nak: Plumb through LDC modes

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28474>

src/nouveau/compiler/nak/encode_sm70.rs

@@ -1492,7 +1492,15 @@ impl SM70Instr {
         );
 
         self.set_mem_type(73..76, op.mem_type);
-        self.set_field(78..80, 0_u8); // subop
+        self.set_field(
+            78..80,
+            match op.mode {
+                LdcMode::Indexed => 0_u8,
+                LdcMode::IndexedLinear => 1_u8,
+                LdcMode::IndexedSegmented => 2_u8,
+                LdcMode::IndexedSegmentedLinear => 3_u8,
+            },
+        );
     }
 
     fn encode_stg(&mut self, op: &OpSt) {

src/nouveau/compiler/nak/from_nir.rs

@@ -2502,10 +2502,12 @@ impl<'a> ShaderFromNir<'a> {
                             dst: dst.into(),
                             cb: cb.into(),
                             offset: off,
+                            mode: LdcMode::Indexed,
                             mem_type: MemType::from_size(size_B, false),
                         });
                     }
                 } else {
+
                     panic!("Indirect UBO indices not yet supported");
                 }
                 self.set_dst(&intrin.def, dst);

src/nouveau/compiler/nak/ir.rs

@@ -3811,6 +3811,25 @@ impl DisplayOp for OpLd {
 }
 impl_display_for_op!(OpLd);
 
+#[allow(dead_code)]
+pub enum LdcMode {
+    Indexed,
+    IndexedLinear,
+    IndexedSegmented,
+    IndexedSegmentedLinear,
+}
+
+impl fmt::Display for LdcMode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            LdcMode::Indexed => Ok(()),
+            LdcMode::IndexedLinear => write!(f, ".il"),
+            LdcMode::IndexedSegmented => write!(f, ".is"),
+            LdcMode::IndexedSegmentedLinear => write!(f, ".isl"),
+        }
+    }
+}
+
 #[repr(C)]
 #[derive(SrcsAsSlice, DstsAsSlice)]
 pub struct OpLdc {
@@ -3822,6 +3841,7 @@ pub struct OpLdc {
     #[src_type(GPR)]
     pub offset: Src,
 
+    pub mode: LdcMode,
     pub mem_type: MemType,
 }
 
@@ -3830,7 +3850,7 @@ impl DisplayOp for OpLdc {
         let SrcRef::CBuf(cb) = self.cb.src_ref else {
             panic!("Not a cbuf");
         };
-        write!(f, "ldc{} {}[", self.mem_type, cb.buf)?;
+        write!(f, "ldc{}{} {}[", self.mode, self.mem_type, cb.buf)?;
         if self.offset.is_zero() {
             write!(f, "+{:#x}", cb.offset)?;
         } else if cb.offset == 0 {