[Mesa-dev] [PATCH 10/10] i965/fs: Add algebraic optimizations for MAD.

[Matt Turner]

total instructions in shared programs: 5764176 -> 5763808 (-0.01%)
instructions in affected programs:     25121 -> 24753 (-1.46%)
helped:                                164
HURT:                                  2
---
 src/mesa/drivers/dri/i965/brw_fs.cpp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 69602a7..6f36e39 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -2417,6 +2417,32 @@ fs_visitor::opt_algebraic()
             }
          }
          break;
+      case BRW_OPCODE_MAD:
+         if (inst->src[1].is_zero() || inst->src[2].is_zero()) {
+            inst->opcode = BRW_OPCODE_MOV;
+            inst->src[1] = reg_undef;
+            inst->src[2] = reg_undef;
+            progress = true;
+         } else if (inst->src[0].is_zero()) {
+            inst->opcode = BRW_OPCODE_MUL;
+            inst->src[0] = inst->src[2];
+            inst->src[2] = reg_undef;
+         } else if (inst->src[1].is_one()) {
+            inst->opcode = BRW_OPCODE_ADD;
+            inst->src[1] = inst->src[2];
+            inst->src[2] = reg_undef;
+            progress = true;
+         } else if (inst->src[2].is_one()) {
+            inst->opcode = BRW_OPCODE_ADD;
+            inst->src[2] = reg_undef;
+            progress = true;
+         } else if (inst->src[1].file == IMM && inst->src[2].file == IMM) {
+            inst->opcode = BRW_OPCODE_MUL;
+            inst->src[1].fixed_hw_reg.dw1.f *= inst->src[2].fixed_hw_reg.dw1.f;
+            inst->src[2] = reg_undef;
+            progress = true;
+         }
+         break;
       case SHADER_OPCODE_RCP: {
          fs_inst *prev = (fs_inst *)inst->prev;
          if (prev->opcode == SHADER_OPCODE_SQRT) {
-- 
2.0.4