From d15b5fadbbe189026ad02a0885fccf1d8b22ab06 Mon Sep 17 00:00:00 2001
From: Mel Henning <mhenning@darkrefraction.com>
Date: Sat, 31 May 2025 12:26:16 -0400
Subject: [PATCH] nir/divergence_analysis: Update LCSSA comment
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Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35271>
---
 src/compiler/nir/nir_divergence_analysis.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/compiler/nir/nir_divergence_analysis.c b/src/compiler/nir/nir_divergence_analysis.c
index 47dda4ec134..409e82ac404 100644
--- a/src/compiler/nir/nir_divergence_analysis.c
+++ b/src/compiler/nir/nir_divergence_analysis.c
@@ -28,7 +28,9 @@
  * That is, the variable has the same value for all invocations
  * of the group.
  *
- * This divergence analysis pass expects the shader to be in LCSSA-form.
+ * If the shader is not in LCSSA-form, passes need to use nir_src_is_divergent()
+ * instead of reading the value from src->ssa->divergent as without LCSSA a src
+ * can have a different divergence than the corresponding SSA-def.
  *
  * This algorithm implements "The Simple Divergence Analysis" from
  * Diogo Sampaio, Rafael De Souza, Sylvain Collange, Fernando Magno Quintão Pereira.