From d92ce8566b015fba5352e1080713f90e2ad1efb0 Mon Sep 17 00:00:00 2001
From: Gert Wollny <gert.wollny@collabora.com>
Date: Fri, 22 Jul 2022 15:51:50 +0200
Subject: [PATCH] r600/sfn: Fix used of local shared write mask

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17678>
---
 src/gallium/drivers/r600/sfn/sfn_shader.cpp | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/gallium/drivers/r600/sfn/sfn_shader.cpp b/src/gallium/drivers/r600/sfn/sfn_shader.cpp
index f123d2dc929..61fd0849eb7 100644
--- a/src/gallium/drivers/r600/sfn/sfn_shader.cpp
+++ b/src/gallium/drivers/r600/sfn/sfn_shader.cpp
@@ -982,12 +982,15 @@ bool Shader::emit_local_store(nir_intrinsic_instr *instr)
    unsigned write_mask = nir_intrinsic_write_mask(instr);
 
    auto address = value_factory().src(instr->src[1], 0);
-   int swizzle_base = (write_mask & 0x3) ? 0 : 2;
-   write_mask |= write_mask >> 2;
+   int swizzle_base = 0;
+   unsigned w = write_mask;
+   while (!(w & 1)) {
+      ++swizzle_base;
+      w >>= 1;
+   }
+   write_mask = write_mask >> swizzle_base;
 
    if ((write_mask & 3) != 3) {
-      if (write_mask == 2)
-         swizzle_base += 1;
       auto value = value_factory().src(instr->src[0], swizzle_base);
       emit_instruction(new LDSAtomicInstr(LDS_WRITE, nullptr, address, {value}));
    } else {