3 files changed, 25 insertions, 10 deletions
diff --git a/compiler/rustc_mir_transform/src/elaborate_drops.rs b/compiler/rustc_mir_transform/src/elaborate_drops.rs
index 6a89d067275..b62d7da2a4c 100644
--- a/compiler/rustc_mir_transform/src/elaborate_drops.rs
+++ b/compiler/rustc_mir_transform/src/elaborate_drops.rs
@@ -170,6 +170,7 @@ impl<'a, 'tcx> DropElaborator<'a, 'tcx> for Elaborator<'a, '_, 'tcx> {
         self.ctxt.param_env()
     }
 
+    #[instrument(level = "debug", skip(self), ret)]
     fn drop_style(&self, path: Self::Path, mode: DropFlagMode) -> DropStyle {
         let ((maybe_live, maybe_dead), multipart) = match mode {
             DropFlagMode::Shallow => (self.ctxt.init_data.maybe_live_dead(path), false),
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 9e4bc456d51..754f2ee8376 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -480,6 +480,7 @@ fn run_runtime_lowering_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     let passes: &[&dyn MirPass<'tcx>] = &[
         // These next passes must be executed together
         &add_call_guards::CriticalCallEdges,
+        &reveal_all::RevealAll, // has to be done before drop elaboration, since we need to drop opaque types, too.
         &elaborate_drops::ElaborateDrops,
         // This will remove extraneous landing pads which are no longer
         // necessary as well as well as forcing any call in a non-unwinding
@@ -526,7 +527,6 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         body,
         &[
             &check_alignment::CheckAlignment,
-            &reveal_all::RevealAll, // has to be done before inlining, since inlined code is in RevealAll mode.
             &lower_slice_len::LowerSliceLenCalls, // has to be done before inlining, otherwise actual call will be almost always inlined. Also simple, so can just do first
             &unreachable_prop::UnreachablePropagation,
             &uninhabited_enum_branching::UninhabitedEnumBranching,
diff --git a/compiler/rustc_mir_transform/src/reveal_all.rs b/compiler/rustc_mir_transform/src/reveal_all.rs
index 065793348e4..55f1eac6f84 100644
--- a/compiler/rustc_mir_transform/src/reveal_all.rs
+++ b/compiler/rustc_mir_transform/src/reveal_all.rs
@@ -8,16 +8,7 @@ use rustc_middle::ty::{self, Ty, TyCtxt};
 pub struct RevealAll;
 
 impl<'tcx> MirPass<'tcx> for RevealAll {
-    fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
-        sess.mir_opt_level() >= 3 || super::inline::Inline.is_enabled(sess)
-    }
-
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        // Do not apply this transformation to generators.
-        if body.generator.is_some() {
-            return;
-        }
-
         let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
         RevealAllVisitor { tcx, param_env }.visit_body_preserves_cfg(body);
     }
@@ -35,6 +26,29 @@ impl<'tcx> MutVisitor<'tcx> for RevealAllVisitor<'tcx> {
     }
 
     #[inline]
+    fn visit_place(
+        &mut self,
+        place: &mut Place<'tcx>,
+        _context: PlaceContext,
+        _location: Location,
+    ) {
+        // Performance optimization: don't reintern if there is no `OpaqueCast` to remove.
+        if place.projection.iter().all(|elem| !matches!(elem, ProjectionElem::OpaqueCast(_))) {
+            return;
+        }
+        // `OpaqueCast` projections are only needed if there are opaque types on which projections are performed.
+        // After the `RevealAll` pass, all opaque types are replaced with their hidden types, so we don't need these
+        // projections anymore.
+        place.projection = self.tcx.mk_place_elems(
+            &place
+                .projection
+                .into_iter()
+                .filter(|elem| !matches!(elem, ProjectionElem::OpaqueCast(_)))
+                .collect::<Vec<_>>(),
+        );
+    }
+
+    #[inline]
     fn visit_constant(&mut self, constant: &mut ConstOperand<'tcx>, _: Location) {
         // We have to use `try_normalize_erasing_regions` here, since it's
         // possible that we visit impossible-to-satisfy where clauses here,