source/libs/luajit/LuaJIT-src/dynasm/dasm_arm.h

   1 /*
   2 ** DynASM ARM encoding engine.
   3 ** Copyright (C) 2005-2015 Mike Pall. All rights reserved.
   4 ** Released under the MIT license. See dynasm.lua for full copyright notice.
   5 */
   6
   7 #include <stddef.h>
   8 #include <stdarg.h>
   9 #include <string.h>
  10 #include <stdlib.h>
  11
  12 #define DASM_ARCH               "arm"
  13
  14 #ifndef DASM_EXTERN
  15 #define DASM_EXTERN(a,b,c,d)    0
  16 #endif
  17
  18 /* Action definitions. */
  19 enum {
  20   DASM_STOP, DASM_SECTION, DASM_ESC, DASM_REL_EXT,
  21   /* The following actions need a buffer position. */
  22   DASM_ALIGN, DASM_REL_LG, DASM_LABEL_LG,
  23   /* The following actions also have an argument. */
  24   DASM_REL_PC, DASM_LABEL_PC,
  25   DASM_IMM, DASM_IMM12, DASM_IMM16, DASM_IMML8, DASM_IMML12, DASM_IMMV8,
  26   DASM__MAX
  27 };
  28
  29 /* Maximum number of section buffer positions for a single dasm_put() call. */
  30 #define DASM_MAXSECPOS          25
  31
  32 /* DynASM encoder status codes. Action list offset or number are or'ed in. */
  33 #define DASM_S_OK               0x00000000
  34 #define DASM_S_NOMEM            0x01000000
  35 #define DASM_S_PHASE            0x02000000
  36 #define DASM_S_MATCH_SEC        0x03000000
  37 #define DASM_S_RANGE_I          0x11000000
  38 #define DASM_S_RANGE_SEC        0x12000000
  39 #define DASM_S_RANGE_LG         0x13000000
  40 #define DASM_S_RANGE_PC         0x14000000
  41 #define DASM_S_RANGE_REL        0x15000000
  42 #define DASM_S_UNDEF_LG         0x21000000
  43 #define DASM_S_UNDEF_PC         0x22000000
  44
  45 /* Macros to convert positions (8 bit section + 24 bit index). */
  46 #define DASM_POS2IDX(pos)       ((pos)&0x00ffffff)
  47 #define DASM_POS2BIAS(pos)      ((pos)&0xff000000)
  48 #define DASM_SEC2POS(sec)       ((sec)<<24)
  49 #define DASM_POS2SEC(pos)       ((pos)>>24)
  50 #define DASM_POS2PTR(D, pos)    (D->sections[DASM_POS2SEC(pos)].rbuf + (pos))
  51
  52 /* Action list type. */
  53 typedef const unsigned int *dasm_ActList;
  54
  55 /* Per-section structure. */
  56 typedef struct dasm_Section {
  57   int *rbuf;            /* Biased buffer pointer (negative section bias). */
  58   int *buf;             /* True buffer pointer. */
  59   size_t bsize;         /* Buffer size in bytes. */
  60   int pos;              /* Biased buffer position. */
  61   int epos;             /* End of biased buffer position - max single put. */
  62   int ofs;              /* Byte offset into section. */
  63 } dasm_Section;
  64
  65 /* Core structure holding the DynASM encoding state. */
  66 struct dasm_State {
  67   size_t psize;                 /* Allocated size of this structure. */
  68   dasm_ActList actionlist;      /* Current actionlist pointer. */
  69   int *lglabels;                /* Local/global chain/pos ptrs. */
  70   size_t lgsize;
  71   int *pclabels;                /* PC label chains/pos ptrs. */
  72   size_t pcsize;
  73   void **globals;               /* Array of globals (bias -10). */
  74   dasm_Section *section;        /* Pointer to active section. */
  75   size_t codesize;              /* Total size of all code sections. */
  76   int maxsection;               /* 0 <= sectionidx < maxsection. */
  77   int status;                   /* Status code. */
  78   dasm_Section sections[1];     /* All sections. Alloc-extended. */
  79 };
  80
  81 /* The size of the core structure depends on the max. number of sections. */
  82 #define DASM_PSZ(ms)    (sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section))
  83
  84
  85 /* Initialize DynASM state. */
  86 void dasm_init(Dst_DECL, int maxsection)
  87 {
  88   dasm_State *D;
  89   size_t psz = 0;
  90   int i;
  91   Dst_REF = NULL;
  92   DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
  93   D = Dst_REF;
  94   D->psize = psz;
  95   D->lglabels = NULL;
  96   D->lgsize = 0;
  97   D->pclabels = NULL;
  98   D->pcsize = 0;
  99   D->globals = NULL;
 100   D->maxsection = maxsection;
 101   for (i = 0; i < maxsection; i++) {
 102     D->sections[i].buf = NULL;  /* Need this for pass3. */
