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-rw-r--r--src/ir_regalloc.c1417
1 files changed, 1417 insertions, 0 deletions
diff --git a/src/ir_regalloc.c b/src/ir_regalloc.c
new file mode 100644
index 0000000..1200c77
--- /dev/null
+++ b/src/ir_regalloc.c
@@ -0,0 +1,1417 @@
+#include "ir.h"
+
+/** Implements linear scan register allocation **/
+/* Some references:
+ * Linear Scan Register Allocation on SSA Form (Wimmer 2010)
+ - https://c9x.me/compile/bib/Wimmer10a.pdf
+ * Linear Scan Register Allocation in the Context of SSA Form
+ and Register Constraints (Mössenböck 2002)
+ - https://bernsteinbear.com/assets/img/linear-scan-ra-context-ssa.pdf
+ */
+
+#if 1
+#define DBG(...) if(ccopt.dbg.r) bfmt(ccopt.dbgout, __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, &addrtab.p[r->i].base, blk);
+ liveuse(defined, ins, &addrtab.p[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 pass 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) >= countof(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) {
+ bfmt(ccopt.dbgout, "<< 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 };
+union alloc { struct { ushort t : 2, a : 14; }; ushort bits; };
+#define afree() ((union alloc) { .t=ADEAD })
+#define areg(r) ((union alloc) { .t=AREG, .a=(r) })
+#define astack(s) ((union alloc) { .t=ASTACK, .a=(s) })
+
+enum { MAXSPILL = 512 };
+
+/* half-closed instr range [from, to) */
+struct range { ushort from, to; };
+#define mkrange(f,t) ((struct range){(f), (t)})
+
+/* a temporary's lifetime interval */
+struct interval {
+ struct interval *next; /* for linked list of active,inactive,handled sets in linear scan */
+ union alloc alloc;
+ schar rhint : 7; /* register hint */
+ bool fpr : 1; /* needs float register? */
+ uint cost; /* spilling cost estimate */
+
+ /* sorted ranges array */
+ ushort nrange;
+ union {
+ struct range _rinl[2];
+ struct range *_rdyn;
+ };
+};
+
+struct rega {
+ struct function *fn;
+ struct arena **arena;
+
+ int intercount; /* number of actual intervals */
+ int ninter; /* size of inter */
+ struct interval *inter; /* map of tmp -> interval */
+ struct fixinterval {
+ struct fixinterval *next;
+ regset rs;
+ struct range range;
+ } *fixed; /* linked list of fixed intervals, always sorted */
+
+ struct bitset freestk[BSSIZE(MAXSPILL)]; /* free stack slots */
+ int maxstk, /* highest stack slot used */
+ stktop;
+};
+
+#define stkslotref(fn, off) \
+ (mkaddr((struct addr){.base = mkref(RREG, mctarg->bpr), .disp = -(fn)->stksiz - 8 - (off)}))
+
+/* Parallel moves algorithm from QBE: https://c9x.me/git/qbe.git/tree/rega.c?id=e493a7f23352f51acc0a1e12284ab19d7894488a#n201 */
+
+enum { PMTOMOVE, PMMOVING, PMDONE };
+struct pmstate {
+ struct function *fn;
+ int npmove;
+ struct pmove {
+ uchar k; /* enum irclass */
+ uchar stat; /* PMTOMOVE|MOVING|DONE */
+ union alloc dst, src;
+ } pmove[MAXREGS];
+};
+
+static void
+pmadd(struct pmstate *pms, enum irclass k, union alloc dst, union alloc src)
+{
+ if (!memcmp(&dst, &src, sizeof dst)) return;
+ assert(pms->npmove < MAXREGS);
+ pms->pmove[pms->npmove++] = (struct pmove) { k, PMTOMOVE, dst, src };
+}
+
+#define mkmove(k, rd, rs) mkinstr(Omove, k, mkref(RREG, rd), mkref(RREG, rs))
+static void
+emitmove(struct function *fn, enum irclass k, union alloc dst, union alloc src, struct block *blk, int curi)
+{
+ struct instr mv = {.keep = 1};
+ int reg;
+ if (dst.t == AREG && src.t == AREG) {
+ insertinstr(blk, curi, mkmove(k, dst.a, src.a));
+ return;
+ }
+ if (src.t == ASTACK) {
+ switch (mv.cls = k) {
+ default: assert(0);
+ case KI32: mv.op = Oloads32; break;
+ case KI64: mv.op = Oloadi64; break;
