Rollup merge of #124579 - RalfJung:align-bytes-usize, r=fmease

Align: add bytes_usize and bits_usize

This matches `Size::bytes/bits_usize`. I recently wanted this in Miri as well.

Author: matthiaskrgr

compiler/rustc_abi/src/lib.rs

@@ -742,11 +742,21 @@ impl Align {
         1 << self.pow2
     }
 
+    #[inline]
+    pub fn bytes_usize(self) -> usize {
+        self.bytes().try_into().unwrap()
+    }
+
     #[inline]
     pub fn bits(self) -> u64 {
         self.bytes() * 8
     }
 
+    #[inline]
+    pub fn bits_usize(self) -> usize {
+        self.bits().try_into().unwrap()
+    }
+
     /// Computes the best alignment possible for the given offset
     /// (the largest power of two that the offset is a multiple of).
     ///

compiler/rustc_transmute/src/layout/tree.rs

@@ -266,7 +266,7 @@ pub(crate) mod rustc {
 
                 ty::Ref(lifetime, ty, mutability) => {
                     let ty_and_layout = cx.layout_of(*ty)?;
-                    let align = ty_and_layout.align.abi.bytes() as usize;
+                    let align = ty_and_layout.align.abi.bytes_usize();
                     let size = ty_and_layout.size.bytes_usize();
                     Ok(Tree::Ref(Ref {
                         lifetime: *lifetime,