From 2ad12150e847978fa8eec83d635c15e75cfe8c7f Mon Sep 17 00:00:00 2001
From: Mel Henning <mhenning@darkrefraction.com>
Date: Mon, 3 Nov 2025 13:45:43 -0500
Subject: [PATCH] nak/opt_lop: Don't handle modifiers in dedup_srcs
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The handling in dedup_srcs was incorrect because it would apply the
modifier from srcs[i] to the LUT without removing the modifier from the
instruction. We can fix and simplify this code by removing all modifiers
before the dedup_srcs() call, which we were doing immediately after the
call anyway.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13966
Fixes: 66c9c40f68bc ("nak: Handle modifiers in dedup_srcs() in opt_lop()")
Reviewed-by: Seán de Búrca <sdeburca@fastmail.net>
Reviewed-by: Lorenzo Rossi <git@rossilorenzo.dev>
(cherry picked from commit 041216e605a89cfb36edb4a5a6c97ffbc835a1a1)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38268>
---
 .pick_status.json                   |  2 +-
 src/nouveau/compiler/nak/opt_lop.rs | 28 +++++++++-------------------
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 8599615ad02..551e3404658 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -204,7 +204,7 @@
         "description": "nak/opt_lop: Don't handle modifiers in dedup_srcs",
         "nominated": true,
         "nomination_type": 2,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "66c9c40f68bcf738b1b5dd9a26d141d4c71e4522",
         "notes": null
diff --git a/src/nouveau/compiler/nak/opt_lop.rs b/src/nouveau/compiler/nak/opt_lop.rs
index a6761891855..416784e0885 100644
--- a/src/nouveau/compiler/nak/opt_lop.rs
+++ b/src/nouveau/compiler/nak/opt_lop.rs
@@ -73,23 +73,11 @@ impl LopPass {
         for i in 0..2 {
             for j in (i + 1)..3 {
                 if srcs[i].src_ref == srcs[j].src_ref {
+                    assert!(srcs[i].is_unmodified());
+                    assert!(srcs[j].is_unmodified());
                     *op = LogicOp3::new_lut(&|x, y, z| {
-                        let dup = [x, y, z][i];
-                        let si = match srcs[i].src_mod {
-                            SrcMod::None => dup,
-                            SrcMod::BNot => !dup,
-                            _ => panic!("Not a bitwise modifer"),
-                        };
-                        let sj = match srcs[j].src_mod {
-                            SrcMod::None => dup,
-                            SrcMod::BNot => !dup,
-                            _ => panic!("Not a bitwise modifer"),
-                        };
-
                         let mut s = [x, y, z];
-                        s[i] = si;
-                        s[j] = sj;
-
+                        s[j] = s[i];
                         op.eval(s[0], s[1], s[2])
                     });
                 }
@@ -220,17 +208,19 @@ impl LopPass {
     }
 
     fn opt_plop3(&mut self, op: &mut OpPLop3) {
-        self.dedup_srcs(&mut op.ops[0], &op.srcs);
-        self.dedup_srcs(&mut op.ops[1], &op.srcs);
-
-        // Replace unused sources with PT
         for (i, src) in op.srcs.iter_mut().enumerate() {
             if src.src_mod.is_bnot() {
                 op.ops[0].invert_src(i);
                 op.ops[1].invert_src(i);
                 src.src_mod = SrcMod::None;
             }
+        }
 
+        self.dedup_srcs(&mut op.ops[0], &op.srcs);
+        self.dedup_srcs(&mut op.ops[1], &op.srcs);
+
+        // Replace unused sources with PT
+        for (i, src) in op.srcs.iter_mut().enumerate() {
             if let Some(b) = src_as_bool(src) {
                 op.ops[0].fix_src(i, b);
                 op.ops[1].fix_src(i, b);