void if_conversion::convert_kill_instructions(region_node *r,
value *em, bool branch,
container_node *c) {
value *cnd = NULL;
for (node_iterator I = c->begin(), E = c->end(), N; I != E; I = N) {
N = I + 1;
if (!I->is_alu_inst())
continue;
alu_node *a = static_cast<alu_node*>(*I);
unsigned flags = a->bc.op_ptr->flags;
if (!(flags & AF_KILL))
continue;
// ignore predicated or non-const kill instructions
if (a->pred || !a->src[0]->is_const() || !a->src[1]->is_const())
continue;
literal l0 = a->src[0]->literal_value;
literal l1 = a->src[1]->literal_value;
expr_handler::apply_alu_src_mod(a->bc, 0, l0);
expr_handler::apply_alu_src_mod(a->bc, 1, l1);
if (expr_handler::evaluate_condition(flags, l0, l1)) {
// kill with constant 'true' condition, we'll convert it to the
// conditional kill outside of the if-then-else block
a->remove();
if (!cnd) {
cnd = get_select_value_for_em(sh, em);
} else {
// more than one kill with the same condition, just remove it
continue;
}
r->insert_before(a);
a->bc.set_op(branch ? ALU_OP2_KILLE_INT : ALU_OP2_KILLNE_INT);
a->src[0] = cnd;
a->src[1] = sh.get_const_value(0);
// clear modifiers
memset(&a->bc.src[0], 0, sizeof(bc_alu_src));
memset(&a->bc.src[1], 0, sizeof(bc_alu_src));
} else {
// kill with constant 'false' condition, this shouldn't happen
// but remove it anyway
a->remove();
}
}
}
unsigned if_conversion::try_convert_kills(region_node* r) {
// handling the simplest (and probably most frequent) case only -
// if - 4 kills - endif
// TODO handle more complex cases
depart_node *d1 = static_cast<depart_node*>(r->front());
if (!d1->is_depart())
return 0;
if_node *f = static_cast<if_node*>(d1->front());
if (!f->is_if())
return 0;
depart_node *d2 = static_cast<depart_node*>(f->front());
if (!d2->is_depart())
return 0;
unsigned cnt = 0;
for (node_iterator I = d2->begin(), E = d2->end(); I != E; ++I) {
alu_node *n = static_cast<alu_node*>(*I);
if (!n->is_alu_inst())
return 0;
if (!(n->bc.op_ptr->flags & AF_KILL))
return 0;
if (n->bc.op_ptr->src_count != 2 || n->src.size() != 2)
return 0;
value *s1 = n->src[0], *s2 = n->src[1];
// assuming that the KILL with constant operands is "always kill"
if (!s1 || !s2 || !s1->is_const() || !s2->is_const())
return 0;
++cnt;
}
if (cnt > 4)
return 0;
value *cond = f->cond;
value *pred = get_select_value_for_em(sh, cond);
if (!pred)
return 0;
for (node_iterator N, I = d2->begin(), E = d2->end(); I != E; I = N) {
N = I; ++N;
alu_node *n = static_cast<alu_node*>(*I);
IFC_DUMP(
cerr << "converting ";
dump::dump_op(n);
cerr << " " << n << "\n";
);
n->remove();
n->bc.set_op(ALU_OP2_KILLE_INT);
n->src[0] = pred;
n->src[1] = sh.get_const_value(0);
// reset src modifiers
memset(&n->bc.src[0], 0, sizeof(bc_alu_src));
memset(&n->bc.src[1], 0, sizeof(bc_alu_src));
r->insert_before(n);
}
