src/lj_bcwrite.c

   1 /*
   2 ** Bytecode writer.
   3 ** Copyright (C) 2005-2012 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #define lj_bcwrite_c
   7 #define LUA_CORE
   8
   9 #include "lj_obj.h"
  10 #include "lj_gc.h"
  11 #include "lj_str.h"
  12 #include "lj_bc.h"
  13 #if LJ_HASFFI
  14 #include "lj_ctype.h"
  15 #endif
  16 #if LJ_HASJIT
  17 #include "lj_dispatch.h"
  18 #include "lj_jit.h"
  19 #endif
  20 #include "lj_bcdump.h"
  21 #include "lj_vm.h"
  22
  23 /* Context for bytecode writer. */
  24 typedef struct BCWriteCtx {
  25   SBuf sb;                      /* Output buffer. */
  26   lua_State *L;                 /* Lua state. */
  27   GCproto *pt;                  /* Root prototype. */
  28   lua_Writer wfunc;             /* Writer callback. */
  29   void *wdata;                  /* Writer callback data. */
  30   int strip;                    /* Strip debug info. */
  31   int status;                   /* Status from writer callback. */
  32 } BCWriteCtx;
  33
  34 /* -- Output buffer handling ---------------------------------------------- */
  35
  36 /* Resize buffer if needed. */
  37 static LJ_NOINLINE void bcwrite_resize(BCWriteCtx *ctx, MSize len)
  38 {
  39   MSize sz = ctx->sb.sz * 2;
  40   while (ctx->sb.n + len > sz) sz = sz * 2;
  41   lj_str_resizebuf(ctx->L, &ctx->sb, sz);
  42 }
  43
  44 /* Need a certain amount of buffer space. */
  45 static LJ_AINLINE void bcwrite_need(BCWriteCtx *ctx, MSize len)
  46 {
  47   if (LJ_UNLIKELY(ctx->sb.n + len > ctx->sb.sz))
  48     bcwrite_resize(ctx, len);
  49 }
  50
  51 /* Add memory block to buffer. */
  52 static void bcwrite_block(BCWriteCtx *ctx, const void *p, MSize len)
  53 {
  54   uint8_t *q = (uint8_t *)(ctx->sb.buf + ctx->sb.n);
  55   MSize i;
  56   ctx->sb.n += len;
  57   for (i = 0; i < len; i++) q[i] = ((uint8_t *)p)[i];
  58 }
  59
  60 /* Add byte to buffer. */
  61 static LJ_AINLINE void bcwrite_byte(BCWriteCtx *ctx, uint8_t b)
  62 {
  63   ctx->sb.buf[ctx->sb.n++] = b;
  64 }
  65
  66 /* Add ULEB128 value to buffer. */
  67 static void bcwrite_uleb128(BCWriteCtx *ctx, uint32_t v)
  68 {
  69   MSize n = ctx->sb.n;
  70   uint8_t *p = (uint8_t *)ctx->sb.buf;
  71   for (; v >= 0x80; v >>= 7)
  72     p[n++] = (uint8_t)((v & 0x7f) | 0x80);
  73   p[n++] = (uint8_t)v;
  74   ctx->sb.n = n;
  75 }
  76
  77 /* -- Bytecode writer ----------------------------------------------------- */
  78
  79 /* Write a single constant key/value of a template table. */
  80 static void bcwrite_ktabk(BCWriteCtx *ctx, cTValue *o, int narrow)
  81 {
  82   bcwrite_need(ctx, 1+10);
  83   if (tvisstr(o)) {
  84     const GCstr *str = strV(o);
  85     MSize len = str->len;
  86     bcwrite_need(ctx, 5+len);
  87     bcwrite_uleb128(ctx, BCDUMP_KTAB_STR+len);
  88     bcwrite_block(ctx, strdata(str), len);
  89   } else if (tvisint(o)) {
  90     bcwrite_byte(ctx, BCDUMP_KTAB_INT);
  91     bcwrite_uleb128(ctx, intV(o));
  92   } else if (tvisnum(o)) {
  93     if (!LJ_DUALNUM && narrow) {  /* Narrow number constants to integers. */
  94       lua_Number num = numV(o);
  95       int32_t k = lj_num2int(num);
  96       if (num == (lua_Number)k) {  /* -0 is never a constant. */
  97         bcwrite_byte(ctx, BCDUMP_KTAB_INT);
  98         bcwrite_uleb128(ctx, k);
  99         return;
 100       }
 101     }
 102     bcwrite_byte(ctx, BCDUMP_KTAB_NUM);
 103     bcwrite_uleb128(ctx, o->u32.lo);
