From 81af1a0ae264378408232dc1e54b00a7dff3529b 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 (cherry picked from commit 463f849097193ad20e7622ddd740fd15b96f4277) --- 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 84da035052d..aa6877f3af5 100644 --- a/src/compiler/nir/nir_loop_analyze.c +++ b/src/compiler/nir/nir_loop_analyze.c @@ -341,8 +341,8 @@ 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 ff27c06cc01..b8efbb5ee93 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); }