nak: Implement load_sample_id and load_sample_mask_in

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24998>

src/nouveau/compiler/nak_encode_sm75.rs

@@ -1536,6 +1536,22 @@ impl SM75Instr {
         self.set_field(72..80, op.idx);
     }
 
+    fn encode_pixld(&mut self, op: &OpPixLd) {
+        self.set_opcode(0x925);
+        self.set_dst(op.dst);
+        self.set_field(
+            78..81,
+            match op.val {
+                PixVal::MsCount => 0_u8,
+                PixVal::CovMask => 1_u8,
+                PixVal::CentroidOffset => 2_u8,
+                PixVal::MyIndex => 3_u8,
+                PixVal::InnerCoverage => 4_u8,
+            },
+        );
+        self.set_pred_dst(81..84, Dst::None);
+    }
+
     fn encode_s2r(&mut self, op: &OpS2R) {
         self.set_opcode(0x919);
         self.set_dst(op.dst);
@@ -1605,6 +1621,7 @@ impl SM75Instr {
             Op::Exit(op) => si.encode_exit(&op),
             Op::Bar(op) => si.encode_bar(&op),
             Op::CS2R(op) => si.encode_cs2r(&op),
+            Op::PixLd(op) => si.encode_pixld(&op),
             Op::S2R(op) => si.encode_s2r(&op),
             _ => panic!("Unhandled instruction"),
         }

src/nouveau/compiler/nak_from_nir.rs

@@ -1264,6 +1264,22 @@ impl<'a> ShaderFromNir<'a> {
                 }
                 self.set_dst(&intrin.def, dst);
             }
+            nir_intrinsic_load_sample_id => {
+                let dst = b.alloc_ssa(RegFile::GPR, 1);
+                b.push_op(OpPixLd {
+                    dst: dst.into(),
+                    val: PixVal::MyIndex,
+                });
+                self.set_dst(&intrin.def, dst);
+            }
+            nir_intrinsic_load_sample_mask_in => {
+                let dst = b.alloc_ssa(RegFile::GPR, 1);
+                b.push_op(OpPixLd {
+                    dst: dst.into(),
+                    val: PixVal::CovMask,
+                });
+                self.set_dst(&intrin.def, dst);
+            }
             nir_intrinsic_load_scratch => {
                 let size_B =
                     (intrin.def.bit_size() / 8) * intrin.def.num_components();

src/nouveau/compiler/nak_ir.rs

@@ -3277,6 +3277,35 @@ impl fmt::Display for OpCS2R {
     }
 }
 
+pub enum PixVal {
+    MsCount,
+    CovMask,
+    CentroidOffset,
+    MyIndex,
+    InnerCoverage,
+}
+
+#[repr(C)]
+#[derive(SrcsAsSlice, DstsAsSlice)]
+pub struct OpPixLd {
+    pub dst: Dst,
+    pub val: PixVal,
+}
+
+impl fmt::Display for OpPixLd {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "PIXLD")?;
+        match self.val {
+            PixVal::MsCount => write!(f, ".MSCOUNT")?,
+            PixVal::CovMask => write!(f, ".COVMASK")?,
+            PixVal::CentroidOffset => write!(f, ".CENTROID_OFFSET")?,
+            PixVal::MyIndex => write!(f, ".MY_INDEX")?,
+            PixVal::InnerCoverage => write!(f, ".INNER_COVERAGE")?,
+        }
+        write!(f, " {}", self.dst)
+    }
+}
+
 #[repr(C)]
 #[derive(SrcsAsSlice, DstsAsSlice)]
 pub struct OpS2R {
@@ -3656,6 +3685,7 @@ pub enum Op {
     Exit(OpExit),
     Bar(OpBar),
     CS2R(OpCS2R),
+    PixLd(OpPixLd),
     S2R(OpS2R),
     Undef(OpUndef),
     PhiSrcs(OpPhiSrcs),
@@ -4044,7 +4074,7 @@ impl Instr {
             Op::Bra(_) | Op::Exit(_) => true,
 
             // Miscellaneous ops
-            Op::Bar(_) | Op::CS2R(_) | Op::S2R(_) => false,
+            Op::Bar(_) | Op::CS2R(_) | Op::PixLd(_) | Op::S2R(_) => false,
 
             // Virtual ops
             Op::Undef(_)