[Mesa-dev] [PATCH 1/2] i965: Combine some dead code elimination NOP'ing code.

[Kenneth Graunke]

In theory we might have incorrectly NOP'd instructions that write the
flag, but where that flag value isn't used, and yet the instruction
either writes the accumulator or has side effects.

I don't believe any such instructions exist, so this is mostly a
code cleanup.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp b/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
index 8a0469a51b9..930dc733b45 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
@@ -70,17 +70,11 @@ fs_visitor::dead_code_eliminate()
             }
          }
 
-         if (inst->dst.is_null() && inst->flags_written()) {
-            if (!(flag_live[0] & inst->flags_written())) {
-               inst->opcode = BRW_OPCODE_NOP;
-               progress = true;
-            }
-         }
-
          if ((inst->opcode != BRW_OPCODE_IF &&
               inst->opcode != BRW_OPCODE_WHILE) &&
              inst->dst.is_null() &&
              !inst->has_side_effects() &&
+             !(flag_live[0] & inst->flags_written()) &&
              !inst->flags_written() &&
              !inst->writes_accumulator) {
             inst->opcode = BRW_OPCODE_NOP;
-- 
2.11.0