  /* Needed for +-0/NaN/absmask. */
 226         return tv;
 227     }
 228   }
 229   /* Constant was not found, need to add it. */
 230   if (!(kp && kp->numk < LJ_MIN_K64SZ)) {  /* Allocate a new array. */
 231     K64Array *kn = lj_mem_newt(J->L, sizeof(K64Array), K64Array);
 232     setmref(kn->next, NULL);
 233     kn->numk = 0;
 234     if (kp)
 235       setmref(kp->next, kn);  /* Chain to the end of the list. */
 236     else
 237       setmref(J->k64, kn);  /* Link first array. */
 238     kp = kn;
 239   }
 240   ntv = &kp->k[kp->numk++];  /* Add to current array. */
 241   ntv->u64 = u64;
 242   return ntv;
 243 }
 244
 245 /* Intern 64 bit constant, given by its address. */
 246 TRef lj_ir_k64(jit_State *J, IROp op, cTValue *tv)
 247 {
 248   IRIns *ir, *cir = J->cur.ir;
 249   IRRef ref;
 250   IRType t = op == IR_KNUM ? IRT_NUM : IRT_I64;
 251   for (ref = J->chain[op]; ref; ref = cir[ref].prev)
 252     if (ir_k64(&cir[ref]) == tv)
 253       goto found;
 254   ref = ir_nextk(J);
 255   ir = IR(ref);
 256   lua_assert(checkptr32(tv));
 257   setmref(ir->ptr, tv);
 258   ir->t.irt = t;
 259   ir->o = op;
 260   ir->prev = J->chain[op];
 261   J->chain[op] = (IRRef1)ref;
 262 found:
 263   return TREF(ref, t);
 264 }
 265
 266 /* Intern FP constant, given by its 64 bit pattern. */
 267 TRef lj_ir_knum_u64(jit_State *J, uint64_t u64)
 268 {
 269   return lj_ir_k64(J, IR_KNUM, lj_ir_k64_find(J, u64));
 270 }
 271
 272 /* Intern 64 bit integer constant. */
 273 TRef lj_ir_kint64(jit_State *J, uint64_t u64)
 274 {
 275   return lj_ir_k64(J, IR_KINT64, lj_ir_k64_find(J, u64));
 276 }
 277
 278 /* Check whether a number is int and return it. -0 is NOT considered an int. */
 279 static int numistrueint(lua_Number n, int32_t *kp)
 280 {
 281   int32_t k = lj_num2int(n);
 282   if (n == (lua_Number)k) {
 283     if (kp) *kp = k;
 284     if (k == 0) {  /* Special check for -0. */
 285       TValue tv;
 286       setnumV(&tv, n);
 287       if (tv.u32.hi != 0)
 288         return 0;
 289     }
 290     return 1;
 291   }
 292   return 0;
 293 }
 294
 295 /* Intern number as int32_t constant if possible, otherwise as FP constant. */
 296 TRef lj_ir_knumint(jit_State *J, lua_Number n)
 297 {
 298   int32_t k;
 299   if (numistrueint(n, &k))
 300     return lj_ir_kint(J, k);
 301   else
 302     return lj_ir_knum(J, n);
 303 }
 304
 305 /* Intern GC object "constant". */
 306 TRef lj_ir_kgc(jit_State *J, GCobj *o, IRType t)
 307 {
 308   IRIns *ir, *cir = J->cur.ir;
 309   IRRef ref;
 310   lua_assert(!isdead(J2G(J), o));
 311   for (ref = J->chain[IR_KGC]; ref; ref = cir[ref].prev)
 312     if (ir_kgc(&cir[ref]) == o)
 313       goto found;
 314   ref = ir_nextk(J);
 315   ir = IR(ref);
 316   /* NOBARRIER: Current trace is a GC root. */
