diff options
Diffstat (limited to 'regalloc.c')
| -rw-r--r-- | regalloc.c | 1195 |
1 files changed, 0 insertions, 1195 deletions
diff --git a/regalloc.c b/regalloc.c deleted file mode 100644 index 64dcfac..0000000 --- a/regalloc.c +++ /dev/null @@ -1,1195 +0,0 @@ -#include "ir.h" - -/** Implements linear scan register allocation **/ - -#if 1 -#define DBG(...) if(ccopt.dbg.r) efmt(__VA_ARGS__) -#else -#define DBG(...) ((void)0) -#endif - -/* The algorithm used here to introduce phis for temporaries whose definitions - * appear later than some of its uses is very similar to that in mem2reg() */ - -static int livelastblk; -struct pendingphi { ushort var, phi; }; -static vec_of(struct pendingphi) *pendingphis; -static int npendingphi; -static ushort **curdefs; -static union ref readvar(struct bitset *defined, enum irclass cls, int var, struct block *blk); - -static void -fillphi(struct bitset *defined, union ref phi, enum irclass cls, int var, struct block *blk) -{ - union ref *args = phitab.p[instrtab[phi.i].l.i]; - assert(blk->npred > 0); - for (int i = 0; i < blk->npred; ++i) - args[i] = readvar(defined, cls, var, blk); -} - -static union ref -readvar(struct bitset *defined, enum irclass cls, int var, struct block *blk) -{ - union ref val; - - if (bstest(defined, var)) return mkref(RTMP, var); - assert(cls && "?"); - - /* memoed definition */ - if (xbcap(curdefs) > blk->id && xbcap(curdefs[blk->id]) > var && curdefs[blk->id][var]) - return mkref(RTMP, curdefs[blk->id][var]); - - xbgrowz(&curdefs, blk->id + 1); - if (blk->id > livelastblk) { - ++npendingphi; - val = insertphi(blk, cls); - xbgrowz(&pendingphis, blk->id + 1); - vpush(&pendingphis[blk->id], ((struct pendingphi) { var, val.i })); - } else if (blk->npred == 1) { - val = readvar(defined, cls, var, blkpred(blk, 0)); - } else { - val = insertphi(blk, cls); - fillphi(defined, val, cls, var, blk); - } - xbgrowz(&curdefs[blk->id], var + 1); - assert(val.i > 0); - curdefs[blk->id][var] = val.i; - return val; -} - -static void -liveuse(struct bitset *defined, struct instr *ins, union ref *r, struct block *blk) -{ - int var; - if (r->t == RADDR) { - liveuse(defined, ins, &addrht[r->i].base, blk); - liveuse(defined, ins, &addrht[r->i].index, blk); - return; - } else if (r->t != RTMP) return; - var = r->i; - if (bstest(defined, var)) return; - - *r = readvar(defined, insrescls(instrtab[r->i]), var, blk); -} - -/* regalloc() assumes every use of a temporary is visited before its definition - * so this function fixes cases where that would not apply by introducing phi functions */ -static void -fixlive(struct function *fn) -{ - extern int ninstr; - struct block *blk = fn->entry; - struct bitset definedbuf[4] = {0}; - struct bitset *defined = definedbuf; - - if (BSSIZE(ninstr) >= arraylength(definedbuf)) - defined = xcalloc(sizeof *defined * BSSIZE(ninstr)); - npendingphi = 0; - - do { - for (int i = 0; i < blk->phi.n; ++i) { - int var = blk->phi.p[i]; - bsset(defined, var); - } - - for (int i = 0; i < blk->ins.n; ++i) { - int var = blk->ins.p[i]; - struct instr *ins = &instrtab[var]; - if (ins->l.t) liveuse(defined, ins, &ins->l, blk); - if (ins->r.t) liveuse(defined, ins, &ins->r, blk); - bsset(defined, var); - } - } while ((blk = blk->lnext) != fn->entry); - - do { - vec_of(struct pendingphi) *pphi; - - if (!npendingphi) break; - if (xbcap(pendingphis) <= blk->id) break; - - pphi = (void *)&pendingphis[blk->id]; - npendingphi -= pphi->n; - for (int i = 0; i < pphi->n; ++i) { - fillphi(defined, mkref(RTMP, pphi->p[i].phi), instrtab[pphi->p[i].phi].cls, pphi->p[i].var, blk); - } - vfree(pphi); - } while ((blk = blk->lnext) != fn->entry); - - if (ccopt.dbg.l) { - DBG("<< After liveness fixup >>\n"); - irdump(fn); - } - if (defined != definedbuf) free(defined); -} - -static regset gpregset, fpregset; - -#define isfpr(reg) in_range((reg), mctarg->fpr0, mctarg->fpr0 + mctarg->nfpr - 1) -#define isgpr(reg) in_range((reg), mctarg->gpr0, mctarg->gpr0 + mctarg->nfpr - 1) - -/* an allocated physical register or stack slot */ -enum { ADEAD, AREG, ASTACK }; -struct alloc { ushort t : 2, a : 14; }; -#define afree() ((struct alloc) { ADEAD }) -#define areg(r) ((struct