From 7375dfd56da07d12dcb3ff4a9bc9047a5d7d3dcd Mon Sep 17 00:00:00 2001
From: Lorenzo Rossi <snowycoder@gmail.com>
Date: Wed, 13 Aug 2025 18:24:41 +0200
Subject: [PATCH] nak/kepler: Refine instruction scheduling

Previously some KeplerA chips failed various dEQP tests when instruction
scheduling was enabled.
In particular, `memory_model.message_passing` had issues where a
`membar` instruction canceled some in-flight predicate writes, and
`barrier.write_image_tess_control_read_image_compute.image_128_r32_uint`
had issues around the `Cont` instruction.

This patch refines instruction scheduling to better match the output of
nvcc. Fixing the various dEQP failing tests.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13528
Fixes: c35990c4bcb ("nak: Add real instruction dependencies for Kepler")
Signed-off-by: Lorenzo Rossi <snowycoder@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36393>
---
 src/nouveau/compiler/nak/calc_instr_deps.rs      |  9 +++++++++
 src/nouveau/compiler/nak/reg_tracker.rs          | 12 ++++++++++++
 src/nouveau/compiler/nak/sm30_instr_latencies.rs |  8 +++++++-
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/nouveau/compiler/nak/calc_instr_deps.rs b/src/nouveau/compiler/nak/calc_instr_deps.rs
index d54f27392e8..e442c9e4751 100644
--- a/src/nouveau/compiler/nak/calc_instr_deps.rs
+++ b/src/nouveau/compiler/nak/calc_instr_deps.rs
@@ -766,6 +766,15 @@ fn calc_delays(f: &mut Function, sm: &dyn ShaderModel) -> u32 {
             uses.for_each_instr_src_mut(instr, |i, c| {
                 c.add_read((ip, i));
             });
+            // Kepler A membar conflicts with predicate writes
+            if sm.is_kepler_a() && matches!(&instr.op, Op::MemBar(_)) {
+                uses.for_each_pred(|c| {
+                    c.add_read((ip, usize::MAX));
+                });
+                uses.for_each_carry(|c| {
+                    c.add_read((ip, usize::MAX));
+                });
+            }
             for (bar, c) in bars.iter_mut().enumerate() {
                 if instr.deps.wt_bar_mask & (1 << bar) != 0 {
                     *c = min_start;
diff --git a/src/nouveau/compiler/nak/reg_tracker.rs b/src/nouveau/compiler/nak/reg_tracker.rs
index 1f422786980..49341ca1e8f 100644
--- a/src/nouveau/compiler/nak/reg_tracker.rs
+++ b/src/nouveau/compiler/nak/reg_tracker.rs
@@ -83,6 +83,18 @@ impl<T> RegTracker<T> {
             }
         }
     }
+
+    pub fn for_each_pred(&mut self, mut f: impl FnMut(&mut T)) {
+        for p in &mut self.pred[..] {
+            f(p);
+        }
+    }
+
+    pub fn for_each_carry(&mut self, mut f: impl FnMut(&mut T)) {
+        for c in &mut self.carry {
+            f(c);
+        }
+    }
 }
 
 impl<T> Index<RegRef> for RegTracker<T> {
diff --git a/src/nouveau/compiler/nak/sm30_instr_latencies.rs b/src/nouveau/compiler/nak/sm30_instr_latencies.rs
index 011da013382..41980ae3fca 100644
--- a/src/nouveau/compiler/nak/sm30_instr_latencies.rs
+++ b/src/nouveau/compiler/nak/sm30_instr_latencies.rs
@@ -13,6 +13,9 @@ pub fn instr_latency(_sm: u8, op: &Op, _dst_idx: usize) -> u32 {
         Op::Ld(_) => 24,
         Op::ALd(_) => 24,
         Op::IMul(_) => 15, // This does not apply to imad, right? right???
+        Op::ISetP(_) => 13,
+        Op::PSetP(_) => 13,
+        Op::IAdd2(o) if !o.carry_out.is_none() => 13,
         Op::Tex(_)
         | Op::Tld(_)
         | Op::Tld4(_)
@@ -23,7 +26,8 @@ pub fn instr_latency(_sm: u8, op: &Op, _dst_idx: usize) -> u32 {
     }
 }
 
-pub fn instr_exec_latency(_sm: u8, op: &Op) -> u32 {
+pub fn instr_exec_latency(sm: u8, op: &Op) -> u32 {
+    let is_kepler_a = sm == 30;
     match op {
         Op::Tex(_)
         | Op::Tld(_)
@@ -31,6 +35,8 @@ pub fn instr_exec_latency(_sm: u8, op: &Op) -> u32 {
         | Op::Tmml(_)
         | Op::Txd(_)
         | Op::Txq(_) => 17,
+        Op::MemBar(_) => 16,
+        Op::Cont(_) | Op::Brk(_) if is_kepler_a => 5,
         Op::Exit(_) => 15,
         _ => 1,
     }