 103     D->sections[i].rbuf = D->sections[i].buf - DASM_SEC2POS(i);
 104     D->sections[i].bsize = 0;
 105     D->sections[i].epos = 0;  /* Wrong, but is recalculated after resize. */
 106   }
 107 }
 108
 109 /* Free DynASM state. */
 110 void dasm_free(Dst_DECL)
 111 {
 112   dasm_State *D = Dst_REF;
 113   int i;
 114   for (i = 0; i < D->maxsection; i++)
 115     if (D->sections[i].buf)
 116       DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
 117   if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
 118   if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
 119   DASM_M_FREE(Dst, D, D->psize);
 120 }
 121
 122 /* Setup global label array. Must be called before dasm_setup(). */
 123 void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
 124 {
 125   dasm_State *D = Dst_REF;
 126   D->globals = gl - 10;  /* Negative bias to compensate for locals. */
 127   DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
 128 }
 129
 130 /* Grow PC label array. Can be called after dasm_setup(), too. */
 131 void dasm_growpc(Dst_DECL, unsigned int maxpc)
 132 {
 133   dasm_State *D = Dst_REF;
 134   size_t osz = D->pcsize;
 135   DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
 136   memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
 137 }
 138
 139 /* Setup encoder. */
 140 void dasm_setup(Dst_DECL, const void *actionlist)
 141 {
 142   dasm_State *D = Dst_REF;
 143   int i;
 144   D->actionlist = (dasm_ActList)actionlist;
 145   D->status = DASM_S_OK;
 146   D->section = &D->sections[0];
 147   memset((void *)D->lglabels, 0, D->lgsize);
 148   if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
 149   for (i = 0; i < D->maxsection; i++) {
 150     D->sections[i].pos = DASM_SEC2POS(i);
 151     D->sections[i].ofs = 0;
 152   }
 153 }
 154
 155
 156 #ifdef DASM_CHECKS
 157 #define CK(x, st) \
 158   do { if (!(x)) { \
 159     D->status = DASM_S_##st|(p-D->actionlist-1); return; } } while (0)
 160 #define CKPL(kind, st) \
 161   do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
 162     D->status = DASM_S_RANGE_##st|(p-D->actionlist-1); return; } } while (0)
 163 #else
 164 #define CK(x, st)       ((void)0)
 165 #define CKPL(kind, st)  ((void)0)
 166 #endif
 167
 168 static int dasm_imm12(unsigned int n)
 169 {
 170   int i;
 171   for (i = 0; i < 16; i++, n = (n << 2) | (n >> 30))
 172     if (n <= 255) return (int)(n + (i << 8));
 173   return -1;
 174 }
 175
 176 /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
 177 void dasm_put(Dst_DECL, int start, ...)
 178 {
 179   va_list ap;
 180   dasm_State *D = Dst_REF;
 181   dasm_ActList p = D->actionlist + start;
 182   dasm_Section *sec = D->section;
 183   int pos = sec->pos, ofs = sec->ofs;
 184   int *b;
 185
 186   if (pos >= sec->epos) {
 187     DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
 188       sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
 189     sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
 190     sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
 191   }
 192
 193   b = sec->rbuf;
 194   b[pos++] = start;
 195
 196   va_start(ap, start);
 197   while (1) {
 198     unsigned int ins = *p++;
 199     unsigned int action = (ins >> 16);
 200     if (action >= DASM__MAX) {
 201       ofs += 4;
 202     } else {
 203       int *pl, n = action >= DASM_REL_PC ? va_arg(ap, int) : 0;
 204       switch (action) {
 205       case DASM_STOP: goto stop;
 206       case DASM_SECTION:
 207         n = (ins & 255); CK(n < D->maxsection, RANGE_SEC);
 208         D->section = &D->sections[n]; goto stop;
 209       case DASM_ESC: p++; ofs += 4; break;
 210       case DASM_REL_EXT: break;
 211       case DASM_ALIGN: ofs += (ins & 255); b[pos++] = ofs; break;
 212       case DASM_REL_LG:
 213         n = (ins & 2047) - 10; pl = D->lglabels + n;
 214         /* Bkwd rel or global. */
 215         if (n >= 0) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
 216         pl += 10; n = *pl;
 217         if (n < 0) n = 0;  /* Start new chain for fwd rel if label exists. */
 218         goto linkrel;
 219       case DASM_REL_PC:
 220         pl = D->pclabels + n; CKPL(pc, PC);
 221       putrel:
