gen.c

   1 /* neatcc code generation */
   2 #include <stdlib.h>
   3 #include <stdio.h>
   4 #include <string.h>
   5 #include "ncc.h"
   6
   7 static struct mem ds;           /* data segment */
   8 static struct mem cs;           /* code segment */
   9 static long bsslen;             /* bss segment size */
  10
  11 static long *loc_off;           /* offset of locals on the stack */
  12 static long loc_n, loc_sz;      /* number of locals */
  13 static long loc_pos;            /* current stack position */
  14 static int *loc_mem;            /* local memory was accessed */
  15 static int *loc_ptr;            /* the address of this local is fetched */
  16 static int *loc_dat;            /* the number of data accesses of this local */
  17
  18 static char (*ds_name)[NAMELEN];/* data section symbols */
  19 static long *ds_off;            /* data section offsets */
  20 static long ds_n, ds_sz;        /* number of data section symbols */
  21
  22 static int func_argc;           /* number of arguments */
  23 static int func_varg;           /* varargs */
  24 static int func_regs;           /* used registers */
  25 static int func_maxargs;        /* the maximum number of arguments on the stack */
  26 static int func_leaf;           /* a leaf function */
  27 static long *ic_luse;           /* the last use of values generated by instructions */
  28 static long *ic_bbeg;           /* whether each instruction begins a basic block */
  29
  30 static long ra_vmap[N_REGS];    /* register to intermediate value assignments */
  31 static long ra_lmap[N_REGS];    /* register to local assignments */
  32 static long ra_lmapglob[N_REGS];        /* global register to local assignments */
  33 static long *ra_gmask;          /* the mask of good registers for each value */
  34 static long ra_live[NTMPS];     /* live values */
  35 static int ra_vmax;             /* the number of values stored on the stack */
  36
  37 static long loc_add(long pos)
  38 {
  39         if (loc_n >= loc_sz) {
  40                 loc_sz = MAX(128, loc_sz * 2);
  41                 loc_off = mextend(loc_off, loc_n, loc_sz, sizeof(loc_off[0]));
  42         }
  43         loc_off[loc_n] = pos;
  44         return loc_n++;
  45 }
  46
  47 long o_mklocal(long sz)
  48 {
  49         loc_pos += ALIGN(sz, ULNG);
  50         return loc_add(loc_pos);
  51 }
  52
  53 void o_rmlocal(long addr, long sz)
  54 {
  55 }
  56
  57 long o_arg2loc(int i)
  58 {
  59         return i;
  60 }
  61
  62 void o_bsnew(char *name, long size, int global)
  63 {
  64         out_def(name, OUT_BSS | (global ? OUT_GLOB : 0), bsslen, size);
  65         bsslen += ALIGN(size, OUT_ALIGNMENT);
  66 }
  67
  68 long o_dsnew(char *name, long size, int global)
  69 {
  70         int idx;
  71         if (ds_n >= ds_sz) {
  72                 ds_sz = MAX(128, ds_sz * 2);
  73                 ds_name = mextend(ds_name, ds_n, ds_sz, sizeof(ds_name[0]));
  74                 ds_off = mextend(ds_off, ds_n, ds_sz, sizeof(ds_off[0]));
  75         }
  76         idx = ds_n++;
  77         strcpy(ds_name[idx], name);
  78         ds_off[idx] = mem_len(&ds);
  79         out_def(name, OUT_DS | (global ? OUT_GLOB : 0), mem_len(&ds), size);
  80         mem_putz(&ds, ALIGN(size, OUT_ALIGNMENT));
  81         return ds_off[idx];
  82 }
  83
  84 void o_dscpy(long addr, void *buf, long len)
  85 {
  86         mem_cpy(&ds, addr, buf, len);
  87 }
  88
  89 static int dat_off(char *name)
  90 {
  91         int i;
  92         for (i = 0; i < ds_n; i++)
  93                 if (!strcmp(name, ds_name[i]))
  94                         return ds_off[i];
  95         return 0;
  96 }
  97
  98 void o_dsset(char *name, long off, long bt)
  99 {
 100         long sym_off = dat_off(name) + off;
 101         long num, roff, rsym;
 102         if (!o_popnum(&num)) {
 103                 mem_cpy(&ds, sym_off, &num, T_SZ(bt));
 104                 return;
 105         }
 106         if (!o_popsym(&rsym, &roff)) {
 107                 out_rel(rsym, OUT_DS, sym_off);
 108                 mem_cpy(&ds, sym_off, &roff, T_SZ(bt));
 109         }
 110 }
 111
 112 /* number of register arguments */
