src/librustc_mir/transform/no_landing_pads.rs

   1 //! This pass removes the unwind branch of all the terminators when the no-landing-pads option is
   2 //! specified.
   3
   4 use rustc::ty::TyCtxt;
   5 use rustc::mir::*;
   6 use rustc::mir::visit::MutVisitor;
   7 use crate::transform::{MirPass, MirSource};
   8
   9 pub struct NoLandingPads<'tcx> {
  10     tcx: TyCtxt<'tcx>,
  11 }
  12
  13 impl<'tcx> NoLandingPads<'tcx> {
  14     pub fn new(tcx: TyCtxt<'tcx>) -> Self {
  15         NoLandingPads { tcx }
  16     }
  17 }
  18
  19 impl<'tcx> MirPass<'tcx> for NoLandingPads<'tcx> {
  20     fn run_pass(&self, tcx: TyCtxt<'tcx>, _: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
  21         no_landing_pads(tcx, body)
  22     }
  23 }
  24
  25 pub fn no_landing_pads<'tcx>(tcx: TyCtxt<'tcx>, body: &mut BodyAndCache<'tcx>) {
  26     if tcx.sess.no_landing_pads() {
  27         NoLandingPads::new(tcx).visit_body(body);
  28     }
  29 }
  30
  31 impl<'tcx> MutVisitor<'tcx> for NoLandingPads<'tcx> {
  32     fn tcx(&self) -> TyCtxt<'tcx> {
  33         self.tcx
  34     }
  35
  36     fn visit_terminator_kind(&mut self,
  37                         kind: &mut TerminatorKind<'tcx>,
  38                         location: Location) {
  39         if let Some(unwind) = kind.unwind_mut() {
  40             unwind.take();
  41         }
  42         self.super_terminator_kind(kind, location);
  43     }
  44 }