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#include "all.h"
static int
loadsz(Ins *l)
{
switch (l->op) {
case Oloadsb: case Oloadub: return 1;
case Oloadsh: case Oloaduh: return 2;
case Oloadsw: case Oloaduw: return 4;
case Oload: return KWIDE(l->cls) ? 8 : 4;
}
die("unreachable");
}
static int
storesz(Ins *s)
{
switch (s->op) {
case Ostoreb: return 1;
case Ostoreh: return 2;
case Ostorew: case Ostores: return 4;
case Ostorel: case Ostored: return 8;
}
die("unreachable");
}
/* require use, maintains use counts */
void
memopt(Fn *fn)
{
Blk *b;
Ins *i, *l;
Tmp *t;
Use *u, *ue;
int s, k;
/* promote uniform stack slots to temporaries */
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];
if (t->ndef != 1)
goto Skip;
k = -1;
s = -1;
for (u=t->use; u != &t->use[t->nuse]; u++) {
if (u->type != UIns)
goto Skip;
l = u->u.ins;
if (isload(l->op))
if (s == -1 || s == loadsz(l)) {
s = loadsz(l);
continue;
}
if (isstore(l->op))
if (req(i->to, l->arg[1]) && !req(i->to, l->arg[0]))
if (s == -1 || s == storesz(l))
if (k == -1 || k == opdesc[l->op].argcls[0][0]) {
s = storesz(l);
k = opdesc[l->op].argcls[0][0];
continue;
}
goto Skip;
}
/* 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)) {
l->cls = k;
l->op = Ocopy;
l->to = l->arg[1];
l->arg[1] = R;
t->nuse--;
t->ndef++;
} else {
if (k == -1)
err("slot %%%s is read but never stored to",
fn->tmp[l->arg[0].val].name);
/* try to turn loads into copies so we
* can eliminate them later */
switch(l->op) {
case Oload:
case Oloadsw:
case Oloaduw:
if (KBASE(k) != KBASE(l->cls))
l->op = Ocast;
else
l->op = Ocopy;
break;
default:
l->op = Oextsb + (l->op - Oloadsb);
break;
}
}
}
Skip:;
}
if (debug['M']) {
fprintf(stderr, "\n> After memory optimization:\n");
printfn(fn, stderr);
}
}
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