ssa.c

   1 #include "all.h"
   2 #include <stdarg.h>
   3
   4 static void
   5 adduse(Tmp *tmp, int ty, Blk *b, ...)
   6 {
   7         Use *u;
   8         int n;
   9         va_list ap;
  10
  11         if (!tmp->use)
  12                 return;
  13         va_start(ap, b);
  14         n = tmp->nuse;
  15         vgrow(&tmp->use, ++tmp->nuse);
  16         u = &tmp->use[n];
  17         u->type = ty;
  18         u->bid = b->id;
  19         switch (ty) {
  20         case UPhi:
  21                 u->u.phi = va_arg(ap, Phi *);
  22                 break;
  23         case UIns:
  24                 u->u.ins = va_arg(ap, Ins *);
  25                 break;
  26         case UJmp:
  27                 break;
  28         default:
  29                 die("unreachable");
  30         }
  31         va_end(ap);
  32 }
  33
  34 /* fill usage, width, phi, and class information
  35  * must not change .visit fields
  36  */
  37 void
  38 filluse(Fn *fn)
  39 {
  40         Blk *b;
  41         Phi *p;
  42         Ins *i;
  43         int m, t, tp, w;
  44         uint a;
  45         Tmp *tmp;
  46
  47         /* todo, is this the correct file? */
  48         tmp = fn->tmp;
  49         for (t=Tmp0; t<fn->ntmp; t++) {
  50                 tmp[t].def = 0;
  51                 tmp[t].bid = -1u;
  52                 tmp[t].ndef = 0;
  53                 tmp[t].nuse = 0;
  54                 tmp[t].cls = 0;
  55                 tmp[t].phi = 0;
  56                 tmp[t].width = WFull;
  57                 if (tmp[t].use == 0)
  58                         tmp[t].use = vnew(0, sizeof(Use), PFn);
  59         }
  60         for (b=fn->start; b; b=b->link) {
  61                 for (p=b->phi; p; p=p->link) {
  62                         assert(rtype(p->to) == RTmp);
  63                         tp = p->to.val;
  64                         tmp[tp].bid = b->id;
  65                         tmp[tp].ndef++;
  66                         tmp[tp].cls = p->cls;
  67                         tp = phicls(tp, fn->tmp);
  68                         for (a=0; a<p->narg; a++)
  69                                 if (rtype(p->arg[a]) == RTmp) {
  70                                         t = p->arg[a].val;
  71                                         adduse(&tmp[t], UPhi, b, p);
  72                                         t = phicls(t, fn->tmp);
  73                                         if (t != tp)
  74                                                 tmp[t].phi = tp;
  75                                 }
  76                 }
  77                 for (i=b->ins; i<&b->ins[b->nins]; i++) {
  78                         if (!req(i->to, R)) {
  79                                 assert(rtype(i->to) == RTmp);
  80                                 w = WFull;
  81                                 if (isparbh(i->op))
  82                                         w = Wsb + (i->op - Oparsb);
  83                                 if (isload(i->op) && i->op != Oload)
  84                                         w = Wsb + (i->op - Oloadsb);
  85                                 if (isext(i->op))
  86                                         w = Wsb + (i->op - Oextsb);
  87                                 if (w == Wsw || w == Wuw)
  88                                 if (i->cls == Kw)
  89                                         w = WFull;
  90                                 t = i->to.val;
  91                                 tmp[t].width = w;
  92                                 tmp[t].def = i;
  93                                 tmp[t].bid = b->id;
  94                                 tmp[t].ndef++;
  95                                 tmp[t].cls = i->cls;
  96                         }
  97                         for (m=0; m<2; m++)
  98                                 if (rtype(i->arg[m]) == RTmp) {
  99                                         t = i->arg[m].val;
 100                                         adduse(&tmp[t], UIns, b, i);
 101                                 }
 102                 }
 103                 if (rtype(b->jmp.arg) == RTmp)
 104                         adduse(&tmp[b->jmp.arg.val], UJmp, b);
 105         }
 106 }
 107
 108 static Ref
 109 refindex(int t, Fn *fn)
 110 {
 111         return newtmp(fn->tmp[t].name, fn->tmp[t].cls, fn);
 112 }
 113
 114 static void
 115 phiins(Fn *fn)
 116 {
 117         BSet u[1], defs[1];
 118         Blk *a, *b, **blist, **be, **bp;
 119         Ins *i;
 120         Phi *p;
 121         Use *use;
 122         Ref r;
 123         int t, nt, ok;
 124         uint n, defb;
 125         short k;
 126
 127         bsinit(u, fn->nblk);
 128         bsinit(defs, fn->nblk);
 129         blist = emalloc(fn->nblk * sizeof blist[0]);
 130         be = &blist[fn->nblk];
 131         nt = fn->ntmp;
 132         for (t=Tmp0; t<nt; t++) {
 133                 fn->tmp[t].visit = 0;
 134                 if (fn->tmp[t].phi != 0)
 135                         continue;
 136                 if (fn->tmp[t].ndef == 1) {
 137                         ok = 1;
 138                         defb = fn->tmp[t].bid;
 139                         use = fn->tmp[t].use;
 140                         for (n=fn->tmp[t].nuse; n--; use++)
 141                                 ok &= use->bid == defb;
 142                         if (ok || defb == fn->start->id)
 143                                 continue;
 144                 }
