compiler/rustc_mir_dataflow/src/un_derefer.rs

   1 use rustc_data_structures::stable_map::FxHashMap;
   2 use rustc_middle::mir::*;
   3 use rustc_middle::ty::TyCtxt;
   4
   5 /// Used for reverting changes made by `DerefSeparator`
   6 pub struct UnDerefer<'tcx> {
   7     pub tcx: TyCtxt<'tcx>,
   8     pub derefer_sidetable: FxHashMap<Local, Place<'tcx>>,
   9 }
  10
  11 impl<'tcx> UnDerefer<'tcx> {
  12     pub fn derefer(&self, place: PlaceRef<'tcx>, body: &Body<'tcx>) -> Option<Place<'tcx>> {
  13         let reffed = self.derefer_sidetable.get(&place.local)?;
  14
  15         let new_place = reffed.project_deeper(place.projection, self.tcx);
  16         if body.local_decls[new_place.local].is_deref_temp() {
  17             return self.derefer(new_place.as_ref(), body);
  18         }
  19         Some(new_place)
  20     }
  21
  22     pub fn ref_finder(&mut self, body: &Body<'tcx>) {
  23         for (_bb, data) in body.basic_blocks().iter_enumerated() {
  24             for stmt in data.statements.iter() {
  25                 match stmt.kind {
  26                     StatementKind::Assign(box (place, Rvalue::CopyForDeref(reffed))) => {
  27                         if body.local_decls[place.local].is_deref_temp() {
  28                             self.derefer_sidetable.insert(place.local, reffed);
  29                         }
  30                     }
  31                     _ => (),
  32                 }
  33             }
  34         }
  35     }
  36 }