diff options
Diffstat (limited to 'optmem.c')
| -rw-r--r-- | optmem.c | 60 |
1 files changed, 33 insertions, 27 deletions
@@ -32,11 +32,16 @@ struct ssabuilder { static union ref readvar(struct ssabuilder *, int var, enum irclass, struct block *); static union ref -deltrivialphis(struct block *blk, union ref phiref) +deltrivialphis(struct ssabuilder *sb, struct block *blk, union ref phiref) { + union ref **pcurdefs; + int var; struct use *use, *uend; union ref *args = phitab.p[instrtab[phiref.i].l.i]; union ref same = {0}; + + assert(instrtab[phiref.i].op == Ophi); + for (int i = 0; i < blk->npred; ++i) { if (args[i].bits == same.bits || args[i].bits == phiref.bits) continue; /* unique value or self-reference */ @@ -50,21 +55,28 @@ deltrivialphis(struct block *blk, union ref phiref) /* replace uses */ replcuses(phiref, same); + imap_each(&sb->curdefs, var, pcurdefs) { + (void)var; + if ((*pcurdefs)[blk->id].bits == phiref.bits) + (*pcurdefs)[blk->id] = same; + } + /* stops infinite recursion and marks phi for removal */ instrtab[phiref.i].op = Onop; /* recursively try to remove all phi users as they might have become trivial */ - for (use = instruse[phiref.i], uend = use + instrnuse[phiref.i]; use < uend; ++use) - if (use->u != USERJUMP && instrtab[use->u].op == Ophi) - deltrivialphis(use->blk, mkref(RTMP, use->u)); - - /* remove phi */ - for (int i = 0; i < blk->phi.n; ++i) { - if (blk->phi.p[i] == phiref.i) { - delphi(blk, i); - break; +Redo: + for (use = instruse[phiref.i], uend = use + instrnuse[phiref.i]; use < uend; ++use) { + if (use->u != USERJUMP && instrtab[use->u].op == Ophi && use->u != phiref.i) { + union ref it = mkref(RTMP, use->u); + union ref vphi2 = deltrivialphis(sb, use->blk, it); + if (vphi2.bits != it.bits) { + /* deletion happened so phiref use may have changed */ + goto Redo; + } } } + return same; } @@ -77,7 +89,7 @@ addphiargs(struct ssabuilder *sb, int var, enum irclass cls, struct block *blk, args[i] = readvar(sb, var, cls, pred); adduse(blk, phiref.i, args[i]); } - return deltrivialphis(blk, phiref); + return deltrivialphis(sb, blk, phiref); } static void @@ -90,24 +102,12 @@ writevar(struct ssabuilder *sb, int var, struct block *blk, union ref val) (*pcurdefs)[blk->id] = val; } -static bool -issealed(struct ssabuilder *sb, struct block *blk) -{ - /* consider block sealed if it has been visited or if no backbranches flow to it */ - if (blk->id < sb->lastvisit) return 1; - for (int i = 0; i < blk->npred; ++i) - if (blkpred(blk, i)->id > blk->id) - return 0; - return 1; -} - - static union ref readvarrec(struct ssabuilder *sb, int var, enum irclass cls, struct block *blk) { union ref val; assert(blk->npred > 0); - if (!issealed(sb, blk)) { + if (blk->id > sb->lastvisit) { /* unsealed block */ val = insertphi(blk, cls); vpush(&sb->pendingphis[blk->id], ((struct pendingphi) { var, val.i })); } else if (blk->npred == 1) { @@ -132,7 +132,7 @@ readvar(struct ssabuilder *sb, int var, enum irclass cls, struct block *blk) return readvarrec(sb, var, cls, blk); } -/* require use, blkid */ +/* require use, blkid; keeps use */ void mem2reg(struct function *fn) { @@ -201,17 +201,23 @@ mem2reg(struct function *fn) Next:; } - /* seal block */ assert(sb.lastvisit == blk->id); - ++sb.lastvisit; pending = (void *) &sb.pendingphis[blk->id]; for (int i = 0; i < pending->n; ++i) { addphiargs(&sb, pending->p[i].var, instrtab[pending->p[i].phi].cls, blk, mkref(RTMP, pending->p[i].phi)); } + ++sb.lastvisit; vfree(pending); } while ((blk = blk->lnext) != fn->entry); + do { + /* remove phis marked for deletion */ + for (int i = 0; i < blk->phi.n; ++i) + if (instrtab[blk->phi.p[i]].op == Onop) + delphi(blk, i--); + } while ((blk = blk->lnext) != fn->entry); + free(sb.pendingphis); for (int i = 0; i < sb.curdefs.mb.N; ++i) |