From ddf6c31b8edc4bc229002035c92dcce290ad83da Mon Sep 17 00:00:00 2001
From: Faith Ekstrand <faith.ekstrand@collabora.com>
Date: Mon, 30 Mar 2026 20:59:46 -0400
Subject: [PATCH] pan/bi: Delete a few instruction encodings

The non-trivial non-replicate swizzles on IADD.v4x8 and ISUB.v4x8 are
either documented wrong or broken in hardware.  Instead of swizzling
b0101 and b2323, they swizzle b0011 and b2233 on G52.  This is either a
hardware bug or an issue with documentation.  In either case, it's
probably best not to trust it.  Those swizzles aren't all that useful
anyway.  We also weren't using any of them before (or they'd have
broken) so this isn't a performance regression.

Cc: mesa-stable
Reviewed-by: Lorenzo Rossi <lorenzo.rossi@collabora.com>
(cherry picked from commit 538b5c411eab0c03c298412f74594d33a0396a9a)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40979>
---
 .pick_status.json                             |  2 +-
 src/panfrost/compiler/bifrost/bifrost/ISA.xml | 36 +++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/.pick_status.json b/.pick_status.json
index ca68d699825..c208c218835 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -3964,7 +3964,7 @@
         "description": "pan/bi: Delete a few instruction encodings",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null,
         "notes": null
diff --git a/src/panfrost/compiler/bifrost/bifrost/ISA.xml b/src/panfrost/compiler/bifrost/bifrost/ISA.xml
index a4ecdaf5063..1ef9b557428 100644
--- a/src/panfrost/compiler/bifrost/bifrost/ISA.xml
+++ b/src/panfrost/compiler/bifrost/bifrost/ISA.xml
@@ -5350,8 +5350,15 @@
       <opt>b1111</opt>
       <opt>b2222</opt>
       <opt>b3333</opt>
+      <!--
+        The docs claim that b0101 and b2323 are also supported but they don't
+        appear to work.  Instead, they seem to be b0011 and b2233 swizzles in
+        practice.  Instead of emitting shaders that violate the HW docs, we
+        simply don't claim support for these swizzles.  These swizzles aren't
+        that useful anyway.
       <opt>b0101</opt>
       <opt>b2323</opt>
+      -->
     </mod>
     <encoding mask="0xffec0" exact="0xbc400">
       <and>
@@ -5376,6 +5383,7 @@
         <eq left="lanes1" right="#b3333"/>
       </derived>
     </encoding>
+    <!--
     <encoding mask="0xffcc0" exact="0xbe840">
       <and>
         <eq left="lanes0" right="#b0123"/>
@@ -5389,6 +5397,7 @@
         <eq left="lanes1" right="#b2323"/>
       </derived>
     </encoding>
+    -->
   </ins>
 
   <ins name="IADD.v4u8" unit="add">
@@ -5404,8 +5413,15 @@
       <opt>b1111</opt>
       <opt>b2222</opt>
       <opt>b3333</opt>
+      <!--
+        The docs claim that b0101 and b2323 are also supported but they don't
+        appear to work.  Instead, they seem to be b0011 and b2233 swizzles in
+        practice.  Instead of emitting shaders that violate the HW docs, we
+        simply don't claim support for these swizzles.  These swizzles aren't
+        that useful anyway.
       <opt>b0101</opt>
       <opt>b2323</opt>
+      -->
     </mod>
     <encoding mask="0xffe40" exact="0xbc400">
       <and>
@@ -5438,6 +5454,7 @@
         <eq left="lanes1" right="#b3333"/>
       </derived>
     </encoding>
+    <!--
     <encoding mask="0xffc40" exact="0xbe840">
       <and>
         <eq left="lanes0" right="#b0123"/>
@@ -5455,6 +5472,7 @@
         <eq left="lanes1" right="#b2323"/>
       </derived>
     </encoding>
+    -->
   </ins>
 
   <ins name="ICMP.i32" mask="0xffb80" exact="0x7b300" unit="add">
@@ -6075,8 +6093,15 @@
       <opt>b1111</opt>
       <opt>b2222</opt>
       <opt>b3333</opt>
+      <!--
+        The docs claim that b0101 and b2323 are also supported but they don't
+        appear to work.  Instead, they seem to be b0011 and b2233 swizzles in
+        practice.  Instead of emitting shaders that violate the HW docs, we
+        simply don't claim support for these swizzles.  These swizzles aren't
+        that useful anyway.
       <opt>b0101</opt>
       <opt>b2323</opt>
+      -->
     </mod>
     <encoding mask="0xffec0" exact="0xbd400">
       <and>
@@ -6101,6 +6126,7 @@
         <eq left="lanes1" right="#b3333"/>
       </derived>
     </encoding>
+    <!--
     <encoding mask="0xffcc0" exact="0xbf840">
       <and>
         <eq left="lanes0" right="#b0123"/>
@@ -6114,6 +6140,7 @@
         <eq left="lanes1" right="#b2323"/>
       </derived>
     </encoding>
+    -->
   </ins>
 
   <ins name="ISUB.v4u8" unit="add">
@@ -6129,8 +6156,15 @@
       <opt>b1111</opt>
       <opt>b2222</opt>
       <opt>b3333</opt>
+      <!--
+        The docs claim that b0101 and b2323 are also supported but they don't
+        appear to work.  Instead, they seem to be b0011 and b2233 swizzles in
+        practice.  Instead of emitting shaders that violate the HW docs, we
+        simply don't claim support for these swizzles.  These swizzles aren't
+        that useful anyway.
       <opt>b0101</opt>
       <opt>b2323</opt>
+      -->
     </mod>
     <encoding mask="0xffe40" exact="0xbd400">
       <and>
@@ -6163,6 +6197,7 @@
         <eq left="lanes1" right="#b3333"/>
       </derived>
     </encoding>
+    <!--
     <encoding mask="0xffc40" exact="0xbf840">
       <and>
         <eq left="lanes0" right="#b0123"/>
@@ -6180,6 +6215,7 @@
         <eq left="lanes1" right="#b2323"/>
       </derived>
     </encoding>
+    -->
   </ins>
 
   <ins name="JUMP" mask="0xffe3f" exact="0x6fe34" last="true" dests="0" unit="add">