static void
opt_constant_if(nir_if *if_stmt, bool condition)
{
/* First, we need to remove any phi nodes after the if by rewriting uses to
* point to the correct source.
*/
nir_block *after = nir_cf_node_as_block(nir_cf_node_next(&if_stmt->cf_node));
nir_block *last_block =
nir_cf_node_as_block(condition ? nir_if_last_then_node(if_stmt)
: nir_if_last_else_node(if_stmt));
nir_foreach_instr_safe(after, instr) {
if (instr->type != nir_instr_type_phi)
break;
nir_phi_instr *phi = nir_instr_as_phi(instr);
nir_ssa_def *def = NULL;
nir_foreach_phi_src(phi, phi_src) {
if (phi_src->pred != last_block)
continue;
assert(phi_src->src.is_ssa);
def = phi_src->src.ssa;
}
assert(def);
assert(phi->dest.is_ssa);
nir_ssa_def_rewrite_uses(&phi->dest.ssa, nir_src_for_ssa(def));
nir_instr_remove(instr);
}
/* The control flow list we're about to paste in may include a jump at the
* end, and in that case we have to delete the rest of the control flow
* list after the if since it's unreachable and the validator will balk if
* we don't.
*/
if (!exec_list_is_empty(&last_block->instr_list)) {
nir_instr *last_instr = nir_block_last_instr(last_block);
if (last_instr->type == nir_instr_type_jump)
remove_after_cf_node(&if_stmt->cf_node);
}
/* Finally, actually paste in the then or else branch and delete the if. */
struct exec_list *cf_list = condition ? &if_stmt->then_list
: &if_stmt->else_list;
nir_cf_list list;
nir_cf_extract(&list, nir_before_cf_list(cf_list),
nir_after_cf_list(cf_list));
nir_cf_reinsert(&list, nir_after_cf_node(&if_stmt->cf_node));
nir_cf_node_remove(&if_stmt->cf_node);
}
static void
emit_indirect_load_store(nir_builder *b, nir_intrinsic_instr *orig_instr,
nir_deref_var *deref, nir_deref *arr_parent,
int start, int end,
nir_ssa_def **dest, nir_ssa_def *src)
{
assert(arr_parent->child &&
arr_parent->child->deref_type == nir_deref_type_array);
nir_deref_array *arr = nir_deref_as_array(arr_parent->child);
assert(arr->deref_array_type == nir_deref_array_type_indirect);
assert(arr->indirect.is_ssa);
assert(start < end);
if (start == end - 1) {
/* Base case. Just emit the load/store op */
nir_deref_array direct = *arr;
direct.deref_array_type = nir_deref_array_type_direct;
direct.base_offset += start;
direct.indirect = NIR_SRC_INIT;
arr_parent->child = &direct.deref;
emit_load_store(b, orig_instr, deref, &arr->deref, dest, src);
arr_parent->child = &arr->deref;
} else {
int mid = start + (end - start) / 2;
nir_ssa_def *then_dest, *else_dest;
nir_if *if_stmt = nir_if_create(b->shader);
if_stmt->condition = nir_src_for_ssa(nir_ilt(b, arr->indirect.ssa,
nir_imm_int(b, mid)));
nir_cf_node_insert(b->cursor, &if_stmt->cf_node);
b->cursor = nir_after_cf_list(&if_stmt->then_list);
emit_indirect_load_store(b, orig_instr, deref, arr_parent,
start, mid, &then_dest, src);
b->cursor = nir_after_cf_list(&if_stmt->else_list);
emit_indirect_load_store(b, orig_instr, deref, arr_parent,
mid, end, &else_dest, src);
b->cursor = nir_after_cf_node(&if_stmt->cf_node);
if (src == NULL) {
/* We're a load. We need to insert a phi node */
nir_phi_instr *phi = nir_phi_instr_create(b->shader);
unsigned bit_size = then_dest->bit_size;
nir_ssa_dest_init(&phi->instr, &phi->dest,
then_dest->num_components, bit_size, NULL);
nir_phi_src *src0 = ralloc(phi, nir_phi_src);
src0->pred = nir_cf_node_as_block(nir_if_last_then_node(if_stmt));
src0->src = nir_src_for_ssa(then_dest);
exec_list_push_tail(&phi->srcs, &src0->node);
nir_phi_src *src1 = ralloc(phi, nir_phi_src);
src1->pred = nir_cf_node_as_block(nir_if_last_else_node(if_stmt));
src1->src = nir_src_for_ssa(else_dest);
exec_list_push_tail(&phi->srcs, &src1->node);
nir_builder_instr_insert(b, &phi->instr);
*dest = &phi->dest.ssa;
}
}
}
