nir/algebraic: add a few masking-before-unpack optimizations

Helps some Dawn of War 3 and F1 2017 shaders with ACO:
Totals from affected shaders:
SGPRS: 2136 -> 2128 (-0.37 %)
VGPRS: 1624 -> 1628 (0.25 %)
Spilled SGPRs: 0 -> 0 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Private memory VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 168068 -> 164332 (-2.22 %) bytes
LDS: 44 -> 44 (0.00 %) blocks
Max Waves: 222 -> 221 (-0.45 %)
Wait states: 0 -> 0 (0.00 %)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 40f718e5ae27206db490125b3931c8f8de547953..26e2fc346ed82895a1d28021a69449f37225a7b8 100644 (file)
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -882,7 +882,15 @@ optimizations.extend([
    (('ishr', 'a@16',  8), ('extract_i8', a, 1), '!options->lower_extract_byte'),
    (('ishr', 'a@32', 24), ('extract_i8', a, 3), '!options->lower_extract_byte'),
    (('ishr', 'a@64', 56), ('extract_i8', a, 7), '!options->lower_extract_byte'),
-   (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte')
+   (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte'),
+
+   # Useless masking before unpacking
+   (('unpack_half_2x16_split_x', ('iand', a, 0xffff)), ('unpack_half_2x16_split_x', a)),
+   (('unpack_32_2x16_split_x', ('iand', a, 0xffff)), ('unpack_32_2x16_split_x', a)),
+   (('unpack_64_2x32_split_x', ('iand', a, 0xffffffff)), ('unpack_64_2x32_split_x', a)),
+   (('unpack_half_2x16_split_y', ('iand', a, 0xffff0000)), ('unpack_half_2x16_split_y', a)),
+   (('unpack_32_2x16_split_y', ('iand', a, 0xffff0000)), ('unpack_32_2x16_split_y', a)),
+   (('unpack_64_2x32_split_y', ('iand', a, 0xffffffff00000000)), ('unpack_64_2x32_split_y', a)),
 ])
 
 # After the ('extract_u8', a, 0) pattern, above, triggers, there will be