 104     bcwrite_uleb128(ctx, o->u32.hi);
 105   } else {
 106     lua_assert(tvispri(o));
 107     bcwrite_byte(ctx, BCDUMP_KTAB_NIL+~itype(o));
 108   }
 109 }
 110
 111 /* Write a template table. */
 112 static void bcwrite_ktab(BCWriteCtx *ctx, const GCtab *t)
 113 {
 114   MSize narray = 0, nhash = 0;
 115   if (t->asize > 0) {  /* Determine max. length of array part. */
 116     ptrdiff_t i;
 117     TValue *array = tvref(t->array);
 118     for (i = (ptrdiff_t)t->asize-1; i >= 0; i--)
 119       if (!tvisnil(&array[i]))
 120         break;
 121     narray = (MSize)(i+1);
 122   }
 123   if (t->hmask > 0) {  /* Count number of used hash slots. */
 124     MSize i, hmask = t->hmask;
 125     Node *node = noderef(t->node);
 126     for (i = 0; i <= hmask; i++)
 127       nhash += !tvisnil(&node[i].val);
 128   }
 129   /* Write number of array slots and hash slots. */
 130   bcwrite_uleb128(ctx, narray);
 131   bcwrite_uleb128(ctx, nhash);
 132   if (narray) {  /* Write array entries (may contain nil). */
 133     MSize i;
 134     TValue *o = tvref(t->array);
 135     for (i = 0; i < narray; i++, o++)
 136       bcwrite_ktabk(ctx, o, 1);
 137   }
 138   if (nhash) {  /* Write hash entries. */
 139     MSize i = nhash;
 140     Node *node = noderef(t->node) + t->hmask;
 141     for (;; node--)
 142       if (!tvisnil(&node->val)) {
 143         bcwrite_ktabk(ctx, &node->key, 0);
 144         bcwrite_ktabk(ctx, &node->val, 1);
 145         if (--i == 0) break;
 146       }
 147   }
 148 }
 149
 150 /* Write GC constants of a prototype. */
 151 static void bcwrite_kgc(BCWriteCtx *ctx, GCproto *pt)
 152 {
 153   MSize i, sizekgc = pt->sizekgc;
 154   GCRef *kr = mref(pt->k, GCRef) - (ptrdiff_t)sizekgc;
 155   for (i = 0; i < sizekgc; i++, kr++) {
 156     GCobj *o = gcref(*kr);
 157     MSize tp, need = 1;
 158     /* Determine constant type and needed size. */
 159     if (o->gch.gct == ~LJ_TSTR) {
 160       tp = BCDUMP_KGC_STR + gco2str(o)->len;
 161       need = 5+gco2str(o)->len;
 162     } else if (o->gch.gct == ~LJ_TPROTO) {
 163       lua_assert((pt->flags & PROTO_CHILD));
 164       tp = BCDUMP_KGC_CHILD;
 165 #if LJ_HASFFI
 166     } else if (o->gch.gct == ~LJ_TCDATA) {
 167       CTypeID id = gco2cd(o)->ctypeid;
 168       need = 1+4*5;
 169       if (id == CTID_INT64) {
 170         tp = BCDUMP_KGC_I64;
 171       } else if (id == CTID_UINT64) {
 172         tp = BCDUMP_KGC_U64;
 173       } else {
 174         lua_assert(id == CTID_COMPLEX_DOUBLE);
 175         tp = BCDUMP_KGC_COMPLEX;
 176       }
 177 #endif
 178     } else {
 179       lua_assert(o->gch.gct == ~LJ_TTAB);
 180       tp = BCDUMP_KGC_TAB;
 181       need = 1+2*5;
 182     }
 183     /* Write constant type. */
 184     bcwrite_need(ctx, need);
 185     bcwrite_uleb128(ctx, tp);
 186     /* Write constant data (if any). */
 187     if (tp >= BCDUMP_KGC_STR) {
 188       bcwrite_block(ctx, strdata(gco2str(o)), gco2str(o)->len);
 189     } else if (tp == BCDUMP_KGC_TAB) {
 190       bcwrite_ktab(ctx, gco2tab(o));
 191 #if LJ_HASFFI
 192     } else if (tp != BCDUMP_KGC_CHILD) {
 193       cTValue *p = (TValue *)cdataptr(gco2cd(o));
 194       bcwrite_uleb128(ctx, p[0].u32.lo);
 195       bcwrite_uleb128(ctx, p[0].u32.hi);
 196       if (tp == BCDUMP_KGC_COMPLEX) {
 197         bcwrite_uleb128(ctx, p[1].u32.lo);
 198         bcwrite_uleb128(ctx, p[1].u32.hi);
 199       }
 200 #endif