+ case KPTR: mv.op = targ_64bit ? Oloadi64 : Oloads32; break;
+ case KF32: mv.op = Oloadf32; break;
+ case KF64: mv.op = Oloadf64; break;
+ }
+ if (dst.t == AREG)
+ reg = dst.a;
+ else
+ reg = kisint(k) ? mctarg->gprscratch : mctarg->fprscratch;
+ mv.reg = reg+1;
+ mv.l = stkslotref(fn, src.a*8);
+ insertinstr(blk, curi++, mv);
+ } else reg = src.a;
+ if (dst.t == ASTACK) {
+ mv = mkinstr(cls2store[k], 0, stkslotref(fn, dst.a*8), mkref(RREG, reg));
+ insertinstr(blk, curi, mv);
+ }
+}
+
+static int
+pmrec(struct pmstate *pms, int i, struct block *blk, int curi, enum irclass *k)
+{
+ struct pmove *pm = &pms->pmove[i];
+ if (pm->dst.bits == pm->src.bits) {
+ pm->stat = PMDONE;
+ return -1;
+ }
+
+ /* widen when necessary */
+ assert(kisint(pm->k) == kisint(*k));
+ if (cls2siz[pm->k] > cls2siz[*k])
+ *k = pm->k;
+
+ int j, c;
+ for (j = 0; j < pms->npmove; ++j) {
+ if (pms->pmove[j].dst.bits == pm->src.bits)
+ break;
+ }
+ if (j == pms->npmove) goto Done;
+ switch (pms->pmove[j].stat) {
+ default: assert(0);
+ case PMMOVING:
+ c = j;
+ Swap:
+ if (pm->src.t == AREG && pm->dst.t == AREG) {
+ insertinstr(blk, curi,
+ mkinstr(Oswap, *k, mkref(RREG, pm->dst.a), mkref(RREG, pm->src.a), .keep = 1));
+ } else if (pm->src.t != pm->dst.t) {
+ union alloc reg, stk, regtmp;
+ if (pm->src.t == AREG)
+ reg = pm->src, stk = pm->dst;
+ else
+ stk = pm->src, reg = pm->dst;
+ assert(reg.t == AREG && stk.t == ASTACK);
+ regtmp = areg(kisint(*k) ? mctarg->gprscratch : mctarg->fprscratch);
+ emitmove(pms->fn, *k, regtmp, stk, blk, curi++);
+ insertinstr(blk, curi++,
+ mkinstr(Oswap, *k, mkref(RREG, reg.a), mkref(RREG, regtmp.a), .keep = 1));
+ emitmove(pms->fn, *k, stk, regtmp, blk, curi++);
+ } else {
+ /* FIXME using scratch gpr and fpr for this is hackish */
+ assert(pm->src.t == ASTACK && pm->dst.t == ASTACK);
+ int r1 = mctarg->gprscratch, r2 = mctarg->fprscratch;
+ enum irclass k1 = siz2intcls[cls2siz[*k]], k2 = KF32 + (cls2siz[*k] == 8);
+ emitmove(pms->fn, k1, areg(r1), pm->src, blk, curi++);
+ emitmove(pms->fn, k2, areg(r2), pm->dst, blk, curi++);
+ emitmove(pms->fn, k1, pm->dst, areg(r1), blk, curi++);
+ emitmove(pms->fn, k2, pm->src, areg(r2), blk, curi++);
+ }
+ break;
+ case PMTOMOVE:
+ pm->stat = PMMOVING;
+ c = pmrec(pms, j, blk, curi, k);
+ if (c == i) {
+ c = -1;
+ break;
+ } else if (c != -1) {
+ goto Swap;
+ }
+ /* fallthru */
+ case PMDONE:
+ Done:
+ c = -1;
+ emitmove(pms->fn, *k, pm->dst, pm->src, blk, curi);
+ break;
+ }
+
+ pm->stat = PMDONE;
+ return c;
+}
+
+static void
+emitpm(struct pmstate *pms, struct block *blk)
+{
+ int curi = blk->ins.n;
+ for (int i = 0; i < pms->npmove; ++i) {
+ if (pms->pmove[i].stat == PMTOMOVE) {
+ pmrec(pms, i, blk, curi, &(enum irclass) { pms->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->npred && blk != ra->fn->entry) {
+ assert(!blk->phi.n);
+ blk->ins.n = 0;
+ return;
+ }
+ if (!blk->s2) n = blk;
+
+ for (predno = 0; predno < suc->npred; ++predno)
+ if (blkpred(suc, predno) == blk)
+ break;
+ assert(predno < suc->npred);
+
+ struct pmstate pms;
+ pms.fn = ra->fn;
+ pms.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];
+ union 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->inter[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->inter[phi - instrtab].alloc;
+ if (to.t == ADEAD) {
+ DBG(" skip dead phi\n");
+ continue;
+ }
+ 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(&pms, phi->cls, to, from);
+ }
+ if (n) emitpm(&pms, 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);
+
+ fn->prop &= ~FNBLKID;
+}
+
+static inline bool
+rangeoverlap(struct range a, struct range b)
+{
+ return a.from < b.to && b.from < a.to;