alloc) { AREG, (r) }) -#define astack(s) ((struct alloc) { ASTACK, (s) }) - -enum { MAXSPILL = 512 }; - -/* half-closed instr range [from, to) */ -struct range { ushort from, to; }; - -/* a temporary's lifetime interval */ -struct interval { - struct interval *next; /* for linked list of active,inactive,handled sets in linear scan */ - struct alloc alloc; - schar rhint : 7, /* register hint */ - fpr : 1; /* needs float register? */ - - /* sorted ranges array */ - uchar nrange; - union { - struct range _inl[2]; - struct range *_dyn; - }; -}; - -struct intervals { - int count; /* number of actual intervals */ - struct interval *temps; /* map of tmp -> interval */ - struct fixinterval { - struct fixinterval *next; - regset rs; - struct range range; - } *fixed; /* linked list of fixed intervals, always sorted */ -}; - -struct rega { - struct function *fn; - struct arena **arena; - regset free; /* free registers */ - struct bitset freestk[BSSIZE(MAXSPILL)]; /* free stack slots */ - int maxstk, /* highest stack slot used */ - stktop; - struct intervals intervals; -}; - -/* materialization of stack slot references is deferred until the end because - * the offset from base pointer depends on how many slots we end up allocating */ -static vec_of(union ref *) stkslotrefs; - -static void -addstkslotref(int instr, uint off) -{ - union ref *ref = &instrtab[instr].l; - *ref = mkref(RICON, off); - vpush(&stkslotrefs, ref); -} - -static struct alloc -allocstk(struct rega *ra) -{ - int s = -1; - - for (int i = 0; i < BSSIZE(MAXSPILL); ++i) { - if (ra->freestk[i].u != 0) { - s = i*64 + lowestsetbit(ra->freestk[i].u); - break; - } - } - if (s != -1) { - bsclr(ra->freestk, s); - if (ra->stktop < s) ra->stktop = s+1; - } else { - s = ra->stktop++; - } - if (ra->maxstk < s+1) ra->maxstk = s+1; - //imap_get(&ra->intervals.temps, var)->alloc = astack(s); - return astack(s); -} - -static void -freestk(struct rega *ra, int slot) -{ - DBG("FREE stk %d\n",slot); - if (slot < MAXSPILL) - bsset(ra->freestk, slot); - else if (slot == ra->stktop - 1) - --ra->stktop; -} - -/* Parallel moves algorithm from QBE: https://c9x.me/git/qbe.git/tree/rega.c?id=e493a7f23352f51acc0a1e12284ab19d7894488a#n201 */ - -#define mkmove(k, rd, rs) mkinstr(Omove, k, mkref(RREG, rd), mkref(RREG, rs)) - -enum pmstat { PMTOMOVE, PMMOVING, PMDONE }; -static struct pmove { - uchar k; - uchar stat; - struct alloc dst, src; -} pmove[MAXREGS]; -static int npmove; - -static void -pmadd(enum irclass k, struct alloc dst, struct alloc src) -{ - if (!memcmp(&dst, &src, sizeof dst)) return; - assert(npmove < MAXREGS); - pmove[npmove++] = (struct pmove) { k, PMTOMOVE, dst, src }; -} - -static void -emitmove(enum irclass k, struct alloc dst, struct alloc src, struct block *blk, int curi) -{ - struct instr mv = {.keep = 1}; - if (dst.t == AREG && src.t == AREG) { - insertinstr(blk, curi, mkmove(k, dst.a, src.a)); - } else if (dst.t == ASTACK && src.t == AREG) { - mv = mkinstr(Ostore1+ilog2(cls2siz[k]), 0, .r = mkref(RREG, src.a)); - addstkslotref(insertinstr(blk, curi, mv).i, dst.a*8); - } else if (dst.t == AREG && src.t == ASTACK) { - switch (mv.cls = k) { - default: assert(0); - case KI4: mv.op = Oloads4; break; - case KI8: mv.op = Oloadi8; break; - case KPTR: mv.op = targ_64bit ? Oloadi8 : Oloads4; break; - case KF4: mv.op = Oloadf4; break; - case KF8: mv.op = Oloadf8; break; - } - mv.reg = dst.a+1; - addstkslotref(insertinstr(blk, curi, mv).i, src.a*8); - } else assert(0); -} - -static int -pmrec(int i, struct block *blk, int curi, enum irclass *k) -{ - int j, c; - - if (!memcmp(&pmove[i].dst, &pmove[i].src, sizeof pmove->dst)) { - pmove[i].stat = PMDONE; - return -1; - } - - /* widen when necessary */ - assert(kisint(pmove[i].k) == kisint(*k)); - if (cls2siz[pmove[i].k] > cls2siz[*k]) - *k = pmove[i].k; - - for (j = 0; j < npmove; ++j) { - if (!memcmp(&pmove[j].dst, &pmove[i].src, sizeof pmove->dst)) { - break; - } - } - if (j == npmove) goto Done; - switch (pmove[j].stat) { - default: assert(0); - case PMMOVING: - c = j; - Swap: - assert(pmove[i].src.t == AREG && pmove[i].dst.t == AREG); - insertinstr(blk, curi, - mkinstr(Oswap, *k, mkref(RREG, pmove[i].dst.a), mkref(RREG, pmove[i].src.a), .keep = 1)); - break; - case PMTOMOVE: - pmove[i].stat = PMMOVING; - c = pmrec(j, blk, curi, k); - if (c == i) { - c = -1; - break; - } else if (c != -1) { - goto Swap; - } - /* fallthru */ - case PMDONE: - Done: - c = -1; - emitmove(*k, pmove[i].dst, pmove[i].src, blk, curi); - break; - } - - pmove[i].stat = PMDONE; - return c; -} - -static void -emitpm(struct block *blk) -{ - int curi = blk->ins.n; - for (int i = 0; i < npmove; ++i) { - if (pmove[i].stat == PMTOMOVE) { - pmrec(i, blk, curi, &(enum irclass) { pmove[i].k }); - } - } -} - -/* remove phis by inserting parallel moves */ -static void -lowerphis(struct rega *ra, struct block *blk, struct block *suc) -{ - int predno; - struct block *n = NULL; - - if (!blk->s2) n = blk; - - for (predno = 0; predno < suc->npred; ++predno) - if (blkpred(suc, predno) == blk) - break; - assert(predno < suc->npred); - - npmove = 0; - /* ensure phi args go to the same slot as phi with parallel copies */ - for (int i = 0; i < suc->phi.n; ++i) { - struct instr *phi = &instrtab[suc->phi.p[i]]; - union ref *arg = &phitab.p[phi->l.i][predno]; - struct alloc from, to; - - if (arg->t == RREG) continue; - assert(arg->t == RTMP); - DBG("resolve phi @%d, @%d, %%%d <- %%%d\n", blk->id, suc->id, phi - instrtab, arg->i); - if (instrtab[arg->i].reg) { - from = areg(instrtab[arg->i].reg - 1); - DBG(" it had R%d\n", from.a); - } else { - from = ra->intervals.temps[arg->i].alloc; - assert(from.t != ADEAD); - DBG(" found %c%d\n", " RS"[from.t], from.a); - if (from.t == AREG) - instrtab[arg->i].reg = from.a+1; - } - if (phi->reg) { - to = areg(phi->reg - 1); - DBG(" phi had R%d\n", to.a); - } else { - to = ra->intervals.temps[phi - instrtab].alloc; - assert(to.t != ADEAD); - DBG(" found phi %c%d\n", " RS"[to.t], to.a); - if (to.t == AREG) - phi->reg = to.a+1; - } - DBG(" > phi move %c%d -> %c%d\n", " RS"[from.t], from.a, " RS"[to.t], to.a); - if (!n) n = insertblk(ra->fn, blk, suc); - pmadd(phi->cls, to, from); - } - if (n) emitpm(n); -} - -/* generate copies for phi operands to transform into conventional-SSA */ -static void -fixcssa(struct function *fn) -{ - struct block *blk = fn->entry; - do { - if (!blk->phi.n) continue; - for (int p = 0; p < blk->npred; ++p) { - struct block *n, *pred = blkpred(blk, p); - if (!pred->s2) { - /* pred only has 1 successor (blk), so insert move directly in it */ - n = pred; - } else { - n = insertblk(fn, pred, blk); - assert(n->jmp.t == Jb && n->s1 == blk); - } - for (int i = 0; i < blk->phi.n; ++i) { - int phi = blk->phi.p[i]; - union ref *args = phitab.p[instrtab[phi].l.i]; - args[p] = insertinstr(n, n->ins.n, mkinstr(Ocopy, instrtab[phi].cls, args[p])); - } - } - } while ((blk = blk->lnext) != fn->entry); -} - -static inline bool -rangeoverlap(struct range a, struct range b) -{ - return a.from < b.to && b.from < a.to; -} - -static void -pushrange(struct interval *lv, struct range r) -{ - if (lv->nrange < 2) lv->_inl[lv->nrange++] = r; - else if (lv->nrange > 2) xbpush(&lv->_dyn, &lv->nrange, r); - else { - struct range *d = NULL; - xbgrow(&d, 4); - memcpy(d, lv->_inl, 2*sizeof *d); - d[lv->nrange++] = r; - lv->_dyn = d; - } -} -#define itrange(lv, i) ((lv)->nrange <= 2 ? (lv)->_inl : (lv)->_dyn)[i] - -static bool -intervaloverlap(struct interval *a, struct interval *b) -{ - for (int i = 0, j = 0; i < a->nrange && j < b->nrange; ) { - struct range r1 = itrange(a, i), r2 = itrange(b, j); - if (rangeoverlap(r1, r2)) return 1; - if (r1.to <= r2.from) ++i; - else ++j; - } - return 0; -} - -static bool -intervaldef(struct intervals *intervals, int t, struct block *blk, int pos, int reghint) -{ - struct interval *it = &intervals->temps[t]; - if (it->nrange) { - assert(itrange(it, 0).from <= pos); - itrange(it, 0).from = pos; - return 1; - } - return 0; -} - -static void -addrange(struct intervals *intervals, int t, struct range new, int reghint) -{ - struct interval *it = &intervals->temps[t]; - struct range *fst; - int n; - - if (!it->nrange) { - ++intervals->count; - it->rhint = reghint; - it->fpr = kisflt(insrescls(instrtab[t])); - pushrange(it, new); - return; - } - - fst = &itrange(it, 0); - /* fully covered by first range? */ - if (fst->from <= new.from && fst->to >= new.to) return; - /* overlaps with first range ? */ - if (fst->from <= new.to && new.to < fst->to) { - fst->from = new.from; - } else { - /* put new range at the start */ - pushrange(it, new); - memmove(&itrange(it, 1), &itrange(it, 0), sizeof(struct range) * (it->nrange - 1)); - itrange(it, 0) = new; - } - - /* new range might cover existing ranges (loop header lives), - * check and succesively merge */ - fst = &itrange(it, 0); - n = 0; - for (int i = 1; i < it->nrange; ++i) { - struct range other = itrange(it, i); - if (fst->to >= other.from) { - fst->to = fst->to > other.to ? fst->to : other.to; - ++n; - } else break; - } - - if (n > 0) { - for (int i = 1; i + n < it->nrange; ++i) - itrange(it, i) = itrange(it, i+n); - if (it->nrange > 2 && it->nrange - n <= 2) { - struct range *dyn = it->_dyn; - memcpy(it->_inl, dyn, (it->nrange - n) * sizeof *dyn); - xbfree(dyn); - } - it->nrange -= n; - } -} - -static void -usereg(struct rega *ra, int reg, struct block *blk, int pos) -{ - struct fixinterval *fxit; - if (rstest(mctarg->rglob, reg)) return; /* regalloc never allocates globally live regs, so don't need intervals for those */ - fxit = alloc(ra->arena, sizeof *fxit, 0); - fxit->next = ra->intervals.fixed; - fxit->range = (struct range) {blk->inumstart, pos}; - fxit->rs = 1<<reg; - ra->intervals.fixed = fxit; -} - -static void -defreg(struct rega *ra, int reg, int pos) { - if (rstest(mctarg->rglob, reg)) return; - for (struct fixinterval *fxit = ra->intervals.fixed; fxit; fxit = fxit->next) { - if (fxit->rs == 1<<reg) { - assert(fxit->range.from <= pos); - fxit->range.from = pos; - // DBG(">>>REG %s range @%d: %d-%d\n", mctarg->rnames[reg], fxit->range.from.blk, fxit->range.from.ins, fxit->range.to.ins); - return; - } - } - assert(0&&"def reg not used"); -} - -/* lifetime interval construction: https://c9x.me/compile/bib/Wimmer10a.pdf */ -static void -buildintervals(struct rega *ra) -{ - extern int ninstr; - struct block *blk, *last; - struct bitset **livein = alloc(ra->arena, ra->fn->nblk * sizeof *livein, 0); - size_t bssize = BSSIZE(ninstr); - for (int i = 0; i < ra->fn->nblk; ++i) - livein[i] = allocz(ra->arena, bssize * sizeof *livein[i], 0); - ra->intervals.temps = allocz(ra->arena, ninstr * sizeof *ra->intervals.temps, 0); - - numberinstrs(ra->fn); - /* visit blocks in reverse, to build lifetime intervals */ - blk = last = ra->fn->entry->lprev; - do { - struct instr *ins = NULL; - struct bitset *live = livein[blk->id]; - struct block *suc = blk->s1; - // DBG("--- @%d ---\n",blk->id); - - /* live = union of successor.liveIn for each successor of b */ - if (blk->s1) bsunion(live, livein[blk->s1->id], bssize); - if (blk->s2) bsunion(live, livein[blk->s2->id], bssize); - - /* for each phi function phi of successors of b do - * live.add(phi.inputOf(b)) - */ - if (suc) do { - int predno; - for (predno = 0; blkpred(suc, predno) != blk; ++predno) ; - for (int i = 0; i < suc->phi.n; ++i) { - struct instr *phi = &instrtab[suc->phi.p[i]]; - union ref *arg = &phitab.p[phi->l.i][predno]; - assert(arg->t == RTMP); - // DBG("from phi set live %%%d\n", arg->i); - bsset(live, arg->i); - } - } while (suc != blk->s2 && (suc = blk->s2)); - - /* for each opd in live do - * intervals[opd].addRange(b.from, b.to) - */ - for (uint i = 0; bsiter(&i, live, bssize); ++i) { - // DBG("itretave %%%d\n",i ); - addrange(&ra->intervals, i, (struct range){blk->inumstart, blk->inumstart + blk->ins.n + 2}, -1); - } - - /* for each operation op of b in reverse order do */ - union ref queue[8] = { blk->jmp.arg[0], blk->jmp.arg[1] }; - goto Branchopd; - for (int curi, pos ; curi >= 0; --curi) { - int out = blk->ins.p[curi], reghint; - ins = &instrtab[out]; - pos = blk->inumstart + 1 + curi; - /* for each output operand opd of op do - * intervals[opd].setFrom(op.id) - * live.remove(opd) - */ - reghint = ins && ins->op == Ocopy && ins->l.t == RREG ? ins->l.i : -1; - if (!intervaldef(&ra->intervals, out, blk, pos, reghint)) { - if (insrescls(*ins) && ins->op != Omove && !ins->keep && !