diff options
| -rw-r--r-- | all.h | 1 | ||||
| -rw-r--r-- | cfg.c | 121 | ||||
| -rw-r--r-- | main.c | 1 |
3 files changed, 123 insertions, 0 deletions
@@ -560,6 +560,7 @@ void simpljmp(Fn *); int reaches(Fn *, Blk *, Blk *); int reachesnotvia(Fn *, Blk *, Blk *, Blk *); int ifgraph(Blk *, Blk **, Blk **, Blk **); +void simplcfg(Fn *); /* mem.c */ void promote(Fn *); @@ -441,3 +441,124 @@ ifgraph(Blk *ifb, Blk **pthenb, Blk **pelseb, Blk **pjoinb) *pjoinb = s1->s1; return 1; } + +typedef struct Jmp Jmp; + +struct Jmp { + int type; + Ref arg; + Blk *s1, *s2; +}; + +static int +jmpeq(Jmp *a, Jmp *b) +{ + return a->type == b->type && req(a->arg, b->arg) + && a->s1 == b->s1 && a->s2 == b->s2; +} + +static int +jmpnophi(Jmp *j) +{ + if (j->s1 && j->s1->phi) + return 0; + if (j->s2 && j->s2->phi) + return 0; + return 1; +} + +/* require cfg rpo, breaks use */ +void +simplcfg(Fn *fn) +{ + Ins cpy, *i; + Blk *b, *bb, **pb; + Jmp *jmp, *j, *jj; + Phi *p; + int *empty, done; + uint n; + + if (debug['C']) { + fprintf(stderr, "\n> Before CFG simplification:\n"); + printfn(fn, stderr); + } + + cpy = (Ins){.op = Ocopy}; + for (b=fn->start; b; b=b->link) + if (b->npred == 1) { + bb = b->pred[0]; + for (p=b->phi; p; p=p->link) { + cpy.cls = p->cls; + cpy.to = p->to; + cpy.arg[0] = phiarg(p, bb); + addins(&bb->ins, &bb->nins, &cpy); + } + b->phi = 0; + } + + jmp = emalloc(fn->nblk * sizeof jmp[0]); + empty = emalloc(fn->nblk * sizeof empty[0]); + for (b=fn->start; b; b=b->link) { + jmp[b->id].type = b->jmp.type; + jmp[b->id].arg = b->jmp.arg; + jmp[b->id].s1 = b->s1; + jmp[b->id].s2 = b->s2; + empty[b->id] = !b->phi; + for (i=b->ins; i<&b->ins[b->nins]; i++) + if (i->op != Onop || i->op != Odbgloc) { + empty[b->id] = 0; + break; + } + } + + do { + done = 1; + for (b=fn->start; b; b=b->link) { + if (b->id == -1u) + continue; + j = &jmp[b->id]; + if (j->type == Jjmp && j->s1->npred == 1) { + assert(!j->s1->phi); + addbins(&b->ins, &b->nins, j->s1); + empty[b->id] &= empty[j->s1->id]; + jj = &jmp[j->s1->id]; + pb = (Blk*[]){jj->s1, jj->s2, 0}; + for (; (bb=*pb); pb++) + for (p=bb->phi; p; p=p->link) { + n = phiargn(p, j->s1); + p->blk[n] = b; + } + j->s1->id = -1u; + *j = *jj; + done = 0; + } + else if (j->type == Jjnz + && empty[j->s1->id] && empty[j->s2->id] + && jmpeq(&jmp[j->s1->id], &jmp[j->s2->id]) + && jmpnophi(&jmp[j->s1->id])) { + *j = jmp[j->s1->id]; + done = 0; + } + } + } while (!done); + + for (b=fn->start; b; b=b->link) + if (b->id != -1u) { + j = &jmp[b->id]; + b->jmp.type = j->type; + b->jmp.arg = j->arg; + b->s1 = j->s1; + b->s2 = j->s2; + assert(!j->s1 || j->s1->id != -1u); + assert(!j->s2 || j->s2->id != -1u); + } + + fillcfg(fn); + free(empty); + free(jmp); + + if (debug['C']) { + fprintf(stderr, "\n> After CFG simplification:\n"); + printfn(fn, stderr); + } +} @@ -77,6 +77,7 @@ func(Fn *fn) ssacheck(fn); gvn(fn); fillcfg(fn); + simplcfg(fn); filluse(fn); filldom(fn); gcm(fn); |