nak: Manually flush denorms for nir_op_fquantize2f16 pre-Volta

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30402>
2024-07-28 12:00:00 -05:00
parent 315e8d6faa
commit 7b84319ec4
1 changed files with 19 additions and 1 deletions
@@ -1160,7 +1160,25 @@ impl<'a> ShaderFromNir<'a> {
                    high: false,
                    integer_rnd: false,
                });
-                dst
+                if b.sm() < 70 {
+                    // Pre-Volta, F2F.ftz doesn't flush denorms so we need to do
+                    // that manually
+                    let denorm = b.alloc_ssa(RegFile::Pred, 1);
+                    b.push_op(OpFSetP {
+                        dst: denorm.into(),
+                        set_op: PredSetOp::And,
+                        cmp_op: FloatCmpOp::OrdLt,
+                        srcs: [srcs[0].fabs(), 0x38800000.into()],
+                        accum: true.into(),
+                        ftz: false,
+                    });
+                    // Get the correctly signed zero
+                    let zero =
+                        b.lop2(LogicOp2::And, srcs[0], 0x80000000.into());
+                    b.sel(denorm.into(), zero.into(), dst.into())
+                } else {
+                    dst
+                }
            }
            nir_op_frcp => {
                assert!(alu.def.bit_size() == 32);