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                                         a->phi = p;
 185                                         if (!bshas(defs, a->id))
 186                                         if (!bshas(u, a->id)) {
 187                                                 bsset(u, a->id);
 188                                                 *--bp = a;
 189                                         }
 190                                 }
 191                         }
 192                 }
 193         }
 194         free(blist);
 195 }
 196
 197 typedef struct Name Name;
 198 struct Name {
 199         Ref r;
 200         Blk *b;
 201         Name *up;
 202 };
 203
 204 static Name *namel;
 205
 206 static Name *
 207 nnew(Ref r, Blk *b, Name *up)
 208 {
 209         Name *n;
 210
 211         if (namel) {
 212                 n = namel;
 213                 namel = n->up;
 214         } else
 215                 /* could use alloc, here
 216                  * but namel should be reset
 217                  */
 218                 n = emalloc(sizeof *n);
 219         n->r = r;
 220         n->b = b;
 221         n->up = up;
 222         return n;
 223 }
 224
 225 static void
 226 nfree(Name *n)
 227 {
 228         n->up = namel;
 229         namel = n;
 230 }
 231
 232 static void
 233 rendef(Ref *r, Blk *b, Name **stk, Fn *fn)
 234 {
 235         Ref r1;
 236         int t;
 237
 238         t = r->val;
 239         if (req(*r, R) || !fn->tmp[t].visit)
 240                 return;
 241         r1 = refindex(t, fn);
 242         fn->tmp[r1.val].visit = t;
 243         stk[t] = nnew(r1, b, stk[t]);
 244         *r = r1;
 245 }
 246
 247 static Ref
 248 getstk(int t, Blk *b, Name **stk)
 249 {
 250         Name *n, *n1;
 251
 252         n = stk[t];
 253         while (n && !dom(n->b, b)) {
 254                 n1 = n;
 255                 n = n->up;
 256                 nfree(n1);
 257         }
 258         stk[t] = n;
 259         if (!n) {
 260                 /* uh, oh, warn */
 261                 return CON_Z;
 262         } else
 263                 return n->r;
 264 }
 265
 266 static void
 267 renblk(Blk *b, Name **stk, Fn *fn)
 268 {
 269         Phi *p;
 270         Ins *i;
 271         Blk *s, **ps, *succ[3];
 272         int t, m;
 273
 274         for (p=b->phi; p; p=p->link)
 275                 rendef(&p->to, b, stk, fn);
 276         for (i=b->ins; i<&b->ins[b->nins]; i++) {
 277                 for (m=0; m<2; m++) {
 278                         t = i->arg[m].val;
 279                         if (rtype(i->arg[m]) == RTmp)
 280                         if (fn->tmp[t].visit)
 281                                 i->arg[m] = getstk(t, b, stk);
 282                 }
 283                 rendef(&i->to, b, stk, fn);
 284         }
 285         t = b->jmp.arg.val;
 286         if (rtype(b->jmp.arg) == RTmp)
 287         if (fn->tmp[t].visit)
 288                 b->jmp.arg = getstk(t, b, stk);
 289         succ[0] = b->s1;
 290         succ[1] = b->s2 == b->s1 ? 0 : b->s2;
 291         succ[2] = 0;
 292         for (ps=succ; (s=*ps); ps++)
 293                 for (p=s->phi; p; p=p->link) {
 294                         t = p->to.val;
 295                         if ((t=fn->tmp[t].visit)) {
 296                                 m = p->narg++;
 297                                 if (m == NPred)
 298                                         die("renblk, too many phi args");
 299                                 p->arg[m] = getstk(t, b, stk);
 300                                 p->blk[m] = b;
 301                         }
 302                 }
 303         for (s=b->dom; s; s=s->dlink)
 304                 renblk(s, stk, fn);
 305 }
 306
 307 /* require rpo and use */
 308 void
 309 ssa(Fn *fn)
 310 {
 311         Name **stk, *n;
 312         int d, nt;
 313         Blk *b, *b1;
 314
 315         nt = fn->ntmp;
 316         stk = emalloc(nt * sizeof stk[0]);
 317         d = debug['L'];
 318         debug['L'] = 0;
 319         filldom(fn);
 320         if (debug['N']) {
 321                 fprintf(stderr, "\n> Dominators:\n");
 322                 for (b1=fn->start; b1; b1=b1->link) {
