Skip to content

Commit

Permalink
Use ResultsVisitor for borrow_check
Browse files Browse the repository at this point in the history
  • Loading branch information
@ecstatic-morse
ecstatic-morse committed Jan 20, 2020
1 parent 141483a commit 171eec5
Show file tree
Hide file tree
Showing 2 changed files with 72 additions and 63 deletions.
2 changes: 2 additions & 0 deletions src/librustc_mir/borrow_check/flows.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@
//! FIXME: this might be better as a "generic" fixed-point combinator,
//! but is not as ugly as it is right now.
#![allow(unused)]

use crate::borrow_check::location::LocationIndex;

use crate::borrow_check::nll::PoloniusOutput;
Expand Down
133 changes: 70 additions & 63 deletions src/librustc_mir/borrow_check/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ use rustc_data_structures::graph::dominators::Dominators;
use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder};
use rustc_hir as hir;
use rustc_hir::{def_id::DefId, HirId, Node};
use rustc_index::bit_set::BitSet;
use rustc_index::vec::IndexVec;

use smallvec::SmallVec;
Expand All @@ -30,7 +31,9 @@ use rustc_span::{Span, DUMMY_SP};
use syntax::ast::Name;

use crate::dataflow;
use crate::dataflow::generic::ResultsCursor;
use crate::dataflow::generic::visitor::{
visit_results, BorrowckAnalyses, BorrowckResults, ResultsVisitable, ResultsVisitor,
};
use crate::dataflow::indexes::{BorrowIndex, InitIndex, MoveOutIndex, MovePathIndex};
use crate::dataflow::move_paths::{InitLocation, LookupResult, MoveData, MoveError, MovePath};
use crate::dataflow::Borrows;
Expand All @@ -40,7 +43,6 @@ use crate::dataflow::{MaybeInitializedPlaces, MaybeUninitializedPlaces};
use crate::transform::MirSource;

use self::diagnostics::{AccessKind, RegionName};
use self::flows::Flows;
use self::location::LocationTable;
use self::prefixes::PrefixSet;
use self::MutateMode::{JustWrite, WriteAndRead};
Expand Down Expand Up @@ -195,7 +197,7 @@ fn do_mir_borrowck<'a, 'tcx>(
Rc::new(BorrowSet::build(tcx, body, locals_are_invalidated_at_exit, &mdpe.move_data));

// Compute non-lexical lifetimes.
let nll::NllOutput { regioncx, polonius_output, opt_closure_req, nll_errors } =
let nll::NllOutput { regioncx, polonius_output: _, opt_closure_req, nll_errors } =
nll::compute_regions(
infcx,
def_id,
Expand Down Expand Up @@ -226,17 +228,14 @@ fn do_mir_borrowck<'a, 'tcx>(

let flow_borrows = Borrows::new(tcx, &body, regioncx.clone(), &borrow_set);
let flow_borrows = dataflow::generic::Engine::new_gen_kill(tcx, &body, def_id, flow_borrows)
.iterate_to_fixpoint()
.into_cursor(&body);
.iterate_to_fixpoint();
let flow_uninits = MaybeUninitializedPlaces::new(tcx, &body, &mdpe);
let flow_uninits = dataflow::generic::Engine::new_gen_kill(tcx, &body, def_id, flow_uninits)
.iterate_to_fixpoint()
.into_cursor(&body);
.iterate_to_fixpoint();
let flow_ever_inits = EverInitializedPlaces::new(tcx, &body, &mdpe);
let flow_ever_inits =
dataflow::generic::Engine::new_gen_kill(tcx, &body, def_id, flow_ever_inits)
.iterate_to_fixpoint()
.into_cursor(&body);
.iterate_to_fixpoint();

let movable_generator = match tcx.hir().get(id) {
Node::Expr(&hir::Expr {
Expand Down Expand Up @@ -276,28 +275,22 @@ fn do_mir_borrowck<'a, 'tcx>(
// Compute and report region errors, if any.
mbcx.report_region_errors(nll_errors);

let mut state = Flows::new(flow_borrows, flow_uninits, flow_ever_inits, polonius_output);
let results = BorrowckAnalyses {
ever_inits: flow_ever_inits,
uninits: flow_uninits,
borrows: flow_borrows,
};

if let Some(errors) = move_errors {
mbcx.report_move_errors(errors);
}

// FIXME: refactor into visitor
for (block, block_data) in traversal::reverse_postorder(*body) {
for (statement_index, stmt) in block_data.statements.iter().enumerate() {
let loc = Location { block, statement_index };
state.borrows.seek_before(loc);
state.uninits.seek_before(loc);
state.ever_inits.seek_before(loc);
mbcx.visit_statement_entry(loc, &stmt, &mut state);
}

let loc = body.terminator_loc(block);
state.borrows.seek_before(loc);
state.uninits.seek_before(loc);
state.ever_inits.seek_before(loc);
mbcx.visit_terminator_entry(loc, block_data.terminator(), &mut state);
}
visit_results(
&*body,
traversal::reverse_postorder(&*body).map(|(bb, _)| bb),
&results,
&mut mbcx,
);

// Convert any reservation warnings into lints.
let reservation_warnings = mem::take(&mut mbcx.reservation_warnings);
Expand Down Expand Up @@ -495,23 +488,23 @@ crate struct MirBorrowckCtxt<'cx, 'tcx> {
next_region_name: RefCell<usize>,
}

type Flows<'mir, 'tcx> = <BorrowckResults<'mir, 'tcx> as ResultsVisitable<'tcx>>::FlowState;

