From 463f849097193ad20e7622ddd740fd15b96f4277 Mon Sep 17 00:00:00 2001 From: Timothy Arceri Date: Mon, 4 Jun 2018 16:26:46 +1000 Subject: [PATCH] nir: fix selection of loop terminator when two or more have the same limit We need to add loop terminators to the list in the order we come across them otherwise if two or more have the same exit condition we will select that last one rather than the first one even though its unreachable. This fix is for simple unrolls where we only have a single exit point. When unrolling these type of loops the unreachable terminators and their unreachable branch are removed prior to unrolling. Because of the logic change we also switch some list access in the complex unrolling logic to avoid breakage. Fixes: 6772a17acc8e ("nir: Add a loop analysis pass") Reviewed-by: Jason Ekstrand --- src/compiler/nir/nir_loop_analyze.c | 4 ++-- src/compiler/nir/nir_opt_loop_unroll.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/src/compiler/nir/nir_loop_analyze.c b/src/compiler/nir/nir_loop_analyze.c index 438e1fa..d564296 100644 --- a/src/compiler/nir/nir_loop_analyze.c +++ b/src/compiler/nir/nir_loop_analyze.c @@ -330,8 +330,8 @@ find_loop_terminators(loop_info_state *state) nir_loop_terminator *terminator = rzalloc(state->loop->info, nir_loop_terminator); - list_add(&terminator->loop_terminator_link, - &state->loop->info->loop_terminator_list); + list_addtail(&terminator->loop_terminator_link, + &state->loop->info->loop_terminator_list); terminator->nif = nif; terminator->break_block = break_blk; diff --git a/src/compiler/nir/nir_opt_loop_unroll.c b/src/compiler/nir/nir_opt_loop_unroll.c index 04caa7c..955dfed 100644 --- a/src/compiler/nir/nir_opt_loop_unroll.c +++ b/src/compiler/nir/nir_opt_loop_unroll.c @@ -530,14 +530,14 @@ process_loops(nir_shader *sh, nir_cf_node *cf_node, bool *innermost_loop) if (num_lt == 2) { bool limiting_term_second = true; nir_loop_terminator *terminator = - list_last_entry(&loop->info->loop_terminator_list, + list_first_entry(&loop->info->loop_terminator_list, nir_loop_terminator, loop_terminator_link); if (terminator->nif == loop->info->limiting_terminator->nif) { limiting_term_second = false; terminator = - list_first_entry(&loop->info->loop_terminator_list, + list_last_entry(&loop->info->loop_terminator_list, nir_loop_terminator, loop_terminator_link); } -- 2.7.4