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#include "all.h"
static void
blit(Ref sd[2], int sz, Fn *fn)
{
struct { int st, ld, cls, size; } *p, tbl[] = {
{ Ostorel, Oload, Kl, 8 },
{ Ostorew, Oload, Kw, 4 },
{ Ostoreh, Oloaduh, Kw, 2 },
{ Ostoreb, Oloadub, Kw, 1 }
};
Ref r, r1, ro;
int off, fwd, n;
fwd = sz >= 0;
sz = abs(sz);
off = fwd ? sz : 0;
for (p=tbl; sz; p++)
for (n=p->size; sz>=n; sz-=n) {
off -= fwd ? n : 0;
r = newtmp("blt", Kl, fn);
r1 = newtmp("blt", Kl, fn);
ro = getcon(off, fn);
emit(p->st, 0, R, r, r1);
emit(Oadd, Kl, r1, sd[1], ro);
r1 = newtmp("blt", Kl, fn);
emit(p->ld, p->cls, r, r1, R);
emit(Oadd, Kl, r1, sd[0], ro);
off += fwd ? 0 : n;
}
}
static int
ulog2_tab64[64] = {
63, 0, 58, 1, 59, 47, 53, 2,
60, 39, 48, 27, 54, 33, 42, 3,
61, 51, 37, 40, 49, 18, 28, 20,
55, 30, 34, 11, 43, 14, 22, 4,
62, 57, 46, 52, 38, 26, 32, 41,
50, 36, 17, 19, 29, 10, 13, 21,
56, 45, 25, 31, 35, 16, 9, 12,
44, 24, 15, 8, 23, 7, 6, 5
};
static int
ulog2(uint64_t pow2)
{
return ulog2_tab64[(pow2 * 0x07EDD5E59A4E28C2) >> 58];
}
static int
ispow2(uint64_t v)
{
return (v & (v - 1)) == 0;
}
static void
ins(Ins **pi, int *new, Blk *b, Fn *fn)
{
ulong ni;
Con *c;
Ins *i;
Ref r;
int n;
i = *pi;
/* simplify more instructions here;
* copy 0 into xor bit rotations,
* etc. */
switch (i->op) {
case Oblit1:
assert(i > b->ins);
assert((i-1)->op == Oblit0);
if (!*new) {
curi = &insb[NIns];
ni = &b->ins[b->nins] - (i+1);
curi -= ni;
icpy(curi, i+1, ni);
*new = 1;
}
blit((i-1)->arg, rsval(i->arg[0]), fn);
*pi = i-1;
break;
case Omul:
case Oudiv:
case Ourem:
r = i->arg[1];
if (KBASE(i->cls) == 0)
if (rtype(r) == RCon) {
c = &fn->con[r.val];
if (c->type == CBits)
if (ispow2(c->bits.i)) {
n = ulog2(c->bits.i);
if (i->op == Ourem) {
i->op = Oand;
i->arg[1] = getcon((1ull<<n) - 1, fn);
} else if (i->op == Oudiv) {
i->op = Oshr;
i->arg[1] = getcon(n, fn);
} else if (i->op == Omul) {
i->op = Oshl;
i->arg[1] = getcon(n, fn);
}
}
}
/* fall through */
default:
if (*new)
emiti(*i);
break;
}
}
void
simpl(Fn *fn)
{
Blk *b;
Ins *i;
int new;
for (b=fn->start; b; b=b->link) {
new = 0;
for (i=&b->ins[b->nins]; i!=b->ins;) {
--i;
ins(&i, &new, b, fn);
}
if (new) {
b->nins = &insb[NIns] - curi;
idup(&b->ins, curi, b->nins);
}
}
}
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