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#include "ir.h"
static const uchar loadszcls[] = {
[Oloads1 - Oloads1] = 1|KI4<<4, [Oloadu1 - Oloads1] = 1|KI4<<4,
[Oloads2 - Oloads1] = 2|KI4<<4, [Oloadu2 - Oloads1] = 2|KI4<<4,
[Oloads4 - Oloads1] = 4|KI4<<4, [Oloadu4 - Oloads1] = 4|KI4<<4,
[Oloadi8 - Oloads1] = 8|KI8<<4,
[Oloadf4 - Oloads1] = 4|KF4<<4,
[Oloadf8 - Oloads1] = 8|KF8<<4,
};
static const uchar load2ext[] = {
[Oloads1 - Oloads1] = Oexts1, [Oloadu1 - Oloads1] = Oextu1,
[Oloads2 - Oloads1] = Oexts2, [Oloadu2 - Oloads1] = Oextu2,
[Oloads4 - Oloads1] = Oexts4, [Oloadu4 - Oloads1] = Oextu4,
[Oloadi8 - Oloads1] = Ocopy,
};
#define loadsz(o) (loadszcls[(o) - Oloads1] & 0xF)
#define loadcls(o) (loadszcls[(o) - Oloads1] >> 4)
#define load2ext(o) (load2ext[(o) - Oloads1])
#define storesz(o) (1 << ((o) - Ostore1))
void
mem2reg(struct function *fn)
{
extern int ninstr;
struct uses *uses = ssauses(fn);
struct block *blk = fn->entry;
do {
for (int i = 0; i < blk->ins.n; ++i) {
struct use *use, *uend;
union ref var;
enum irclass k = 0;
int sz = 0, ndef = 0;
enum op ext;
int t = blk->ins.p[i];
struct instr *ins = &instrtab[t];
if (!oisalloca(ins->op)) continue;
for (use = uses[t].use, uend = &uses[t].use[uses[t].nuse]; use < uend; ++use) {
struct instr *m;
if (use->isjmp) goto Next;
m = &instrtab[use->ins];
if (oisload(m->op) && (!sz || sz == loadsz(m->op))) {
sz = loadsz(m->op);
k = loadcls(m->op);
if (sz < 4) ext = load2ext(m->op);
continue;
}
if (oisstore(m->op) && m->l.bits == mkref(RTMP, t).bits
&& (!sz || sz == storesz(m->op))) {
sz = storesz(m->op);
++ndef;
continue;
}
goto Next;
}
if (!ndef) /* slot is read from but never written to */
goto Next;
if (ndef>1) /* TODO phi construction */
goto Next;
/* remove alloca */
*ins = mkinstr(Onop, 0,);
var.t = 0;
for (use = uses[t].use; use < uend; ++use) {
struct instr *m = &instrtab[use->ins];
if (oisstore(m->op)) {
if (sz < 4) {
*m = mkinstr(ext, KI4, m->r);
var = mkref(RTMP, use->ins);
} else {
var = m->r;
*m = mkinstr(Onop,0,);
}
} else if (oisload(m->op)) {
if (!var.t) /* use before def */
goto Next;
*m = mkinstr(Ocopy, k, var);
}
}
Next:;
}
} while ((blk = blk->lnext) != fn->entry);
freeuses(uses, ninstr);
if (ccopt.dbg.m) {
efmt("<< After mem2reg >>\n");
irdump(fn);
}
}
/* vim:set ts=3 sw=3 expandtab: */
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