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") --- 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 d5281a5faa4..8f726986dac 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 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); } -- 2.14.3 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev