nak/legalize: Fold immediate sources before instructions

This way, if we insert a copy to move the immediate to a GPR, the
immediate we place in the copy is also folded.

Fixes: 85462f7455 ("nak: Legalize immediates with source modifiers")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29591>

src/nouveau/compiler/nak/legalize.rs

@@ -815,6 +815,11 @@ fn legalize_instr(
     ip: usize,
     instr: &mut Instr,
 ) {
+    let src_types = instr.src_types();
+    for (i, src) in instr.srcs_mut().iter_mut().enumerate() {
+        *src = src.fold_imm(src_types[i]);
+    }
+
     if b.sm() >= 70 {
         legalize_sm70_instr(b, bl, ip, instr);
     } else if b.sm() >= 50 {
@@ -823,11 +828,6 @@ fn legalize_instr(
         panic!("Unknown shader model SM{}", b.sm());
     }
 
-    let src_types = instr.src_types();
-    for (i, src) in instr.srcs_mut().iter_mut().enumerate() {
-        *src = src.fold_imm(src_types[i]);
-    }
-
     let mut vec_src_map: HashMap<SSARef, SSARef> = HashMap::new();
     let mut vec_comps = HashSet::new();
     for src in instr.srcs_mut() {