 145                 bszero(u);
 146                 k = -1;
 147                 bp = be;
 148                 for (b=fn->start; b; b=b->link) {
 149                         b->visit = 0;
 150                         r = R;
 151                         for (i=b->ins; i<&b->ins[b->nins]; i++) {
 152                                 if (!req(r, R)) {
 153                                         if (req(i->arg[0], TMP(t)))
 154                                                 i->arg[0] = r;
 155                                         if (req(i->arg[1], TMP(t)))
 156                                                 i->arg[1] = r;
 157                                 }
 158                                 if (req(i->to, TMP(t))) {
 159                                         if (!bshas(b->out, t)) {
 160                                                 r = refindex(t, fn);
 161                                                 i->to = r;
 162                                         } else {
 163                                                 if (!bshas(u, b->id)) {
 164                                                         bsset(u, b->id);
 165                                                         *--bp = b;
 166                                                 }
 167                                                 if (clsmerge(&k, i->cls))
 168                                                         die("invalid input");
 169                                         }
 170                                 }
 171                         }
 172                         if (!req(r, R) && req(b->jmp.arg, TMP(t)))
 173                                 b->jmp.arg = r;
 174                 }
 175                 bscopy(defs, u);
 176                 while (bp != be) {
 177                         fn->tmp[t].visit = t;
 178                         b = *bp++;
 179                         bsclr(u, b->id);
 180                         for (n=0; n<b->nfron; n++) {
 181                                 a = b->fron[n];
 182                                 if (a->visit++ == 0)
 183                                 if (bshas(a->in, t)) {
 184                                         p = alloc(sizeof *p);
 185                                         p->cls = k;
 186                                         p->to = TMP(t);
 187                                         p->link = a->phi;
 188                                         p->arg = vnew(0, sizeof p->arg[0], PFn);
 189                                         p->blk = vnew(0, sizeof p->blk[0], PFn);
 190                                         a->phi = p;
 191                                         if (!bshas(defs, a->id))
 192                                         if (!bshas(u, a->id)) {
 193                                                 bsset(u, a->id);
 194                                                 *--bp = a;
 195                                         }
 196                                 }
 197                         }
 198                 }
 199         }
 200         free(blist);
 201 }
 202
 203 typedef struct Name Name;
 204 struct Name {
 205         Ref r;
 206         Blk *b;
 207         Name *up;
 208 };
 209
 210 static Name *namel;
 211
 212 static Name *
 213 nnew(Ref r, Blk *b, Name *up)
 214 {
 215         Name *n;
 216
 217         if (namel) {
 218                 n = namel;
 219                 namel = n->up;
 220         } else
 221                 /* could use alloc, here
 222                  * but namel should be reset
 223                  */
 224                 n = emalloc(sizeof *n);
 225         n->r = r;
 226         n->b = b;
 227         n->up = up;
 228         return n;
 229 }
 230
 231 static void
 232 nfree(Name *n)
 233 {
 234         n->up = namel;
 235         namel = n;
 236 }
 237
 238 static void
 239 rendef(Ref *r, Blk *b, Name **stk, Fn *fn)
 240 {
 241         Ref r1;
 242         int t;
 243
 244         t = r->val;
 245         if (req(*r, R) || !fn->tmp[t].visit)
 246                 return;
 247         r1 = refindex(t, fn);
 248         fn->tmp[r1.val].visit = t;
 249         stk[t] = nnew(r1, b, stk[t]);
 250         *r = r1;
 251 }
 252
 253 static Ref
 254 getstk(int t, Blk *b, Name **stk)
 255 {
 256         Name *n, *n1;
 257
 258         n = stk[t];
 259         while (n && !dom(n->b, b)) {
 260                 n1 = n;
 261                 n = n->up;
 262                 nfree(n1);
 263         }
 264         stk[t] = n;
 265         if (!n) {
 266                 /* uh, oh, warn */
 267                 return UNDEF;
 268         } else
 269                 return n->r;
 270 }
 271
 272 static void
 273 renblk(Blk *b, Name **stk, Fn *fn)
 274 {
 275         Phi *p;
 276         Ins *i;
 277         Blk *s, **ps, *succ[3];
 278         int t, m;
 279
 280         for (p=b->phi; p; p=p->link)
 281                 rendef(&p->to, b, stk, fn);
 282         for (i=b->ins; i<&b->ins[b->nins]; i++) {
 283                 for (m=0; m<2; m++) {
 284                         t = i->arg[m].val;
 285                         if (rtype(i->arg[m]) == RTmp)
 286                         if (fn->tmp[t].visit)
 287                                 i->arg[m] = getstk(t, b, stk);
 288                 }
 289                 rendef(&i->to, b, stk, fn);
 290         }
 291         t = b->jmp.arg.val;
 292         if (rtype(b->jmp.arg) == RTmp)
 293         if (fn->tmp[t].visit)
