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::{self, TyCtxt};
16 use rustc::mir::repr::*;
17 use rustc::mir::visit::MutVisitor;
18 use rustc::mir::transform::{MirPass, Pass};
19 use syntax::ast::NodeId;
21 struct EraseRegionsVisitor<'a, 'tcx: 'a> {
22 tcx: &'a TyCtxt<'tcx>,
25 impl<'a, 'tcx> EraseRegionsVisitor<'a, 'tcx> {
26 pub fn new(tcx: &'a TyCtxt<'tcx>) -> Self {
32 fn erase_regions_return_ty(&mut self, fn_output: &mut ty::FnOutput<'tcx>) {
34 ty::FnConverging(ref mut ty) => {
35 *ty = self.tcx.erase_regions(ty);
41 fn erase_regions_tys<'b, T>(&mut self, tys: T)
42 where T: Iterator<Item = &'b mut ty::Ty<'tcx>>,
46 *ty = self.tcx.erase_regions(ty);
51 impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
52 fn visit_mir(&mut self, mir: &mut Mir<'tcx>) {
53 self.erase_regions_return_ty(&mut mir.return_ty);
54 self.erase_regions_tys(mir.var_decls.iter_mut().map(|d| &mut d.ty));
55 self.erase_regions_tys(mir.arg_decls.iter_mut().map(|d| &mut d.ty));
56 self.erase_regions_tys(mir.temp_decls.iter_mut().map(|d| &mut d.ty));
60 fn visit_terminator(&mut self, bb: BasicBlock, terminator: &mut Terminator<'tcx>) {
62 Terminator::Goto { .. } |
65 Terminator::If { .. } |
66 Terminator::Switch { .. } |
67 Terminator::Drop { .. } |
68 Terminator::Call { .. } => {
71 Terminator::SwitchInt { ref mut switch_ty, .. } => {
72 *switch_ty = self.tcx.erase_regions(switch_ty);
75 self.super_terminator(bb, terminator);
78 fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>) {
82 Rvalue::BinaryOp(_, _, _) |
83 Rvalue::UnaryOp(_, _) |
84 Rvalue::Slice { input: _, from_start: _, from_end: _ } |
85 Rvalue::InlineAsm(_) => {},
87 Rvalue::Repeat(_, ref mut value) => value.ty = self.tcx.erase_regions(&value.ty),
88 Rvalue::Ref(ref mut region, _, _) => *region = ty::ReStatic,
89 Rvalue::Cast(_, _, ref mut ty) => *ty = self.tcx.erase_regions(ty),
90 Rvalue::Box(ref mut ty) => *ty = self.tcx.erase_regions(ty),
93 Rvalue::Aggregate(AggregateKind::Vec, _) |
94 Rvalue::Aggregate(AggregateKind::Tuple, _) => {},
95 Rvalue::Aggregate(AggregateKind::Adt(_, _, ref mut substs), _) =>
96 *substs = self.tcx.mk_substs(self.tcx.erase_regions(*substs)),
97 Rvalue::Aggregate(AggregateKind::Closure(def_id, ref mut closure_substs), _) => {
98 let cloned = Box::new(closure_substs.clone());
99 let ty = self.tcx.mk_closure_from_closure_substs(def_id, cloned);
100 let erased = self.tcx.erase_regions(&ty);
101 *closure_substs = match erased.sty {
102 ty::TyClosure(_, ref closure_substs) => &*closure_substs,
107 self.super_rvalue(rvalue);
110 fn visit_constant(&mut self, constant: &mut Constant<'tcx>) {
111 constant.ty = self.tcx.erase_regions(&constant.ty);
112 match constant.literal {
113 Literal::Item { ref mut substs, .. } => {
114 *substs = self.tcx.mk_substs(self.tcx.erase_regions(substs));
116 Literal::Value { .. } => { /* nothing to do */ }
118 self.super_constant(constant);
122 pub struct EraseRegions;
124 impl Pass for EraseRegions {}
126 impl<'tcx> MirPass<'tcx> for EraseRegions {
127 fn run_pass(&mut self, tcx: &TyCtxt<'tcx>, _: NodeId, mir: &mut Mir<'tcx>) {
128 EraseRegionsVisitor::new(tcx).visit_mir(mir);