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;
19 use transform::MirPass;
21 pub fn erase_regions<'tcx>(tcx: &ty::ctxt<'tcx>, mir_map: &mut MirMap<'tcx>) {
22 let mut eraser = EraseRegions::new(tcx);
24 for mir in mir_map.iter_mut().map(|(_, v)| v) {
25 eraser.run_on_mir(mir);
29 pub struct EraseRegions<'a, 'tcx: 'a> {
30 tcx: &'a ty::ctxt<'tcx>,
33 impl<'a, 'tcx> EraseRegions<'a, 'tcx> {
34 pub fn new(tcx: &'a ty::ctxt<'tcx>) -> EraseRegions<'a, 'tcx> {
40 fn erase_regions_return_ty(&mut self, fn_output: &mut ty::FnOutput<'tcx>) {
42 ty::FnConverging(ref mut ty) => {
43 *ty = self.tcx.erase_regions(ty);
49 fn erase_regions_tys<'b, T>(&mut self, tys: T)
50 where T: Iterator<Item = &'b mut ty::Ty<'tcx>>,
54 *ty = self.tcx.erase_regions(ty);
59 impl<'a, 'tcx> MirPass<'tcx> for EraseRegions<'a, 'tcx> {
60 fn run_on_mir(&mut self, mir: &mut Mir<'tcx>) {
65 impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegions<'a, 'tcx> {
66 fn visit_mir(&mut self, mir: &mut Mir<'tcx>) {
67 self.erase_regions_return_ty(&mut mir.return_ty);
68 self.erase_regions_tys(mir.var_decls.iter_mut().map(|d| &mut d.ty));
69 self.erase_regions_tys(mir.arg_decls.iter_mut().map(|d| &mut d.ty));
70 self.erase_regions_tys(mir.temp_decls.iter_mut().map(|d| &mut d.ty));
74 fn visit_terminator(&mut self, bb: BasicBlock, terminator: &mut Terminator<'tcx>) {
76 Terminator::Goto { .. } |
79 Terminator::If { .. } |
80 Terminator::Switch { .. } |
81 Terminator::Drop { .. } |
82 Terminator::Call { .. } => {
85 Terminator::SwitchInt { ref mut switch_ty, .. } => {
86 *switch_ty = self.tcx.erase_regions(switch_ty);
89 self.super_terminator(bb, terminator);
92 fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>) {
96 Rvalue::BinaryOp(_, _, _) |
97 Rvalue::UnaryOp(_, _) |
98 Rvalue::Slice { input: _, from_start: _, from_end: _ } |
99 Rvalue::InlineAsm(_) => {},
101 Rvalue::Repeat(_, ref mut value) => value.ty = self.tcx.erase_regions(&value.ty),
102 Rvalue::Ref(ref mut region, _, _) => *region = ty::ReStatic,
103 Rvalue::Cast(_, _, ref mut ty) => *ty = self.tcx.erase_regions(ty),
104 Rvalue::Box(ref mut ty) => *ty = self.tcx.erase_regions(ty),
107 Rvalue::Aggregate(AggregateKind::Vec, _) |
108 Rvalue::Aggregate(AggregateKind::Tuple, _) => {},
109 Rvalue::Aggregate(AggregateKind::Adt(_, _, ref mut substs), _) =>
110 *substs = self.tcx.mk_substs(self.tcx.erase_regions(*substs)),
111 Rvalue::Aggregate(AggregateKind::Closure(def_id, ref mut closure_substs), _) => {
112 let cloned = Box::new(closure_substs.clone());
113 let ty = self.tcx.mk_closure_from_closure_substs(def_id, cloned);
114 let erased = self.tcx.erase_regions(&ty);
115 *closure_substs = match erased.sty {
116 ty::TyClosure(_, ref closure_substs) => &*closure_substs,
121 self.super_rvalue(rvalue);
124 fn visit_constant(&mut self, constant: &mut Constant<'tcx>) {
125 constant.ty = self.tcx.erase_regions(&constant.ty);
126 match constant.literal {
127 Literal::Item { ref mut substs, .. } => {
128 *substs = self.tcx.mk_substs(self.tcx.erase_regions(substs));
130 Literal::Value { .. } => { /* nothing to do */ }
132 self.super_constant(constant);