erase coroutine shim dereftemps

Author: beepster4096

compiler/rustc_mir_transform/src/coroutine.rs

@@ -93,6 +93,7 @@ use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode, Obliga
 use tracing::{debug, instrument, trace};
 
 use crate::deref_separator::deref_finder;
+use crate::erase_deref_temps::deref_temp_eraser;
 use crate::{abort_unwinding_calls, errors, pass_manager as pm, simplify};
 
 pub(super) struct StateTransform;
@@ -1622,27 +1623,30 @@ impl<'tcx> crate::MirPass<'tcx> for StateTransform {
             let mut drop_shim =
                 create_coroutine_drop_shim_async(tcx, &transform, body, drop_clean, can_unwind);
             // Run derefer to fix Derefs that are not in the first place
-            deref_finder(tcx, &mut drop_shim);
+            deref_finder(tcx, &mut drop_shim, false);
+            deref_temp_eraser(tcx, &mut drop_shim);
             body.coroutine.as_mut().unwrap().coroutine_drop_async = Some(drop_shim);
         } else {
             // If coroutine has no async drops, generating sync drop shim
             let mut drop_shim =
                 create_coroutine_drop_shim(tcx, &transform, coroutine_ty, body, drop_clean);
             // Run derefer to fix Derefs that are not in the first place
-            deref_finder(tcx, &mut drop_shim);
+            deref_finder(tcx, &mut drop_shim, false);
+            deref_temp_eraser(tcx, &mut drop_shim);
             body.coroutine.as_mut().unwrap().coroutine_drop = Some(drop_shim);
 
             // For coroutine with sync drop, generating async proxy for `future_drop_poll` call
             let mut proxy_shim = create_coroutine_drop_shim_proxy_async(tcx, body);
-            deref_finder(tcx, &mut proxy_shim);
+            deref_finder(tcx, &mut proxy_shim, false);
+            deref_temp_eraser(tcx, &mut proxy_shim);
             body.coroutine.as_mut().unwrap().coroutine_drop_proxy_async = Some(proxy_shim);
         }
 
         // Create the Coroutine::resume / Future::poll function
         create_coroutine_resume_function(tcx, transform, body, can_return, can_unwind);
 
         // Run derefer to fix Derefs that are not in the first place
-        deref_finder(tcx, body);
+        deref_finder(tcx, body, true);
     }
 
     fn is_required(&self) -> bool {

compiler/rustc_mir_transform/src/deref_separator.rs

@@ -6,11 +6,13 @@ use rustc_middle::ty::TyCtxt;
 use crate::patch::MirPatch;
 
 pub(super) struct Derefer;
+pub(super) struct DereferErased;
 
 struct DerefChecker<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     patcher: MirPatch<'tcx>,
     local_decls: &'a LocalDecls<'tcx>,
+    add_deref_metadata: bool,
 }
 
 impl<'a, 'tcx> MutVisitor<'tcx> for DerefChecker<'a, 'tcx> {
@@ -39,7 +41,11 @@ impl<'a, 'tcx> MutVisitor<'tcx> for DerefChecker<'a, 'tcx> {
                     let temp = self.patcher.new_local_with_info(
                         ty,
                         self.local_decls[p_ref.local].source_info.span,
-                        LocalInfo::DerefTemp,
+                        if self.add_deref_metadata {
+                            LocalInfo::DerefTemp
+                        } else {
+                            LocalInfo::Boring
+                        },
                     );
 
                     // We are adding current p_ref's projections to our
@@ -50,7 +56,11 @@ impl<'a, 'tcx> MutVisitor<'tcx> for DerefChecker<'a, 'tcx> {
                     self.patcher.add_assign(
                         loc,
                         Place::from(temp),
-                        Rvalue::CopyForDeref(deref_place),
+                        if self.add_deref_metadata {
+                            Rvalue::CopyForDeref(deref_place)
+                        } else {
+                            Rvalue::Use(Operand::Copy(deref_place))
+                        },
                     );
                     place_local = temp;
                     last_len = p_ref.projection.len();
@@ -67,9 +77,14 @@ impl<'a, 'tcx> MutVisitor<'tcx> for DerefChecker<'a, 'tcx> {
     }
 }
 