+}
+
+static void
+pushrange(struct interval *it, struct range r)
+{
+ if (it->nrange < 2) it->_rinl[it->nrange++] = r;
+ else if (it->nrange > 2) xbpush(&it->_rdyn, &it->nrange, r);
+ else {
+ struct range *d = NULL;
+ xbgrow(&d, 4);
+ memcpy(d, it->_rinl, 2*sizeof *d);
+ d[it->nrange++] = r;
+ it->_rdyn = d;
+ }
+}
+#define itrange(it, i) ((it)->nrange <= 2 ? (it)->_rinl : (it)->_rdyn)[i]
+
+static inline int
+intervalbeg(struct interval *it)
+{
+ assert(it->nrange);
+ return itrange(it, 0).from;
+}
+
+static inline int
+intervalend(struct interval *it)
+{
+ assert(it->nrange);
+ return itrange(it, it->nrange-1).to;
+}
+
+static bool
+intersoverlap(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 inline void
+incrcost(struct interval *it, struct block *blk)
+{
+ /* treat each loop as executing instr 8 times */
+ it->cost += 1 << (blk->loop * 3);
+}
+
+static bool
+intervaldef(struct rega *ra, int t, struct block *blk, int pos, int reghint)
+{
+ struct interval *it = &ra->inter[t];
+ if (it->nrange) {
+ ushort *beg = &itrange(it, 0).from;
+ assert(*beg <= pos);
+ incrcost(it, blk);
+ *beg = pos;
+ return 1;
+ }
+ return 0;
+}
+
+static void
+addrange(struct rega *ra, int t, struct range new, int reghint)
+{
+ struct interval *it = &ra->inter[t];
+ struct range *fst;
+ int n;
+
+ if (!it->nrange) {
+ ++ra->intercount;
+ 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->_rdyn;
+ memcpy(it->_rinl, 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 */
+ for (struct fixinterval *prev = NULL, *fxit = ra->fixed; fxit; prev = fxit, fxit = fxit->next) {
+ if (fxit->range.from > pos) break;
+ if (fxit->rs == BIT(reg) && fxit->range.from <= pos && pos < fxit->range.to) {
+ /* contained by existing interval */
+ fxit->range.from = blk->inumstart;
+ /* insert at head */
+ //DBG(">>>extend REG %s range %d-%d\n", mctarg->rnames[reg], fxit->range.from, fxit->range.to);
+ if (prev) {
+ prev->next = fxit->next;
+ fxit->next = ra->fixed;
+ ra->fixed = fxit;
+ }
+ return;
+ }
+ }
+ fxit = alloc(ra->arena, sizeof *fxit, 0);
+ fxit->next = ra->fixed;
+ fxit->range = (struct range) {blk->inumstart, pos};
+ fxit->rs = BIT(reg);
+ ra->fixed = fxit;
+}
+
+static bool
+defreg(struct rega *ra, int reg, int pos) {
+ if (rstest(mctarg->rglob, reg)) return 1;
+ for (struct fixinterval *prev = NULL, *fxit = ra->fixed; fxit; prev = fxit, fxit = fxit->next) {
+ if (fxit->rs == BIT(reg)) {
+ if (fxit->range.from <= pos) {
+ fxit->range.from = pos;
+ struct fixinterval **at = &ra->fixed;
+ if ((*at)->range.from > pos) {
+ /* keep sorted */
+ //DBG("moved %s\n", mctarg->rnames[reg]);
+ if (prev) prev->next = fxit->next;
+ while ((*at)->range.from < pos) at = &(*at)->next;
+ fxit->next = *at;
+ *at = fxit;
+ }
+ //DBG(">>>def REG %s range %d-%d\n", mctarg->rnames[reg], fxit->range.from, fxit->range.to);
+ return 1;
+ }
+ break;
+ }
+ }
+ return 0;
+}
+
+/* lifetime interval construction */
+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);
+ struct loops { /* list of loops */
+ struct loops *next;
+ struct block *hdr, *end;
+ } *loops = NULL;
+ for (int i = 0; i < ra->fn->nblk; ++i)
+ livein[i] = allocz(ra->arena, bssize * sizeof *livein[i], 0);
+ ra->inter = allocz(ra->arena, ninstr * sizeof *ra->inter, 0);
+ ra->ninter = ninstr;
+
+ uint n = numberinstrs(ra->fn);
+ assert((ushort)n == n && "too many instrs for struct range");
+ /* visit blocks in reverse, to build lifetime intervals */
+ blk = last = ra->fn->entry->lprev;
+ do {
+ struct bitset *live = livein[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))
+ */
+ for (struct block *suc = blk->s1; suc; suc = blk->s2) {
