src/lib_jit.c

   1 /*
   2 ** JIT library.
   3 ** Copyright (C) 2005-2012 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #define lib_jit_c
   7 #define LUA_LIB
   8
   9 #include "lua.h"
  10 #include "lauxlib.h"
  11 #include "lualib.h"
  12
  13 #include "lj_arch.h"
  14 #include "lj_obj.h"
  15 #include "lj_err.h"
  16 #include "lj_debug.h"
  17 #include "lj_str.h"
  18 #include "lj_tab.h"
  19 #include "lj_bc.h"
  20 #if LJ_HASJIT
  21 #include "lj_ir.h"
  22 #include "lj_jit.h"
  23 #include "lj_ircall.h"
  24 #include "lj_iropt.h"
  25 #include "lj_target.h"
  26 #endif
  27 #include "lj_dispatch.h"
  28 #include "lj_vm.h"
  29 #include "lj_vmevent.h"
  30 #include "lj_lib.h"
  31
  32 #include "luajit.h"
  33
  34 /* -- jit.* functions ----------------------------------------------------- */
  35
  36 #define LJLIB_MODULE_jit
  37
  38 static int setjitmode(lua_State *L, int mode)
  39 {
  40   int idx = 0;
  41   if (L->base == L->top || tvisnil(L->base)) {  /* jit.on/off/flush([nil]) */
  42     mode |= LUAJIT_MODE_ENGINE;
  43   } else {
  44     /* jit.on/off/flush(func|proto, nil|true|false) */
  45     if (tvisfunc(L->base) || tvisproto(L->base))
  46       idx = 1;
  47     else if (!tvistrue(L->base))  /* jit.on/off/flush(true, nil|true|false) */
  48       goto err;
  49     if (L->base+1 < L->top && tvisbool(L->base+1))
  50       mode |= boolV(L->base+1) ? LUAJIT_MODE_ALLFUNC : LUAJIT_MODE_ALLSUBFUNC;
  51     else
  52       mode |= LUAJIT_MODE_FUNC;
  53   }
  54   if (luaJIT_setmode(L, idx, mode) != 1) {
  55     if ((mode & LUAJIT_MODE_MASK) == LUAJIT_MODE_ENGINE)
  56       lj_err_caller(L, LJ_ERR_NOJIT);
  57   err:
  58     lj_err_argt(L, 1, LUA_TFUNCTION);
  59   }
  60   return 0;
  61 }
  62
  63 LJLIB_CF(jit_on)
  64 {
  65   return setjitmode(L, LUAJIT_MODE_ON);
  66 }
  67
  68 LJLIB_CF(jit_off)
  69 {
  70   return setjitmode(L, LUAJIT_MODE_OFF);
  71 }
  72
  73 LJLIB_CF(jit_flush)
  74 {
  75 #if LJ_HASJIT
  76   if (L->base < L->top && !tvisnil(L->base)) {
  77     int traceno = lj_lib_checkint(L, 1);
  78     luaJIT_setmode(L, traceno, LUAJIT_MODE_FLUSH|LUAJIT_MODE_TRACE);
  79     return 0;
  80   }
  81 #endif
  82   return setjitmode(L, LUAJIT_MODE_FLUSH);
  83 }
  84
  85 #if LJ_HASJIT
  86 /* Push a string for every flag bit that is set. */
  87 static void flagbits_to_strings(lua_State *L, uint32_t flags, uint32_t base,
  88                                 const char *str)
  89 {
  90   for (; *str; base <<= 1, str += 1+*str)
  91     if (flags & base)
  92       setstrV(L, L->top++, lj_str_new(L, str+1, *(uint8_t *)str));
  93 }
  94 #endif
  95
  96 LJLIB_CF(jit_status)
  97 {
  98 #if LJ_HASJIT
  99   jit_State *J = L2J(L);
 100   L->top = L->base;
 101   setboolV(L->top++, (J->flags & JIT_F_ON) ? 1 : 0);
 102   flagbits_to_strings(L, J->flags, JIT_F_CPU_FIRST, JIT_F_CPUSTRING);
 103   flagbits_to_strings(L, J->flags, JIT_F_OPT_FIRST, JIT_F_OPTSTRING);
 104   return (int)(L->top - L->base);
 105 #else