(ins->op == Ocopy && ins->l.t == RREG)) { - /* dead */ - *ins = mkinstr(Onop,0,); - } - } - bsclr(live, out); - - /* gather fixed intervals */ - if (ins->op == Omove) { - assert(ins->l.t == RREG); - defreg(ra, ins->l.i, pos); - } else if (ins->op == Ocall) { - struct call *call = &calltab.p[ins->r.i]; - regset rclob = (gpregset | fpregset) &~ (mctarg->rglob | mctarg->rcallee); - ra->fn->isleaf = 0; - - for (int i = 0; i < 2; ++i) { - if (call->abiret[i].ty.bits) { - int reg = call->abiret[i].reg; - rsclr(&rclob, reg); - defreg(ra, reg, pos); - } - } - if (rclob) { - struct fixinterval *fxit = alloc(ra->arena, sizeof *fxit, 0); - fxit->next = ra->intervals.fixed; - fxit->range = (struct range) {pos, pos}; - fxit->rs = rclob; - ra->intervals.fixed = fxit; - } - for (int j = call->narg - 1; j >= 0; --j) { - int reg = call->abiarg[j].reg; - if (reg >= 0) { - usereg(ra, reg, blk, pos); - } - } - } - - - /* for each input operand opd of op do - * intervals[opd].addRange(b.from, op.id) - * live.add(opd) - */ - reghint = (ins && ins->op == Omove && ins->l.t == RREG) ? ins->l.i : -1; - queue[0] = ins->r, queue[1] = ins->l; - if (0) { - Branchopd: - reghint = -1; - curi = blk->ins.n; - pos = blk->inumstart + blk->ins.n + 1; - } - for (int nqueue = ins && ins->op == Omove ? 1 : 2; nqueue > 0;) { - union ref r = queue[--nqueue]; - - /* do not allocate a reg for a cmp op used as branch argument, since it's a pseudo op */ - if (curi == blk->ins.n && blk->jmp.t == Jb && r.t == RTMP && instrtab[r.i].keep) - continue; - - if (r.t == RTMP) { - addrange(&ra->intervals, r.i, (struct range){blk->inumstart, pos}, reghint); - bsset(live, r.i); - } else if (r.t == RREG) { - usereg(ra, r.i, blk, pos); - } else if (r.t == RADDR) { - reghint = -1; - queue[nqueue++] = addrht[r.i].base; - queue[nqueue++] = addrht[r.i].index; - } - } - } - - /* for each phi function phi of b do - * live.remove(phi.output) - */ - for (int i = 0; i < blk->phi.n; ++i) - bsclr(live, blk->phi.p[i]); - - /* if b is loop header then - * loopEnd = last block of the loop starting at b - * for each opd in live do - * &ra->intervals[opd].addRange(b.from, loopEnd.to) - */ - struct block *loopend = NULL; - for (int i = 0; i < blk->npred; ++i) { - struct block *pred = blkpred(blk, i); - if (pred->id > blk->id) - loopend = loopend && loopend->id > pred->id ? loopend : pred; - } - if (loopend) { - // DBG("i'm loop header - @%d (to @%d)\n", blk->id, loopend->id); - for (uint opd = 0; bsiter(&opd, live, bssize); ++opd) { - // DBG(" i have live %%%d\n", opd); - addrange(&ra->intervals, opd, (struct range){blk->inumstart, loopend->inumstart + loopend->ins.n+1}, -1); - /* struct interval *lv = imap_get(&ra->intervals.temps, opd); - for (int i = 0; i < lv->n; ++i) { - struct range r = itrange(lv, i); - // DBG(" @%d:%d - @%d:%d\n", r.from.blk, r.from.ins, r.to.blk, r.to.ins); - } */ - } - } - } while ((blk = blk->lprev) != last); - - for (int var = 0; var < ninstr; ++var) { - struct interval *it = &ra->intervals.temps[var]; - if (!it->nrange) continue; - DBG("lifetime of %%%d: ", var); - for (int i = 0; i < it->nrange; ++i) { - struct range r = itrange(it, i); - DBG("[%d,%d)%s", r.from, r.to, i < it->nrange-1 ? ", " : ""); - } - DBG("\n"); - } - for (struct fixinterval *fx = ra->intervals.fixed; fx; fx = fx->next) { - DBG("fixed {"); - for (int r = 0; rsiter(&r, fx->rs); ++r) - DBG("%s,", mctarg->rnames[r]); - DBG("}: [%d,%d)\n", fx->range.from, fx->range.to); - } -} - -static bool -itcontainspos(const struct interval *it, int pos) -{ - for (int i = 0; i < it->nrange; ++i) { - struct range r = itrange(it, i); - if (r.from > pos) return 0; - if (pos < r.to) return 1; - } - return 0; -} - -/* quicksort */ -static void -sortintervals(struct interval **xs, int lo, int hi) -{ - assert(lo >= 0 && hi >= 0); - while (lo < hi) { - /* partition */ - int i = lo - 1, p = hi + 1, - pivot = itrange(xs[lo], 0).from; - for (;;) { - struct interval *tmp; - do ++i; while (itrange(xs[i], 0).from < pivot); - do --p; while (itrange(xs[p], 0).from > pivot); - if (i >= p) break; - /* swap */ - tmp = xs[i]; - xs[i] = xs[p]; - xs[p] = tmp; - } - /* recur */ - if (p + 1 >= hi) { - hi = p; - } else { - if (lo < p) - sortintervals(xs, lo, p); - lo = p + 1; - } - } -} - -static void -linearscan(struct rega *ra) -{ - struct intervals *intervals = &ra->intervals; - int