Mesa (master): i965/fs: Eliminate unary op on operand of compare-with-zero

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Module: Mesa
Branch: master
Commit: 9a83c3d3b3f147eb8ae17c9a40e518e77db41432
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=9a83c3d3b3f147eb8ae17c9a40e518e77db41432

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Fri Jun 22 08:34:03 2018 -0700

i965/fs: Eliminate unary op on operand of compare-with-zero

The (-abs(x) >= 0) => (x == 0) optimization is removed from the vec4 and
scalar parts. In the VS part, adding the new pattern was not
helpful. The pattern that is removed is really old, and it has been
handled by NIR for ages.

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>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin 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 3125e5feb1..590a9b32a8 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -2406,6 +2406,16 @@ 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;
 
@@ -2510,13 +2520,12 @@ 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 6ed07b72f3..8cbbdd4ec7 100644
--- a/src/intel/compiler/brw_vec4.cpp
+++ b/src/intel/compiler/brw_vec4.cpp
@@ -892,18 +892,6 @@ 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()) {