Revert "rustc: don't unpack newtypes of scalar-pairs with mismatched alignment."

This reverts commit db9d4b1.

Author: arielb1

src/librustc/ty/layout.rs

@@ -1083,9 +1083,7 @@ impl<'a, 'tcx> LayoutDetails {
                         // We have exactly one non-ZST field.
                         (Some((i, field)), None, None) => {
                             // Field fills the struct and it has a scalar or scalar pair ABI.
-                            if offsets[i].bytes() == 0 &&
-                               align.abi() == field.align.abi() &&
-                               size == field.size {
+                            if offsets[i].bytes() == 0 && size == field.size {
                                 match field.abi {
                                     // For plain scalars we can't unpack newtypes
                                     // for `#[repr(C)]`, as that affects C ABIs.

src/test/codegen/packed.rs

@@ -57,14 +57,3 @@ pub fn pkd_pair(pair1: &mut PackedPair, pair2: &mut PackedPair) {
 // CHECK: call void @llvm.memcpy.{{.*}}(i8* %{{.*}}, i8* %{{.*}}, i{{[0-9]+}} 5, i32 1, i1 false)
     *pair2 = *pair1;
 }
-
-#[repr(packed)]
-#[derive(Copy, Clone)]
-pub struct PackedNestedPair((u32, u32));
-
-// CHECK-LABEL: @pkd_nested_pair
-#[no_mangle]
-pub fn pkd_nested_pair(pair1: &mut PackedNestedPair, pair2: &mut PackedNestedPair) {
-// CHECK: call void @llvm.memcpy.{{.*}}(i8* %{{.*}}, i8* %{{.*}}, i{{[0-9]+}} 8, i32 1, i1 false)
-    *pair2 = *pair1;
-}