 113 static int ic_regcnt(struct ic *ic)
 114 {
 115         long o = ic->op;
 116         if (o & O_BOP)
 117                 return o & (O_NUM | O_SYM | O_LOC) ? 2 : 3;
 118         if (o & O_UOP)
 119                 return o & (O_NUM | O_SYM | O_LOC) ? 1 : 2;
 120         if (o & O_CALL)
 121                 return o & (O_NUM | O_SYM | O_LOC) ? 1 : 2;
 122         if (o & O_MOV)
 123                 return o & (O_NUM | O_SYM | O_LOC) ? 1 : 2;
 124         if (o & O_MEM)
 125                 return 3;
 126         if (o & O_JMP)
 127                 return 0;
 128         if (o & O_JZ)
 129                 return 1;
 130         if (o & O_JCC)
 131                 return o & (O_NUM | O_SYM | O_LOC) ? 1 : 2;
 132         if (o & O_RET)
 133                 return 1;
 134         if (o & (O_LD | O_ST) && o & (O_SYM | O_LOC))
 135                 return 1;
 136         if (o & (O_LD | O_ST))
 137                 return o & O_NUM ? 2 : 3;
 138         return 0;
 139 }
 140
 141 static int ra_vreg(int val)
 142 {
 143         int i;
 144         for (i = 0; i < LEN(ra_vmap); i++)
 145                 if (ra_vmap[i] == val)
 146                         return i;
 147         return -1;
 148 }
 149
 150 static int ra_lreg(int loc)
 151 {
 152         int i;
 153         for (i = 0; i < LEN(ra_lmap); i++)
 154                 if (ra_lmap[i] == loc)
 155                         return i;
 156         return -1;
 157 }
 158
 159 /* find a register, with the given good, acceptable, and bad register masks */
 160 static long ra_regget(long iv, long gmask, long amask, long bmask)
 161 {
 162         int i;
 163         gmask &= ~bmask & amask;
 164         amask &= ~bmask;
 165         if (ra_vreg(iv) >= 0 && (1 << ra_vreg(iv)) & (gmask | amask))
 166                 return ra_vreg(iv);
 167         for (i = 0; i < N_TMPS; i++)
 168                 if ((1 << tmpregs[i]) & gmask && ra_vmap[tmpregs[i]] < 0 &&
 169                                                 ra_lmap[tmpregs[i]] < 0)
 170                         return tmpregs[i];
 171         for (i = 0; i < N_TMPS; i++)
 172                 if ((1 << tmpregs[i]) & amask && ra_vmap[tmpregs[i]] < 0 &&
 173                                                 ra_lmap[tmpregs[i]] < 0)
 174                         return tmpregs[i];
 175         for (i = 0; i < N_TMPS; i++)
 176                 if ((1 << tmpregs[i]) & gmask)
 177                         return tmpregs[i];
 178         for (i = 0; i < N_TMPS; i++)
 179                 if ((1 << tmpregs[i]) & amask)
 180                         return tmpregs[i];
 181         die("neatcc: cannot allocate an acceptable register\n");
 182         return 0;
 183 }
 184
 185 /* allocate registers for a 3-operand instruction */
 186 static void ra_map(struct ic *ic, int *r0, int *r1, int *r2, long *mt)
 187 {
 188         long m0, m1, m2;
 189         long all = 0;
 190         int n = ic_regcnt(ic);
 191         int oc = O_C(ic->op);
 192         int i;
 193         *r0 = -1;
 194         *r1 = -1;
 195         *r2 = -1;
 196         *mt = 0;
 197         /* optimizing loading locals: point to local's register */
 198         if (oc == (O_LD | O_LOC) && ra_lreg(ic->arg1) >= 0 &&
 199                         ra_vmap[ra_lreg(ic->arg1)] < 0) {
 200                 *r0 = ra_lreg(ic->arg1);
 201                 func_regs |= 1 << *r0;
 202                 return;
 203         }
 204         /* do not use argument registers to hold call destination */
 205         if (oc & O_CALL)
 206                 for (i = 0; i < MIN(ic->arg2, N_ARGS); i++)
 207                         all |= (1 << argregs[i]);
 208         /* instructions on locals can be simplified */
 209         if (oc & O_LOC) {
 210                 if (oc & O_MOV)
 211                         oc = O_ADD | O_NUM;
 212                 if (oc & (O_ST | O_LD))
 213                         oc = (oc & ~O_LOC) & O_NUM;
 214         }
 215         if (i_reg(ic->op, &m0, &m1, &m2, mt))
 216                 die("neatcc: instruction %08lx not supported\n", ic->op);
 217         /*
 218          * the registers used in global register allocation should not
 219          * be used in the last instruction of a basic block.