 201     }
 202   }
 203 }
 204
 205 /* Write number constants of a prototype. */
 206 static void bcwrite_knum(BCWriteCtx *ctx, GCproto *pt)
 207 {
 208   MSize i, sizekn = pt->sizekn;
 209   cTValue *o = mref(pt->k, TValue);
 210   bcwrite_need(ctx, 10*sizekn);
 211   for (i = 0; i < sizekn; i++, o++) {
 212     int32_t k;
 213     if (tvisint(o)) {
 214       k = intV(o);
 215       goto save_int;
 216     } else {
 217       /* Write a 33 bit ULEB128 for the int (lsb=0) or loword (lsb=1). */
 218       if (!LJ_DUALNUM) {  /* Narrow number constants to integers. */
 219         lua_Number num = numV(o);
 220         k = lj_num2int(num);
 221         if (num == (lua_Number)k) {  /* -0 is never a constant. */
 222         save_int:
 223           bcwrite_uleb128(ctx, 2*(uint32_t)k | ((uint32_t)k & 0x80000000u));
 224           if (k < 0) {
 225             char *p = &ctx->sb.buf[ctx->sb.n-1];
 226             *p = (*p & 7) | ((k>>27) & 0x18);
 227           }
 228           continue;
 229         }
 230       }
 231       bcwrite_uleb128(ctx, 1+(2*o->u32.lo | (o->u32.lo & 0x80000000u)));
 232       if (o->u32.lo >= 0x80000000u) {
 233         char *p = &ctx->sb.buf[ctx->sb.n-1];
 234         *p = (*p & 7) | ((o->u32.lo>>27) & 0x18);
 235       }
 236       bcwrite_uleb128(ctx, o->u32.hi);
 237     }
 238   }
 239 }
 240
 241 /* Write bytecode instructions. */
 242 static void bcwrite_bytecode(BCWriteCtx *ctx, GCproto *pt)
 243 {
 244   MSize nbc = pt->sizebc-1;  /* Omit the [JI]FUNC* header. */
 245 #if LJ_HASJIT
 246   uint8_t *p = (uint8_t *)&ctx->sb.buf[ctx->sb.n];
 247 #endif
 248   bcwrite_block(ctx, proto_bc(pt)+1, nbc*(MSize)sizeof(BCIns));
 249 #if LJ_HASJIT
 250   /* Unpatch modified bytecode containing ILOOP/JLOOP etc. */
 251   if ((pt->flags & PROTO_ILOOP) || pt->trace) {
 252     jit_State *J = L2J(ctx->L);
 253     MSize i;
 254     for (i = 0; i < nbc; i++, p += sizeof(BCIns)) {
 255       BCOp op = (BCOp)p[LJ_ENDIAN_SELECT(0, 3)];
 256       if (op == BC_IFORL || op == BC_IITERL || op == BC_ILOOP ||
 257           op == BC_JFORI) {
 258         p[LJ_ENDIAN_SELECT(0, 3)] = (uint8_t)(op-BC_IFORL+BC_FORL);
 259       } else if (op == BC_JFORL || op == BC_JITERL || op == BC_JLOOP) {
 260         BCReg rd = p[LJ_ENDIAN_SELECT(2, 1)] + (p[LJ_ENDIAN_SELECT(3, 0)] << 8);
 261         BCIns ins = traceref(J, rd)->startins;
 262         p[LJ_ENDIAN_SELECT(0, 3)] = (uint8_t)(op-BC_JFORL+BC_FORL);
 263         p[LJ_ENDIAN_SELECT(2, 1)] = bc_c(ins);
 264         p[LJ_ENDIAN_SELECT(3, 0)] = bc_b(ins);
 265       }
 266     }
 267   }
 268 #endif
 269 }
 270
 271 /* Write prototype. */
 272 static void bcwrite_proto(BCWriteCtx *ctx, GCproto *pt)
 273 {
 274   MSize sizedbg = 0;
 275
 276   /* Recursively write children of prototype. */
 277   if ((pt->flags & PROTO_CHILD)) {
 278     ptrdiff_t i, n = pt->sizekgc;
 279     GCRef *kr = mref(pt->k, GCRef) - 1;
 280     for (i = 0; i < n; i++, kr--) {
 281       GCobj *o = gcref(*kr);
 282       if (o->gch.gct == ~LJ_TPROTO)
 283         bcwrite_proto(ctx, gco2pt(o));
 284     }
 285   }
 286
 287   /* Start writing the prototype info to a buffer. */
 288   lj_str_resetbuf(&ctx->sb);
 289   ctx->sb.n = 5;  /* Leave room for final size. */
 290   bcwrite_need(ctx, 4+6*5+(pt->sizebc-1)*(MSize)sizeof(BCIns)+pt->sizeuv*2);
 291
 292   /* Write prototype header. */
 293   bcwrite_byte(ctx, (pt->flags & (PROTO_CHILD|PROTO_VARARG|PROTO_FFI)));
