aarch64-linux: properly handle 128bit aligned aggregates

compiler/rustc_abi/src/lib.rs

@@ -1536,6 +1536,11 @@ pub struct LayoutS {
     /// Only used on i686-windows, where the argument passing ABI is different when alignment is
     /// requested, even if the requested alignment is equal to the natural alignment.
     pub repr_align: Option<Align>,
+
+    /// The alignment the type would have, ignoring any `repr(align)` but including `repr(packed)`.
+    /// Only used on aarch64-linux, where the argument passing ABI ignores the requested alignment
+    /// in some cases.
+    pub unadjusted_abi_align: Align,
 }
 
 impl LayoutS {
@@ -1551,6 +1556,7 @@ impl LayoutS {
             size,
             align,
             repr_align: None,
+            unadjusted_abi_align: align.abi,
         }
     }
 }
@@ -1560,7 +1566,16 @@ impl fmt::Debug for LayoutS {
         // This is how `Layout` used to print before it become
         // `Interned<LayoutS>`. We print it like this to avoid having to update
         // expected output in a lot of tests.
-        let LayoutS { size, align, abi, fields, largest_niche, variants, repr_align } = self;
+        let LayoutS {
+            size,
+            align,
+            abi,
+            fields,
+            largest_niche,
+            variants,
+            repr_align,
+            unadjusted_abi_align,
+        } = self;
         f.debug_struct("Layout")
             .field("size", size)
             .field("align", align)
@@ -1569,6 +1584,7 @@ impl fmt::Debug for LayoutS {
             .field("largest_niche", largest_niche)
             .field("variants", variants)
             .field("repr_align", repr_align)
+            .field("unadjusted_abi_align", unadjusted_abi_align)
             .finish()
     }
 }
@@ -1613,6 +1629,10 @@ impl<'a> Layout<'a> {
         self.0.0.repr_align
     }
 
+    pub fn unadjusted_abi_align(self) -> Align {
+        self.0.0.unadjusted_abi_align
+    }
+
     /// Whether the layout is from a type that implements [`std::marker::PointerLike`].
     ///
     /// Currently, that means that the type is pointer-sized, pointer-aligned,