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