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#include "lisc.h"
static void
bset(Ref r, Blk *b, Bits *rb, int *nlv)
{
Bits *bs;
switch (rtype(r)) {
case RSym:
bs = &b->in;
BSET(b->gen, r.val);
break;
case RReg:
bs = rb;
break;
default:
diag("live: unhandled reference");
return;
}
if (!BGET(*bs, r.val)) {
++*nlv;
BSET(*bs, r.val);
}
}
/* liveness analysis
* requires rpo computation
*/
void
filllive(Fn *f)
{
Blk *b;
Ins *i;
Phi *p;
int z, n, chg, nlv;
uint a;
Bits tb, rb;
assert(f->nsym <= NBit*BITS);
for (b=f->start; b; b=b->link) {
b->in = (Bits){{0}};
b->out = (Bits){{0}};
b->gen = (Bits){{0}};
}
chg = 1;
Again:
for (n=f->nblk-1; n>=0; n--) {
b = f->rpo[n];
tb = b->out;
if (b->s1)
for (z=0; z<BITS; z++)
b->out.t[z] |= b->s1->in.t[z];
if (b->s2)
for (z=0; z<BITS; z++)
b->out.t[z] |= b->s2->in.t[z];
chg |= memcmp(&b->out, &tb, sizeof(Bits));
b->in = b->out;
rb = (Bits){{0}};
nlv = bcnt(&b->in);
bset(b->jmp.arg, b, &rb, &nlv);
b->nlive = nlv;
for (i=&b->ins[b->nins]; i!=b->ins;) {
i--;
switch (rtype(i->to)) {
case RSym:
nlv -= BGET(b->in, i->to.val);
BCLR(b->in, i->to.val);
break;
case RReg:
nlv -= BGET(rb, i->to.val);
BCLR(rb, i->to.val);
default:
diag("live: unhandled destination");
}
bset(i->arg[0], b, &rb, &nlv);
bset(i->arg[1], b, &rb, &nlv);
if (nlv > b->nlive)
b->nlive = nlv;
}
for (p=b->phi; p; p=p->link) {
BCLR(b->in, p->to.val);
for (a=0; a<p->narg; a++)
if (rtype(p->arg[a]) == RSym)
BSET(p->blk[a]->out, p->arg[a].val);
}
}
if (chg) {
chg = 0;
goto Again;
}
}
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