Ignore more types of mut-use context

Author: ohadravid

compiler/rustc_mir_transform/src/copy_prop.rs

@@ -49,17 +49,17 @@ impl<'tcx> crate::MirPass<'tcx> for CopyProp {
 
         let any_replacement = ssa.copy_classes().iter_enumerated().any(|(l, &h)| l != h);
 
-        if any_replacement {
-            let storage_to_remove = DenseBitSet::new_empty(fully_moved.domain_size());
+        let storage_to_remove = DenseBitSet::new_empty(fully_moved.domain_size());
 
-            Replacer {
-                tcx,
-                copy_classes: ssa.copy_classes(),
-                fully_moved,
-                borrowed_locals: ssa.borrowed_locals(),
-            }
-            .visit_body_preserves_cfg(body);
+        Replacer {
+            tcx,
+            copy_classes: ssa.copy_classes(),
+            fully_moved,
+            borrowed_locals: ssa.borrowed_locals(),
+        }
+        .visit_body_preserves_cfg(body);
 
+        if any_replacement {
             let move_data = MoveData::gather_moves(body, tcx, |_| true);
 
             let maybe_uninit = MaybeUninitializedPlaces::new(tcx, body, &move_data)
@@ -77,9 +77,7 @@ impl<'tcx> crate::MirPass<'tcx> for CopyProp {
                 storage_checker.storage_to_remove
             };
             StorageRemover { tcx, storage_to_remove }.visit_body_preserves_cfg(body);
-        }
 
-        if any_replacement {
             crate::simplify::remove_unused_definitions(body);
         }
     }
@@ -187,7 +185,6 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'_, 'tcx> {
                 *rhs
             && lhs == rhs
         {
-            debug!(?stmt, ?loc, ?lhs, ?rhs, "removing tautological assignment");
             stmt.make_nop();
         }
     }
@@ -201,9 +198,14 @@ struct StorageChecker<'a, 'tcx> {
 
 impl<'a, 'tcx> Visitor<'tcx> for StorageChecker<'a, 'tcx> {
     fn visit_local(&mut self, local: Local, context: PlaceContext, loc: Location) {
-        // We don't need to check storage statements and stores (for which the local doesn't need to be initialized).
+        // We don't need to check storage statements and statements for which the local doesn't need to be initialized.
         match context {
-            PlaceContext::MutatingUse(MutatingUseContext::Store) | PlaceContext::NonUse(_) => {
+            PlaceContext::MutatingUse(
+                MutatingUseContext::Store
+                | MutatingUseContext::Call
+                | MutatingUseContext::AsmOutput,
+            )
+            | PlaceContext::NonUse(_) => {
                 return;
             }
             _ => {}
@@ -234,7 +236,6 @@ impl<'a, 'tcx> Visitor<'tcx> for StorageChecker<'a, 'tcx> {
     }
 }
 
-/// Utility to help performing substitution of `*pattern` by `target`.
 struct StorageRemover<'tcx> {
     tcx: TyCtxt<'tcx>,
     storage_to_remove: DenseBitSet<Local>,