 106   setboolV(L->top++, 0);
 107   return 1;
 108 #endif
 109 }
 110
 111 LJLIB_CF(jit_attach)
 112 {
 113 #ifdef LUAJIT_DISABLE_VMEVENT
 114   luaL_error(L, "vmevent API disabled");
 115 #else
 116   GCfunc *fn = lj_lib_checkfunc(L, 1);
 117   GCstr *s = lj_lib_optstr(L, 2);
 118   luaL_findtable(L, LUA_REGISTRYINDEX, LJ_VMEVENTS_REGKEY, LJ_VMEVENTS_HSIZE);
 119   if (s) {  /* Attach to given event. */
 120     const uint8_t *p = (const uint8_t *)strdata(s);
 121     uint32_t h = s->len;
 122     while (*p) h = h ^ (lj_rol(h, 6) + *p++);
 123     lua_pushvalue(L, 1);
 124     lua_rawseti(L, -2, VMEVENT_HASHIDX(h));
 125     G(L)->vmevmask = VMEVENT_NOCACHE;  /* Invalidate cache. */
 126   } else {  /* Detach if no event given. */
 127     setnilV(L->top++);
 128     while (lua_next(L, -2)) {
 129       L->top--;
 130       if (tvisfunc(L->top) && funcV(L->top) == fn) {
 131         setnilV(lj_tab_set(L, tabV(L->top-2), L->top-1));
 132       }
 133     }
 134   }
 135 #endif
 136   return 0;
 137 }
 138
 139 LJLIB_PUSH(top-5) LJLIB_SET(os)
 140 LJLIB_PUSH(top-4) LJLIB_SET(arch)
 141 LJLIB_PUSH(top-3) LJLIB_SET(version_num)
 142 LJLIB_PUSH(top-2) LJLIB_SET(version)
 143
 144 #include "lj_libdef.h"
 145
 146 /* -- jit.util.* functions ------------------------------------------------ */
 147
 148 #define LJLIB_MODULE_jit_util
 149
 150 /* -- Reflection API for Lua functions ------------------------------------ */
 151
 152 /* Return prototype of first argument (Lua function or prototype object) */
 153 static GCproto *check_Lproto(lua_State *L, int nolua)
 154 {
 155   TValue *o = L->base;
 156   if (L->top > o) {
 157     if (tvisproto(o)) {
 158       return protoV(o);
 159     } else if (tvisfunc(o)) {
 160       if (isluafunc(funcV(o)))
 161         return funcproto(funcV(o));
 162       else if (nolua)
 163         return NULL;
 164     }
 165   }
 166   lj_err_argt(L, 1, LUA_TFUNCTION);
 167   return NULL;  /* unreachable */
 168 }
 169
 170 static void setintfield(lua_State *L, GCtab *t, const char *name, int32_t val)
 171 {
 172   setintV(lj_tab_setstr(L, t, lj_str_newz(L, name)), val);
 173 }
 174
 175 /* local info = jit.util.funcinfo(func [,pc]) */
 176 LJLIB_CF(jit_util_funcinfo)
 177 {
 178   GCproto *pt = check_Lproto(L, 1);
 179   if (pt) {
 180     BCPos pc = (BCPos)lj_lib_optint(L, 2, 0);
 181     GCtab *t;
 182     lua_createtable(L, 0, 16);  /* Increment hash size if fields are added. */
 183     t = tabV(L->top-1);
 184     setintfield(L, t, "linedefined", pt->firstline);
 185     setintfield(L, t, "lastlinedefined", pt->firstline + pt->numline);
 186     setintfield(L, t, "stackslots", pt->framesize);
 187     setintfield(L, t, "params", pt->numparams);
 188     setintfield(L, t, "bytecodes", (int32_t)pt->sizebc);
 189     setintfield(L, t, "gcconsts", (int32_t)pt->sizekgc);
 190     setintfield(L, t, "nconsts", (int32_t)pt->sizekn);
 191     setintfield(L, t, "upvalues", (int32_t)pt->sizeuv);
 192     if (pc < pt->sizebc)