+ 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);
+ bsset(live, arg->i);
+ incrcost(&ra->inter[arg->i], blk);
+ }
+ if (suc == blk->s2) break;
+ }
+
+ /* for each opd in live do
+ * intervals[opd].addRange(b.from, b.to)
+ */
+ for (uint i = 0; bsiter(&i, live, bssize); ++i) {
+ addrange(ra, i, mkrange(blk->inumstart, blk->inumstart + blk->ins.n + 2), -1);
+ }
+
+ /* for each operation op of b in reverse order do */
+ struct instr *ins = NULL;
+ 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, 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);
+ if (ins->l.bits == ins->r.bits) {/* special case `move Rx,Rx`: clobber reg, not a real use */
+ usereg(ra, ins->l.i, blk, pos);
+ assert(defreg(ra, ins->l.i, pos));
+ } else if (!defreg(ra, ins->l.i, pos)) {
+ if (ins->keep) { /* clobber here */
+ usereg(ra, ins->l.i, blk, pos);
+ assert(defreg(ra, ins->l.i, pos));
+ } else {
+ /* dead register use. for example if
+ * move RCX, %1
+ * %2 = shl 1, RCX
+ * and %2 is dead, the move to RCX can be killed */
+ *ins = mkinstr(Onop,0,);
+ }
+ } else {
+ rsset(&ra->fn->regusage, ins->l.i);
+ }
+ if (ins->l.bits == ins->r.bits)
+ continue;
+ } 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->fixed;
+ fxit->range = mkrange(pos, pos);
+ fxit->rs = rclob;
+ ra->fixed = fxit;
+ }
+ for (int j = call->narg - 1; j >= 0; --j) {
+ struct abiarg abi = call->abiarg[j];
+ if (!abi.isstk) {
+ usereg(ra, abi.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) {
+ assert(instrtab[r.i].op != Onop);
+ incrcost(&ra->inter[r.i], blk);
+ addrange(ra, r.i, mkrange(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++] = addrtab.p[r.i].base;
+ queue[nqueue++] = addrtab.p[r.i].index;
+ }
+ }
+ }
+
+ /* for each phi function phi of b do
+ * live.remove(phi.output)
+ */
+ for (int i = 0; i < blk->phi.n; ++i) {
+ int phi = blk->phi.p[i];
+ bsclr(live, phi);
+ for (int i = 0; i < blk->npred; ++i)
+ incrcost(&ra->inter[phi], blkpred(blk, i));
+ }
+
+ /* if b is loop header then
+ * loopEnd = last block of the loop starting at b
+ * for each opd in live do
+ * 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) {
+ if (loops) DBG("@lp @%d\n", blk->id);
+ for (struct loops *l = loops; l; l = l->next) {
+ /* a nested loop might end later than loopend, which lengthens this outer loop. */
+ /* XXX is this correct? more loop analysis might be required? */
+ if (l->hdr->id > loopend->id) break;
+ DBG(" check <@%d-@%d>\n", l->hdr->id, l->end->id);
+ if (l->hdr->id > blk->id && l->hdr->id < loopend->id && l->end->id > loopend->id)
+ loopend = l->end;
+ }
+ DBG("loop header @%d (to @%d)\n", blk->id, loopend->id);
+ /* append to loop list */
+ loops = alloccopy(ra->arena, &(struct loops){loops, blk, loopend}, sizeof *loops, 0);
+ for (uint opd = 0; bsiter(&opd, live, bssize); ++opd) {
+ // DBG(" i have live %%%d\n", opd);
+ addrange(ra, opd, mkrange(blk->inumstart, loopend->inumstart + loopend->ins.n+1), -1);
+ }
+ }
+ } while ((blk = blk->lprev) != last);
+
+ if (ccopt.dbg.r) {
+ for (int var = 0; var < ninstr; ++var) {
+ struct interval *it = &ra->inter[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(" spill cost: %d\n", it->cost);
+ }
+ for (struct fixinterval *fx = ra->fixed; fx; fx = fx->next) {
+ DBG("fixed {");
+ for (int r = 0, f=1; rsiter(&r, fx->rs); ++r, f=0)
+ DBG(&" %s"[f], mctarg->rnames[r]);
+ DBG("}: [%d,%d)\n", fx->range.from, fx->range.to);
+ }
+ }
+}
+
+static bool
+itcontainspos(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 = intervalbeg(xs[lo]);
+ for (;;) {
+ struct interval *tmp;
+ do ++i; while (intervalbeg(xs[i]) < pivot);
