Fix Switch for 128bit integers

cranelift/codegen/meta/src/cdsl/typevar.rs

@@ -302,7 +302,7 @@ impl TypeVar {
     pub fn to_rust_code(&self) -> String {
         match &self.base {
             Some(base) => format!(
-                "{}.{}()",
+                "{}.{}().unwrap()",
                 base.type_var.to_rust_code(),
                 base.derived_func.name()
             ),

cranelift/codegen/meta/src/shared/legalize.rs

@@ -402,6 +402,17 @@ pub(crate) fn define(insts: &InstructionGroup, imm: &Immediates) -> TransformGro
         );
     }
 
+    let zero = Literal::constant(&imm.imm64, 0);
+    narrow.legalize(
+        def!(a = iadd_imm.I128(x, c)),
+        vec![
+            def!(yh = iconst.I64(zero)),
+            def!(yl = iconst.I64(c)),
+            def!(y = iconcat.I64(yh, yl)),
+            def!(a = iadd(x, y)),
+        ],
+    );
+
     // Widen instructions with one input operand.
     for &op in &[bnot, popcnt] {
         for &int_ty in &[I8, I16] {