 193       setintfield(L, t, "currentline", lj_debug_line(pt, pc));
 194     lua_pushboolean(L, (pt->flags & PROTO_VARARG));
 195     lua_setfield(L, -2, "isvararg");
 196     lua_pushboolean(L, (pt->flags & PROTO_CHILD));
 197     lua_setfield(L, -2, "children");
 198     setstrV(L, L->top++, proto_chunkname(pt));
 199     lua_setfield(L, -2, "source");
 200     lj_debug_pushloc(L, pt, pc);
 201     lua_setfield(L, -2, "loc");
 202   } else {
 203     GCfunc *fn = funcV(L->base);
 204     GCtab *t;
 205     lua_createtable(L, 0, 4);  /* Increment hash size if fields are added. */
 206     t = tabV(L->top-1);
 207     if (!iscfunc(fn))
 208       setintfield(L, t, "ffid", fn->c.ffid);
 209     setintptrV(lj_tab_setstr(L, t, lj_str_newlit(L, "addr")),
 210                (intptr_t)(void *)fn->c.f);
 211     setintfield(L, t, "upvalues", fn->c.nupvalues);
 212   }
 213   return 1;
 214 }
 215
 216 /* local ins, m = jit.util.funcbc(func, pc) */
 217 LJLIB_CF(jit_util_funcbc)
 218 {
 219   GCproto *pt = check_Lproto(L, 0);
 220   BCPos pc = (BCPos)lj_lib_checkint(L, 2);
 221   if (pc < pt->sizebc) {
 222     BCIns ins = proto_bc(pt)[pc];
 223     BCOp op = bc_op(ins);
 224     lua_assert(op < BC__MAX);
 225     setintV(L->top, ins);
 226     setintV(L->top+1, lj_bc_mode[op]);
 227     L->top += 2;
 228     return 2;
 229   }
 230   return 0;
 231 }
 232
 233 /* local k = jit.util.funck(func, idx) */
 234 LJLIB_CF(jit_util_funck)
 235 {
 236   GCproto *pt = check_Lproto(L, 0);
 237   ptrdiff_t idx = (ptrdiff_t)lj_lib_checkint(L, 2);
 238   if (idx >= 0) {
 239     if (idx < (ptrdiff_t)pt->sizekn) {
 240       copyTV(L, L->top-1, proto_knumtv(pt, idx));
 241       return 1;
 242     }
 243   } else {
 244     if (~idx < (ptrdiff_t)pt->sizekgc) {
 245       GCobj *gc = proto_kgc(pt, idx);
 246       setgcV(L, L->top-1, gc, ~gc->gch.gct);
 247       return 1;
 248     }
 249   }
 250   return 0;
 251 }
 252
 253 /* local name = jit.util.funcuvname(func, idx) */
 254 LJLIB_CF(jit_util_funcuvname)
 255 {
 256   GCproto *pt = check_Lproto(L, 0);
 257   uint32_t idx = (uint32_t)lj_lib_checkint(L, 2);
 258   if (idx < pt->sizeuv) {
 259     setstrV(L, L->top-1, lj_str_newz(L, lj_debug_uvname(pt, idx)));
 260     return 1;
 261   }
 262   return 0;
 263 }
 264
 265 /* -- Reflection API for traces ------------------------------------------- */
 266
 267 #if LJ_HASJIT
 268
 269 /* Check trace argument. Must not throw for non-existent trace numbers. */
 270 static GCtrace *jit_checktrace(lua_State *L)
 271 {
 272   TraceNo tr = (TraceNo)lj_lib_checkint(L, 1);
 273   jit_State *J = L2J(L);
 274   if (tr > 0 && tr < J->sizetrace)
 275     return traceref(J, tr);
 276   return NULL;
 277 }
 278
 279 /* Names of link types. ORDER LJ_TRLINK */
 280 static const char *const jit_trlinkname[] = {
 281   "none", "root", "loop", "tail-recursion", "up-recursion", "down-recursion",
 282   "interpreter", "return"
 283 };
 284
 285 /* local info = jit.util.traceinfo(tr) */
 286 LJLIB_CF(jit_util_traceinfo)