+ do --p; while (intervalbeg(xs[p]) > 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 union alloc
+allocstk(struct rega *ra)
+{
+ uint s = 0;
+ if (bsiter(&s, ra->freestk, BSSIZE(MAXSPILL))) {
+ 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;
+ 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;
+}
+
+#define interval2temp(it) (int)(it - ra->inter)
+
+static void
+linearscan(struct rega *ra)
+{
+ if (!ra->intercount) return;
+
+ /* sort intervals */
+ struct interval **unhandled = alloc(ra->arena, sizeof *unhandled * ra->intercount, 0);
+ int nunhandled = 0;
+ for (int i = 0; i < ra->ninter; ++i) {
+ if (!ra->inter[i].nrange) continue;
+ unhandled[nunhandled++] = &ra->inter[i];
+ }
+ assert(nunhandled == ra->intercount);
+ sortintervals(unhandled, 0, nunhandled-1);
+
+ regset freeregs = (gpregset | fpregset) &~ (mctarg->rglob | (1ull<<mctarg->gprscratch) | (1ull<<mctarg->fprscratch));
+ memset(ra->freestk, 0xFF, sizeof ra->freestk);
+
+ /* LINEAR SCAN */
+ struct interval *actives[2] = {0}, /* gpr set and fpr set */
+ *inactives[2] = {0},
+ *spilled = NULL, **spilled_tail = &spilled;
+ for (struct interval **pcurrent = unhandled; nunhandled > 0; ++pcurrent, --nunhandled) {
+ struct interval *current = *pcurrent;
+ int pos = intervalbeg(current);
+
+ struct interval **active = &actives[current->fpr], **inactive = &inactives[current->fpr],
+ **lnk, *it, *next;
+ /* Expire old intervals */
+ /* check for intervals in active that are handled or inactive */
+ for (lnk = active, it = *lnk; (next = it?it->next:0), it; it = next) {
+ assert(it->alloc.t == AREG);
+ /* ends before position? */
+ if (intervalend(it) <= pos) {
+ /* move from active to handled */
+ *lnk = next;
+ //DBG(" unblock %s %X\n", mctarg->rnames[it->alloc.a], ra->free);
+ rsset(&freeregs, it->alloc.a);
+ } else if (!itcontainspos(it, pos)) { /* it does not cover position? */
+ /* move from active to inactive */
+ *lnk = next;
+ it->next = *inactive;
+ *inactive = it;
+ rsset(&freeregs, it->alloc.a);
+ DBG(" >> %%%zd unblock %s\n", interval2temp(it), mctarg->rnames[it->alloc.a]);
+ } else lnk = &it->next;
+ }
+ /* check for intervals in inactive that are handled or active */
+ for (lnk = inactive, it = *lnk; (next = it?it->next:0), it; it = next) {
+ assert(it->alloc.t == AREG);
+ /* ends before position? */
+ if (intervalend(it) <= pos) {
+ /* move from inactive to handled */
+ *lnk = next;
+ } else if (itcontainspos(it, pos)) { /* it covers position? */
+ /* move from inactive to active */
+ *lnk = next;
+ it->next = *active;
+ *active = it;
+ assert(it->alloc.t == AREG);
+ assert(rstest(freeregs, it->alloc.a));
+ rsclr(&freeregs, it->alloc.a);
+ DBG(" << %%%zd reblock %s\n", interval2temp(it), mctarg->rnames[it->alloc.a]);
+ } else lnk = &it->next;
+ }
+
+ /** find a register for current **/
+
+ int this = interval2temp(current);
+ regset avail = freeregs & (current->fpr ? fpregset : gpregset),
+ fixexcl = 0, excl = 0;
+ struct instr *ins = &instrtab[this];
+ int reg = 0;
+
+ /* exclude regs from overlapping fixed intervals */
+ int end = intervalend(current);
+ for (struct fixinterval *last = NULL, *fxit = ra->fixed; fxit;
+ last = fxit, fxit = fxit->next) {
+ if (last) assert(last->range.from <= fxit->range.from && "unsorted fixintervals");
+ if (fxit->range.to <= pos) {
+ ra->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))) {
+ fixexcl |= fxit->rs;
+ }
+ }
+ }
+ /* exclude regs from overlapping inactive intervals */
+ for (struct interval *it = *inactive; it; it = it->next) {
+ if (it->alloc.t == AREG && intersoverlap(it, current)) {
+ rsset(&excl, it->alloc.a);
+ }
+ }
