vc4: Optimize out silly SUBs of 0.

Drops instructions on vs-temp-array-mat4-index-col-row-wr.shader_test, which I was looking at because it's failing to register allocate.
2014-09-24 21:57:06 -07:00
parent 64122b16ce
commit 76cd9955d9
1 changed files with 11 additions and 0 deletions
@@ -117,6 +117,17 @@ qir_opt_algebraic(struct vc4_compile *c)
                        }
                        break;

+                case QOP_FSUB:
+                case QOP_SUB:
+                        if (is_zero(c, defs, inst->src[1])) {
+                                dump_from(c, inst);
+                                inst->op = QOP_MOV;
+                                inst->src[1] = c->undef;
+                                progress = true;
+                                dump_to(c, inst);
+                        }
+                        break;
+
                default:
                        break;
                }