nak: add hw_test for MUFU.F16

Reviewed-by: Mel Henning <mhenning@darkrefraction.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40392>

src/nouveau/compiler/nak/hw_tests.rs

@@ -2009,3 +2009,82 @@ fn test_op_sgxt() {
         });
     }
 }
+
+#[test]
+fn test_op_mufu_f16_down() {
+    let run = &RunSingleton::get();
+    if run.sm.sm() < 73 {
+        return;
+    }
+
+    for op in [
+        MuFuOp::Cos,
+        MuFuOp::Sin,
+        MuFuOp::Exp2,
+        MuFuOp::Log2,
+        MuFuOp::Rcp,
+        MuFuOp::Rsq,
+        MuFuOp::Sqrt,
+        MuFuOp::Tanh,
+    ] {
+        let mut b = TestShaderBuilder::new(&run.sm);
+        let src: Src = b.ld_test_data(0, MemType::B32).into();
+        let up_convert = b.alloc_ssa(RegFile::GPR);
+        let mufu = b.alloc_ssa(RegFile::GPR);
+        let dst = b.alloc_ssa(RegFile::GPR);
+        let dst16 = b.alloc_ssa(RegFile::GPR);
+
+        b.push_op(OpF2F {
+            dst: up_convert.into(),
+            src: src.clone(),
+            src_type: FloatType::F16,
+            dst_type: FloatType::F32,
+            ftz: false,
+            rnd_mode: FRndMode::NearestEven,
+            integer_rnd: false,
+        });
+        b.push_op(OpMuFu {
+            dst: mufu.into(),
+            src: up_convert.into(),
+            op: op,
+            op_type: FloatType::F32,
+        });
+        b.push_op(OpMuFu {
+            dst: dst16.into(),
+            src: src,
+            op: op,
+            op_type: FloatType::F16,
+        });
+        b.push_op(OpF2F {
+            dst: dst.into(),
+            src: mufu.into(),
+            src_type: FloatType::F32,
+            dst_type: FloatType::F16,
+            ftz: false,
+            rnd_mode: FRndMode::Zero,
+            integer_rnd: false,
+        });
+
+        b.st_test_data(4, MemType::B32, dst.into());
+        b.st_test_data(8, MemType::B32, dst16.into());
+
+        let bin = b.compile();
+
+        let mut data = Vec::new();
+        for i in 0..=u16::MAX {
+            data.push([u32::from(i), 0, 0]);
+        }
+
+        run.run.run(&bin, &mut data).unwrap();
+        for [_, fp32, fp16] in data {
+            // Around infinity we get a _slightly_ different result for Exp2 and Rcp
+            if fp16 == 0x7c00 && matches!(op, MuFuOp::Exp2 | MuFuOp::Rcp) {
+                assert!(fp32 == 0x7c00 || fp32 == 0x7bff);
+            } else if fp16 == 0xfc00 && matches!(op, MuFuOp::Rcp) {
+                assert!(fp32 == 0xfc00 || fp32 == 0xfbff);
+            } else {
+                assert_eq!(fp32, fp16);
+            }
+        }
+    }
+}