/* Remove continue if its the last instruction in the loop */
nir_instr *last_instr = nir_block_last_instr(nir_loop_last_block(loop));
if (last_instr && last_instr->type == nir_instr_type_jump) {
- assert(nir_instr_as_jump(last_instr)->type == nir_jump_continue);
nir_instr_remove(last_instr);
}
}
static bool
wrapper_unroll(nir_loop *loop)
{
- bool progress = false;
-
- nir_block *blk_after_loop =
- nir_cursor_current_block(nir_after_cf_node(&loop->cf_node));
-
- /* There may still be some single src phis following the loop that
- * have not yet been cleaned up by another pass. Tidy those up before
- * unrolling the loop.
- */
- nir_foreach_instr_safe(instr, blk_after_loop) {
- if (instr->type != nir_instr_type_phi)
- break;
+ if (!list_empty(&loop->info->loop_terminator_list)) {
- nir_phi_instr *phi = nir_instr_as_phi(instr);
- assert(exec_list_length(&phi->srcs) == 1);
+ /* Unrolling a loop with a large number of exits can result in a
+ * large inrease in register pressure. For now we just skip
+ * unrolling if we have more than 3 exits (not including the break
+ * at the end of the loop).
+ *
+ * TODO: Most loops that fit this pattern are simply switch
+ * statements that are converted to a loop to take advantage of
+ * exiting jump instruction handling. In this case we could make
+ * use of a binary seach pattern like we do in
+ * nir_lower_indirect_derefs(), this should allow us to unroll the
+ * loops in an optimal way and should also avoid some of the
+ * register pressure that comes from simply nesting the
+ * terminators one after the other.
+ */
+ if (list_length(&loop->info->loop_terminator_list) > 3)
+ return false;
+
+ loop_prepare_for_unroll(loop);
+
+ nir_cursor loop_end = nir_after_block(nir_loop_last_block(loop));
+ list_for_each_entry(nir_loop_terminator, terminator,
+ &loop->info->loop_terminator_list,
+ loop_terminator_link) {
+
+ /* Remove break from the terminator */
+ nir_instr *break_instr =
+ nir_block_last_instr(terminator->break_block);
+ nir_instr_remove(break_instr);
+
+ /* Pluck out the loop body. */
+ nir_cf_list loop_body;
+ nir_cf_extract(&loop_body,
+ nir_after_cf_node(&terminator->nif->cf_node),
+ loop_end);
+
+ /* Reinsert loop body into continue from block */
+ nir_cf_reinsert(&loop_body,
+ nir_after_block(terminator->continue_from_block));
+
+ loop_end = terminator->continue_from_then ?
+ nir_after_block(nir_if_last_then_block(terminator->nif)) :
+ nir_after_block(nir_if_last_else_block(terminator->nif));
+ }
+ } else {
+ nir_block *blk_after_loop =
+ nir_cursor_current_block(nir_after_cf_node(&loop->cf_node));
- nir_phi_src *phi_src = exec_node_data(nir_phi_src,
- exec_list_get_head(&phi->srcs),
- node);
+ /* There may still be some single src phis following the loop that
+ * have not yet been cleaned up by another pass. Tidy those up
+ * before unrolling the loop.
+ */
+ nir_foreach_instr_safe(instr, blk_after_loop) {
+ if (instr->type != nir_instr_type_phi)
+ break;
- nir_ssa_def_rewrite_uses(&phi->dest.ssa, phi_src->src);
- nir_instr_remove(instr);
+ nir_phi_instr *phi = nir_instr_as_phi(instr);
+ assert(exec_list_length(&phi->srcs) == 1);
- progress = true;
- }
+ nir_phi_src *phi_src =
+ exec_node_data(nir_phi_src, exec_list_get_head(&phi->srcs), node);
- nir_block *last_loop_blk = nir_loop_last_block(loop);
- if (nir_block_ends_in_break(last_loop_blk)) {
+ nir_ssa_def_rewrite_uses(&phi->dest.ssa, phi_src->src);
+ nir_instr_remove(instr);
+ }
/* Remove break at end of the loop */
+ nir_block *last_loop_blk = nir_loop_last_block(loop);
nir_instr *break_instr = nir_block_last_instr(last_loop_blk);
nir_instr_remove(break_instr);
+ }
- /* Pluck out the loop body. */
- nir_cf_list loop_body;
- nir_cf_extract(&loop_body, nir_before_block(nir_loop_first_block(loop)),
- nir_after_block(nir_loop_last_block(loop)));
-
- /* Reinsert loop body after the loop */
- nir_cf_reinsert(&loop_body, nir_after_cf_node(&loop->cf_node));
+ /* Pluck out the loop body. */
+ nir_cf_list loop_body;
+ nir_cf_extract(&loop_body, nir_before_block(nir_loop_first_block(loop)),
+ nir_after_block(nir_loop_last_block(loop)));
- /* The loop has been unrolled so remove it. */
- nir_cf_node_remove(&loop->cf_node);
+ /* Reinsert loop body after the loop */
+ nir_cf_reinsert(&loop_body, nir_after_cf_node(&loop->cf_node));
- progress = true;
- }
+ /* The loop has been unrolled so remove it. */
+ nir_cf_node_remove(&loop->cf_node);
- return progress;
+ return true;
}
static bool
* statements in a loop like this.
*/
if (loop->info->limiting_terminator == NULL &&
- list_empty(&loop->info->loop_terminator_list) &&
!loop->info->complex_loop) {
+ nir_block *last_loop_blk = nir_loop_last_block(loop);
+ if (!nir_block_ends_in_break(last_loop_blk))
+ goto exit;
+
progress = wrapper_unroll(loop);
goto exit;
projects / mesa.git / blobdiff