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