60 lines
1.8 KiB
Rust
60 lines
1.8 KiB
Rust
//! This pass erases all early-bound regions from the types occurring in the MIR.
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//! We want to do this once just before codegen, so codegen does not have to take
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//! care erasing regions all over the place.
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//! N.B., we do _not_ erase regions of statements that are relevant for
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//! "types-as-contracts"-validation, namely, `AcquireValid` and `ReleaseValid`.
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use rustc::ty::subst::SubstsRef;
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use rustc::ty::{self, Ty, TyCtxt};
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use rustc::mir::*;
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use rustc::mir::visit::{MutVisitor, TyContext};
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use crate::transform::{MirPass, MirSource};
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struct EraseRegionsVisitor<'tcx> {
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tcx: TyCtxt<'tcx, 'tcx, 'tcx>,
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}
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impl EraseRegionsVisitor<'tcx> {
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pub fn new(tcx: TyCtxt<'tcx, 'tcx, 'tcx>) -> Self {
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EraseRegionsVisitor {
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tcx,
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}
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}
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}
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impl MutVisitor<'tcx> for EraseRegionsVisitor<'tcx> {
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fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
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*ty = self.tcx.erase_regions(ty);
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self.super_ty(ty);
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}
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fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
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*region = self.tcx.lifetimes.re_erased;
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}
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fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _: Location) {
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*constant = self.tcx.erase_regions(constant);
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}
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fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, _: Location) {
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*substs = self.tcx.erase_regions(substs);
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}
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fn visit_statement(&mut self,
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statement: &mut Statement<'tcx>,
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location: Location) {
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self.super_statement(statement, location);
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}
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}
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pub struct EraseRegions;
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impl MirPass for EraseRegions {
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fn run_pass<'tcx>(&self,
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tcx: TyCtxt<'tcx, 'tcx, 'tcx>,
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_: MirSource<'tcx>,
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body: &mut Body<'tcx>) {
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EraseRegionsVisitor::new(tcx).visit_body(body);
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}
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}
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