+ /* for 2-address instrs, exclude reg from 2nd arg (unless arg#1 == arg#2) */
+ if (ins->inplace && opnarg[ins->op] == 2) {
+ int xreg;
+ if (ins->r.t == RREG) rsset(&excl, ins->r.i);
+ else if (ins->r.t == RTMP && (xreg = instrtab[ins->r.i].reg)) {
+ if (ins->r.bits != ins->l.bits)
+ rsset(&fixexcl, xreg-1);
+ }
+ }
+ excl |= fixexcl;
+ avail &= ~excl;
+
+ if (!avail) { /* no regs left, must spill */
+ struct interval **ptospill = NULL, *tospill = current;
+ /* heuristic: look for longest-lived active interval with lower spill cost */
+ int curend = intervalend(current);
+ for (lnk = active, it = *lnk; (next = it ? it->next : 0), it; it = next) {
+ int end = intervalend(it);
+ if (it->cost < tospill->cost && end > curend && !rstest(fixexcl, it->alloc.a)) {
+ ptospill = lnk;
+ tospill = it;
+ reg = tospill->alloc.a;
+ }
+ lnk = &it->next;
+ }
+
+ /* insert in spilled, keep sorted */
+ if (ptospill) {
+ *ptospill = tospill->next; /* remove from active */
+ int from = intervalbeg(tospill);
+ lnk = &spilled;
+ /* XXX potentially slow linear search */
+ while (*lnk && intervalbeg(*lnk) < from)
+ lnk = &(*lnk)->next;
+ tospill->next = *lnk;
+ *lnk = tospill;
+ } else { /* tospill == current, so we can just append and keep it sorted */
+ *spilled_tail = tospill;
+ tospill->next = NULL;
+ }
+ if (!tospill->next) /* update spilled list tail */
+ spilled_tail = &tospill->next;
+
+ assert(spilled != NULL);
+ if (tospill == current) {
+ DBG("spilled %%%d\n", this);
+ continue;
+ } else {
+ instrtab[interval2temp(tospill)].reg = 0;
+ DBG("%%%d takes %s from %%%d (spilled)\n", this, mctarg->rnames[reg],
+ interval2temp(tospill));
+ goto GotReg;
+ }
+ }
+
+ /* have free regs, try to use hint */
+ if (current->rhint >= 0)
+ DBG("have hint %s for %%%zd\n",
+ mctarg->rnames[current->rhint], interval2temp(current));
+ if (current->rhint >= 0 && rstest(avail, 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(avail, reg = ins->l.i))
+ goto GotReg;
+ if (ins->l.t == RTMP)
+ if ((reg = instrtab[ins->l.i].reg-1) >= 0)
+ if (rstest(avail, 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(avail, reg = arg->i)) goto GotReg;
+ if (arg->t == RTMP)
+ if ((reg = instrtab[arg->i].reg-1) >= 0)
+ if (rstest(avail, reg))
+ goto GotReg;
+ }
+ }
+
+ /* no hints to use */
+ if (avail &~ mctarg->rcallee) /* prefer caller-saved regs */
+ avail &=~ mctarg->rcallee;
+ /* and pick first available reg */
+ reg = lowestsetbit(avail);
+ }
+ GotReg:
+ current->alloc = areg(reg);
+ ins->reg = reg + 1;
+ DBG("%%%d got %s\n", this, mctarg->rnames[reg]);
+ rsclr(&freeregs, reg);
+ rsset(&ra->fn->regusage, reg);
+
+ /* add current to active */
+ current->next = *active;
+ *active = current;
+ }
+
+ if (ccopt.dbg.r) {
+ DBG("regusage: ");
+ for (int r = 0; r < MAXREGS; ++r) {
+ if (rstest(ra->fn->regusage, r)) DBG(" %s", mctarg->rnames[r]);
+ }
+ DBG("\n");
+ }
+ /* allocate stack slots for spilled intervals
+ * this is like another (simplified) linear scan pass */
+ struct interval *active = NULL;
+ int prevpos = -1;
+ if (spilled) DBG("spilled:\n");
+ for (struct interval *current = spilled, *next; current; current = next) {
+ int pos = intervalbeg(current);
+ DBG(" %%%zd: [%d,%d)\n", interval2temp(current), pos, intervalend(current));
+ assert(pos >= prevpos && "unsorted spilled?");
+ prevpos = pos;
+ /* Expire old intervals */
+ struct interval **lnk, *it, *lnext;
+ for (lnk = &active, it = *lnk; (lnext = it ? it->next : 0), it; it = lnext) {
+ /* ends before position? */
+ if (intervalend(it) <= pos) {
+ /* move from active to handled */
+ *lnk = lnext;
+ freestk(ra, it->alloc.a);
+ } else lnk = &it->next;
+ }
+ /* allocate a stack slot for current and move to active */
