From 1c87479193d0a5e2b97c668f9c5e5d0c2fb7b723 Mon Sep 17 00:00:00 2001
From: Mary Guillemard <mary.guillemard@collabora.com>
Date: Thu, 24 Jul 2025 09:33:12 +0000
Subject: [PATCH] pan/bi: Properly handle SWZ.v4i8 lowering on v11+

We were not supporting non replicate swizzle and this trigger an
assertion on fossils/parallel-rdp/small_subgroup.foz.

Signed-off-by: Mary Guillemard <mary.guillemard@collabora.com>
Fixes: 1481b14fcb54 ("pan/bi: Lower SWZ.v4i8 to multiple MKVEC.v2i8 on v11+")
Reviewed-by: Olivia Lee <olivia.lee@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36349>
(cherry picked from commit 525f2972a66ca9d952e8dcb5bea18e13da9e4c39)
---
 .pick_status.json                             |  2 +-
 src/panfrost/compiler/valhall/va_lower_isel.c | 59 +++++++++++++++++--
 2 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 02f0120eb6a..b3be4e86381 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -1374,7 +1374,7 @@
         "description": "pan/bi: Properly handle SWZ.v4i8 lowering on v11+",
         "nominated": true,
         "nomination_type": 2,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "1481b14fcb54af9b2263caddc2788dc11e7dca08",
         "notes": null
diff --git a/src/panfrost/compiler/valhall/va_lower_isel.c b/src/panfrost/compiler/valhall/va_lower_isel.c
index d69b37f6e10..4a9e2f313c4 100644
--- a/src/panfrost/compiler/valhall/va_lower_isel.c
+++ b/src/panfrost/compiler/valhall/va_lower_isel.c
@@ -22,9 +22,54 @@
  */
 
 #include "bi_builder.h"
+#include "compiler.h"
 #include "va_compiler.h"
 #include "valhall.h"
 
+static void
+va_compose_mkvec_swz_v4i8(bi_index *b, enum bi_swizzle swz)
+{
+#define B(b0, b1, b2, b3)                                                      \
+   case BI_SWIZZLE_B##b0##b1##b2##b3:                                          \
+      b[0].swizzle = BI_SWIZZLE_B##b0;                                         \
+      b[1].swizzle = BI_SWIZZLE_B##b1;                                         \
+      b[2].swizzle = BI_SWIZZLE_B##b2;                                         \
+      b[3].swizzle = BI_SWIZZLE_B##b3;                                         \
+      break;
+
+   switch (swz) {
+      B(0, 1, 0, 1);
+      B(0, 1, 2, 3);
+      B(2, 3, 0, 1);
+      B(2, 3, 2, 3);
+      B(0, 0, 0, 0);
+      B(1, 1, 1, 1);
+      B(2, 2, 2, 2);
+      B(3, 3, 3, 3);
+      B(0, 0, 1, 1);
+      B(2, 2, 3, 3);
+      B(1, 0, 3, 2);
+      B(3, 2, 1, 0);
+      B(0, 0, 2, 2);
+      B(1, 1, 0, 0);
+      B(2, 2, 0, 0);
+      B(3, 3, 0, 0);
+      B(2, 2, 1, 1);
+      B(3, 3, 1, 1);
+      B(1, 1, 2, 2);
+      B(3, 3, 2, 2);
+      B(0, 0, 3, 3);
+      B(1, 1, 3, 3);
+      B(1, 1, 2, 3);
+
+   default:
+      unreachable("Invalid swizzle");
+      break;
+   }
+
+#undef B
+}
+
 static bi_instr *
 lower(bi_builder *b, bi_instr *I)
 {
@@ -37,10 +82,16 @@ lower(bi_builder *b, bi_instr *I)
    case BI_OPCODE_SWZ_V4I8: {
       /* IADD.v4u8 is gone on v11 */
       if (b->shader->arch >= 11) {
-         assert(I->src[0].swizzle >= BI_SWIZZLE_B0000 &&
-                I->src[0].swizzle <= BI_SWIZZLE_B3333);
-         bi_index tmp = bi_mkvec_v2i8(b, I->src[0], I->src[0], bi_zero());
-         return bi_mkvec_v2i8_to(b, I->dest[0], I->src[0], I->src[0], tmp);
+         bi_index bytes[4] = {
+            I->src[0],
+            I->src[0],
+            I->src[0],
+            I->src[0],
+         };
+
+         va_compose_mkvec_swz_v4i8(bytes, I->src[0].swizzle);
+         bi_index high = bi_mkvec_v2i8(b, bytes[2], bytes[3], bi_zero());
+         return bi_mkvec_v2i8_to(b, I->dest[0], bytes[0], bytes[1], high);
       }
 
       return bi_iadd_v4u8_to(b, I->dest[0], I->src[0], bi_zero(), false);