nak: Add tests for OpFlo

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30402>

src/nouveau/compiler/nak/hw_tests.rs

@@ -515,6 +515,30 @@ pub fn test_foldable_op(op: impl Foldable + Clone + Into<Op>) {
     test_foldable_op_with(op, &mut |_| a.get_u32());
 }
 
+#[test]
+fn test_op_flo() {
+    for i in 0..4 {
+        let op = OpFlo {
+            dst: Dst::None,
+            src: 0.into(),
+            signed: i & 0x1 != 0,
+            return_shift_amount: i & 0x2 != 0,
+        };
+
+        let mut a = Acorn::new();
+        test_foldable_op_with(op, &mut |_| {
+            let x = a.get_uint(36);
+            let signed = x & (1 << 32) != 0;
+            let shift = x >> 33;
+            if signed {
+                ((x as i32) >> shift) as u32
+            } else {
+                (x as u32) >> shift
+            }
+        });
+    }
+}
+
 #[test]
 fn test_op_iabs() {
     if RunSingleton::get().sm.sm() >= 70 {

src/nouveau/compiler/nak/ir.rs

@@ -3225,7 +3225,7 @@ impl DisplayOp for OpBfe {
 impl_display_for_op!(OpBfe);
 
 #[repr(C)]
-#[derive(SrcsAsSlice, DstsAsSlice)]
+#[derive(Clone, SrcsAsSlice, DstsAsSlice)]
 pub struct OpFlo {
     #[dst_type(GPR)]
     pub dst: Dst,
@@ -3237,6 +3237,23 @@ pub struct OpFlo {
     pub return_shift_amount: bool,
 }
 
+impl Foldable for OpFlo {
+    fn fold(&self, _sm: &dyn ShaderModel, f: &mut OpFoldData<'_>) {
+        let src = f.get_u32_src(self, &self.src);
+        let leading = if self.signed && (src & 0x80000000) != 0 {
+            (!src).leading_zeros()
+        } else {
+            src.leading_zeros()
+        };
+        let dst = if self.return_shift_amount {
+            leading
+        } else {
+            31 - leading
+        };
+        f.set_u32_dst(self, &self.dst, dst);
+    }
+}
+
 impl DisplayOp for OpFlo {
     fn fmt_op(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "flo")?;