i965/fs: Eliminate null-dst instructions without side-effects.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
2014-08-22 11:01:13 -07:00
parent 7452f18b22
commit 3759a89ad3
1 changed files with 11 additions and 0 deletions
@@ -85,6 +85,17 @@ fs_visitor::dead_code_eliminate()
            }
         }

+         if ((inst->opcode != BRW_OPCODE_IF &&
+              inst->opcode != BRW_OPCODE_WHILE) &&
+             inst->dst.is_null() &&
+             !inst->has_side_effects() &&
+             !inst->writes_flag() &&
+             !inst->writes_accumulator) {
+            inst->opcode = BRW_OPCODE_NOP;
+            progress = true;
+            continue;
+         }
+
         if (inst->dst.file == GRF) {
            if (!inst->is_partial_write()) {
               int var = live_intervals->var_from_reg(inst->dst);