+ current->alloc = allocstk(ra);
+ DBG(" got stk%d\n", current->alloc.a);
+ next = current->next;
+ current->next = active;
+ active = current;
+ }
+}
+
+static bool
+isstoreimm(union ref r)
+{
+ if (r.t == RTMP) return 1; /* register OK */
+ if (isintcon(r)) switch (target.arch) {
+ case ISxxx: assert(0);
+ /* TODO don't hard code this architecture dependent dispatch */
+ case ISx86_64: return concls(r) == KI32; /* x86: MOV [addr], imm32 */
+ case ISaarch64: return r.i == 0; /* arm doesn't have STR <imm>, but has zero register */
+ }
+ return 0;
+}
+
+/* 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;
+ union alloc spillsave[4] = {0};
+ memset(ra->freestk, 0, BSSIZE(MAXSPILL) * sizeof *ra->freestk);
+
+ for (int curi = 0; curi < blk->ins.n; ++curi) {
+ int temp = blk->ins.p[curi];
+ struct instr *ins = &instrtab[temp];
+ struct interval *it;
+ union alloc *alloc;
+ struct addr newaddr;
+ union ref *argref[4];
+ int curi0;
+ int naddr = 0;
+ int nargref = 0;
+ int nspill = 0;
+
+ /** devirtualize operands **/
+ for (int i = 0; i < 2; ++i) {
+ union ref *r = &i[&ins->l];
+ if (r->t == RADDR) {
+ struct addr *a = &addrtab.p[r->i];
+ ++naddr;
+ newaddr = *a;
+ argref[nargref++] = &newaddr.base;
+ argref[nargref++] = &newaddr.index;
+ } else {
+ argref[nargref++] = r;
+ }
+ }
+ for (int i = 0; i < nargref; ++i) {
+ union ref *r = argref[i];
+ int tr;
+ if (r->t == RTMP && (it = &ra->inter[r->i])->nrange > 0) {
+ alloc = &it->alloc;
+ if (alloc->t == ASTACK && ins->op == Omove && kisint(ins->cls) == kisint(instrtab[r->i].cls)) {
+ /* move [reg], [stk] -> [reg] = load [stk] */
+ assert(r == &ins->r && ins->l.t == RREG);
+ ins->reg = ins->l.i+1;
+ ins->op = cls2load[instrtab[r->i].cls];
+ ins->l = stkslotref(fn, alloc->a*8);
+ ins->r = NOREF;
+ } else if (alloc->t == ASTACK && ins->op == Ocopy && r == &ins->l && ins->reg && kisint(ins->cls) == kisint(instrtab[r->i].cls)) {
+ /* [reg] = copy [stk] -> [reg] = load [stk] */
+ ins->op = cls2load[instrtab[r->i].cls];
+ ins->l = stkslotref(fn, 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 = 0;
+ /* pick scratch register, or any register that doesn't conflict with this instr's srcs/dst */
+ if (nspill > 0) {
+ regset avail = (kisflt(ld.cls) ? fpregset : gpregset) &~ mctarg->rglob;
+ if (ins->reg) rsclr(&avail, ins->reg-1);
+ for (int j = 0; j < nargref; ++j) {
+ struct interval *it;
+ if (argref[j]->t == RREG) rsclr(&avail, argref[j]->i);
+ else if (argref[j]->t == RTMP) {
+ it = &ra->inter[argref[j]->i];
+ if (it->alloc.t == AREG) rsclr(&avail, it->alloc.a);
+ }
+ }
+ assert(avail != 0);
+ if (avail &~ (fn->regusage | mctarg->rcallee)) avail &= ~(fn->regusage | mctarg->rcallee);
+ reg = lowestsetbit(avail);
+ /* if not the designated scratch register, we need to save+restore */
+ if (rstest(fn->regusage, reg) || rstest(mctarg->rcallee, reg)) {
+ dosave = 1;
+ if (!spillsave[nspill-1].t) spillsave[nspill-1] = allocstk(ra);
+ emitmove(fn, isgpr(reg) ? KPTR : KF64, spillsave[nspill-1], areg(reg), blk, curi++);
+ }
+ }
+ ld.reg = reg+1;
+ ld.op = cls2load[ld.cls];
+ ld.l = stkslotref(fn, alloc->a*8);
+ insertinstr(blk, curi++, ld);
+ *r = mkref(RREG, reg);
+ if (nspill > 0 && dosave) {
+ emitmove(fn, isgpr(reg) ? KPTR : KF64, areg(reg), spillsave[nspill-1], blk, curi+1);
+ }
+ ++nspill;
+ } else if ((tr = instrtab[r->i].reg)) {
+ assert(alloc && alloc->t == AREG && alloc->a == tr-1);
+ *r = mkref(RREG, tr-1);
+ }
+ }
+ }
+ if (nspill > 1) assert(ins->op != Ocall);
+ if (naddr) {
+ union ref *r = ins->l.t == RADDR ? &ins->l : &ins->r;
+ *r = mkaddr(newaddr);
+ }
+
+ /* devirtualize destination */
