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#include "all.h"
/* Memory optimization:
*
* - replace alloced slots used only in
* load/store operations
* Assumption: all the accesses have the
* same size (this could be wrong...)
*/
/* require use, maintains use counts */
void
memopt(Fn *fn)
{
Blk *b;
Ins *i, *l;
Tmp *t;
Use *u, *ue;
int a;
b = fn->start;
for (i=b->ins; i-b->ins < b->nins; i++) {
if (OAlloc > i->op || i->op > OAlloc1)
continue;
/* specific to NAlign == 3 */
assert(rtype(i->to) == RTmp);
t = &fn->tmp[i->to.val];
for (u=t->use; u != &t->use[t->nuse]; u++) {
if (u->type != UIns)
goto NextIns;
l = u->u.ins;
if (!isload(l->op)
&& (!isstore(l->op) || req(i->to, l->arg[0])))
goto NextIns;
}
/* get rid of the alloc and replace uses */
*i = (Ins){.op = ONop};
t->ndef--;
ue = &t->use[t->nuse];
for (u=t->use; u!=ue; u++) {
l = u->u.ins;
if (isstore(l->op)) {
if (l->op == OStores)
l->cls = Kd;
else if (l->op == OStored)
l->cls = Kd;
else if (l->op == OStorel)
l->cls = Kl;
else
l->cls = Kw;
l->op = OCopy;
l->to = l->arg[1];
l->arg[1] = R;
t->nuse--;
t->ndef++;
} else
/* try to turn loads into copies so we
* can eliminate them later */
switch(l->op) {
case OLoad:
l->op = OCopy;
break;
case OLoadsw:
case OLoaduw:
l->cls = Kw;
l->op = OCopy;
break;
default:
/* keep l->cls */
a = l->op - OLoadsb;
l->op = OExtsb + a;
break;
}
}
NextIns:;
}
if (debug['M']) {
fprintf(stderr, "\n> After memory optimization:\n");
printfn(fn, stderr);
}
}
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