Remove all usages of iconst.i128

Support was removed from Cranelift

src/cast.rs

@@ -149,7 +149,7 @@ pub(crate) fn clif_int_or_float_cast(
         }
 
         let is_not_nan = fx.bcx.ins().fcmp(FloatCC::Equal, from, from);
-        let zero = fx.bcx.ins().iconst(to_ty, 0);
+        let zero = type_zero_value(&mut fx.bcx, to_ty);
         fx.bcx.ins().select(is_not_nan, val, zero)
     } else if from_ty.is_float() && to_ty.is_float() {
         // float -> float

src/common.rs

@@ -167,6 +167,15 @@ pub(crate) fn codegen_icmp_imm(
     }
 }
 
+pub(crate) fn type_zero_value(bcx: &mut FunctionBuilder<'_>, ty: Type) -> Value {
+    if ty == types::I128 {
+        let zero = bcx.ins().iconst(types::I64, 0);
+        bcx.ins().iconcat(zero, zero)
+    } else {
+        bcx.ins().iconst(ty, 0)
+    }
+}
+
 pub(crate) fn type_min_max_value(
     bcx: &mut FunctionBuilder<'_>,
     ty: Type,

src/discriminant.rs

@@ -278,8 +278,14 @@ pub(crate) fn codegen_get_discriminant<'tcx>(
                 fx.bcx.ins().iadd(tagged_discr, delta)
             };
 
-            let untagged_variant =
+            let untagged_variant = if cast_to == types::I128 {
-                fx.bcx.ins().iconst(cast_to, i64::from(untagged_variant.as_u32()));
+                let zero = fx.bcx.ins().iconst(types::I64, 0);
+                let untagged_variant =
+                    fx.bcx.ins().iconst(types::I64, i64::from(untagged_variant.as_u32()));
+                fx.bcx.ins().iconcat(untagged_variant, zero)
+            } else {
+                fx.bcx.ins().iconst(cast_to, i64::from(untagged_variant.as_u32()))
+            };
             let discr = fx.bcx.ins().select(is_niche, tagged_discr, untagged_variant);
             let res = CValue::by_val(discr, dest_layout);
             dest.write_cvalue(fx, res);

src/intrinsics/simd.rs

@@ -713,7 +713,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
 
             let res_type =
                 Type::int_with_byte_size(u16::try_from(expected_bytes).unwrap()).unwrap();
-            let mut res = fx.bcx.ins().iconst(res_type, 0);
+            let mut res = type_zero_value(&mut fx.bcx, res_type);
 
             let lanes = match fx.tcx.sess.target.endian {
                 Endian::Big => Box::new(0..lane_count) as Box<dyn Iterator<Item = u64>>,