compiler/rustc_mir_transform/src/reveal_all.rs

   1 //! Normalizes MIR in RevealAll mode.
   2
   3 use crate::MirPass;
   4 use rustc_middle::mir::visit::*;
   5 use rustc_middle::mir::*;
   6 use rustc_middle::ty::{self, Ty, TyCtxt};
   7
   8 pub struct RevealAll;
   9
  10 impl<'tcx> MirPass<'tcx> for RevealAll {
  11     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
  12         let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
  13         RevealAllVisitor { tcx, param_env }.visit_body_preserves_cfg(body);
  14     }
  15 }
  16
  17 struct RevealAllVisitor<'tcx> {
  18     tcx: TyCtxt<'tcx>,
  19     param_env: ty::ParamEnv<'tcx>,
  20 }
  21
  22 impl<'tcx> MutVisitor<'tcx> for RevealAllVisitor<'tcx> {
  23     #[inline]
  24     fn tcx(&self) -> TyCtxt<'tcx> {
  25         self.tcx
  26     }
  27
  28     #[inline]
  29     fn visit_place(
  30         &mut self,
  31         place: &mut Place<'tcx>,
  32         _context: PlaceContext,
  33         _location: Location,
  34     ) {
  35         // Performance optimization: don't reintern if there is no `OpaqueCast` to remove.
  36         if place.projection.iter().all(|elem| !matches!(elem, ProjectionElem::OpaqueCast(_))) {
  37             return;
  38         }
  39         // `OpaqueCast` projections are only needed if there are opaque types on which projections are performed.
  40         // After the `RevealAll` pass, all opaque types are replaced with their hidden types, so we don't need these
  41         // projections anymore.
  42         place.projection = self.tcx.mk_place_elems(
  43             &place
  44                 .projection
  45                 .into_iter()
  46                 .filter(|elem| !matches!(elem, ProjectionElem::OpaqueCast(_)))
  47                 .collect::<Vec<_>>(),
  48         );
  49         self.super_place(place, _context, _location);
  50     }
  51
  52     #[inline]
  53     fn visit_constant(&mut self, constant: &mut ConstOperand<'tcx>, location: Location) {
  54         // We have to use `try_normalize_erasing_regions` here, since it's
  55         // possible that we visit impossible-to-satisfy where clauses here,
  56         // see #91745
  57         if let Ok(c) = self.tcx.try_normalize_erasing_regions(self.param_env, constant.const_) {
  58             constant.const_ = c;
  59         }
  60         self.super_constant(constant, location);
  61     }
  62
  63     #[inline]
  64     fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
  65         // We have to use `try_normalize_erasing_regions` here, since it's
  66         // possible that we visit impossible-to-satisfy where clauses here,
  67         // see #91745
  68         if let Ok(t) = self.tcx.try_normalize_erasing_regions(self.param_env, *ty) {
  69             *ty = t;
  70         }
  71     }
  72 }