From 8329c04521884145bf15ec2cb4c85471fc8cdf61 Mon Sep 17 00:00:00 2001
From: Ian Romanick <ian.d.romanick@intel.com>
Date: Tue, 1 Oct 2024 09:42:00 -0700
Subject: [PATCH] brw/copy: Don't remove instructions w/ conditional modifier

Fixes: 9e750f00c3b ("intel/brw: Make opt_copy_propagation_defs clean up its own trash")
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31834>
---
 src/intel/compiler/brw_fs_copy_propagation.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/intel/compiler/brw_fs_copy_propagation.cpp b/src/intel/compiler/brw_fs_copy_propagation.cpp
index c22a74d9f7d..84369d97f2f 100644
--- a/src/intel/compiler/brw_fs_copy_propagation.cpp
+++ b/src/intel/compiler/brw_fs_copy_propagation.cpp
@@ -1849,8 +1849,17 @@ brw_fs_opt_copy_propagation_defs(fs_visitor &s)
          if (source_progress) {
             instruction_progress = true;
             ++uses_deleted[def->dst.nr];
-            if (defs.get_use_count(def->dst) == uses_deleted[def->dst.nr])
+
+            /* We can copy propagate through an instruction like
+             *
+             *    mov.nz.f0.0(8) %2:D, -%78:D
+             *
+             * but deleting the instruction may alter the program.
+             */
+            if (def->conditional_mod == BRW_CONDITIONAL_NONE &&
+                defs.get_use_count(def->dst) == uses_deleted[def->dst.nr]) {
                def->remove(defs.get_block(def->dst), true);
+            }
          }
       }