[Mesa-dev] [PATCH 3/5] i965/fs: Eliminate unary op on operand of compare-with-zero

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

All Gen7+ platforms had similar results. (Broadwell shown)
total instructions in shared programs: 14715715 -> 14715709 (<.01%)
instructions in affected programs: 474 -> 468 (-1.27%)
helped: 6
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 1.12% max: 1.35% x̄: 1.28% x̃: 1.35%
95% mean confidence interval for instructions value: -1.00 -1.00
95% mean confidence interval for instructions %-change: -1.40% -1.15%
Instructions are helped.

total cycles in shared programs: 559569911 -> 559569809 (<.01%)
cycles in affected programs: 5963 -> 5861 (-1.71%)
helped: 6
HURT: 0
helped stats (abs) min: 16 max: 18 x̄: 17.00 x̃: 17
helped stats (rel) min: 1.45% max: 1.88% x̄: 1.73% x̃: 1.85%
95% mean confidence interval for cycles value: -18.15 -15.85
95% mean confidence interval for cycles %-change: -1.95% -1.51%
Cycles are helped.

Iron Lake and Sandy Bridge had similar results. (Iron Lake shown)
total instructions in shared programs: 7780915 -> 7780913 (<.01%)
instructions in affected programs: 246 -> 244 (-0.81%)
helped: 2
HURT: 0

total cycles in shared programs: 177876108 -> 177876106 (<.01%)
cycles in affected programs: 3636 -> 3634 (-0.06%)
helped: 1
HURT: 0

GM45
total instructions in shared programs: 4799152 -> 4799151 (<.01%)
instructions in affected programs: 126 -> 125 (-0.79%)
helped: 1
HURT: 0

total cycles in shared programs: 122052654 -> 122052652 (<.01%)
cycles in affected programs: 3640 -> 3638 (-0.05%)
helped: 1
HURT: 0

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/intel/compiler/brw_fs.cpp   | 19 ++++++++++++++-----
 src/intel/compiler/brw_vec4.cpp | 12 ------------
 2 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index 58736503f9a..9d7051e279f 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -2388,6 +2388,16 @@ fs_visitor::opt_algebraic()
    foreach_block_and_inst(block, fs_inst, inst, cfg) {
       switch (inst->opcode) {
       case BRW_OPCODE_MOV:
+         if ((inst->conditional_mod == BRW_CONDITIONAL_Z ||
+              inst->conditional_mod == BRW_CONDITIONAL_NZ) &&
+             inst->dst.is_null() &&
+             (inst->src[0].abs || inst->src[0].negate)) {
+            inst->src[0].abs = false;
+            inst->src[0].negate = false;
+            progress = true;
+            break;
+         }
+
          if (inst->src[0].file != IMM)
             break;
 
@@ -2492,13 +2502,12 @@ fs_visitor::opt_algebraic()
          }
          break;
       case BRW_OPCODE_CMP:
-         if (inst->conditional_mod == BRW_CONDITIONAL_GE &&
-             inst->src[0].abs &&
-             inst->src[0].negate &&
-             inst->src[1].is_zero()) {
+         if ((inst->conditional_mod == BRW_CONDITIONAL_Z ||
+              inst->conditional_mod == BRW_CONDITIONAL_NZ) &&
+             inst->src[1].is_zero() &&
+             (inst->src[0].abs || inst->src[0].negate)) {
             inst->src[0].abs = false;
             inst->src[0].negate = false;
-            inst->conditional_mod = BRW_CONDITIONAL_Z;
             progress = true;
             break;
          }
diff --git a/src/intel/compiler/brw_vec4.cpp b/src/intel/compiler/brw_vec4.cpp
index 4e242e03032..3d5d4fb5b4d 100644
--- a/src/intel/compiler/brw_vec4.cpp
+++ b/src/intel/compiler/brw_vec4.cpp
@@ -871,18 +871,6 @@ vec4_visitor::opt_algebraic()
             progress = true;
 	 }
 	 break;
-      case BRW_OPCODE_CMP:
-         if (inst->conditional_mod == BRW_CONDITIONAL_GE &&
-             inst->src[0].abs &&
-             inst->src[0].negate &&
-             inst->src[1].is_zero()) {
-            inst->src[0].abs = false;
-            inst->src[0].negate = false;
-            inst->conditional_mod = BRW_CONDITIONAL_Z;
-            progress = true;
-            break;
-         }
-         break;
       case SHADER_OPCODE_BROADCAST:
          if (is_uniform(inst->src[0]) ||
              inst->src[1].is_zero()) {
-- 
2.14.4