 222         n = *pl;
 223         if (n < 0) {  /* Label exists. Get label pos and store it. */
 224           b[pos] = -n;
 225         } else {
 226       linkrel:
 227           b[pos] = n;  /* Else link to rel chain, anchored at label. */
 228           *pl = pos;
 229         }
 230         pos++;
 231         break;
 232       case DASM_LABEL_LG:
 233         pl = D->lglabels + (ins & 2047) - 10; CKPL(lg, LG); goto putlabel;
 234       case DASM_LABEL_PC:
 235         pl = D->pclabels + n; CKPL(pc, PC);
 236       putlabel:
 237         n = *pl;  /* n > 0: Collapse rel chain and replace with label pos. */
 238         while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos;
 239         }
 240         *pl = -pos;  /* Label exists now. */
 241         b[pos++] = ofs;  /* Store pass1 offset estimate. */
 242         break;
 243       case DASM_IMM:
 244       case DASM_IMM16:
 245 #ifdef DASM_CHECKS
 246         CK((n & ((1<<((ins>>10)&31))-1)) == 0, RANGE_I);
 247         if ((ins & 0x8000))
 248           CK(((n + (1<<(((ins>>5)&31)-1)))>>((ins>>5)&31)) == 0, RANGE_I);
 249         else
 250           CK((n>>((ins>>5)&31)) == 0, RANGE_I);
 251 #endif
 252         b[pos++] = n;
 253         break;
 254       case DASM_IMMV8:
 255         CK((n & 3) == 0, RANGE_I);
 256         n >>= 2;
 257       case DASM_IMML8:
 258       case DASM_IMML12:
 259         CK(n >= 0 ? ((n>>((ins>>5)&31)) == 0) :
 260                     (((-n)>>((ins>>5)&31)) == 0), RANGE_I);
 261         b[pos++] = n;
 262         break;
 263       case DASM_IMM12:
 264         CK(dasm_imm12((unsigned int)n) != -1, RANGE_I);
 265         b[pos++] = n;
 266         break;
 267       }
 268     }
 269   }
 270 stop:
 271   va_end(ap);
 272   sec->pos = pos;
 273   sec->ofs = ofs;
 274 }
 275 #undef CK
 276
 277 /* Pass 2: Link sections, shrink aligns, fix label offsets. */
 278 int dasm_link(Dst_DECL, size_t *szp)
 279 {
 280   dasm_State *D = Dst_REF;
 281   int secnum;
 282   int ofs = 0;
 283
 284 #ifdef DASM_CHECKS
 285   *szp = 0;
 286   if (D->status != DASM_S_OK) return D->status;
 287   {
 288     int pc;
 289     for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
 290       if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
 291   }
 292 #endif
 293
 294   { /* Handle globals not defined in this translation unit. */
 295     int idx;
 296     for (idx = 20; idx*sizeof(int) < D->lgsize; idx++) {
 297       int n = D->lglabels[idx];
 298       /* Undefined label: Collapse rel chain and replace with marker (< 0). */
 299       while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
 300     }
 301   }
 302
 303   /* Combine all code sections. No support for data sections (yet). */
 304   for (secnum = 0; secnum < D->maxsection; secnum++) {
 305     dasm_Section *sec = D->sections + secnum;
 306     int *b = sec->rbuf;
 307     int pos = DASM_SEC2POS(secnum);
 308     int lastpos = sec->pos;
 309
 310     while (pos != lastpos) {
 311       dasm_ActList p = D->actionlist + b[pos++];
 312       while (1) {
 313         unsigned int ins = *p++;
 314         unsigned int action = (ins >> 16);
 315         switch (action) {
 316         case DASM_STOP: case DASM_SECTION: goto stop;
 317         case DASM_ESC: p++; break;
 318         case DASM_REL_EXT: break;
 319         case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
 320         case DASM_REL_LG: case DASM_REL_PC: pos++; break;
 321         case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
 322         case DASM_IMM: case DASM_IMM12: case DASM_IMM16:
 323         case DASM_IMML8: case DASM_IMML12: case DASM_IMMV8: pos++; break;
 324         }
 325       }
 326       stop: (void)0;
 327     }
 328     ofs += sec->ofs;  /* Next section starts right after current section. */
 329   }
 330
 331   D->codesize = ofs;  /* Total size of all code sections */
 332   *szp = ofs;
 333   return DASM_S_OK;
 334 }
 335
 336 #ifdef DASM_CHECKS
 337 #define CK(x, st) \
 338   do { if (!(x)) return DASM_S_##st|(p-D->actionlist-1); } while (0)
 339 #else
 340 #define CK(x, st)       ((void)0)
 341 #endif
 342
 343 /* Pass 3: Encode sections. */
 344 int dasm_encode(Dst_DECL, void *buffer)