 287 {
 288   GCtrace *T = jit_checktrace(L);
 289   if (T) {
 290     GCtab *t;
 291     lua_createtable(L, 0, 8);  /* Increment hash size if fields are added. */
 292     t = tabV(L->top-1);
 293     setintfield(L, t, "nins", (int32_t)T->nins - REF_BIAS - 1);
 294     setintfield(L, t, "nk", REF_BIAS - (int32_t)T->nk);
 295     setintfield(L, t, "link", T->link);
 296     setintfield(L, t, "nexit", T->nsnap);
 297     setstrV(L, L->top++, lj_str_newz(L, jit_trlinkname[T->linktype]));
 298     lua_setfield(L, -2, "linktype");
 299     /* There are many more fields. Add them only when needed. */
 300     return 1;
 301   }
 302   return 0;
 303 }
 304
 305 /* local m, ot, op1, op2, prev = jit.util.traceir(tr, idx) */
 306 LJLIB_CF(jit_util_traceir)
 307 {
 308   GCtrace *T = jit_checktrace(L);
 309   IRRef ref = (IRRef)lj_lib_checkint(L, 2) + REF_BIAS;
 310   if (T && ref >= REF_BIAS && ref < T->nins) {
 311     IRIns *ir = &T->ir[ref];
 312     int32_t m = lj_ir_mode[ir->o];
 313     setintV(L->top-2, m);
 314     setintV(L->top-1, ir->ot);
 315     setintV(L->top++, (int32_t)ir->op1 - (irm_op1(m)==IRMref ? REF_BIAS : 0));
 316     setintV(L->top++, (int32_t)ir->op2 - (irm_op2(m)==IRMref ? REF_BIAS : 0));
 317     setintV(L->top++, ir->prev);
 318     return 5;
 319   }
 320   return 0;
 321 }
 322
 323 /* local k, t [, slot] = jit.util.tracek(tr, idx) */
 324 LJLIB_CF(jit_util_tracek)
 325 {
 326   GCtrace *T = jit_checktrace(L);
 327   IRRef ref = (IRRef)lj_lib_checkint(L, 2) + REF_BIAS;
 328   if (T && ref >= T->nk && ref < REF_BIAS) {
 329     IRIns *ir = &T->ir[ref];
 330     int32_t slot = -1;
 331     if (ir->o == IR_KSLOT) {
 332       slot = ir->op2;
 333       ir = &T->ir[ir->op1];
 334     }
 335     lj_ir_kvalue(L, L->top-2, ir);
 336     setintV(L->top-1, (int32_t)irt_type(ir->t));
 337     if (slot == -1)
 338       return 2;
 339     setintV(L->top++, slot);
 340     return 3;
 341   }
 342   return 0;
 343 }
 344
 345 /* local snap = jit.util.tracesnap(tr, sn) */
 346 LJLIB_CF(jit_util_tracesnap)
 347 {
 348   GCtrace *T = jit_checktrace(L);
 349   SnapNo sn = (SnapNo)lj_lib_checkint(L, 2);
 350   if (T && sn < T->nsnap) {
 351     SnapShot *snap = &T->snap[sn];
 352     SnapEntry *map = &T->snapmap[snap->mapofs];
 353     MSize n, nent = snap->nent;
 354     GCtab *t;
 355     lua_createtable(L, nent+2, 0);
 356     t = tabV(L->top-1);
 357     setintV(lj_tab_setint(L, t, 0), (int32_t)snap->ref - REF_BIAS);
 358     setintV(lj_tab_setint(L, t, 1), (int32_t)snap->nslots);
 359     for (n = 0; n < nent; n++)
 360       setintV(lj_tab_setint(L, t, (int32_t)(n+2)), (int32_t)map[n]);
 361     setintV(lj_tab_setint(L, t, (int32_t)(nent+2)), (int32_t)SNAP(255, 0, 0));
 362     return 1;
 363   }
 364   return 0;
 365 }
 366
 367 /* local mcode, addr, loop = jit.util.tracemc(tr) */
 368 LJLIB_CF(jit_util_tracemc)
 369 {
 370   GCtrace *T = jit_checktrace(L);
 371   if (T && T->mcode != NULL) {
 372     setstrV(L, L->top-1, lj_str_new(L, (const char *)T->mcode, T->szmcode));
