[Mesa-dev] [PATCH 05/10] i965/fs: Add a couple more algebraic cases that help some ARB_fp patterns.

[Eric Anholt]

ARB_fp doesn't go through the GLSL optimizer, and these were things you see
frequently thanks to conditionals being lowered to SLT/SGE and MUL.
---
 src/mesa/drivers/dri/i965/brw_fs.cpp |   23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 9ac2a49..fea5980 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1435,7 +1435,30 @@ fs_visitor::opt_algebraic()
 	    break;
 	 }
 
+         /* a * 0.0 = 0.0 */
+         if (inst->src[1].type == BRW_REGISTER_TYPE_F &&
+             inst->src[1].imm.f == 0.0) {
+            inst->opcode = BRW_OPCODE_MOV;
+            inst->src[0] = fs_reg(0.0f);
+            inst->src[1] = reg_undef;
+            progress = true;
+            break;
+         }
+
 	 break;
+      case BRW_OPCODE_ADD:
+         if (inst->src[1].file != IMM)
+            continue;
+
+         /* a + 0.0 = a */
+         if (inst->src[1].type == BRW_REGISTER_TYPE_F &&
+             inst->src[1].imm.f == 0.0) {
+            inst->opcode = BRW_OPCODE_MOV;
+            inst->src[1] = reg_undef;
+            progress = true;
+            break;
+         }
+         break;
       default:
 	 break;
       }
-- 
1.7.10.4