 317   setgcref(ir->gcr, o);
 318   ir->t.irt = (uint8_t)t;
 319   ir->o = IR_KGC;
 320   ir->prev = J->chain[IR_KGC];
 321   J->chain[IR_KGC] = (IRRef1)ref;
 322 found:
 323   return TREF(ref, t);
 324 }
 325
 326 /* Intern 32 bit pointer constant. */
 327 TRef lj_ir_kptr_(jit_State *J, IROp op, void *ptr)
 328 {
 329   IRIns *ir, *cir = J->cur.ir;
 330   IRRef ref;
 331   lua_assert((void *)(intptr_t)i32ptr(ptr) == ptr);
 332   for (ref = J->chain[op]; ref; ref = cir[ref].prev)
 333     if (mref(cir[ref].ptr, void) == ptr)
 334       goto found;
 335   ref = ir_nextk(J);
 336   ir = IR(ref);
 337   setmref(ir->ptr, ptr);
 338   ir->t.irt = IRT_P32;
 339   ir->o = op;
 340   ir->prev = J->chain[op];
 341   J->chain[op] = (IRRef1)ref;
 342 found:
 343   return TREF(ref, IRT_P32);
 344 }
 345
 346 /* Intern typed NULL constant. */
 347 TRef lj_ir_knull(jit_State *J, IRType t)
 348 {
 349   IRIns *ir, *cir = J->cur.ir;
 350   IRRef ref;
 351   for (ref = J->chain[IR_KNULL]; ref; ref = cir[ref].prev)
 352     if (irt_t(cir[ref].t) == t)
 353       goto found;
 354   ref = ir_nextk(J);
 355   ir = IR(ref);
 356   ir->i = 0;
 357   ir->t.irt = (uint8_t)t;
 358   ir->o = IR_KNULL;
 359   ir->prev = J->chain[IR_KNULL];
 360   J->chain[IR_KNULL] = (IRRef1)ref;
 361 found:
 362   return TREF(ref, t);
 363 }
 364
 365 /* Intern key slot. */
 366 TRef lj_ir_kslot(jit_State *J, TRef key, IRRef slot)
 367 {
 368   IRIns *ir, *cir = J->cur.ir;
 369   IRRef2 op12 = IRREF2((IRRef1)key, (IRRef1)slot);
 370   IRRef ref;
 371   /* Const part is not touched by CSE/DCE, so 0-65535 is ok for IRMlit here. */
 372   lua_assert(tref_isk(key) && slot == (IRRef)(IRRef1)slot);
 373   for (ref = J->chain[IR_KSLOT]; ref; ref = cir[ref].prev)
 374     if (cir[ref].op12 == op12)
 375       goto found;
 376   ref = ir_nextk(J);
 377   ir = IR(ref);
 378   ir->op12 = op12;
 379   ir->t.irt = IRT_P32;
 380   ir->o = IR_KSLOT;
 381   ir->prev = J->chain[IR_KSLOT];
 382   J->chain[IR_KSLOT] = (IRRef1)ref;
 383 found:
 384   return TREF(ref, IRT_P32);
 385 }
 386
 387 /* -- Access to IR constants ---------------------------------------------- */
 388
 389 /* Copy value of IR constant. */
 390 void lj_ir_kvalue(lua_State *L, TValue *tv, const IRIns *ir)
 391 {
 392   UNUSED(L);
 393   lua_assert(ir->o != IR_KSLOT);  /* Common mistake. */
 394   switch (ir->o) {
 395   case IR_KPRI: setitype(tv, irt_toitype(ir->t)); break;
 396   case IR_KINT: setintV(tv, ir->i); break;
 397   case IR_KGC: setgcV(L, tv, ir_kgc(ir), irt_toitype(ir->t)); break;
 398   case IR_KPTR: case IR_KKPTR: case IR_KNULL:
 399     setlightudV(tv, mref(ir->ptr, void));
 400     break;
 401   case IR_KNUM: setnumV(tv, ir_knum(ir)->n); break;
 402 #if LJ_HASFFI
 403   case IR_KINT64: {
 404     GCcdata *cd = lj_cdata_new_(L, CTID_INT64, 8);
