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@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index 3125e5feb1dfbf29eefef3d7f9f9bf6a030ed43d..590a9b32a8e8df6f7f20b3bc97a3b6e206228cfc 100644 (file)
--- 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 6ed07b72f314710a1c8f7c348f4d3f6aef38820c..8cbbdd4ec706c31930c22e34c62d198eba08d2b1 100644 (file)
--- 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()) {