 323                         if (!b1->dom)
 324                                 continue;
 325                         fprintf(stderr, "%10s:", b1->name);
 326                         for (b=b1->dom; b; b=b->dlink)
 327                                 fprintf(stderr, " %s", b->name);
 328                         fprintf(stderr, "\n");
 329                 }
 330         }
 331         fillfron(fn);
 332         filllive(fn);
 333         phiins(fn);
 334         renblk(fn->start, stk, fn);
 335         while (nt--)
 336                 while ((n=stk[nt])) {
 337                         stk[nt] = n->up;
 338                         nfree(n);
 339                 }
 340         debug['L'] = d;
 341         free(stk);
 342         if (debug['N']) {
 343                 fprintf(stderr, "\n> After SSA construction:\n");
 344                 printfn(fn, stderr);
 345         }
 346 }
 347
 348 static int
 349 phicheck(Phi *p, Blk *b, Ref t)
 350 {
 351         Blk *b1;
 352         uint n;
 353
 354         for (n=0; n<p->narg; n++)
 355                 if (req(p->arg[n], t)) {
 356                         b1 = p->blk[n];
 357                         if (b1 != b && !sdom(b, b1))
 358                                 return 1;
 359                 }
 360         return 0;
 361 }
 362
 363 /* require use and ssa */
 364 void
 365 ssacheck(Fn *fn)
 366 {
 367         Tmp *t;
 368         Ins *i;
 369         Phi *p;
 370         Use *u;
 371         Blk *b, *bu;
 372         Ref r;
 373
 374         for (t=&fn->tmp[Tmp0]; t-fn->tmp < fn->ntmp; t++) {
 375                 if (t->ndef > 1)
 376                         err("ssa temporary %%%s defined more than once",
 377                                 t->name);
 378                 if (t->nuse > 0 && t->ndef == 0) {
 379                         bu = fn->rpo[t->use[0].bid];
 380                         goto Err;
 381                 }
 382         }
 383         for (b=fn->start; b; b=b->link) {
 384                 for (p=b->phi; p; p=p->link) {
 385                         r = p->to;
 386                         t = &fn->tmp[r.val];
 387                         for (u=t->use; u<&t->use[t->nuse]; u++) {
 388                                 bu = fn->rpo[u->bid];
 389                                 if (u->type == UPhi) {
 390                                         if (phicheck(u->u.phi, b, r))
 391                                                 goto Err;
 392                                 } else
 393                                         if (bu != b && !sdom(b, bu))
 394                                                 goto Err;
 395                         }
 396                 }
 397                 for (i=b->ins; i<&b->ins[b->nins]; i++) {
 398                         if (rtype(i->to) != RTmp)
 399                                 continue;
 400                         r = i->to;
 401                         t = &fn->tmp[r.val];
 402                         for (u=t->use; u<&t->use[t->nuse]; u++) {
 403                                 bu = fn->rpo[u->bid];
 404                                 if (u->type == UPhi) {
 405                                         if (phicheck(u->u.phi, b, r))
 406                                                 goto Err;
 407                                 } else {
 408                                         if (bu == b) {
 409                                                 if (u->type == UIns)
 410                                                         if (u->u.ins <= i)
 411                                                                 goto Err;
 412                                         } else
 413                                                 if (!sdom(b, bu))
 414                                                         goto Err;
 415                                 }
 416                         }
 417                 }
 418         }
 419         return;
 420 Err:
 421         if (t->visit)
 422                 die("%%%s violates ssa invariant", t->name);
 423         else
 424                 err("ssa temporary %%%s is used undefined in @%s",
 425                         t->name, bu->name);
 426 }