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