From b617a5230806090d433ce9ac17c27a1394931a1f Mon Sep 17 00:00:00 2001 From: Rhys Perry Date: Mon, 7 Sep 2020 11:33:44 +0100 Subject: [PATCH] nir/opt_if: fix opt_if_merge when destination branch has a jump Fixes a case where opt_if_merge created code like: if (...) { break; loop { ... } } which caused opt_peel_loop_initial_if to complain that the loop pre-header wasn't a predecessor of the loop header. This patch prevents this (invalid, I think) unreachable code from being created. Signed-off-by: Rhys Perry Reviewed-by: Timothy Arceri Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3496 Fixes: 4d3f6cb9739 ('nir: merge some basic consecutive ifs') Part-of: (cherry picked from commit 6cef8040672e84393e59ed6efa9953c95f5f8c92) --- .pick_status.json | 2 +- src/compiler/nir/nir_opt_if.c | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/.pick_status.json b/.pick_status.json index 600f32f68b5..fffc404ff2b 100644 --- a/.pick_status.json +++ b/.pick_status.json @@ -1066,7 +1066,7 @@ "description": "nir/opt_if: fix opt_if_merge when destination branch has a jump", "nominated": true, "nomination_type": 1, - "resolution": 0, + "resolution": 1, "master_sha": null, "because_sha": "4d3f6cb9739dfeaf9605fcd2f5318e03acf5066e" }, diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c index a7feac1db93..4a255201318 100644 --- a/src/compiler/nir/nir_opt_if.c +++ b/src/compiler/nir/nir_opt_if.c @@ -1274,6 +1274,13 @@ opt_if_merge(nir_if *nif) if (nif->condition.ssa == next_if->condition.ssa && exec_list_is_empty(&next_blk->instr_list)) { + /* This optimization isn't made to work in this case and + * opt_if_evaluate_condition_use will optimize it later. + */ + if (nir_block_ends_in_jump(nir_if_last_then_block(nif)) || + nir_block_ends_in_jump(nir_if_last_else_block(nif))) + return false; + simple_merge_if(nif, next_if, true, true); simple_merge_if(nif, next_if, false, false);