+ curi0 = curi;
+ alloc = temp < ra->ninter && (it = &ra->inter[temp]) && it->nrange ? &it->alloc : NULL;
+ if (alloc && alloc->t == ASTACK) {
+ enum irclass cls = insrescls(*ins);
+ int store = cls2store[cls];
+ /* t was spilled, gen store */
+ if (ins->op == Ocopy && (ins->l.t == RREG || isstoreimm(ins->l))) {
+ ins->op = store;
+ ins->r = ins->l;
+ ins->l = stkslotref(fn, alloc->a*8);
+ } else {
+ bool dosave = 0;
+ int reg = kisint(insrescls(*ins)) ? mctarg->gprscratch : mctarg->fprscratch;
+ if (nspill > 0) {
+ regset avail = (kisflt(cls) ? fpregset : gpregset) &~ mctarg->rglob;
+ for (int j = 0; j < nargref; ++j) {
+ if (argref[j]->t == RREG) rsclr(&avail, argref[j]->i);
+ }
+ assert(avail != 0);
+ if (avail &~ (fn->regusage | mctarg->rcallee)) avail &= ~(fn->regusage | mctarg->rcallee);
+ /* if not the designated scratch register, we need to save+restore */
+ reg = lowestsetbit(avail);
+ if (rstest(fn->regusage, reg) || rstest(mctarg->rcallee, reg)) {
+ dosave = 1;
+ if (!spillsave[nspill-1].t) spillsave[nspill-1] = allocstk(ra);
+ emitmove(fn, isgpr(reg) ? KPTR : KF64, spillsave[nspill-1], areg(reg), blk, curi++);
+ curi0 = curi;
+ }
+ }
+ ins->reg = reg+1;
+ insertinstr(blk, ++curi,
+ mkinstr(store, 0, stkslotref(fn, alloc->a*8), mkref(RREG, reg)));
+ if (nspill > 0 && dosave) {
+ emitmove(fn, isgpr(reg) ? KPTR : KF64, areg(reg),
+ spillsave[nspill-1], blk, ++curi);
+ }
+ }
+ }
+ if (!ins->reg && insrescls(*ins) && ins->op != Omove && !ins->keep && !oisstore(ins->op)) {
+ /* 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->op != Onop) {
+ allnops = 0;
+ }
+ 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, curi0, mkmove(ins->cls, ins->reg-1, ins->l.i));
+ ++curi;
+ ins->l.i = ins->reg-1;
+ }
+ if (!ins->reg && in_range(ins->op, Oloads8, Oloadf64)) {
+ assert(ins->keep);
+ ins->reg = kisint(ins->cls) ? mctarg->gprscratch+1 : mctarg->fprscratch+1;
+ }
+ }
+
+ if (allnops) vfree(&blk->ins);
+ return allnops;
+}
+
+static void
+fini(struct rega *ra)
+{
+ int id = 0;
+ struct function *fn = ra->fn;
+ struct block *blk = fn->entry;
+
+ do {
+ blk->id = id++;
+ bool allnops = devirt(ra, blk);
+ if (allnops && !blk->s2 && blk->npred > 0) { /* remove no-op blocks */
+ bool delet = 1;
+ for (int i = 0; i < blk->npred; ++i) {
+ struct block *p = blkpred(blk, i);
+ if (p == blk || (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/trap
+ */
+ assert(p->s1 == blk);
+ p->jmp.t = blk->jmp.t;
+ p->s1 = NULL;
+ } else if (blk->s1 && blk->s1 != blk) {
+ /* 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;
+ }
+ } else if (allnops) {
+ vfree(&blk->ins);
+ }
+ } while ((blk = blk->lnext) != fn->entry);
+}
+
+void
+regalloc(struct function *fn)
+{
+ struct rega ra = {fn, .arena = fn->passarena};
+ 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);
+ }
+ }
+ fn->regusage = 0;
+ fn->stksiz = alignup(fn->stksiz, 8);
+ fn->isleaf = 1;
+
+ /* put into reverse post order */
+ sortrpo(fn);
+
+ /* fix liveness ranges */
+ fixlive(fn);
+
+ /* transform into CSSA */
+ fixcssa(fn);
+
+ fillblkids(fn);
+ fillloop(fn);
+
+ if (ccopt.dbg.r) {
+ bfmt(ccopt.dbgout, "<< 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);
+ fn->stksiz += ra.maxstk*8;
+ if (fn->stksiz > 1<<24) error(NULL, "'%s' stack frame too big", fn->name);
+
+ for (struct interval *it = ra.inter; ra.intercount > 0; ++it) {
+ if (it->nrange > 2) xbfree(it->_rdyn);
+ if (it->nrange > 0) --ra.intercount;
+ }
+
+ if (ccopt.dbg.r) {
+ bfmt(ccopt.dbgout, "<< After regalloc >>\n");
+ irdump(fn);
+ }
+}
+
+/* vim:set ts=3 sw=3 expandtab: */
generated by cgit v1.2.3 (git 2.39.1) at 2026-05-01 22:31:17 +0000