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Auto merge of #43559 - Nashenas88:nll-region-renumberer, r=arielb1
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Non-lexical lifetimes region renumberer

Regenerates region variables for all regions in a cloned MIR in the nll mir pass. This is part of the work for #43234.
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bors committed Aug 10, 2017
2 parents b617960 + 0d29cd4 commit 13d94d5
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Showing 2 changed files with 114 additions and 14 deletions.
1 change: 1 addition & 0 deletions src/librustc/mir/visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -753,6 +753,7 @@ macro_rules! make_mir_visitor {
make_mir_visitor!(Visitor,);
make_mir_visitor!(MutVisitor,mut);

#[derive(Copy, Clone, Debug)]
pub enum Lookup {
Loc(Location),
Src(SourceInfo),
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127 changes: 113 additions & 14 deletions src/librustc_mir/transform/nll.rs
Original file line number Diff line number Diff line change
Expand Up @@ -8,26 +8,119 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use rustc::ty::TyCtxt;
use rustc::mir::Mir;
use rustc::mir::visit::MutVisitor;
use rustc::ty::TypeFoldable;
use rustc::ty::subst::{Kind, Substs};
use rustc::ty::{Ty, TyCtxt, ClosureSubsts, RegionVid, RegionKind};
use rustc::mir::{Mir, Location, Rvalue, BasicBlock, Statement, StatementKind};
use rustc::mir::visit::{MutVisitor, Lookup};
use rustc::mir::transform::{MirPass, MirSource};
use rustc::infer::{self, InferCtxt};
use syntax_pos::DUMMY_SP;
use std::collections::HashMap;

#[allow(dead_code)]
struct NLLVisitor<'a, 'tcx: 'a> {
tcx: TyCtxt<'a, 'tcx, 'tcx>,
struct NLLVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
lookup_map: HashMap<RegionVid, Lookup>,
infcx: InferCtxt<'a, 'gcx, 'tcx>,
}

impl<'a, 'tcx> NLLVisitor<'a, 'tcx> {
pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Self {
impl<'a, 'gcx, 'tcx> NLLVisitor<'a, 'gcx, 'tcx> {
pub fn new(infcx: InferCtxt<'a, 'gcx, 'tcx>) -> Self {
NLLVisitor {
tcx: tcx
infcx: infcx,
lookup_map: HashMap::new(),
}
}

pub fn into_results(self) -> HashMap<RegionVid, Lookup> {
self.lookup_map
}

fn renumber_regions<T>(&self, value: &T) -> T where T: TypeFoldable<'tcx> {
self.infcx.tcx.fold_regions(value, &mut false, |_region, _depth| {
self.infcx.next_region_var(infer::MiscVariable(DUMMY_SP))
})
}

fn store_region(&mut self, region: &RegionKind, lookup: Lookup) {
if let RegionKind::ReVar(rid) = *region {
self.lookup_map.entry(rid).or_insert(lookup);
}
}

fn store_ty_regions(&mut self, ty: &Ty<'tcx>, lookup: Lookup) {
for region in ty.regions() {
self.store_region(region, lookup);
}
}

fn store_kind_regions(&mut self, kind: &'tcx Kind, lookup: Lookup) {
if let Some(ty) = kind.as_type() {
self.store_ty_regions(&ty, lookup);
} else if let Some(region) = kind.as_region() {
self.store_region(region, lookup);
}
}
}

impl<'a, 'tcx> MutVisitor<'tcx> for NLLVisitor<'a, 'tcx> {
// FIXME: Nashenas88: implement me!
impl<'a, 'gcx, 'tcx> MutVisitor<'tcx> for NLLVisitor<'a, 'gcx, 'tcx> {
fn visit_ty(&mut self, ty: &mut Ty<'tcx>, lookup: Lookup) {
let old_ty = *ty;
*ty = self.renumber_regions(&old_ty);
self.store_ty_regions(ty, lookup);
}

fn visit_substs(&mut self, substs: &mut &'tcx Substs<'tcx>, location: Location) {
*substs = self.renumber_regions(&{*substs});
let lookup = Lookup::Loc(location);
for kind in *substs {
self.store_kind_regions(kind, lookup);
}
}

fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>, location: Location) {
match *rvalue {
Rvalue::Ref(ref mut r, _, _) => {
let old_r = *r;
*r = self.renumber_regions(&old_r);
let lookup = Lookup::Loc(location);
self.store_region(r, lookup);
}
Rvalue::Use(..) |
Rvalue::Repeat(..) |
Rvalue::Len(..) |
Rvalue::Cast(..) |
Rvalue::BinaryOp(..) |
Rvalue::CheckedBinaryOp(..) |
Rvalue::UnaryOp(..) |
Rvalue::Discriminant(..) |
Rvalue::NullaryOp(..) |
Rvalue::Aggregate(..) => {
// These variants don't contain regions.
}
}
self.super_rvalue(rvalue, location);
}

fn visit_closure_substs(&mut self,
substs: &mut ClosureSubsts<'tcx>,
location: Location) {
*substs = self.renumber_regions(substs);
let lookup = Lookup::Loc(location);
for kind in substs.substs {
self.store_kind_regions(kind, lookup);
}
}

fn visit_statement(&mut self,
block: BasicBlock,
statement: &mut Statement<'tcx>,
location: Location) {
if let StatementKind::EndRegion(_) = statement.kind {
statement.kind = StatementKind::Nop;
}
self.super_statement(block, statement, location);
}
}

// MIR Pass for non-lexical lifetimes
Expand All @@ -38,10 +131,16 @@ impl MirPass for NLL {
tcx: TyCtxt<'a, 'tcx, 'tcx>,
_: MirSource,
mir: &mut Mir<'tcx>) {
if tcx.sess.opts.debugging_opts.nll {
// Clone mir so we can mutate it without disturbing the rest
// of the compiler
NLLVisitor::new(tcx).visit_mir(&mut mir.clone());
if !tcx.sess.opts.debugging_opts.nll {
return;
}

tcx.infer_ctxt().enter(|infcx| {
// Clone mir so we can mutate it without disturbing the rest of the compiler
let mut renumbered_mir = mir.clone();
let mut visitor = NLLVisitor::new(infcx);
visitor.visit_mir(&mut renumbered_mir);
let _results = visitor.into_results();
})
}
}

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