 405     *(uint64_t *)cdataptr(cd) = ir_kint64(ir)->u64;
 406     setcdataV(L, tv, cd);
 407     break;
 408     }
 409 #endif
 410   default: lua_assert(0); break;
 411   }
 412 }
 413
 414 /* -- Convert IR operand types -------------------------------------------- */
 415
 416 /* Convert from string to number. */
 417 TRef LJ_FASTCALL lj_ir_tonumber(jit_State *J, TRef tr)
 418 {
 419   if (!tref_isnumber(tr)) {
 420     if (tref_isstr(tr))
 421       tr = emitir(IRTG(IR_STRTO, IRT_NUM), tr, 0);
 422     else
 423       lj_trace_err(J, LJ_TRERR_BADTYPE);
 424   }
 425   return tr;
 426 }
 427
 428 /* Convert from integer or string to number. */
 429 TRef LJ_FASTCALL lj_ir_tonum(jit_State *J, TRef tr)
 430 {
 431   if (!tref_isnum(tr)) {
 432     if (tref_isinteger(tr))
 433       tr = emitir(IRTN(IR_CONV), tr, IRCONV_NUM_INT);
 434     else if (tref_isstr(tr))
 435       tr = emitir(IRTG(IR_STRTO, IRT_NUM), tr, 0);
 436     else
 437       lj_trace_err(J, LJ_TRERR_BADTYPE);
 438   }
 439   return tr;
 440 }
 441
 442 /* Convert from integer or number to string. */
 443 TRef LJ_FASTCALL lj_ir_tostr(jit_State *J, TRef tr)
 444 {
 445   if (!tref_isstr(tr)) {
 446     if (!tref_isnumber(tr))
 447       lj_trace_err(J, LJ_TRERR_BADTYPE);
 448     tr = emitir(IRT(IR_TOSTR, IRT_STR), tr,
 449                 tref_isnum(tr) ? IRTOSTR_NUM : IRTOSTR_INT);
 450   }
 451   return tr;
 452 }
 453
 454 /* -- Miscellaneous IR ops ------------------------------------------------ */
 455
 456 /* Evaluate numeric comparison. */
 457 int lj_ir_numcmp(lua_Number a, lua_Number b, IROp op)
 458 {
 459   switch (op) {
 460   case IR_EQ: return (a == b);
 461   case IR_NE: return (a != b);
 462   case IR_LT: return (a < b);
 463   case IR_GE: return (a >= b);
 464   case IR_LE: return (a <= b);
 465   case IR_GT: return (a > b);
 466   case IR_ULT: return !(a >= b);
 467   case IR_UGE: return !(a < b);
 468   case IR_ULE: return !(a > b);
 469   case IR_UGT: return !(a <= b);
 470   default: lua_assert(0); return 0;
 471   }
 472 }
 473
 474 /* Evaluate string comparison. */
 475 int lj_ir_strcmp(GCstr *a, GCstr *b, IROp op)
 476 {
 477   int res = lj_str_cmp(a, b);
 478   switch (op) {
 479   case IR_LT: return (res < 0);
 480   case IR_GE: return (res >= 0);
 481   case IR_LE: return (res <= 0);
 482   case IR_GT: return (res > 0);
 483   default: lua_assert(0); return 0;
 484   }
 485 }
 486
 487 /* Rollback IR to previous state. */
 488 void lj_ir_rollback(jit_State *J, IRRef ref)
 489 {
 490   IRRef nins = J->cur.nins;
 491   while (nins > ref) {
 492     IRIns *ir;
 493     nins--;
 494     ir = IR(nins);
 495     J->chain[ir->o] = ir->prev;
 496   }
 497   J->cur.nins = nins;
 498 }
 499
 500 #undef IR
 501 #undef fins
 502 #undef emitir
 503
 504 #endif