Avoid repeated interning in SelfArgVisitor.

Author: nnethercote

compiler/rustc_mir_transform/src/coroutine.rs

@@ -115,8 +115,14 @@ impl<'tcx> MutVisitor<'tcx> for RenameLocalVisitor<'tcx> {
 }
 
 structSelfArgVisitor<'tcx>{
-elem:ProjectionElem<Local,Ty<'tcx>>,
 tcx:TyCtxt<'tcx>,
+new_base:Place<'tcx>,
+}
+
+impl<'tcx>SelfArgVisitor<'tcx>{
+fnnew(tcx:TyCtxt<'tcx>,elem:ProjectionElem<Local,Ty<'tcx>>) -> Self{
+Self{ tcx,new_base:Place{local:SELF_ARG,projection: tcx.mk_place_elems(&[elem])}}
+}
 }
 
 impl<'tcx>MutVisitor<'tcx>forSelfArgVisitor<'tcx>{
@@ -130,11 +136,7 @@ impl<'tcx> MutVisitor<'tcx> for SelfArgVisitor<'tcx> {
 
 fnvisit_place(&mutself,place:&mutPlace<'tcx>,context:PlaceContext,location:Location){
 if place.local == SELF_ARG{
-replace_base(
- place,
-Place{local:SELF_ARG,projection:self.tcx().mk_place_elems(&[self.elem])},
-self.tcx,
-);
+replace_base(place,self.new_base,self.tcx);
 }else{
 self.visit_local(&mut place.local, context, location);
 
@@ -475,7 +477,7 @@ fn make_coroutine_state_argument_indirect<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Bo
  body.local_decls.raw[1].ty = ref_coroutine_ty;
 
 // Add a deref to accesses of the coroutine state
-SelfArgVisitor{tcx,elem:ProjectionElem::Deref}.visit_body(body);
+SelfArgVisitor::new(tcx,ProjectionElem::Deref).visit_body(body);
 }
 
 fnmake_coroutine_state_argument_pinned<'tcx>(tcx:TyCtxt<'tcx>,body:&mutBody<'tcx>){
@@ -490,7 +492,7 @@ fn make_coroutine_state_argument_pinned<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body
  body.local_decls.raw[1].ty = pin_ref_coroutine_ty;
 
 // Add the Pin field access to accesses of the coroutine state
-SelfArgVisitor{tcx,elem:ProjectionElem::Field(FieldIdx::ZERO, ref_coroutine_ty)}
+SelfArgVisitor::new(tcx,ProjectionElem::Field(FieldIdx::ZERO, ref_coroutine_ty))
 .visit_body(body);
 }