 220          */
 221         if (ic->op & (O_JZ | O_JCC))
 222                 for (i = 0; i < LEN(ra_lmap); i++)
 223                         if (ra_lmapglob[i] >= 0 && ra_lmap[i] != ra_lmapglob[i])
 224                                 all |= (1 << i);
 225         /* allocating registers for the operands */
 226         if (n >= 3) {
 227                 *r2 = ra_regget(ic->arg2, m2, m2, all);
 228                 all |= (1 << *r2);
 229         }
 230         if (n >= 2) {
 231                 *r1 = ra_regget(ic->arg1, m1, m1, all);
 232                 all |= (1 << *r1);
 233         }
 234         if (n >= 1 && m0) {
 235                 int wop = ic->op & O_OUT;
 236                 if (wop && n >= 3 && m0 & (1 << *r2))
 237                         *r0 = *r2;
 238                 else if (wop && n >= 2 && m0 & (1 << *r1))
 239                         *r0 = *r1;
 240                 else
 241                         *r0 = ra_regget(ic->arg0, ra_gmask[ic->arg0],
 242                                 m0, wop ? 0 : all);
 243         }
 244         if (n >= 1 && !m0)
 245                 *r0 = *r1;
 246         /* if r0 is overwritten and it is a local; use another register */
 247         if (n >= 1 && oc & O_OUT && ra_lmap[*r0] >= 0) {
 248                 long m3 = (m0 ? m0 : m1) & ~(all | (1 << *r0));
 249                 long arg3 = m0 ? ic->arg0 : ic->arg1;
 250                 if (m3 != 0) {
 251                         int r3 = ra_regget(arg3, ra_gmask[ic->arg0], m3, 0);
 252                         if (n >= 2 && *r0 == *r1)
 253                                 *r1 = r3;
 254                         if (n >= 3 && *r0 == *r2)
 255                                 *r2 = r3;
 256                         *r0 = r3;
 257                 }
 258         }
 259         if (n)
 260                 all |= (1 << *r0);
 261         func_regs |= all | *mt;
 262 }
 263
 264 static long iv_rank(long iv)
 265 {
 266         int i;
 267         for (i = 0; i < LEN(ra_live); i++)
 268                 if (ra_live[i] == iv)
 269                         return i;
 270         die("neatcc: the specified value is not live\n");
 271         return 0;
 272 }
 273
 274 static long iv_addr(long rank)
 275 {
 276         return loc_pos + rank * ULNG + ULNG;
 277 }
 278
 279 static void loc_toreg(long loc, long off, int reg, int bt)
 280 {
 281         loc_mem[loc]++;
 282         i_ins(O_MK(O_LD | O_NUM, bt), reg, REG_FP, -loc_off[loc] + off);
 283 }
 284
 285 static void loc_tomem(long loc, long off, int reg, int bt)
 286 {
 287         loc_mem[loc]++;
 288         i_ins(O_MK(O_ST | O_NUM, bt), reg, REG_FP, -loc_off[loc] + off);
 289 }
 290
 291 static void loc_toadd(long loc, long off, int reg)
 292 {
 293         loc_mem[loc]++;
 294         i_ins(O_ADD | O_NUM, reg, REG_FP, -loc_off[loc] + off);
 295 }
 296
 297 static void val_toreg(long val, int reg)
 298 {
 299         i_ins(O_MK(O_LD | O_NUM, ULNG), reg, REG_FP, -iv_addr(iv_rank(val)));
 300 }
 301
 302 static void val_tomem(long val, int reg)
 303 {
 304         long rank = iv_rank(val);
 305         ra_vmax = MAX(ra_vmax, rank + 1);
 306         i_ins(O_MK(O_ST | O_NUM, ULNG), reg, REG_FP, -iv_addr(rank));
 307 }
 308
 309 /* move the value to the stack */
 310 static void ra_spill(int reg)
 311 {
 312         if (ra_vmap[reg] >= 0) {
 313                 val_tomem(ra_vmap[reg], reg);
 314                 ra_vmap[reg] = -1;
 315         }
 316         if (ra_lmap[reg] >= 0) {
 317                 if (ra_lmap[reg] == ra_lmapglob[reg])
 318                         loc_tomem(ra_lmap[reg], 0, reg, ULNG);
 319                 ra_lmap[reg] = -1;
 320         }
 321 }
 322
 323 /* set the value to the given register */
 324 static void ra_vsave(long iv, int reg)
 325 {
 326         int i;
 327         ra_vmap[reg] = iv;