 373     setintptrV(L->top++, (intptr_t)(void *)T->mcode);
 374     setintV(L->top++, T->mcloop);
 375     return 3;
 376   }
 377   return 0;
 378 }
 379
 380 /* local addr = jit.util.traceexitstub([tr,] exitno) */
 381 LJLIB_CF(jit_util_traceexitstub)
 382 {
 383 #ifdef EXITSTUBS_PER_GROUP
 384   ExitNo exitno = (ExitNo)lj_lib_checkint(L, 1);
 385   jit_State *J = L2J(L);
 386   if (exitno < EXITSTUBS_PER_GROUP*LJ_MAX_EXITSTUBGR) {
 387     setintptrV(L->top-1, (intptr_t)(void *)exitstub_addr(J, exitno));
 388     return 1;
 389   }
 390 #else
 391   if (L->top > L->base+1) {  /* Don't throw for one-argument variant. */
 392     GCtrace *T = jit_checktrace(L);
 393     ExitNo exitno = (ExitNo)lj_lib_checkint(L, 2);
 394     ExitNo maxexit = T->root ? T->nsnap+1 : T->nsnap;
 395     if (T && T->mcode != NULL && exitno < maxexit) {
 396       setintptrV(L->top-1, (intptr_t)(void *)exitstub_trace_addr(T, exitno));
 397       return 1;
 398     }
 399   }
 400 #endif
 401   return 0;
 402 }
 403
 404 /* local addr = jit.util.ircalladdr(idx) */
 405 LJLIB_CF(jit_util_ircalladdr)
 406 {
 407   uint32_t idx = (uint32_t)lj_lib_checkint(L, 1);
 408   if (idx < IRCALL__MAX) {
 409     setintptrV(L->top-1, (intptr_t)(void *)lj_ir_callinfo[idx].func);
 410     return 1;
 411   }
 412   return 0;
 413 }
 414
 415 #endif
 416
 417 #include "lj_libdef.h"
 418
 419 /* -- jit.opt module ------------------------------------------------------ */
 420
 421 #if LJ_HASJIT
 422
 423 #define LJLIB_MODULE_jit_opt
 424
 425 /* Parse optimization level. */
 426 static int jitopt_level(jit_State *J, const char *str)
 427 {
 428   if (str[0] >= '0' && str[0] <= '9' && str[1] == '\0') {
 429     uint32_t flags;
 430     if (str[0] == '0') flags = JIT_F_OPT_0;
 431     else if (str[0] == '1') flags = JIT_F_OPT_1;
 432     else if (str[0] == '2') flags = JIT_F_OPT_2;
 433     else flags = JIT_F_OPT_3;
 434     J->flags = (J->flags & ~JIT_F_OPT_MASK) | flags;
 435     return 1;  /* Ok. */
 436   }
 437   return 0;  /* No match. */
 438 }
 439
 440 /* Parse optimization flag. */
 441 static int jitopt_flag(jit_State *J, const char *str)
 442 {
 443   const char *lst = JIT_F_OPTSTRING;
 444   uint32_t opt;
 445   int set = 1;
 446   if (str[0] == '+') {
 447     str++;
 448   } else if (str[0] == '-') {
 449     str++;
 450     set = 0;
 451   } else if (str[0] == 'n' && str[1] == 'o') {
 452     str += str[2] == '-' ? 3 : 2;
 453     set = 0;
 454   }
 455   for (opt = JIT_F_OPT_FIRST; ; opt <<= 1) {
 456     size_t len = *(const uint8_t *)lst;
 457     if (len == 0)
 458       break;
 459     if (strncmp(str, lst+1, len) == 0 && str[len] == '\0') {
 460       if (set) J->flags |= opt; else J->flags &= ~opt;
 461       return 1;  /* Ok. */
 462     }
 463     lst += 1+len;
 464   }
 465   return 0;  /* No match. */
 466 }
 467
 468 /* Parse optimization parameter. */
 469 static int jitopt_param(jit_State *J, const char *str)
 470 {
 471   const char *lst = JIT_P_STRING;
