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#include "ir.h"
void
copyopt(Function *fn)
{
Block *blk = fn->entry;
FREQUIRE(FNUSE);
do {
for (int i = 0; i < blk->phi.n; ++i) {
/* simplify same-arg phi */
int phi = blk->phi.p[i];
Ref *arg = phitab.p[instrtab[phi].l.i];
for (int j = 1; j < blk->npred; ++j) {
if (arg[j].bits != arg->bits) goto Next;
}
/* being conservative here because phis could have circular dependencies? */
if (arg->t != RTMP || instrtab[arg->i].op != Ophi) {
replcuses(mkref(RTMP, phi), *arg);
delphi(blk, i--);
}
Next:;
}
for (int i = 0; i < blk->ins.n; ++i) {
Ref var = mkref(RTMP, blk->ins.p[i]);
Instr *ins = &instrtab[var.i];
enum irclass k;
if (ins->op == Ocopy) {
Ref arg = ins->l;
if (arg.t == RTMP) k = insrescls(instrtab[arg.i]);
else if (arg.t == RICON) k = cls2siz[ins->cls] == 4 ? KI32 : KI64;
else if (arg.t == RXCON) k = isnumcon(arg) ? concls(arg) : KPTR;
else continue;
if (ins->cls != k) continue;
replcuses(var, arg);
*ins = mkinstr(Onop,0,);
deluses(var.i);
}
}
delnops(blk);
} while ((blk = blk->lnext) != fn->entry);
}
/* vim:set ts=3 sw=3 expandtab: */
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