nunhandled = 0; - struct interval **unhandled = NULL; - struct interval *active = NULL, *inactive = NULL, *handled = NULL; - - if (!intervals->count) return; - /* sort intervals */ - { - extern int ninstr; - unhandled = alloc(ra->arena, sizeof *unhandled * intervals->count, 0); - - for (int i = 0; i < ninstr; ++i) { - if (!intervals->temps[i].nrange) continue; - unhandled[nunhandled++] = &intervals->temps[i]; - } - assert(nunhandled == intervals->count); - sortintervals(unhandled, 0, nunhandled-1); - } - - /* LINEAR SCAN */ - for (struct interval **pcurrent = unhandled; nunhandled-- > 0; ++pcurrent) { - struct interval *current = *pcurrent; - int pos = itrange(current, 0).from; - - /* Expire old intervals */ - - /* check for intervals in active that are handled or inactive */ - for (struct interval **lnk = &active, *it = *lnk, *next; (next = it?it->next:0), it; it = next) { - //DBG("< im active %%%d\n", intervals->temps.mb.k[it - intervals->temps.v]); - /* ends before position? */ - if (itrange(it, it->nrange-1).to <= pos) { - /* move from active to handled */ - *lnk = next; - it->next = handled; - handled = it; - if (it->alloc.t == AREG) { - ra->free |= 1<<it->alloc.a; - //DBG(" unblock %s\n", mctarg->rnames[it->reg]); - } else if (it->alloc.t == ASTACK) { - freestk(ra, it->alloc.a); - } - } else - /* it does not cover position? */ - if (!itcontainspos(it, pos)) { - /* move from active to inactive */ - *lnk = next; - it->next = inactive; - inactive = it; - if (it->alloc.t == AREG) { - ra->free |= 1<<it->alloc.a; - DBG(" >> %%%zd unblock %s\n", it-ra->intervals.temps, mctarg->rnames[it->alloc.a]); - } - } else lnk = &it->next; - } - - /* check for intervals in inactive that are handled or active */ - for (struct interval **lnk = &inactive, *it = *lnk, *next; (next = it?it->next:0), it; it = next) { - //DBG("< im inactive %%%d\n", intervals->temps.mb.k[it - intervals->temps.v]); - /* ends before position? */ - if (itrange(it, it->nrange-1).to <= pos) { - /* move from inactive to handled */ - *lnk = next; - it->next = handled; - handled = it; - if (it->alloc.t == ASTACK) { - freestk(ra, it->alloc.a); - } - } else - /* it covers position? */ - if (itcontainspos(it, pos)) { - /* move from inactive to active */ - *lnk = next; - it->next = active; - active = it; - if (it->alloc.t == AREG) { - assert(rstest(ra->free, it->alloc.a)); - ra->free &= ~(1<<it->alloc.a); - DBG(" << %%%zd reblock %s\n", it-ra->intervals.temps, mctarg->rnames[it->alloc.a]); - } - } else lnk = &it->next; - } - - /* find a register for current */ - { - int this = current - intervals->temps; - regset free = ra->free & (current->fpr ? fpregset : gpregset); - struct instr *ins = &instrtab[this]; - int reg = 0; - int end = itrange(current, current->nrange-1).to; - - /* exclude regs from overlapping fixed intervals */ - for (struct fixinterval *fxit = intervals->fixed; fxit; fxit = fxit->next) { - if (fxit->range.to <= pos) { - intervals->fixed = fxit->next; - continue; - } else if (fxit->range.from >= end) { - break; - } - - for (int i = 0; i < current->nrange; ++i) { - if (rangeoverlap(fxit->range, itrange(current, i))) { - free &=~ fxit->rs; - } - } - } - /* exclude regs from overlapping inactive intervals */ - for (struct interval *it = inactive; it; it = it->next) { - if (it->alloc.t == AREG && intervaloverlap(it, current)) { - rsclr(&free, it->alloc.a); - } - } - /* for 2-address instrs, exclude reg from 2nd arg */ - if (ins->inplace && opnarg[ins->op] == 2) { - int xreg; - if (ins->r.t == RREG) rsclr(&free, ins->r.i); - else if (ins->r.t == RTMP && (xreg = instrtab[ins->r.i].reg)) - rsclr(&free, xreg-1); - } - - if (!free) { - /* spill */ - current->alloc = allocstk(ra); - DBG("%%%d got stk%d\n", this, current->alloc.a); - /* move current to active */ - current->next = active; - active = current; - continue; - } - - /* have free regs, try to use hint */ - if (current->rhint >= 0) - DBG("have hint %s for %%%zd\n", - mctarg->rnames[current->rhint], current - intervals->temps); - if (current->rhint >= 0 && rstest(free, current->rhint)) { - DBG(" (used hint)\n"); - reg = current->rhint; - goto GotReg; - } else { - /* for two-address