From 22fd4cf885a3eb2367c4cbdb2602c48237ad25ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Sch=C3=BCrmann?= <daniel@schuermann.dev>
Date: Wed, 6 May 2026 09:31:49 +0200
Subject: [PATCH 1/2] nir/opt_algebraic: optimize downcast followed by upcast
 to extract

Totals from 217 (0.10% of 208640) affected shaders: (Navi48)
Instrs: 283561 -> 282870 (-0.24%)
CodeSize: 1604864 -> 1601136 (-0.23%); split: -0.24%, +0.01%
Latency: 2992301 -> 2990107 (-0.07%); split: -0.09%, +0.02%
InvThroughput: 602722 -> 601316 (-0.23%); split: -0.23%, +0.00%
Copies: 26490 -> 26471 (-0.07%); split: -0.10%, +0.03%
VALU: 147735 -> 147176 (-0.38%)
SALU: 51545 -> 51541 (-0.01%)
VOPD: 11140 -> 11204 (+0.57%)
---
 src/compiler/nir/nir_opt_algebraic.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 9d0cd043504..9b431f998d4 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -2186,6 +2186,16 @@ optimizations.extend([
    (('extract_u16', ('extract_i16', a, b), 0), ('extract_u16', a, b)),
    (('extract_u16', ('extract_u16', a, b), 0), ('extract_u16', a, b)),
 
+   # Downcast followed by upcast
+   (('u2u32', ('u2u8', 'a@32')), ('extract_u8', a, 0), '!options->lower_extract_byte'),
+   (('u2u32', ('i2i8', 'a@32')), ('extract_u8', a, 0), '!options->lower_extract_byte'),
+   (('i2i32', ('i2i8', 'a@32')), ('extract_i8', a, 0), '!options->lower_extract_byte'),
+   (('i2i32', ('u2u8', 'a@32')), ('extract_i8', a, 0), '!options->lower_extract_byte'),
+   (('u2u32', ('u2u16', 'a@32')), ('extract_u16', a, 0), '!options->lower_extract_word'),
+   (('u2u32', ('i2i16', 'a@32')), ('extract_u16', a, 0), '!options->lower_extract_word'),
+   (('i2i32', ('i2i16', 'a@32')), ('extract_i16', a, 0), '!options->lower_extract_word'),
+   (('i2i32', ('u2u16', 'a@32')), ('extract_i16', a, 0), '!options->lower_extract_word'),
+
    # The extract_X16(a & 0xff) patterns aren't included because the iand will
    # already be converted to extract_u8.
    (('extract_i16', ('iand', a, 0x00ff0000), 1), ('extract_u8', a, 2), '!options->lower_extract_byte'), # extract_u8 is correct

From dace9adfe25e1d610ff29dadc38d072f4bfbf38f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Sch=C3=BCrmann?= <daniel@schuermann.dev>
Date: Wed, 6 May 2026 09:40:23 +0200
Subject: [PATCH 2/2] nir/opt_algebraic: extend some extract_u8 pattern to
 extract_i8

and remove some duplicate extract pattern.
---
 src/compiler/nir/nir_opt_algebraic.py | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 9b431f998d4..ec1c53f6087 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -2128,13 +2128,6 @@ optimizations.extend([
    (('ior', ('bcsel', ('ine', ('iand', a, 0x00800000), 0), ~0xff, 0), ('extract_u8', a, 2)), ('extract_i8', a, 2)),
    (('ior', ('bcsel', ('ilt',          'a@32',         0), ~0xff, 0), ('extract_u8', a, 3)), ('extract_i8', a, 3)),
 
-   (('extract_i8', ('ushr', a, 8), 0), ('extract_i8', a, 1)),
-   (('extract_i8', ('ushr', a, 8), 1), ('extract_i8', a, 2)),
-   (('extract_i8', ('ushr', a, 8), 2), ('extract_i8', a, 3)),
-   (('extract_u8', ('ushr', a, 8), 0), ('extract_u8', a, 1)),
-   (('extract_u8', ('ushr', a, 8), 1), ('extract_u8', a, 2)),
-   (('extract_u8', ('ushr', a, 8), 2), ('extract_u8', a, 3)),
-
    (('extract_i8', ('extract_i16', a, 1), 0), ('extract_i8', a, 2)),
    (('extract_i8', ('extract_i16', a, 1), 1), ('extract_i8', a, 3)),
    (('extract_i8', ('extract_u16', a, 1), 0), ('extract_i8', a, 2)),
@@ -2304,12 +2297,11 @@ optimizations.extend([
 
 # After the ('extract_u8', a, 0) pattern, above, triggers, there will be
 # patterns like those below.
-for op in ('ushr', 'ishr'):
-   optimizations.extend([(('extract_u8', (op, 'a@16',  8),     0), ('extract_u8', a, 1))])
-   optimizations.extend([(('extract_u8', (op, 'a@32',  8 * i), 0), ('extract_u8', a, i)) for i in range(1, 4)])
-   optimizations.extend([(('extract_u8', (op, 'a@64',  8 * i), 0), ('extract_u8', a, i)) for i in range(1, 8)])
-
-optimizations.extend([(('extract_u8', ('extract_u16', a, 1), 0), ('extract_u8', a, 2))])
+for extract_op in ('extract_u8', 'extract_i8'):
+   for op in ('ushr', 'ishr'):
+      optimizations.extend([((extract_op, (op, a, 8), i), (extract_op, a, i + 1)) for i in range (0, 3)])
+      optimizations.extend([((extract_op, (op, 'a@32',  8 * i), 0), (extract_op, a, i)) for i in range(2, 4)])
+      optimizations.extend([((extract_op, (op, 'a@64',  8 * i), 0), (extract_op, a, i)) for i in range(2, 8)])
 
 # After the ('extract_[iu]8', a, 3) patterns, above, trigger, there will be
 # patterns like those below.