80 lines
2.5 KiB
Rust
80 lines
2.5 KiB
Rust
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! This pass erases all early-bound regions from the types occuring in the MIR.
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//! We want to do this once just before trans, so trans does not have to take
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//! care erasing regions all over the place.
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use rustc::ty::subst::Substs;
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use rustc::ty::{Ty, TyCtxt, ReErased, ClosureSubsts};
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use rustc::mir::*;
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use rustc::mir::visit::MutVisitor;
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use rustc::mir::transform::{MirPass, MirSource, Pass};
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struct EraseRegionsVisitor<'a, 'tcx: 'a> {
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tcx: TyCtxt<'a, 'tcx, 'tcx>,
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}
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impl<'a, 'tcx> EraseRegionsVisitor<'a, 'tcx> {
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pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Self {
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EraseRegionsVisitor {
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tcx: tcx
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}
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}
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}
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impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
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fn visit_ty(&mut self, ty: &mut Ty<'tcx>) {
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let old_ty = *ty;
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*ty = self.tcx.erase_regions(&old_ty);
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}
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fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>) {
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*substs = self.tcx.erase_regions(&{*substs});
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}
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fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>, location: Location) {
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match *rvalue {
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Rvalue::Ref(ref mut r, _, _) => {
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*r = self.tcx.mk_region(ReErased);
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}
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Rvalue::Use(..) |
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Rvalue::Repeat(..) |
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Rvalue::Len(..) |
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Rvalue::Cast(..) |
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Rvalue::BinaryOp(..) |
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Rvalue::CheckedBinaryOp(..) |
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Rvalue::UnaryOp(..) |
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Rvalue::Discriminant(..) |
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Rvalue::Box(..) |
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Rvalue::Aggregate(..) => {
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// These variants don't contain regions.
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}
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}
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self.super_rvalue(rvalue, location);
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}
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fn visit_closure_substs(&mut self,
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substs: &mut ClosureSubsts<'tcx>) {
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*substs = self.tcx.erase_regions(substs);
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}
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}
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pub struct EraseRegions;
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impl Pass for EraseRegions {}
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impl<'tcx> MirPass<'tcx> for EraseRegions {
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fn run_pass<'a>(&mut self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
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_: MirSource, mir: &mut Mir<'tcx>) {
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EraseRegionsVisitor::new(tcx).visit_mir(mir);
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}
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}
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