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use rustc_data_structures::fx::FxHashSet;
use rustc::middle::region;
use rustc::mir::{BasicBlock, Location, Mir, Rvalue, Statement, StatementKind};
use rustc::mir::visit::{MutVisitor, Visitor, TyContext};
use rustc::ty::{Ty, RegionKind, TyCtxt};
use transform::{MirPass, MirSource};
pub struct CleanEndRegions;
struct GatherBorrowedRegions {
seen_regions: FxHashSet<region::Scope>,
}
struct DeleteTrivialEndRegions<'a> {
seen_regions: &'a FxHashSet<region::Scope>,
}
impl MirPass for CleanEndRegions {
fn run_pass<'a, 'tcx>(&self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
_source: MirSource,
mir: &mut Mir<'tcx>) {
if !tcx.emit_end_regions() { return; }
let mut gather = GatherBorrowedRegions {
seen_regions: FxHashSet()
};
gather.visit_mir(mir);
let mut delete = DeleteTrivialEndRegions { seen_regions: &mut gather.seen_regions };
delete.visit_mir(mir);
}
}
impl<'tcx> Visitor<'tcx> for GatherBorrowedRegions {
fn visit_rvalue(&mut self,
rvalue: &Rvalue<'tcx>,
location: Location) {
if let Rvalue::Ref(r, _, _) = *rvalue {
if let RegionKind::ReScope(ce) = *r {
self.seen_regions.insert(ce);
}
}
self.super_rvalue(rvalue, location);
}
fn visit_ty(&mut self, ty: &Ty<'tcx>, _: TyContext) {
for re in ty.walk().flat_map(|t| t.regions()) {
match *re {
RegionKind::ReScope(ce) => { self.seen_regions.insert(ce); }
_ => {},
}
}
self.super_ty(ty);
}
}
impl<'a, 'tcx> MutVisitor<'tcx> for DeleteTrivialEndRegions<'a> {
fn visit_statement(&mut self,
block: BasicBlock,
statement: &mut Statement<'tcx>,
location: Location) {
let mut delete_it = false;
if let StatementKind::EndRegion(ref region_scope) = statement.kind {
if !self.seen_regions.contains(region_scope) {
delete_it = true;
}
}
if delete_it {
statement.make_nop();
}
self.super_statement(block, statement, location);
}
}
pub struct CleanUserAssertTy;
pub struct DeleteUserAssertTy;
impl MirPass for CleanUserAssertTy {
fn run_pass<'a, 'tcx>(&self,
_tcx: TyCtxt<'a, 'tcx, 'tcx>,
_source: MirSource,
mir: &mut Mir<'tcx>) {
let mut delete = DeleteUserAssertTy;
delete.visit_mir(mir);
}
}
impl<'tcx> MutVisitor<'tcx> for DeleteUserAssertTy {
fn visit_statement(&mut self,
block: BasicBlock,
statement: &mut Statement<'tcx>,
location: Location) {
if let StatementKind::UserAssertTy(..) = statement.kind {
statement.make_nop();
}
self.super_statement(block, statement, location);
}
}