 328         for (i = 0; i < LEN(ra_live); i++)
 329                 if (ra_live[i] < 0)
 330                         break;
 331         if (i == LEN(ra_live))
 332                 die("neatcc: too many live values\n");
 333         ra_live[i] = iv;
 334 }
 335
 336 /* load the value into a register */
 337 static void ra_vload(long iv, int reg)
 338 {
 339         if (ra_vmap[reg] == iv)
 340                 return;
 341         if (ra_vmap[reg] >= 0 || ra_lmap[reg] >= 0)
 342                 ra_spill(reg);
 343         if (ra_vreg(iv) >= 0) {
 344                 i_ins(O_MK(O_MOV, ULNG), reg, ra_vreg(iv), 0);
 345                 ra_vmap[ra_vreg(iv)] = -1;
 346         } else {
 347                 val_toreg(iv, reg);
 348         }
 349         ra_vmap[reg] = iv;
 350 }
 351
 352 /* the value is no longer needed */
 353 static void ra_vdrop(long iv)
 354 {
 355         int i;
 356         for (i = 0; i < LEN(ra_live); i++)
 357                 if (ra_live[i] == iv)
 358                         ra_live[i] = -1;
 359         if (ra_vreg(iv) >= 0)
 360                 ra_vmap[ra_vreg(iv)] = -1;
 361 }
 362
 363 /* load the value of local loc into register reg */
 364 static void ra_lload(long loc, long off, int reg, int bt)
 365 {
 366         if (ra_lreg(loc) < 0 && !loc_ptr[loc] && loc_dat[loc] > 2) {
 367                 ra_lmap[reg] = loc;
 368                 loc_toreg(loc, off, reg, bt);
 369         }
 370         if (ra_lreg(loc) >= 0) {
 371                 if (ra_lreg(loc) != reg)
 372                         i_ins(O_MK(O_MOV, bt), reg, ra_lreg(loc), 0);
 373         } else {
 374                 loc_toreg(loc, off, reg, bt);
 375         }
 376 }
 377
 378 /* register reg contains the value of local loc */
 379 static void ra_lsave(long loc, long off, int reg, int bt)
 380 {
 381         int lreg = ra_lreg(loc);
 382         if (lreg >= 0 && ra_lmapglob[lreg] == ra_lmap[lreg]) {
 383                 if (ra_vmap[lreg] >= 0) {       /* values using the same register */
 384                         val_tomem(ra_vmap[lreg], lreg);
 385                         ra_vmap[lreg] = -1;
 386                 }
 387                 i_ins(O_MK(O_MOV, bt), lreg, reg, 0);
 388         } else {
 389                 if (lreg >= 0)
 390                         ra_lmap[lreg] = -1;
 391                 loc_tomem(loc, off, reg, bt);
 392                 if (!loc_ptr[loc] && loc_dat[loc] > 2)
 393                         ra_lmap[reg] = loc;
 394         }
 395 }
 396
 397 /* end of a basic block */
 398 static void ra_bbend(void)
 399 {
 400         int i;
 401         /* save values to memory */
 402         for (i = 0; i < LEN(ra_vmap); i++)
 403                 if (ra_vmap[i] >= 0)
 404                         ra_spill(i);
 405         /* dropping local caches */
 406         for (i = 0; i < LEN(ra_lmap); i++)
 407                 if (ra_lmap[i] != ra_lmapglob[i] && ra_lmap[i] >= 0)
 408                         ra_spill(i);
 409         /* load global register allocations from memory */
 410         for (i = 0; i < LEN(ra_lmap); i++) {
 411                 if (ra_lmap[i] != ra_lmapglob[i]) {
 412                         ra_lmap[i] = ra_lmapglob[i];
 413                         loc_toreg(ra_lmap[i], 0, i, ULNG);
 414                 }
 415         }
 416 }
 417
 418 /* perform global register allocation */
 419 static void ra_glob(struct ic *ic, int ic_n)
 420 {
 421         int *srt;
 422         long mask;
 423         int nregs;
 424         int i, j;
 425         mask = func_leaf ? R_TMPS : R_PERM;
 426         nregs = MIN(N_TMPS >> 1, 4);
 427         srt = malloc(loc_n * sizeof(srt[0]));
 428         /* sorting locals */
 429         for (i = 0; i < loc_n; i++) {
 430                 for (j = i - 1; j >= 0 && loc_dat[i] > loc_dat[srt[j]]; j--)
