3 files changed, 19 insertions, 8 deletions
diff --git a/compiler/rustc_mir_transform/src/dead_store_elimination.rs b/compiler/rustc_mir_transform/src/dead_store_elimination.rs
index 42c580c63f0..09546330cec 100644
--- a/compiler/rustc_mir_transform/src/dead_store_elimination.rs
+++ b/compiler/rustc_mir_transform/src/dead_store_elimination.rs
@@ -71,7 +71,7 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitS
         bbs[block].statements[statement_index].make_nop();
     }
 
-    crate::simplify::SimplifyLocals.run_pass(tcx, body)
+    crate::simplify::simplify_locals(body, tcx)
 }
 
 pub struct DeadStoreElimination;
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index ae79c2290f6..16b8a901f36 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -524,11 +524,8 @@ fn run_runtime_lowering_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 
 /// Returns the sequence of passes that do the initial cleanup of runtime MIR.
 fn run_runtime_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-    let passes: &[&dyn MirPass<'tcx>] = &[
-        &elaborate_box_derefs::ElaborateBoxDerefs,
-        &lower_intrinsics::LowerIntrinsics,
-        &simplify::SimplifyCfg::new("elaborate-drops"),
-    ];
+    let passes: &[&dyn MirPass<'tcx>] =
+        &[&lower_intrinsics::LowerIntrinsics, &simplify::SimplifyCfg::new("elaborate-drops")];
 
     pm::run_passes(tcx, body, passes, Some(MirPhase::Runtime(RuntimePhase::PostCleanup)));
 }
@@ -560,6 +557,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             &multiple_return_terminators::MultipleReturnTerminators,
             &instcombine::InstCombine,
             &separate_const_switch::SeparateConstSwitch,
+            &simplify::SimplifyLocals::new("before-const-prop"),
             //
             // FIXME(#70073): This pass is responsible for both optimization as well as some lints.
             &const_prop::ConstProp,
@@ -578,7 +576,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             &o1(remove_noop_landing_pads::RemoveNoopLandingPads),
             &o1(simplify::SimplifyCfg::new("final")),
             &nrvo::RenameReturnPlace,
-            &simplify::SimplifyLocals,
+            &simplify::SimplifyLocals::new("final"),
             &multiple_return_terminators::MultipleReturnTerminators,
             &deduplicate_blocks::DeduplicateBlocks,
             // Some cleanup necessary at least for LLVM and potentially other codegen backends.
diff --git a/compiler/rustc_mir_transform/src/simplify.rs b/compiler/rustc_mir_transform/src/simplify.rs
index 8212a7b523b..8f6abe7a912 100644
--- a/compiler/rustc_mir_transform/src/simplify.rs
+++ b/compiler/rustc_mir_transform/src/simplify.rs
@@ -379,9 +379,21 @@ fn save_unreachable_coverage(
     ));
 }
 
-pub struct SimplifyLocals;
+pub struct SimplifyLocals {
+    label: String,
+}
+
+impl SimplifyLocals {
+    pub fn new(label: &str) -> SimplifyLocals {
+        SimplifyLocals { label: format!("SimplifyLocals-{}", label) }
+    }
+}
 
 impl<'tcx> MirPass<'tcx> for SimplifyLocals {
+    fn name(&self) -> &str {
+        &self.label
+    }
+
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.mir_opt_level() > 0
     }
@@ -557,6 +569,7 @@ fn remove_unused_definitions(used_locals: &mut UsedLocals, body: &mut Body<'_>)
 
                     StatementKind::SetDiscriminant { ref place, .. }
                     | StatementKind::Deinit(ref place) => used_locals.is_used(place.local),
+                    StatementKind::Nop => false,
                     _ => true,
                 };