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#include "lisc.h"
typedef struct RList RList;
struct RList {
int t;
RList *l;
};
static Ref
copyof(Ref r, Ref *cp)
{
if (rtype(r) == RTmp)
return cp[r.val];
else
return r;
}
static void
update(Ref r, Ref rcp, Ref *cp, RList **w)
{
RList *l;
if (!req(cp[r.val], rcp)) {
cp[r.val] = rcp;
l = emalloc(sizeof *l);
l->t = r.val;
l->l = *w;
*w = l;
}
}
static void
visitphi(Phi *p, Ref *cp, RList **w)
{
uint a;
Ref r, r1;
r = R;
for (a=0; a<p->narg; a++) {
r1 = copyof(p->arg[a], cp);
if (req(r1, R))
continue;
if (req(r, R) || req(r, r1))
r = r1;
else {
r = p->to;
break;
}
}
assert(!req(r, R));
update(p->to, r, cp, w);
}
static void
visitins(Ins *i, Ref *cp, RList **w)
{
Ref r;
if (i->op != OCopy) {
if (!req(i->to, R)) {
assert(rtype(i->to) == RTmp);
update(i->to, i->to, cp, w);
}
} else {
assert(rtype(i->to) == RTmp);
r = copyof(i->arg[0], cp);
update(i->to, r, cp, w);
}
}
void
copy(Fn *fn)
{
Blk *b;
Ref *cp, r;
RList *w, *w1;
Use *u, *u1;
Ins *i;
Phi *p, **pp;
uint a;
int t;
w = 0;
cp = emalloc(fn->ntmp * sizeof cp[0]);
for (b=fn->start; b; b=b->link) {
for (p=b->phi; p; p=p->link)
visitphi(p, cp, &w);
for (i=b->ins; i-b->ins < b->nins; i++)
visitins(i, cp, &w);
}
while ((w1=w)) {
t = w->t;
w = w->l;
free(w1);
u = fn->tmp[t].use;
u1 = u + fn->tmp[t].nuse;
for (; u<u1; u++)
switch (u->type) {
default:
diag("copy: invalid use");
case UPhi:
visitphi(u->u.phi, cp, &w);
break;
case UIns:
visitins(u->u.ins, cp, &w);
break;
case UJmp:
break;
}
}
for (b=fn->start; b; b=b->link) {
for (pp=&b->phi; (p=*pp);) {
r = cp[p->to.val];
if (!req(r, p->to)) {
*pp = p->link;
continue;
}
for (a=0; a<p->narg; a++)
if (rtype(p->arg[a]) == RTmp) {
r = cp[p->arg[a].val];
assert(!req(r, R));
p->arg[a] = r;
}
pp=&p->link;
}
for (i=b->ins; i-b->ins < b->nins; i++) {
r = cp[i->to.val];
if (!req(r, i->to)) {
*i = (Ins){.op = ONop};
continue;
}
for (a=0; a<2; a++)
if (rtype(i->arg[a]) == RTmp) {
r = cp[i->arg[a].val];
assert(!req(r, R));
i->arg[a] = r;
}
}
if (rtype(b->jmp.arg) == RTmp) {
r = cp[b->jmp.arg.val];
assert(!req(r, R));
b->jmp.arg = r;
}
}
if (debug['C']) {
fprintf(stderr, "\n> Copy information:");
for (t=Tmp0; t<fn->ntmp; t++) {
if (req(cp[t], R)) {
fprintf(stderr, "\n%10s not seen!",
fn->tmp[t].name);
}
else if (!req(cp[t], TMP(t))) {
fprintf(stderr, "\n%10s copy of ",
fn->tmp[t].name);
printref(cp[t], fn, stderr);
}
}
fprintf(stderr, "\n\n> After copy elimination:\n");
printfn(fn, stderr);
}
free(cp);
}
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