From cbbc24a4737f3768f423474f1a4740946b90e89c Mon Sep 17 00:00:00 2001
From: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Date: Sat, 19 Jul 2025 18:39:03 -0400
Subject: [PATCH] agx: fix dead phis

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36257>
---
 src/asahi/compiler/agx_compile.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/asahi/compiler/agx_compile.c b/src/asahi/compiler/agx_compile.c
index 2db7c4e6087..98dbeeeec85 100644
--- a/src/asahi/compiler/agx_compile.c
+++ b/src/asahi/compiler/agx_compile.c
@@ -3256,7 +3256,16 @@ agx_optimize_nir(nir_shader *nir, bool soft_fault, uint16_t *preamble_size,
 
    NIR_PASS(_, nir, nir_opt_sink, move_all);
    NIR_PASS(_, nir, nir_opt_move, move_all);
-   NIR_PASS(_, nir, nir_lower_all_phis_to_scalar);
+   NIR_PASS(progress, nir, nir_lower_all_phis_to_scalar);
+
+   /* After lowering phis to scalar, we must copy prop/DCE for correctness. RA
+    * can't deal with dead phis.
+    */
+   do {
+      NIR_PASS(progress, nir, nir_copy_prop);
+      NIR_PASS(progress, nir, nir_opt_dce);
+      progress = false;
+   } while (progress);
 }
 
 /*