// Check that:
// 1. assignments are always made to mutable locations (FIXME: does that still really go here?)
// 2. loans made in overlapping scopes do not conflict
// 3. assignments do not affect things loaned out as immutable
// 4. moves do not affect things loaned out in any way
impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
fn body(&self) -> &'cx Body<'tcx> {
*self.body
}
impl<'cx, 'tcx> ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tcx> {
type FlowState = Flows<'cx, 'tcx>;

fn visit_statement_entry(
fn visit_statement(
&mut self,
location: Location,
flow_state: &Flows<'cx, 'tcx>,
stmt: &'cx Statement<'tcx>,
flow_state: &mut Flows<'cx, 'tcx>,
location: Location,
) {
debug!("MirBorrowckCtxt::process_statement({:?}, {:?}): {}", location, stmt, flow_state);
debug!("MirBorrowckCtxt::process_statement({:?}, {:?}): {:?}", location, stmt, flow_state);
let span = stmt.source_info.span;

self.check_activations(location, span, flow_state);
Expand Down Expand Up @@ -594,13 +587,13 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
}
}

fn visit_terminator_entry(
fn visit_terminator(
&mut self,
loc: Location,
flow_state: &Flows<'cx, 'tcx>,
term: &'cx Terminator<'tcx>,
flow_state: &mut Flows<'cx, 'tcx>,
loc: Location,
) {
debug!("MirBorrowckCtxt::process_terminator({:?}, {:?}): {}", loc, term, flow_state);
debug!("MirBorrowckCtxt::process_terminator({:?}, {:?}): {:?}", loc, term, flow_state);
let span = term.source_info.span;

self.check_activations(loc, span, flow_state);
Expand Down Expand Up @@ -672,18 +665,36 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {

TerminatorKind::Yield { ref value, resume: _, drop: _ } => {
self.consume_operand(loc, (value, span), flow_state);
}

TerminatorKind::Goto { target: _ }
| TerminatorKind::Abort
| TerminatorKind::Unreachable
| TerminatorKind::Resume
| TerminatorKind::Return
| TerminatorKind::GeneratorDrop
| TerminatorKind::FalseEdges { real_target: _, imaginary_target: _ }
| TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => {
// no data used, thus irrelevant to borrowck
}
}
}

if self.movable_generator {
// Look for any active borrows to locals
let borrow_set = self.borrow_set.clone();
fn visit_terminator_exit(
&mut self,
flow_state: &Flows<'cx, 'tcx>,
term: &'cx Terminator<'tcx>,
loc: Location,
) {
let span = term.source_info.span;

// FIXME: Don't call `seek_after` manually, instead use a visitor that visits
// the exit of a basic block.
flow_state.borrows.seek_after(loc);
for i in flow_state.borrows.get().iter() {
let borrow = &borrow_set[i];
self.check_for_local_borrow(borrow, span);
}
match term.kind {
TerminatorKind::Yield { value: _, resume: _, drop: _ } if self.movable_generator => {
// Look for any active borrows to locals
let borrow_set = self.borrow_set.clone();
for i in flow_state.borrows.iter() {
let borrow = &borrow_set[i];
self.check_for_local_borrow(borrow, span);
}
}

Expand All @@ -693,22 +704,13 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
// StorageDead, but we don't always emit those (notably on unwind paths),
// so this "extra check" serves as a kind of backup.
let borrow_set = self.borrow_set.clone();

// FIXME: Don't call `seek_after` manually, instead use a visitor that visits
// the exit of a basic block.
flow_state.borrows.seek_after(loc);
for i in flow_state.borrows.get().iter() {
for i in flow_state.borrows.iter() {
let borrow = &borrow_set[i];
self.check_for_invalidation_at_exit(loc, borrow, span);
}
}
TerminatorKind::Goto { target: _ }
| TerminatorKind::Abort
| TerminatorKind::Unreachable
| TerminatorKind::FalseEdges { real_target: _, imaginary_target: _ }
| TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => {
// no data used, thus irrelevant to borrowck
}

_ => {}
}
}
}
Expand Down Expand Up @@ -843,6 +845,10 @@ impl InitializationRequiringAction {
}

impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
fn body(&self) -> &'cx Body<'tcx> {
*self.body
}

/// Checks an access to the given place to see if it is allowed. Examines the set of borrows
/// that are in scope, as well as which paths have been initialized, to ensure that (a) the
/// place is initialized and (b) it is not borrowed in some way that would prevent this
Expand Down Expand Up @@ -922,7 +928,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let tcx = self.infcx.tcx;
let body = self.body;
let body: &Body<'_> = &body;
let location_table = self.location_table.start_index(location);
let _location_table = self.location_table.start_index(location);
let borrow_set = self.borrow_set.clone();
each_borrow_involving_path(
self,
Expand All @@ -931,7 +937,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
location,
(sd, place_span.0),
&borrow_set,
flow_state.borrows_in_scope(location_table),
// flow_state.borrows_in_scope(location_table),
flow_state.borrows.iter(),
|this, borrow_index, borrow| match (rw, borrow.kind) {
// Obviously an activation is compatible with its own
// reservation (or even prior activating uses of same
Expand Down Expand Up @@ -1553,7 +1560,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
location: Location,
desired_action: InitializationRequiringAction,
place_span: (PlaceRef<'cx, 'tcx>, Span),
maybe_uninits: &ResultsCursor<'cx, 'tcx, MaybeUninitializedPlaces<'cx, 'tcx>>,
maybe_uninits: &BitSet<MovePathIndex>,
from: u32,
to: u32,
) {
Expand Down

0 comments on commit 171eec5

Please sign in to comment.