Auto merge of #99667 - ouz-a:some_branch, r=oli-obk

Optimize `UnDerefer`

Addresses the performance [issues](https://github.com/rust-lang/rust/pull/98145#issuecomment-1183548597) faced here.

r? `@oli-obk`

2 files changed, 4 insertions, 5 deletions

diff --git a/compiler/rustc_mir_transform/src/elaborate_drops.rs b/compiler/rustc_mir_transform/src/elaborate_drops.rs
index 71ab6dee1b6..9c1fcbaa69d 100644
--- a/compiler/rustc_mir_transform/src/elaborate_drops.rs
+++ b/compiler/rustc_mir_transform/src/elaborate_drops.rs
@@ -28,20 +28,19 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         debug!("elaborate_drops({:?} @ {:?})", body.source, body.span);
 
-        let mut un_derefer = UnDerefer { tcx: tcx, derefer_sidetable: Default::default() };
-        un_derefer.ref_finder(body);
         let def_id = body.source.def_id();
         let param_env = tcx.param_env_reveal_all_normalized(def_id);
-        let move_data = match MoveData::gather_moves(body, tcx, param_env) {
+        let (side_table, move_data) = match MoveData::gather_moves(body, tcx, param_env) {
             Ok(move_data) => move_data,
             Err((move_data, _)) => {
                 tcx.sess.delay_span_bug(
                     body.span,
                     "No `move_errors` should be allowed in MIR borrowck",
                 );
-                move_data
+                (Default::default(), move_data)
             }
         };
+        let un_derefer = UnDerefer { tcx: tcx, derefer_sidetable: side_table };
         let elaborate_patch = {
             let body = &*body;
             let env = MoveDataParamEnv { move_data, param_env };
diff --git a/compiler/rustc_mir_transform/src/remove_uninit_drops.rs b/compiler/rustc_mir_transform/src/remove_uninit_drops.rs
index c48aa9a90ef..96b715402e7 100644
--- a/compiler/rustc_mir_transform/src/remove_uninit_drops.rs
+++ b/compiler/rustc_mir_transform/src/remove_uninit_drops.rs
@@ -21,7 +21,7 @@ pub struct RemoveUninitDrops;
 impl<'tcx> MirPass<'tcx> for RemoveUninitDrops {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         let param_env = tcx.param_env(body.source.def_id());
-        let Ok(move_data) = MoveData::gather_moves(body, tcx, param_env) else {
+        let Ok((_,move_data)) = MoveData::gather_moves(body, tcx, param_env) else {
             // We could continue if there are move errors, but there's not much point since our
             // init data isn't complete.
             return;