 431                         srt[j + 1] = srt[j];
 432                 srt[j + 1] = i;
 433         }
 434         /* allocating registers */
 435         for (i = 0; i < loc_n && nregs > 0; i++) {
 436                 int l = srt[i];
 437                 if (loc_ptr[l])
 438                         continue;
 439                 if (func_leaf && l < N_ARGS && l < func_argc &&
 440                                 ra_lmapglob[argregs[l]] < 0) {
 441                         ra_lmapglob[argregs[l]] = l;
 442                         nregs--;
 443                         continue;
 444                 }
 445                 if (loc_dat[l] < 2)
 446                         continue;
 447                 for (j = func_leaf ? 1 : 3; j < N_TMPS; j++) {
 448                         int r = tmpregs[j];
 449                         if (ra_lmapglob[r] < 0 && (1 << r) & mask) {
 450                                 ra_lmapglob[r] = l;
 451                                 nregs--;
 452                                 break;
 453                         }
 454                 }
 455         }
 456         free(srt);
 457 }
 458
 459 /* return the values written to and read from in the given instruction */
 460 static void ic_info(struct ic *ic, long **w, long **r1, long **r2, long **r3)
 461 {
 462         long n = ic_regcnt(ic);
 463         long o = ic->op & O_OUT;
 464         *r1 = NULL;
 465         *r2 = NULL;
 466         *r3 = NULL;
 467         *w = NULL;
 468         if (o) {
 469                 *w = &ic->arg0;
 470                 *r1 = n >= 2 ? &ic->arg1 : NULL;
 471                 *r2 = n >= 3 ? &ic->arg2 : NULL;
 472         } else {
 473                 *r1 = n >= 1 ? &ic->arg0 : NULL;
 474                 *r2 = n >= 2 ? &ic->arg1 : NULL;
 475                 *r3 = n >= 3 ? &ic->arg2 : NULL;
 476         }
 477 }
 478
 479 static void ra_init(struct ic *ic, int ic_n)
 480 {
 481         long m0, m1, m2, mt;
 482         int *loc_sz;
 483         int i, j;
 484         ic_luse = calloc(ic_n, sizeof(ic_luse[0]));
 485         ic_bbeg = calloc(ic_n, sizeof(ic_bbeg[0]));
 486         ra_gmask = calloc(ic_n, sizeof(ra_gmask[0]));
 487         loc_mem = calloc(loc_n, sizeof(loc_mem[0]));
 488         /* ic_luse */
 489         for (i = ic_n - 1; i >= 0; --i) {
 490                 long *w, *r1, *r2, *r3;
 491                 ic_info(ic + i, &w, &r1, &r2, &r3);
 492                 if (!ic_luse[i])
 493                         if (!w || ic[i].op & O_CALL)
 494                                 ic_luse[i] = -1;
 495                 if (!ic_luse[i])
 496                         continue;
 497                 if (r1 && !ic_luse[*r1])
 498                         ic_luse[*r1] = i;
 499                 if (r2 && !ic_luse[*r2])
 500                         ic_luse[*r2] = i;
 501                 if (r3 && !ic_luse[*r3])
 502                         ic_luse[*r3] = i;
 503                 if (ic[i].op & O_CALL)
 504                         for (j = 0; j < ic[i].arg2; j++)
 505                                 if (!ic_luse[ic[i].args[j]])
 506                                         ic_luse[ic[i].args[j]] = i;
 507         }
 508         /* ic_bbeg */
 509         for (i = 0; i < ic_n; i++) {
 510                 if (!ic_luse[i])
 511                         continue;
 512                 if (i + 1 < ic_n && ic[i].op & (O_JXX | O_RET))
 513                         ic_bbeg[i + 1] = 1;
 514                 if (ic[i].op & O_JXX && ic[i].arg2 < ic_n)
 515                         ic_bbeg[ic[i].arg2] = 1;
 516         }
 517         /* ra_gmask */
 518         for (i = 0; i < ic_n; i++) {
 519                 int n = ic_regcnt(ic + i);
 520                 int op = ic[i].op;
 521                 if (!ic_luse[i])
 522                         continue;
 523                 i_reg(op, &m0, &m1, &m2, &mt);