 472   int i;
 473   for (i = 0; i < JIT_P__MAX; i++) {
 474     size_t len = *(const uint8_t *)lst;
 475     lua_assert(len != 0);
 476     if (strncmp(str, lst+1, len) == 0 && str[len] == '=') {
 477       int32_t n = 0;
 478       const char *p = &str[len+1];
 479       while (*p >= '0' && *p <= '9')
 480         n = n*10 + (*p++ - '0');
 481       if (*p) return 0;  /* Malformed number. */
 482       J->param[i] = n;
 483       if (i == JIT_P_hotloop)
 484         lj_dispatch_init_hotcount(J2G(J));
 485       return 1;  /* Ok. */
 486     }
 487     lst += 1+len;
 488   }
 489   return 0;  /* No match. */
 490 }
 491
 492 /* jit.opt.start(flags...) */
 493 LJLIB_CF(jit_opt_start)
 494 {
 495   jit_State *J = L2J(L);
 496   int nargs = (int)(L->top - L->base);
 497   if (nargs == 0) {
 498     J->flags = (J->flags & ~JIT_F_OPT_MASK) | JIT_F_OPT_DEFAULT;
 499   } else {
 500     int i;
 501     for (i = 1; i <= nargs; i++) {
 502       const char *str = strdata(lj_lib_checkstr(L, i));
 503       if (!jitopt_level(J, str) &&
 504           !jitopt_flag(J, str) &&
 505           !jitopt_param(J, str))
 506         lj_err_callerv(L, LJ_ERR_JITOPT, str);
 507     }
 508   }
 509   return 0;
 510 }
 511
 512 #include "lj_libdef.h"
 513
 514 #endif
 515
 516 /* -- JIT compiler initialization ----------------------------------------- */
 517
 518 #if LJ_HASJIT
 519 /* Default values for JIT parameters. */
 520 static const int32_t jit_param_default[JIT_P__MAX+1] = {
 521 #define JIT_PARAMINIT(len, name, value) (value),
 522 JIT_PARAMDEF(JIT_PARAMINIT)
 523 #undef JIT_PARAMINIT
 524   0
 525 };
 526 #endif
 527
 528 #if LJ_TARGET_ARM && LJ_TARGET_LINUX
 529 #include <sys/utsname.h>
 530 #endif
 531
 532 /* Arch-dependent CPU detection. */
 533 static uint32_t jit_cpudetect(lua_State *L)
 534 {
 535   uint32_t flags = 0;
 536 #if LJ_TARGET_X86ORX64
 537   uint32_t vendor[4];
 538   uint32_t features[4];
 539   if (lj_vm_cpuid(0, vendor) && lj_vm_cpuid(1, features)) {
 540 #if !LJ_HASJIT
 541 #define JIT_F_CMOV      1
 542 #define JIT_F_SSE2      2
 543 #endif
 544     flags |= ((features[3] >> 15)&1) * JIT_F_CMOV;
 545     flags |= ((features[3] >> 26)&1) * JIT_F_SSE2;
 546 #if LJ_HASJIT
 547     flags |= ((features[2] >> 0)&1) * JIT_F_SSE3;
 548     flags |= ((features[2] >> 19)&1) * JIT_F_SSE4_1;
 549     if (vendor[2] == 0x6c65746e) {  /* Intel. */
 550       if ((features[0] & 0x0ff00f00) == 0x00000f00)  /* P4. */
 551         flags |= JIT_F_P4;  /* Currently unused. */
 552       else if ((features[0] & 0x0fff0ff0) == 0x000106c0)  /* Atom. */
 553         flags |= JIT_F_LEA_AGU;
 554     } else if (vendor[2] == 0x444d4163) {  /* AMD. */
 555       uint32_t fam = (features[0] & 0x0ff00f00);
 556       if (fam == 0x00000f00)  /* K8. */
 557         flags |= JIT_F_SPLIT_XMM;
 558       if (fam >= 0x00000f00)  /* K8, K10. */
 559         flags |= JIT_F_PREFER_IMUL;
 560     }
 561 #endif
 562   }
 563   /* Check for required instruction set support on x86 (unnecessary on x64). */
