Optimize away a move

Author: Zoxc

src/librustc/ty/query/plumbing.rs

@@ -136,11 +136,14 @@ impl<'a, 'tcx, Q: QueryDescription<'tcx>> JobOwner<'a, 'tcx, Q> {
                 Entry::Vacant(entry) => {
                     // No job entry for this query. Return a new one to be started later
                     return tls::with_related_context(tcx, |icx| {
+                        // Create the `parent` variable before `info`. This allows LLVM
+                        // to elide the move of `info`
+                        let parent = icx.query.clone();
                         let info = QueryInfo {
                             span,
                             query: Q::query(key.clone()),
                         };
-                        let job = Lrc::new(QueryJob::new(info, icx.query.clone()));
+                        let job = Lrc::new(QueryJob::new(info, parent));
                         let owner = JobOwner {
                             cache,
                             job: job.clone(),