-pub(super) fn deref_finder<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+pub(super) fn deref_finder<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    body: &mut Body<'tcx>,
+    add_deref_metadata: bool,
+) {
     let patch = MirPatch::new(body);
-    let mut checker = DerefChecker { tcx, patcher: patch, local_decls: &body.local_decls };
+    let mut checker =
+        DerefChecker { tcx, patcher: patch, local_decls: &body.local_decls, add_deref_metadata };
 
     for (bb, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() {
         checker.visit_basic_block_data(bb, data);
@@ -80,7 +95,17 @@ pub(super) fn deref_finder<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 
 impl<'tcx> crate::MirPass<'tcx> for Derefer {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        deref_finder(tcx, body);
+        deref_finder(tcx, body, true);
+    }
+
+    fn is_required(&self) -> bool {
+        true
+    }
+}
+
+impl<'tcx> crate::MirPass<'tcx> for DereferErased {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        deref_finder(tcx, body, false);
     }
 
     fn is_required(&self) -> bool {

compiler/rustc_mir_transform/src/elaborate_drops.rs

@@ -87,7 +87,7 @@ impl<'tcx> crate::MirPass<'tcx> for ElaborateDrops {
             .elaborate()
         };
         elaborate_patch.apply(body);
-        deref_finder(tcx, body);
+        deref_finder(tcx, body, true);
     }
 
     fn is_required(&self) -> bool {

compiler/rustc_mir_transform/src/erase_deref_temps.rs

@@ -28,11 +28,15 @@ impl<'tcx> MutVisitor<'tcx> for EraseDerefTempsVisitor<'tcx> {
     }
 }
 
+pub(super) fn deref_temp_eraser<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+    EraseDerefTempsVisitor { tcx }.visit_body_preserves_cfg(body);
+}
+
 pub(super) struct EraseDerefTemps;
 
 impl<'tcx> crate::MirPass<'tcx> for EraseDerefTemps {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        EraseDerefTempsVisitor { tcx }.visit_body_preserves_cfg(body);
+        deref_temp_eraser(tcx, body);
     }
 
     fn is_required(&self) -> bool {

compiler/rustc_mir_transform/src/inline.rs

@@ -64,7 +64,7 @@ impl<'tcx> crate::MirPass<'tcx> for Inline {
         if inline::<NormalInliner<'tcx>>(tcx, body) {
             debug!("running simplify cfg on {:?}", body.source);
             simplify_cfg(tcx, body);
-            deref_finder(tcx, body);
+            deref_finder(tcx, body, false);
         }
     }
 
@@ -100,7 +100,7 @@ impl<'tcx> crate::MirPass<'tcx> for ForceInline {
         if inline::<ForceInliner<'tcx>>(tcx, body) {
             debug!("running simplify cfg on {:?}", body.source);
             simplify_cfg(tcx, body);
-            deref_finder(tcx, body);
+            deref_finder(tcx, body, false);
         }
     }
 }

compiler/rustc_mir_transform/src/lib.rs

@@ -133,7 +133,7 @@ declare_passes! {
         Initial,
         Final
     };
-    mod deref_separator : Derefer;
+    mod deref_separator : Derefer, DereferErased;
     mod dest_prop : DestinationPropagation;
     pub mod dump_mir : Marker;
     mod early_otherwise_branch : EarlyOtherwiseBranch;

compiler/rustc_mir_transform/src/shim.rs

@@ -232,7 +232,7 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceKind<'tcx>) -> Body<
         &[
             &mentioned_items::MentionedItems,
             &add_moves_for_packed_drops::AddMovesForPackedDrops,
-            &deref_separator::Derefer,
+            &deref_separator::DereferErased,
             &remove_noop_landing_pads::RemoveNoopLandingPads,
             &simplify::SimplifyCfg::MakeShim,
             &instsimplify::InstSimplify::BeforeInline,