 294                 b->jmp.arg = getstk(t, b, stk);
 295         succ[0] = b->s1;
 296         succ[1] = b->s2 == b->s1 ? 0 : b->s2;
 297         succ[2] = 0;
 298         for (ps=succ; (s=*ps); ps++)
 299                 for (p=s->phi; p; p=p->link) {
 300                         t = p->to.val;
 301                         if ((t=fn->tmp[t].visit)) {
 302                                 m = p->narg++;
 303                                 vgrow(&p->arg, p->narg);
 304                                 vgrow(&p->blk, p->narg);
 305                                 p->arg[m] = getstk(t, b, stk);
 306                                 p->blk[m] = b;
 307                         }
 308                 }
 309         for (s=b->dom; s; s=s->dlink)
 310                 renblk(s, stk, fn);
 311 }
 312
 313 /* require rpo and use */
 314 void
 315 ssa(Fn *fn)
 316 {
 317         Name **stk, *n;
 318         int d, nt;
 319         Blk *b, *b1;
 320
 321         nt = fn->ntmp;
 322         stk = emalloc(nt * sizeof stk[0]);
 323         d = debug['L'];
 324         debug['L'] = 0;
 325         filldom(fn);
 326         if (debug['N']) {
 327                 fprintf(stderr, "\n> Dominators:\n");
 328                 for (b1=fn->start; b1; b1=b1->link) {
 329                         if (!b1->dom)
 330                                 continue;
 331                         fprintf(stderr, "%10s:", b1->name);
 332                         for (b=b1->dom; b; b=b->dlink)
 333                                 fprintf(stderr, " %s", b->name);
 334                         fprintf(stderr, "\n");
 335                 }
 336         }
 337         fillfron(fn);
 338         filllive(fn);
 339         phiins(fn);
 340         renblk(fn->start, stk, fn);
 341         while (nt--)
 342                 while ((n=stk[nt])) {
 343                         stk[nt] = n->up;
 344                         nfree(n);
 345                 }
 346         debug['L'] = d;
 347         free(stk);
 348         if (debug['N']) {
 349                 fprintf(stderr, "\n> After SSA construction:\n");
 350                 printfn(fn, stderr);
 351         }
 352 }
 353
 354 static int
 355 phicheck(Phi *p, Blk *b, Ref t)
 356 {
 357         Blk *b1;
 358         uint n;
 359
 360         for (n=0; n<p->narg; n++)
 361                 if (req(p->arg[n], t)) {
 362                         b1 = p->blk[n];
 363                         if (b1 != b && !sdom(b, b1))
 364                                 return 1;
 365                 }
 366         return 0;
 367 }
 368
 369 /* require use and ssa */
 370 void
 371 ssacheck(Fn *fn)
 372 {
 373         Tmp *t;
 374         Ins *i;
 375         Phi *p;
 376         Use *u;
 377         Blk *b, *bu;
 378         Ref r;
 379
 380         for (t=&fn->tmp[Tmp0]; t-fn->tmp < fn->ntmp; t++) {
 381                 if (t->ndef > 1)
 382                         err("ssa temporary %%%s defined more than once",
 383                                 t->name);
 384                 if (t->nuse > 0 && t->ndef == 0) {
 385                         bu = fn->rpo[t->use[0].bid];
 386                         goto Err;
 387                 }
 388         }
 389         for (b=fn->start; b; b=b->link) {
 390                 for (p=b->phi; p; p=p->link) {
 391                         r = p->to;
 392                         t = &fn->tmp[r.val];
 393                         for (u=t->use; u<&t->use[t->nuse]; u++) {
 394                                 bu = fn->rpo[u->bid];
 395                                 if (u->type == UPhi) {
 396                                         if (phicheck(u->u.phi, b, r))
 397                                                 goto Err;
 398                                 } else
 399                                         if (bu != b && !sdom(b, bu))
 400                                                 goto Err;
 401                         }
 402                 }
 403                 for (i=b->ins; i<&b->ins[b->nins]; i++) {
 404                         if (rtype(i->to) != RTmp)
 405                                 continue;
 406                         r = i->to;
 407                         t = &fn->tmp[r.val];
 408                         for (u=t->use; u<&t->use[t->nuse]; u++) {
 409                                 bu = fn->rpo[u->bid];
 410                                 if (u->type == UPhi) {
 411                                         if (phicheck(u->u.phi, b, r))
 412                                                 goto Err;
 413                                 } else {
 414                                         if (bu == b) {
 415                                                 if (u->type == UIns)
 416                                                         if (u->u.ins <= i)
 417                                                                 goto Err;
 418                                         } else
 419                                                 if (!sdom(b, bu))
 420                                                         goto Err;
 421                                 }
 422                         }
 423                 }
 424         }
 425         return;
 426 Err:
 427         if (t->visit)
 428                 die("%%%s violates ssa invariant", t->name);
 429         else
 430                 err("ssa temporary %%%s is used undefined in @%s",
 431                         t->name, bu->name);
 432 }