instructions, try to use the reg of left arg */ - if (ins->op != Ophi && (opnarg[ins->op] == 1 || (opnarg[ins->op] == 2 && ins->inplace))) { - DBG(" %%%d try %d,%d\n", this, ins->l.t,ins->l.i); - if (ins->l.t == RREG && rstest(free, reg = ins->l.i)) - goto GotReg; - if (ins->l.t == RTMP) - if ((reg = instrtab[ins->l.i].reg-1) >= 0) - if (rstest(free, reg)) - goto GotReg; - /* for phi, try to use reg of any arg */ - } else if (ins->op == Ophi) { - union ref *arg = phitab.p[ins->l.i]; - for (int i = 0; i < xbcap(arg); ++i) { - if (arg->t == RREG && rstest(free, reg = arg->i)) goto GotReg; - if (arg->t == RTMP) - if ((reg = instrtab[arg->i].reg-1) >= 0) - if (rstest(free, reg)) - goto GotReg; - } - } - - /* prefer caller-saved registers */ - if (free &~ mctarg->rcallee) free &=~ mctarg->rcallee; - - for (reg = 0; !rstest(free, reg); ++reg); - } - GotReg: - current->alloc = areg(reg); - ins->reg = reg + 1; - DBG("%%%d got %s\n", this, mctarg->rnames[reg]); - rsclr(&ra->free, reg); - rsset(&ra->fn->regusage, reg); - - //if current has a register assigned then add current to active - current->next = active; - active = current; - } - } -} - -/* replace temps with physical regs, add loads & stores for spilled temps */ -static bool -devirt(struct rega *ra, struct block *blk) -{ - bool allnops = 1; - struct function *fn = ra->fn; - for (int curi = 0; curi < blk->ins.n; ++curi) { - int temp = blk->ins.p[curi]; - struct instr *ins = &instrtab[temp]; - struct interval *it; - struct alloc *alloc; - union ref *argref[4]; - int nargref = 0; - int nspill = 0; - - /* devirtualize ref args */ - for (int i = 0; i < 2; ++i) { - union ref *r = &i[&ins->l]; - if (r->t == RADDR) { - /* XXX mutating hashed addr.. should be fine though (because - * new RADDRs shouldn't be created after regalloc) - * maybe hashing them in the first place is unnecessary */ - struct addr *a = &addrht[r->i]; - argref[nargref++] = &a->base; - argref[nargref++] = &a->index; - } else { - argref[nargref++] = r; - } - } - for (int i = 0; i < nargref; ++i) { - static uchar cls2load[] = { - [KI4] = Oloads4, [KI8] = Oloadi8, [KF4] = Oloadf4, [KF8] = Oloadf8, [KPTR] = 0 - }; - cls2load[KPTR] = targ_64bit ? Oloadi8 : Oloads4; - union ref *r = argref[i]; - int tr; - if (r->t == RTMP) { - alloc = (it = &ra->intervals.temps[r->i]) && it->nrange ? &it->alloc : NULL; - if (alloc->t == ASTACK && ins->op == Omove) { - /* move [reg], [stk] -> [reg] = load [stk] */ - assert(r == &ins->r && ins->l.t == RREG); - ins->reg = ins->l.i+1; - ins->op = cls2load[ins->cls]; - ins->r = NOREF; - addstkslotref(temp, alloc->a*8); - } else if (alloc->t == ASTACK && ins->op == Ocopy) { - /* [reg] = copy [stk] -> [reg] = load [stk] */ - assert(r == &ins->l && ins->reg); - ins->op = cls2load[ins->cls]; - addstkslotref(temp, alloc->a*8); - } else if (alloc->t == ASTACK) { - /* ref was spilled, gen load to scratch register and use it */ - struct instr ld = {.cls = insrescls(instrtab[r->i])}; - int reg = kisint(ld.cls) ? mctarg->gprscratch : mctarg->fprscratch; - bool dosave; - /* pick scratch register, or any register that doesn't conflict with this instr's srcs/dst */ - if (nspill > 0) { - for (reg = kisflt(ld.cls) ? mctarg->fpr0 : mctarg->gpr0;; ++reg) { - if (reg == ins->reg-1) continue; - for (int j = 0; j < i; ++j) - if (argref[j]->t == RREG && argref[j]->i == reg) continue; - break; - } - /* if not the designated scratch register, we need to save+restore */ - if ((dosave = rstest(fn->regusage, reg) || rstest(mctarg->rcallee, reg))) { - insertinstr(blk, curi++, mkinstr(Oxsave, 0, .l = mkref(RREG, reg))); - } - } - ld.reg = reg+1; - ld.op = cls2load[ld.cls]; - addstkslotref(insertinstr(blk, curi++, ld).i, alloc->a*8); - *r = mkref(RREG, reg); - if (nspill > 0 && dosave) { - insertinstr(blk, curi+1, mkinstr(Oxrestore, 0, .l = mkref(RREG, reg))); - } - ++nspill; - } else if ((tr = instrtab[r->i].reg)) { - assert(alloc && alloc->t == AREG && alloc->a == tr-1); - *r = mkref(RREG, tr-1); - } - } - } - if (nspill > 0) assert(ins->op != Ocall); - - /* devirtualize destination */ - alloc = temp < ra->intervals.count && (it = &ra->intervals.temps[temp]) && it->nrange ? &it->alloc : NULL; - if (alloc && alloc->t == ASTACK) { - int store = Ostore1 + ilog2(cls2siz[insrescls(*ins)]); - /* t was spilled, gen store */ - if (ins->op == Ocopy) { - ins->op = store; - ins->r = ins->l; - addstkslotref(temp, alloc->a*8); - } else { - int reg = kisint(insrescls(*ins)) ? mctarg->gprscratch : mctarg->fprscratch; - assert(nspill == 0); - ins->reg = reg+1; - addstkslotref( - insertinstr(blk, ++curi, mkinstr(store, 0, .r = mkref(RREG, reg))).i, - alloc->a*8); - } - } else if (!ins->reg && insrescls(*ins) && ins->op != Omove && !ins->keep) { - /* dead */ - Nop: - ins->op = Onop; - } else if (ins->op == Omove && ins->r.t == RREG && ins->l.i == ins->r.i) { - /* move r1,r2 / r1=r2 */ - goto Nop; - } else if (ins->op == Ocopy && ins->l.t == RREG && ins->reg-1 == ins->l.i) { - /* r1 = copy r2 / r1=r2 */ - goto Nop; - } else if (ins->inplace && ins->l.t == RREG && ins->reg && ins->reg-1 != ins->l.i) { - /* fixup in-place (two-address) instructions */ - allnops = 0; - insertinstr(blk, curi++, mkmove(ins->cls, ins->reg-1, ins->l.i)); - ins->l.i = ins->reg-1; - } else if (ins->op != Onop) allnops = 0; - } - - return allnops; -} - -static void -fini(struct rega *ra) -{ - int id = 0; - struct function *fn = ra->fn; - struct block *blk = fn->entry; - - do { - bool allnops; - - blk->id = id++; - allnops = devirt(ra, blk); - - /* remove no-op blocks */ - if (allnops && !blk->s2 && blk->npred > 0) { - bool delet = 1; - for (int i = 0; i < blk->npred; ++i) { - struct block *p = blkpred(blk, i); - if (p->s2 && !blk->s1) - delet = 0; - } - for (int i = 0; i < blk->npred; ++i) { - struct block *p = blkpred(blk, i); - if (!p->s2 && !blk->s1) { - /* simplify: - * - * @p: - * ... - * b @blk - * @blk: - * NOP - * ret - */ - assert(p->s1 == blk); - p->jmp.t = Jret; - p->s1 = NULL; - } else if (blk->s1) { - /* simplify: - * - * @p: - * ... - * b %x, @blk, @other - * @blk: - * NOP - * b @next - */ - struct block *next = blk->s1; - if (p->s1 == blk) p->s1 = next; - else if (p->s2 == blk) p->s2 = next; - else continue; - for (int i = 0; i < next->npred; ++i) { - if (blkpred(next, i) == blk) { - blkpred(next, i) = p; - goto NextPred; - } - } - addpred(next, p); - } - NextPred:; - } - if (delet) { - freeblk(fn, blk); - --id; - } - } - } while ((blk = blk->lnext) != fn->entry); -} - -void -regalloc(struct function *fn) -{ - static union ref *stkslotrefsbuf[64]; - struct rega ra = {fn, .arena = fn->arena}; - struct block *blk, *last; - - /* setup */ - if (!fpregset || !gpregset) { - for (int r = 0; r < MAXREGS; ++r) { - if (isfpr(r)) - rsset(&fpregset, r); - else if (isgpr(r)) - rsset(&gpregset, r); - } - } - ra.free = (gpregset | fpregset) &~ (mctarg->rglob | (1ull<<mctarg->gprscratch) | (1ull<<mctarg->fprscratch)); - memset(ra.freestk, 0xFF, sizeof ra.freestk); - fn->regusage = 0; - fn->stksiz = alignup(fn->stksiz, 8); - fn->isleaf = 1; - vinit(&stkslotrefs, stkslotrefsbuf, arraylength(stkslotrefsbuf)); - - /* put into reverse post order */ - sortrpo(fn); - - /* fix liveness ranges */ - fixlive(fn); - - /* transform into CSSA */ - fixcssa(fn); - - fillblkids(fn); - - if (ccopt.dbg.r) { - efmt("<< Before linear scan >>\n"); - irdump(fn); - } - - /* linear scan: build lifetime intervals */ - buildintervals(&ra); - - /* linear scan: assign physical registers and stack slots */ - linearscan(&ra); - - /* get out of SSA */ - blk = last = fn->entry->lprev; - do { - if (blk->id < 0) continue; - for (int i = 0; i < blk->npred; ++i) { - lowerphis(&ra, blkpred(blk, i), blk); - } - vfree(&blk->phi); - } while ((blk = blk->lprev) != last); - - /* devirtualize & final cleanup */ - fini(&ra); - - for (struct interval *it = ra.intervals.temps; ra.intervals.count > 0; ++it) { - if (it->nrange > 2) xbfree(it->_dyn); - if (it->nrange > 0) --ra.intervals.count; - } - - fn->stksiz += ra.maxstk*8; - if (fn->stksiz > 1<<24) error(NULL, "'%s' stack frame too big", fn->name); - while (stkslotrefs.n) { - union ref *adr = stkslotrefs.p[--stkslotrefs.n]; - *adr = mkaddr((struct addr) { .base = mkref(RREG, mctarg->bpr), .disp = -fn->stksiz + adr->i }); - } - vfree(&stkslotrefs); - - if (ccopt.dbg.r) { - DBG("<< After regalloc >>\n"); - irdump(fn); - } -} - -/* vim:set ts=3 sw=3 expandtab: */ |