[Mesa-dev] [PATCH 4/5] i965/fs: Allow saturate propagation to propagate negations into MADs.

[Matt Turner]

Allows us to transform

   mad      res  src0   src1   src2
   mov.sat  dst  -res

into

   mad.sat  dst  -src0 -src1   src2

instructions in affected programs: 3712 -> 3688 (-0.65%)
helped: 24
---
 src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp
index 7c82509..dc2b0c8 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp
@@ -86,6 +86,10 @@ opt_saturate_propagation_local(fs_visitor *v, bblock_t *block)
                      if (scan_inst->opcode == BRW_OPCODE_MUL) {
                         scan_inst->src[0].negate = !scan_inst->src[0].negate;
                         inst->src[0].negate = false;
+                     } else if (scan_inst->opcode == BRW_OPCODE_MAD) {
+                        scan_inst->src[0].negate = !scan_inst->src[0].negate;
+                        scan_inst->src[1].negate = !scan_inst->src[1].negate;
+                        inst->src[0].negate = false;
                      } else if (scan_inst->opcode == BRW_OPCODE_ADD) {
                         if (scan_inst->src[1].file == IMM) {
                            if (!brw_negate_immediate(scan_inst->src[1].type,
-- 
2.4.10