Move ArgAbi::pad_i32 into PassMode::Cast.

Because it's only needed for that variant. This shrinks the types and
clarifies the logic.

Author: nnethercote

src/abi/pass_mode.rs

@@ -100,7 +100,10 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                 }
                 _ => unreachable!("{:?}", self.layout.abi),
             },
-            PassMode::Cast(ref cast) => cast_target_to_abi_params(cast),
+            PassMode::Cast(ref cast, pad_i32) => {
+                assert!(!pad_i32, "padding support not yet implemented");
+                cast_target_to_abi_params(cast)
+            }
             PassMode::Indirect { attrs, extra_attrs: None, on_stack } => {
                 if on_stack {
                     // Abi requires aligning struct size to pointer size
@@ -145,7 +148,7 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                 }
                 _ => unreachable!("{:?}", self.layout.abi),
             },
-            PassMode::Cast(ref cast) => {
+            PassMode::Cast(ref cast, _) => {
                 (None, cast_target_to_abi_params(cast).into_iter().collect())
             }
             PassMode::Indirect { attrs: _, extra_attrs: None, on_stack } => {
@@ -226,7 +229,7 @@ pub(super) fn adjust_arg_for_abi<'tcx>(
             let (a, b) = arg.load_scalar_pair(fx);
             smallvec![a, b]
         }
-        PassMode::Cast(ref cast) => to_casted_value(fx, arg, cast),
+        PassMode::Cast(ref cast, _) => to_casted_value(fx, arg, cast),
         PassMode::Indirect { .. } => {
             if is_owned {
                 match arg.force_stack(fx) {
@@ -284,7 +287,7 @@ pub(super) fn cvalue_for_param<'tcx>(
             assert_eq!(block_params.len(), 2, "{:?}", block_params);
             Some(CValue::by_val_pair(block_params[0], block_params[1], arg_abi.layout))
         }
-        PassMode::Cast(ref cast) => {
+        PassMode::Cast(ref cast, _) => {
             Some(from_casted_value(fx, &block_params, arg_abi.layout, cast))
         }
         PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {

src/abi/returning.rs

@@ -13,7 +13,7 @@ pub(super) fn codegen_return_param<'tcx>(
     block_params_iter: &mut impl Iterator<Item = Value>,
 ) -> CPlace<'tcx> {
     let (ret_place, ret_param): (_, SmallVec<[_; 2]>) = match fx.fn_abi.as_ref().unwrap().ret.mode {
-        PassMode::Ignore | PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(_) => {
+        PassMode::Ignore | PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(..) => {
             let is_ssa = ssa_analyzed[RETURN_PLACE] == crate::analyze::SsaKind::Ssa;
             (
                 super::make_local_place(
@@ -75,7 +75,7 @@ pub(super) fn codegen_with_call_return_arg<'tcx>(
         PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
             unreachable!("unsized return value")
         }
-        PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(_) => (None, None),
+        PassMode::Direct(_) | PassMode::Pair(_, _) | PassMode::Cast(..) => (None, None),
     };
 
     let call_inst = f(fx, return_ptr);
@@ -92,7 +92,7 @@ pub(super) fn codegen_with_call_return_arg<'tcx>(
             ret_place
                 .write_cvalue(fx, CValue::by_val_pair(ret_val_a, ret_val_b, ret_arg_abi.layout));
         }
-        PassMode::Cast(ref cast) => {
+        PassMode::Cast(ref cast, _) => {
             let results =
                 fx.bcx.inst_results(call_inst).iter().copied().collect::<SmallVec<[Value; 2]>>();
             let result =
@@ -131,7 +131,7 @@ pub(crate) fn codegen_return(fx: &mut FunctionCx<'_, '_, '_>) {
             let (ret_val_a, ret_val_b) = place.to_cvalue(fx).load_scalar_pair(fx);
             fx.bcx.ins().return_(&[ret_val_a, ret_val_b]);
         }
-        PassMode::Cast(ref cast) => {
+        PassMode::Cast(ref cast, _) => {
             let place = fx.get_local_place(RETURN_PLACE);
             let ret_val = place.to_cvalue(fx);
             let ret_vals = super::pass_mode::to_casted_value(fx, ret_val, cast);