From 82e682e3c033b80ea363b314cdaf19c57b55bc70 Mon Sep 17 00:00:00 2001
From: Georg Lehmann <dadschoorse@gmail.com>
Date: Mon, 26 Jan 2026 13:59:16 +0100
Subject: [PATCH] aco: fix demote in header of single iteration loop
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The control is not divergent before a divergent break in a single iteration loop,
but we already pushed the loop mask on the stack.

Fixes: 90faadae722 ("aco/insert_exec_mask: don't disable dead quads on demote in divergent CF")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/14733
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
(cherry picked from commit 4b1996b1c7a1c8676654c50b32e717e788cd1cb9)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39745>
---
 .pick_status.json                         |  2 +-
 src/amd/compiler/aco_insert_exec_mask.cpp | 15 +++++++++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index c0b1eae78b8..2c4e171584f 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -204,7 +204,7 @@
         "description": "aco: fix demote in header of single iteration loop",
         "nominated": true,
         "nomination_type": 2,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "90faadae72280f0da4abef016889bfbdb6a4d3d9",
         "notes": null
diff --git a/src/amd/compiler/aco_insert_exec_mask.cpp b/src/amd/compiler/aco_insert_exec_mask.cpp
index 94f68ce3e3e..23cf2124682 100644
--- a/src/amd/compiler/aco_insert_exec_mask.cpp
+++ b/src/amd/compiler/aco_insert_exec_mask.cpp
@@ -484,10 +484,17 @@ process_instructions(exec_ctx& ctx, Block* block, std::vector<aco_ptr<Instructio
          Operand exit_cond = Operand(exec, bld.lm);
 
          if (state == Exact) {
-            assert(info.exec.size() == 1);
-            bld.sop2(Builder::s_andn2, Definition(exec, bld.lm), bld.def(s1, scc), info.exec[0].op,
-                     src);
-            info.exec[0].op = Operand(exec, bld.lm);
+            bld.sop2(Builder::s_andn2, Definition(exec, bld.lm), bld.def(s1, scc),
+                     info.exec.back().op, src);
+            info.exec.back().op = Operand(exec, bld.lm);
+
+            /* Although this is in uniform CF, it might be a loop without back-edge.
+             * Update the loop restore mask as well.
+             */
+            for (unsigned i = 0; i < info.exec.size() - 1; i++) {
+               assert(info.exec[i + 1].type & mask_type_loop);
+               info.exec[i].op = bld.copy(bld.def(bld.lm), Operand(exec, bld.lm));
+            }
          } else {
             Temp cond = bld.tmp(s1);
             info.exec[0].op = bld.sop2(Builder::s_andn2, bld.def(bld.lm), Definition(cond, scc),