1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! This pass erases all early-bound regions from the types occuring in the MIR.
12 //! We want to do this once just before trans, so trans does not have to take
13 //! care erasing regions all over the place.
15 use rustc::middle::ty;
16 use rustc::mir::repr::*;
17 use rustc::mir::visit::MutVisitor;
18 use rustc::mir::mir_map::MirMap;
20 pub fn erase_regions<'tcx>(tcx: &ty::ctxt<'tcx>, mir_map: &mut MirMap<'tcx>) {
21 for (_, mir) in &mut mir_map.map {
22 EraseRegionsVisitor::new(tcx).visit_mir(mir);
26 struct EraseRegionsVisitor<'a, 'tcx: 'a> {
27 tcx: &'a ty::ctxt<'tcx>,
30 impl<'a, 'tcx> EraseRegionsVisitor<'a, 'tcx> {
31 pub fn new(tcx: &'a ty::ctxt<'tcx>) -> Self {
37 fn erase_regions_return_ty(&mut self, fn_output: &mut ty::FnOutput<'tcx>) {
39 ty::FnConverging(ref mut ty) => {
40 *ty = self.tcx.erase_regions(ty);
46 fn erase_regions_tys<'b, T>(&mut self, tys: T)
47 where T: Iterator<Item = &'b mut ty::Ty<'tcx>>,
51 *ty = self.tcx.erase_regions(ty);
56 impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
57 fn visit_mir(&mut self, mir: &mut Mir<'tcx>) {
58 self.erase_regions_return_ty(&mut mir.return_ty);
59 self.erase_regions_tys(mir.var_decls.iter_mut().map(|d| &mut d.ty));
60 self.erase_regions_tys(mir.arg_decls.iter_mut().map(|d| &mut d.ty));
61 self.erase_regions_tys(mir.temp_decls.iter_mut().map(|d| &mut d.ty));
65 fn visit_terminator(&mut self, bb: BasicBlock, terminator: &mut Terminator<'tcx>) {
67 Terminator::Goto { .. } |
70 Terminator::If { .. } |
71 Terminator::Switch { .. } |
72 Terminator::Drop { .. } |
73 Terminator::Call { .. } => {
76 Terminator::SwitchInt { ref mut switch_ty, .. } => {
77 *switch_ty = self.tcx.erase_regions(switch_ty);
80 self.super_terminator(bb, terminator);
83 fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>) {
87 Rvalue::BinaryOp(_, _, _) |
88 Rvalue::UnaryOp(_, _) |
89 Rvalue::Slice { input: _, from_start: _, from_end: _ } |
90 Rvalue::InlineAsm(_) => {},
92 Rvalue::Repeat(_, ref mut value) => value.ty = self.tcx.erase_regions(&value.ty),
93 Rvalue::Ref(ref mut region, _, _) => *region = ty::ReStatic,
94 Rvalue::Cast(_, _, ref mut ty) => *ty = self.tcx.erase_regions(ty),
95 Rvalue::Box(ref mut ty) => *ty = self.tcx.erase_regions(ty),
98 Rvalue::Aggregate(AggregateKind::Vec, _) |
99 Rvalue::Aggregate(AggregateKind::Tuple, _) => {},
100 Rvalue::Aggregate(AggregateKind::Adt(_, _, ref mut substs), _) =>
101 *substs = self.tcx.mk_substs(self.tcx.erase_regions(*substs)),
102 Rvalue::Aggregate(AggregateKind::Closure(def_id, ref mut closure_substs), _) => {
103 let cloned = Box::new(closure_substs.clone());
104 let ty = self.tcx.mk_closure_from_closure_substs(def_id, cloned);
105 let erased = self.tcx.erase_regions(&ty);
106 *closure_substs = match erased.sty {
107 ty::TyClosure(_, ref closure_substs) => &*closure_substs,
112 self.super_rvalue(rvalue);
115 fn visit_constant(&mut self, constant: &mut Constant<'tcx>) {
116 constant.ty = self.tcx.erase_regions(&constant.ty);
117 match constant.literal {
118 Literal::Item { ref mut substs, .. } => {
119 *substs = self.tcx.mk_substs(self.tcx.erase_regions(substs));
121 Literal::Value { .. } => { /* nothing to do */ }
123 self.super_constant(constant);