 524                 if (n >= 1 && !(op & O_OUT))
 525                         ra_gmask[ic[i].arg0] = m0;
 526                 if (n >= 2)
 527                         ra_gmask[ic[i].arg1] = m1;
 528                 if (n >= 3)
 529                         ra_gmask[ic[i].arg2] = m2;
 530                 if (op & O_CALL)
 531                         for (j = 0; j < MIN(N_ARGS, ic[i].arg2); j++)
 532                                 ra_gmask[ic[i].args[j]] = 1 << argregs[j];
 533         }
 534         /* loc_ptr and loc_dat */
 535         loc_ptr = calloc(loc_n, sizeof(loc_ptr[0]));
 536         loc_dat = calloc(loc_n, sizeof(loc_dat[0]));
 537         loc_sz = calloc(loc_n, sizeof(loc_sz[0]));
 538         for (i = 0; i < ic_n; i++) {
 539                 long oc = O_C(ic[i].op);
 540                 if (!ic_luse[i])
 541                         continue;
 542                 if (oc == (O_LD | O_LOC) || oc == (O_ST | O_LOC)) {
 543                         int loc = ic[i].arg1;
 544                         int sz = T_SZ(O_T(ic[i].op));
 545                         if (!loc_sz[loc])
 546                                 loc_sz[loc] = sz;
 547                         if (ic[i].arg2 || sz < 2 || sz != loc_sz[loc])
 548                                 loc_ptr[loc]++;
 549                         else
 550                                 loc_dat[loc]++;
 551                 }
 552                 if (oc == (O_MOV | O_LOC))
 553                         loc_ptr[ic[i].arg1]++;
 554         }
 555         free(loc_sz);
 556         /* func_leaf */
 557         func_leaf = 1;
 558         for (i = 0; i < ic_n; i++)
 559                 if (ic_luse[i] && ic[i].op & O_CALL)
 560                         func_leaf = 0;
 561         /* ra_vmap */
 562         for (i = 0; i < LEN(ra_vmap); i++)
 563                 ra_vmap[i] = -1;
 564         /* ra_lmap */
 565         for (i = 0; i < N_REGS; i++)
 566                 ra_lmapglob[i] = -1;
 567         ra_glob(ic, ic_n);
 568         memcpy(ra_lmap, ra_lmapglob, sizeof(ra_lmap));
 569         /* ra_lmask */
 570         for (i = 0; i < LEN(ra_lmapglob); i++)
 571                 if (ra_lmapglob[i] >= 0)
 572                         func_regs |= (1 << i);
 573         /* ra_live */
 574         for (i = 0; i < LEN(ra_live); i++)
 575                 ra_live[i] = -1;
 576         ra_vmax = 0;
 577         func_maxargs = 0;
 578 }
 579
 580 static void ra_done(void)
 581 {
 582         free(ic_luse);
 583         free(ic_bbeg);
 584         free(ra_gmask);
 585         free(loc_mem);
 586         free(loc_ptr);
 587         free(loc_dat);
 588 }
 589
 590 static void ic_gencode(struct ic *ic, int ic_n)
 591 {
 592         int r0, r1, r2;
 593         long mt;
 594         int i, j;
 595         /* loading arguments in their allocated registers */
 596         for (i = 0; i < LEN(ra_lmap); i++) {
 597                 int loc = ra_lmap[i];
 598                 if (loc >= 0 && loc < func_argc)
 599                         if (loc >= N_ARGS || i != argregs[loc])
 600                                 loc_toreg(loc, 0, i, ULNG);
 601         }
 602         /* generating code */
 603         for (i = 0; i < ic_n; i++) {
 604                 long op = ic[i].op;
 605                 long oc = O_C(op);
 606                 int n = ic_regcnt(ic + i);
 607                 i_label(i);
 608                 if (!ic_luse[i])
 609                         continue;
 610                 ra_map(ic + i, &r0, &r1, &r2, &mt);
 611                 if (oc & O_CALL) {
 612                         int argc = ic[i].arg2;
 613                         int aregs = MIN(N_ARGS, argc);
 614                         /* arguments passed via stack */
 615                         for (j = argc - 1; j >= aregs; --j) {