 564 #if LJ_TARGET_X86
 565 #if !defined(LUAJIT_CPU_NOCMOV)
 566   if (!(flags & JIT_F_CMOV))
 567     luaL_error(L, "CPU not supported");
 568 #endif
 569 #if defined(LUAJIT_CPU_SSE2)
 570   if (!(flags & JIT_F_SSE2))
 571     luaL_error(L, "CPU does not support SSE2 (recompile without -DLUAJIT_CPU_SSE2)");
 572 #endif
 573 #endif
 574 #elif LJ_TARGET_ARM
 575 #if LJ_HASJIT
 576   int ver = LJ_ARCH_VERSION;  /* Compile-time ARM CPU detection. */
 577 #if LJ_TARGET_LINUX
 578   if (ver < 70) {  /* Runtime ARM CPU detection. */
 579     struct utsname ut;
 580     uname(&ut);
 581     if (strncmp(ut.machine, "armv", 4) == 0) {
 582       if (ut.machine[4] >= '7')
 583         ver = 70;
 584       else if (ut.machine[4] == '6')
 585         ver = 60;
 586     }
 587   }
 588 #endif
 589   flags |= ver >= 70 ? JIT_F_ARMV7 :
 590            ver >= 61 ? JIT_F_ARMV6T2_ :
 591            ver >= 60 ? JIT_F_ARMV6_ : 0;
 592   flags |= LJ_ARCH_HASFPU == 0 ? 0 : ver >= 70 ? JIT_F_VFPV3 : JIT_F_VFPV2;
 593 #endif
 594 #elif LJ_TARGET_PPC
 595 #if LJ_HASJIT
 596 #if LJ_ARCH_SQRT
 597   flags |= JIT_F_SQRT;
 598 #endif
 599 #if LJ_ARCH_ROUND
 600   flags |= JIT_F_ROUND;
 601 #endif
 602 #endif
 603 #elif LJ_TARGET_PPCSPE
 604   /* Nothing to do. */
 605 #elif LJ_TARGET_MIPS
 606 #if LJ_HASJIT
 607   /* Compile-time MIPS CPU detection. */
 608 #if LJ_ARCH_VERSION >= 20
 609   flags |= JIT_F_MIPS32R2;
 610 #endif
 611   /* Runtime MIPS CPU detection. */
 612 #if defined(__GNUC__)
 613   if (!(flags & JIT_F_MIPS32R2)) {
 614     int x;
 615     /* On MIPS32R1 rotr is treated as srl. rotr r2,r2,1 -> srl r2,r2,1. */
 616     __asm__("li $2, 1\n\t.long 0x00221042\n\tmove %0, $2" : "=r"(x) : : "$2");
 617     if (x) flags |= JIT_F_MIPS32R2;  /* Either 0x80000000 (R2) or 0 (R1). */
 618   }
 619 #endif
 620 #endif
 621 #else
 622 #error "Missing CPU detection for this architecture"
 623 #endif
 624   UNUSED(L);
 625   return flags;
 626 }
 627
 628 /* Initialize JIT compiler. */
 629 static void jit_init(lua_State *L)
 630 {
 631   uint32_t flags = jit_cpudetect(L);
 632 #if LJ_HASJIT
 633   jit_State *J = L2J(L);
 634 #if LJ_TARGET_X86
 635   /* Silently turn off the JIT compiler on CPUs without SSE2. */
 636   if ((flags & JIT_F_SSE2))
 637 #endif
 638     J->flags = flags | JIT_F_ON | JIT_F_OPT_DEFAULT;
 639   memcpy(J->param, jit_param_default, sizeof(J->param));
 640   lj_dispatch_update(G(L));
 641 #else
 642   UNUSED(flags);
 643 #endif
 644 }
 645
 646 LUALIB_API int luaopen_jit(lua_State *L)
 647 {
 648   lua_pushliteral(L, LJ_OS_NAME);
 649   lua_pushliteral(L, LJ_ARCH_NAME);
 650   lua_pushinteger(L, LUAJIT_VERSION_NUM);
 651   lua_pushliteral(L, LUAJIT_VERSION);
 652   LJ_LIB_REG(L, LUA_JITLIBNAME, jit);
 653 #ifndef LUAJIT_DISABLE_JITUTIL
 654   LJ_LIB_REG(L, "jit.util", jit_util);
 655 #endif
 656 #if LJ_HASJIT
 657   LJ_LIB_REG(L, "jit.opt", jit_opt);
 658 #endif
 659   L->top -= 2;
 660   jit_init(L);
 661   return 1;
 662 }
 663