From: Ian Romanick <ian.d.roman...@intel.com>
This was specifically designed to simplify 1+mix(0, a-1, condition) to
mix(1, a, condition) by pushing the 1+ inside.
Skylake, Broadwell, and Haswell had similar results. Skylake shown.
total instructions in shared programs: 14521938 -> 14521901 (<.01%)
instructions in affected programs: 10619 -> 10582 (-0.35%)
helped: 51
HURT: 14
helped stats (abs) min: 1 max: 12 x̄: 1.43 x̃: 1
helped stats (rel) min: 0.20% max: 3.58% x̄: 1.01% x̃: 0.95%
HURT stats (abs) min: 1 max: 11 x̄: 2.57 x̃: 1
HURT stats (rel) min: 0.22% max: 1.75% x̄: 1.20% x̃: 1.32%
abs t: -1.50, p: 13.87%
rel t: -1.11, p: 27.06%
Inconclusive result (cannot disprove both null hypothoses).
total cycles in shared programs: 533003159 -> 533006487 (<.01%)
cycles in affected programs: 110610 -> 113938 (3.01%)
helped: 43
HURT: 28
helped stats (abs) min: 6 max: 440 x̄: 27.12 x̃: 16
helped stats (rel) min: 0.39% max: 4.84% x̄: 1.60% x̃: 1.67%
HURT stats (abs) min: 2 max: 3066 x̄: 160.50 x̃: 14
HURT stats (rel) min: 0.08% max: 77.78% x̄: 5.16% x̃: 0.62%
abs t: -1.47, p: 14.70%
rel t: -1.43, p: 15.77%
Inconclusive result (cannot disprove both null hypothoses).
Ivy Bridge, Sandy Bridge, and Iron Lake had similar results. Ivy Bridge
shown.
total instructions in shared programs: 11817064 -> 11816937 (<.01%)
instructions in affected programs: 9431 -> 9304 (-1.35%)
helped: 51
HURT: 3
helped stats (abs) min: 1 max: 80 x̄: 2.76 x̃: 1
helped stats (rel) min: 0.20% max: 16.43% x̄: 1.16% x̃: 0.81%
HURT stats (abs) min: 1 max: 12 x̄: 4.67 x̃: 1
HURT stats (rel) min: 0.22% max: 1.33% x̄: 0.59% x̃: 0.22%
abs t: -0.29, p: 77.20%
rel t: 0.44, p: 66.15%
Inconclusive result (cannot disprove both null hypothoses).
total cycles in shared programs: 257573443 -> 257574281 (<.01%)
cycles in affected programs: 123831 -> 124669 (0.68%)
helped: 44
HURT: 24
helped stats (abs) min: 2 max: 114 x̄: 49.93 x̃: 30
helped stats (rel) min: 0.11% max: 11.01% x̄: 4.26% x̃: 2.73%
HURT stats (abs) min: 1 max: 2341 x̄: 126.46 x̃: 12
HURT stats (rel) min: 0.06% max: 37.11% x̄: 2.67% x̃: 0.63%
abs t: -1.07, p: 28.77%
rel t: 1.19, p: 23.86%
Inconclusive result (cannot disprove both null hypothoses).
GM45
total instructions in shared programs: 4857762 -> 4857661 (<.01%)
instructions in affected programs: 5523 -> 5422 (-1.83%)
helped: 25
HURT: 1
helped stats (abs) min: 1 max: 78 x̄: 4.08 x̃: 1
helped stats (rel) min: 0.34% max: 13.61% x̄: 1.04% x̃: 0.52%
HURT stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel) min: 0.86% max: 0.86% x̄: 0.86% x̃: 0.86%
total cycles in shared programs: 122179674 -> 122179194 (<.01%)
cycles in affected programs: 530162 -> 529682 (-0.09%)
helped: 22
HURT: 1
helped stats (abs) min: 2 max: 292 x̄: 21.91 x̃: 7
helped stats (rel) min: <.01% max: 8.65% x̄: 0.44% x̃: 0.04%
HURT stats (abs) min: 2 max: 2 x̄: 2.00 x̃: 2
HURT stats (rel) min: 0.03% max: 0.03% x̄: 0.03% x̃: 0.03%
Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
---
src/compiler/nir/nir_opt_algebraic.py | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/src/compiler/nir/nir_opt_algebraic.py
b/src/compiler/nir/nir_opt_algebraic.py
index d9ca57b..35fe8af 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -602,6 +602,21 @@ for op in ['flt', 'fge', 'feq', 'fne',
('bcsel', 'a', (op, 'd', 'b'), (op, 'd', 'c'))),
]
+
+# For example, this converts things like
+#
+# 1 + mix(0, a - 1, condition)
+#
+# into
+#
+# mix(1, (a-1)+1, condition)
+#
+# Other optimizations will rearrange the constants.
+for op in ['fadd', 'fmul', 'iadd', 'imul']:
+ optimizations += [
+ ((op, ('bcsel(is_used_once)', a, '#b', c), '#d'), ('bcsel', a, (op, b,
d), (op, c, d)))
+ ]
+
# This section contains "late" optimizations that should be run before
# creating ffmas and calling regular optimizations for the final time.
# Optimizations should go here if they help code generation and conflict
--
2.9.5
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