Use to_le_bytes and from_le_bytes instead of manual byte shuffling

Author: bjorn3

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -647,10 +647,7 @@ impl<'tcx> MetadataBlob {
     crate fn get_root(&self) -> CrateRoot<'tcx> {
         let slice = &self.blob()[..];
         let offset = METADATA_HEADER.len();
-        let pos = (((slice[offset + 0] as u32) << 24)
-            | ((slice[offset + 1] as u32) << 16)
-            | ((slice[offset + 2] as u32) << 8)
-            | ((slice[offset + 3] as u32) << 0)) as usize;
+        let pos = (u32::from_le_bytes(slice[offset..offset + 4].try_into().unwrap())) as usize;
         Lazy::<CrateRoot<'tcx>>::from_position(NonZeroUsize::new(pos).unwrap()).decode(self)
     }
 

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -2214,10 +2214,7 @@ fn encode_metadata_impl(tcx: TyCtxt<'_>) -> EncodedMetadata {
     // Encode the root position.
     let header = METADATA_HEADER.len();
     let pos = root.position.get();
-    result[header + 0] = (pos >> 24) as u8;
-    result[header + 1] = (pos >> 16) as u8;
-    result[header + 2] = (pos >> 8) as u8;
-    result[header + 3] = (pos >> 0) as u8;
+    result[header..header + 4].copy_from_slice(&pos.to_le_bytes());
 
     // Record metadata size for self-profiling
     tcx.prof.artifact_size("crate_metadata", "crate_metadata", result.len() as u64);