 616                                 int v = ic[i].args[j];
 617                                 int rx = ra_vreg(v) >= 0 ? ra_vreg(v) : r0;
 618                                 ra_vload(v, rx);
 619                                 i_ins(O_MK(O_ST | O_NUM, ULNG), rx, REG_SP,
 620                                         (j - aregs) * ULNG);
 621                                 ra_vdrop(v);
 622                         }
 623                         func_maxargs = MAX(func_maxargs, argc - aregs);
 624                         /* arguments passed via registers */
 625                         for (j = aregs - 1; j >= 0; --j)
 626                                 ra_vload(ic[i].args[j], argregs[j]);
 627                 }
 628                 /* loading the operands */
 629                 if (n >= 1 && !(oc & O_OUT))
 630                         ra_vload(ic[i].arg0, r0);
 631                 if (n >= 2 && !(oc & O_LOC))
 632                         ra_vload(ic[i].arg1, r1);
 633                 if (n >= 3)
 634                         ra_vload(ic[i].arg2, r2);
 635                 /* dropping values that are no longer used */
 636                 for (j = 0; j < LEN(ra_live); j++)
 637                         if (ra_live[j] >= 0 && ic_luse[ra_live[j]] <= i)
 638                                 ra_vdrop(ra_live[j]);
 639                 /* saving values stored in registers that may change */
 640                 for (j = 0; j < N_REGS; j++)
 641                         if (mt & (1 << j))
 642                                 ra_spill(j);
 643                 /* overwriting a value that is needed later (unless loading a local to its register) */
 644                 if (n >= 1 && oc & O_OUT)
 645                         if (oc != (O_LD | O_LOC) || ra_lmap[r0] != ic[i].arg1 ||
 646                                         ra_vmap[r0] >= 0)
 647                                 ra_spill(r0);
 648                 /* before the last instruction of a basic block; for jumps */
 649                 if (i + 1 < ic_n && ic_bbeg[i + 1] && oc & O_JXX)
 650                         ra_bbend();
 651                 /* performing the instruction */
 652                 if (oc & O_BOP)
 653                         i_ins(op, r0, r1, oc & O_NUM ? ic[i].arg2 : r2);
 654                 if (oc & O_UOP)
 655                         i_ins(op, r0, r1, r2);
 656                 if (oc == (O_LD | O_NUM))
 657                         i_ins(op, r0, r1, ic[i].arg2);
 658                 if (oc == (O_LD | O_LOC))
 659                         ra_lload(ic[i].arg1, ic[i].arg2, r0, O_T(op));
 660                 if (oc == (O_ST | O_NUM))
 661                         i_ins(op, r0, r1, ic[i].arg2);
 662                 if (oc == (O_ST | O_LOC))
 663                         ra_lsave(ic[i].arg1, ic[i].arg2, r0, O_T(op));
 664                 if (oc == O_RET)
 665                         i_ins(op, r0, 0, 0);
 666                 if (oc == O_MOV)
 667                         i_ins(op, r0, r0, 0);
 668                 if (oc == (O_MOV | O_NUM))
 669                         i_ins(op, r0, ic[i].arg1, 0);
 670                 if (oc == (O_MOV | O_LOC))
 671                         loc_toadd(ic[i].arg1, ic[i].arg2, r0);
 672                 if (oc == (O_MOV | O_SYM))
 673                         i_ins(op, r0, ic[i].arg1, ic[i].arg2);
 674                 if (oc == O_CALL)
 675                         i_ins(op, r0, r1, 0);
 676                 if (oc == (O_CALL | O_SYM))
 677                         i_ins(op, r0, ic[i].arg1, 0);
 678                 if (oc == O_JMP)
 679                         i_ins(op, 0, 0, ic[i].arg2);
 680                 if (oc & O_JZ)
 681                         i_ins(op, r0, 0, ic[i].arg2);
 682                 if (oc & O_JCC)
 683                         i_ins(op, r0, oc & O_NUM ? ic[i].arg1 : r1, ic[i].arg2);