 345 {
 346   dasm_State *D = Dst_REF;
 347   char *base = (char *)buffer;
 348   unsigned int *cp = (unsigned int *)buffer;
 349   int secnum;
 350
 351   /* Encode all code sections. No support for data sections (yet). */
 352   for (secnum = 0; secnum < D->maxsection; secnum++) {
 353     dasm_Section *sec = D->sections + secnum;
 354     int *b = sec->buf;
 355     int *endb = sec->rbuf + sec->pos;
 356
 357     while (b != endb) {
 358       dasm_ActList p = D->actionlist + *b++;
 359       while (1) {
 360         unsigned int ins = *p++;
 361         unsigned int action = (ins >> 16);
 362         int n = (action >= DASM_ALIGN && action < DASM__MAX) ? *b++ : 0;
 363         switch (action) {
 364         case DASM_STOP: case DASM_SECTION: goto stop;
 365         case DASM_ESC: *cp++ = *p++; break;
 366         case DASM_REL_EXT:
 367           n = DASM_EXTERN(Dst, (unsigned char *)cp, (ins&2047), !(ins&2048));
 368           goto patchrel;
 369         case DASM_ALIGN:
 370           ins &= 255; while ((((char *)cp - base) & ins)) *cp++ = 0xe1a00000;
 371           break;
 372         case DASM_REL_LG:
 373           CK(n >= 0, UNDEF_LG);
 374         case DASM_REL_PC:
 375           CK(n >= 0, UNDEF_PC);
 376           n = *DASM_POS2PTR(D, n) - (int)((char *)cp - base) - 4;
 377         patchrel:
 378           if ((ins & 0x800) == 0) {
 379             CK((n & 3) == 0 && ((n+0x02000000) >> 26) == 0, RANGE_REL);
 380             cp[-1] |= ((n >> 2) & 0x00ffffff);
 381           } else if ((ins & 0x1000)) {
 382             CK((n & 3) == 0 && -256 <= n && n <= 256, RANGE_REL);
 383             goto patchimml8;
 384           } else if ((ins & 0x2000) == 0) {
 385             CK((n & 3) == 0 && -4096 <= n && n <= 4096, RANGE_REL);
 386             goto patchimml;
 387           } else {
 388             CK((n & 3) == 0 && -1020 <= n && n <= 1020, RANGE_REL);
 389             n >>= 2;
 390             goto patchimml;
 391           }
 392           break;
 393         case DASM_LABEL_LG:
 394           ins &= 2047; if (ins >= 20) D->globals[ins-10] = (void *)(base + n);
 395           break;
 396         case DASM_LABEL_PC: break;
 397         case DASM_IMM:
 398           cp[-1] |= ((n>>((ins>>10)&31)) & ((1<<((ins>>5)&31))-1)) << (ins&31);
 399           break;
 400         case DASM_IMM12:
 401           cp[-1] |= dasm_imm12((unsigned int)n);
 402           break;
 403         case DASM_IMM16:
 404           cp[-1] |= ((n & 0xf000) << 4) | (n & 0x0fff);
 405           break;
 406         case DASM_IMML8: patchimml8:
 407           cp[-1] |= n >= 0 ? (0x00800000 | (n & 0x0f) | ((n & 0xf0) << 4)) :
 408                              ((-n & 0x0f) | ((-n & 0xf0) << 4));
 409           break;
 410         case DASM_IMML12: case DASM_IMMV8: patchimml:
 411           cp[-1] |= n >= 0 ? (0x00800000 | n) : (-n);
 412           break;
 413         default: *cp++ = ins; break;
 414         }
 415       }
 416       stop: (void)0;
 417     }
 418   }
 419
 420   if (base + D->codesize != (char *)cp)  /* Check for phase errors. */
 421     return DASM_S_PHASE;
 422   return DASM_S_OK;
 423 }
 424 #undef CK
 425
 426 /* Get PC label offset. */
 427 int dasm_getpclabel(Dst_DECL, unsigned int pc)
 428 {
 429   dasm_State *D = Dst_REF;
 430   if (pc*sizeof(int) < D->pcsize) {
 431     int pos = D->pclabels[pc];
 432     if (pos < 0) return *DASM_POS2PTR(D, -pos);
 433     if (pos > 0) return -1;  /* Undefined. */
 434   }
 435   return -2;  /* Unused or out of range. */
 436 }
 437
 438 #ifdef DASM_CHECKS
 439 /* Optional sanity checker to call between isolated encoding steps. */
 440 int dasm_checkstep(Dst_DECL, int secmatch)
 441 {
 442   dasm_State *D = Dst_REF;
 443   if (D->status == DASM_S_OK) {
 444     int i;
 445     for (i = 1; i <= 9; i++) {
 446       if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_LG|i; break; }
 447       D->lglabels[i] = 0;
 448     }
 449   }
 450   if (D->status == DASM_S_OK && secmatch >= 0 &&
 451       D->section != &D->sections[secmatch])
 452     D->status = DASM_S_MATCH_SEC|(D->section-D->sections);
 453   return D->status;
 454 }
 455 #endif
 456