 294   bcwrite_byte(ctx, pt->numparams);
 295   bcwrite_byte(ctx, pt->framesize);
 296   bcwrite_byte(ctx, pt->sizeuv);
 297   bcwrite_uleb128(ctx, pt->sizekgc);
 298   bcwrite_uleb128(ctx, pt->sizekn);
 299   bcwrite_uleb128(ctx, pt->sizebc-1);
 300   if (!ctx->strip) {
 301     if (proto_lineinfo(pt))
 302       sizedbg = pt->sizept - (MSize)((char *)proto_lineinfo(pt) - (char *)pt);
 303     bcwrite_uleb128(ctx, sizedbg);
 304     if (sizedbg) {
 305       bcwrite_uleb128(ctx, pt->firstline);
 306       bcwrite_uleb128(ctx, pt->numline);
 307     }
 308   }
 309
 310   /* Write bytecode instructions and upvalue refs. */
 311   bcwrite_bytecode(ctx, pt);
 312   bcwrite_block(ctx, proto_uv(pt), pt->sizeuv*2);
 313
 314   /* Write constants. */
 315   bcwrite_kgc(ctx, pt);
 316   bcwrite_knum(ctx, pt);
 317
 318   /* Write debug info, if not stripped. */
 319   if (sizedbg) {
 320     bcwrite_need(ctx, sizedbg);
 321     bcwrite_block(ctx, proto_lineinfo(pt), sizedbg);
 322   }
 323
 324   /* Pass buffer to writer function. */
 325   if (ctx->status == 0) {
 326     MSize n = ctx->sb.n - 5;
 327     MSize nn = 1 + lj_fls(n)/7;
 328     ctx->sb.n = 5 - nn;
 329     bcwrite_uleb128(ctx, n);  /* Fill in final size. */
 330     lua_assert(ctx->sb.n == 5);
 331     ctx->status = ctx->wfunc(ctx->L, ctx->sb.buf+5-nn, nn+n, ctx->wdata);
 332   }
 333 }
 334
 335 /* Write header of bytecode dump. */
 336 static void bcwrite_header(BCWriteCtx *ctx)
 337 {
 338   GCstr *chunkname = proto_chunkname(ctx->pt);
 339   const char *name = strdata(chunkname);
 340   MSize len = chunkname->len;
 341   lj_str_resetbuf(&ctx->sb);
 342   bcwrite_need(ctx, 5+5+len);
 343   bcwrite_byte(ctx, BCDUMP_HEAD1);
 344   bcwrite_byte(ctx, BCDUMP_HEAD2);
 345   bcwrite_byte(ctx, BCDUMP_HEAD3);
 346   bcwrite_byte(ctx, BCDUMP_VERSION);
 347   bcwrite_byte(ctx, (ctx->strip ? BCDUMP_F_STRIP : 0) +
 348                    (LJ_BE ? BCDUMP_F_BE : 0) +
 349                    ((ctx->pt->flags & PROTO_FFI) ? BCDUMP_F_FFI : 0));
 350   if (!ctx->strip) {
 351     bcwrite_uleb128(ctx, len);
 352     bcwrite_block(ctx, name, len);
 353   }
 354   ctx->status = ctx->wfunc(ctx->L, ctx->sb.buf, ctx->sb.n, ctx->wdata);
 355 }
 356
 357 /* Write footer of bytecode dump. */
 358 static void bcwrite_footer(BCWriteCtx *ctx)
 359 {
 360   if (ctx->status == 0) {
 361     uint8_t zero = 0;
 362     ctx->status = ctx->wfunc(ctx->L, &zero, 1, ctx->wdata);
 363   }
 364 }
 365
 366 /* Protected callback for bytecode writer. */
 367 static TValue *cpwriter(lua_State *L, lua_CFunction dummy, void *ud)
 368 {
 369   BCWriteCtx *ctx = (BCWriteCtx *)ud;
 370   UNUSED(dummy);
 371   lj_str_resizebuf(L, &ctx->sb, 1024);  /* Avoids resize for most prototypes. */
 372   bcwrite_header(ctx);
 373   bcwrite_proto(ctx, ctx->pt);
 374   bcwrite_footer(ctx);
 375   return NULL;
 376 }
 377
 378 /* Write bytecode for a prototype. */
 379 int lj_bcwrite(lua_State *L, GCproto *pt, lua_Writer writer, void *data,
 380               int strip)
 381 {
 382   BCWriteCtx ctx;
 383   int status;
 384   ctx.L = L;
 385   ctx.pt = pt;
 386   ctx.wfunc = writer;
 387   ctx.wdata = data;
 388   ctx.strip = strip;
 389   ctx.status = 0;
 390   lj_str_initbuf(&ctx.sb);
 391   status = lj_vm_cpcall(L, NULL, &ctx, cpwriter);
 392   if (status == 0) status = ctx.status;
 393   lj_str_freebuf(G(ctx.L), &ctx.sb);
 394   return status;
 395 }
 396