 684                 if (oc == O_MSET)
 685                         i_ins(op, r0, r1, r2);
 686                 if (oc == O_MCPY)
 687                         i_ins(op, r0, r1, r2);
 688                 /* saving back the output register */
 689                 if (oc & O_OUT)
 690                         ra_vsave(ic[i].arg0, r0);
 691                 /* after the last instruction of a basic block */
 692                 if (i + 1 < ic_n && ic_bbeg[i + 1] && !(oc & O_JXX))
 693                         ra_bbend();
 694         }
 695         i_label(ic_n);
 696 }
 697
 698 static void ic_reset(void)
 699 {
 700         o_tmpdrop(-1);
 701         o_back(0);
 702         free(loc_off);
 703         loc_off = NULL;
 704         loc_n = 0;
 705         loc_sz = 0;
 706         loc_pos = I_LOC0;
 707 }
 708
 709 void o_func_beg(char *name, int argc, int global, int varg)
 710 {
 711         int i;
 712         func_argc = argc;
 713         func_varg = varg;
 714         func_regs = 0;
 715         ic_reset();
 716         for (i = 0; i < argc; i++)
 717                 loc_add(I_ARG0 + -i * ULNG);
 718         out_def(name, (global ? OUT_GLOB : 0) | OUT_CS, mem_len(&cs), 0);
 719 }
 720
 721 void o_code(char *name, char *c, long c_len)
 722 {
 723         out_def(name, OUT_CS, mem_len(&cs), 0);
 724         mem_put(&cs, c, c_len);
 725 }
 726
 727 void o_func_end(void)
 728 {
 729         struct ic *ic;
 730         long ic_n, spsub;
 731         long sargs = 0;
 732         long sargs_last = -1;
 733         long sregs_pos;
 734         char *c;
 735         long c_len, *rsym, *rflg, *roff, rcnt;
 736         int locs = 0;                   /* accessing locals on the stack */
 737         int i;
 738         ic_get(&ic, &ic_n);             /* the intermediate code */
 739         ra_init(ic, ic_n);              /* initialize register allocation */
 740         ic_gencode(ic, ic_n);           /* generating machine code */
 741         /* deciding which arguments to save */
 742         for (i = 0; i < func_argc; i++)
 743                 if (loc_mem[i])
 744                         sargs_last = i + 1;
 745         for (i = 0; i < N_ARGS && (func_varg || i < sargs_last); i++)
 746                 sargs |= 1 << argregs[i];
 747         /* computing the amount of stack subtraction */
 748         for (i = 0; i < loc_n; i++)
 749                 if (loc_mem[i])
 750                         locs = 1;
 751         spsub = (locs || ra_vmax) ? loc_pos + ra_vmax * ULNG : 0;
 752         for (i = 0; i < N_TMPS; i++)
 753                 if (((1 << tmpregs[i]) & func_regs & R_PERM) != 0)
 754                         spsub += ULNG;
 755         sregs_pos = spsub;
 756         spsub += func_maxargs * ULNG;
 757         /* adding function prologue and epilogue */
 758         i_wrap(func_argc, sargs, spsub, spsub || locs || !func_leaf,
 759                 func_regs & R_PERM, -sregs_pos);
 760         ra_done();
 761         i_code(&c, &c_len, &rsym, &rflg, &roff, &rcnt);
 762         for (i = 0; i < rcnt; i++)      /* adding the relocations */
 763                 out_rel(rsym[i], rflg[i], roff[i] + mem_len(&cs));
 764         mem_put(&cs, c, c_len);         /* appending function code */
 765         free(c);
 766         free(rsym);
 767         free(rflg);
 768         free(roff);
 769         for (i = 0; i < ic_n; i++)
 770                 if (ic[i].op & O_CALL)
 771                         free(ic[i].args);
 772         free(ic);
 773         ic_reset();
 774 }
 775
 776 void o_write(int fd)
 777 {
 778         i_done();
 779         out_write(fd, mem_buf(&cs), mem_len(&cs), mem_buf(&ds), mem_len(&ds));
 780         free(loc_off);
 781         free(ds_name);
 782         free(ds_off);
 783         mem_done(&cs);
 784         mem_done(&ds);
 785 }