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Remove ResultsVisitable #132134

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Nov 17, 2024
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Remove ResultsVisitable #132134

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3350edf
Replace `BorrowckResults` with `Borrowck`.
nnethercote Oct 31, 2024
c904c6a
Remove `ResultsVisitable`.
nnethercote Oct 31, 2024
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160 changes: 119 additions & 41 deletions compiler/rustc_borrowck/src/dataflow.rs
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Original file line number Diff line number Diff line change
@@ -1,93 +1,171 @@
use std::fmt;

use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::graph;
use rustc_index::bit_set::BitSet;
use rustc_middle::mir::{self, BasicBlock, Body, Location, Place, TerminatorEdges};
use rustc_middle::mir::{
self, BasicBlock, Body, CallReturnPlaces, Location, Place, TerminatorEdges,
};
use rustc_middle::ty::{RegionVid, TyCtxt};
use rustc_mir_dataflow::fmt::DebugWithContext;
use rustc_mir_dataflow::impls::{EverInitializedPlaces, MaybeUninitializedPlaces};
use rustc_mir_dataflow::{Analysis, Forward, GenKill, Results, ResultsVisitable};
use rustc_mir_dataflow::{Analysis, GenKill, JoinSemiLattice, SwitchIntEdgeEffects};
use tracing::debug;

use crate::{BorrowSet, PlaceConflictBias, PlaceExt, RegionInferenceContext, places_conflict};

/// The results of the dataflow analyses used by the borrow checker.
pub(crate) struct BorrowckResults<'a, 'tcx> {
pub(crate) borrows: Results<'tcx, Borrows<'a, 'tcx>>,
pub(crate) uninits: Results<'tcx, MaybeUninitializedPlaces<'a, 'tcx>>,
pub(crate) ever_inits: Results<'tcx, EverInitializedPlaces<'a, 'tcx>>,
}

/// The transient state of the dataflow analyses used by the borrow checker.
#[derive(Debug)]
pub(crate) struct BorrowckDomain<'a, 'tcx> {
pub(crate) borrows: <Borrows<'a, 'tcx> as Analysis<'tcx>>::Domain,
pub(crate) uninits: <MaybeUninitializedPlaces<'a, 'tcx> as Analysis<'tcx>>::Domain,
pub(crate) ever_inits: <EverInitializedPlaces<'a, 'tcx> as Analysis<'tcx>>::Domain,
// This analysis is different to most others. Its results aren't computed with
// `iterate_to_fixpoint`, but are instead composed from the results of three sub-analyses that are
// computed individually with `iterate_to_fixpoint`.
pub(crate) struct Borrowck<'a, 'tcx> {
pub(crate) borrows: Borrows<'a, 'tcx>,
pub(crate) uninits: MaybeUninitializedPlaces<'a, 'tcx>,
pub(crate) ever_inits: EverInitializedPlaces<'a, 'tcx>,
}

impl<'a, 'tcx> ResultsVisitable<'tcx> for BorrowckResults<'a, 'tcx> {
type Direction = Forward;
impl<'a, 'tcx> Analysis<'tcx> for Borrowck<'a, 'tcx> {
type Domain = BorrowckDomain<'a, 'tcx>;

const NAME: &'static str = "borrowck";

fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
BorrowckDomain {
borrows: self.borrows.analysis.bottom_value(body),
uninits: self.uninits.analysis.bottom_value(body),
ever_inits: self.ever_inits.analysis.bottom_value(body),
borrows: self.borrows.bottom_value(body),
uninits: self.uninits.bottom_value(body),
ever_inits: self.ever_inits.bottom_value(body),
}
}

fn reset_to_block_entry(&self, state: &mut Self::Domain, block: BasicBlock) {
state.borrows.clone_from(self.borrows.entry_set_for_block(block));
state.uninits.clone_from(self.uninits.entry_set_for_block(block));
state.ever_inits.clone_from(self.ever_inits.entry_set_for_block(block));
fn initialize_start_block(&self, _body: &mir::Body<'tcx>, _state: &mut Self::Domain) {
// This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
unreachable!();
}

fn reconstruct_before_statement_effect(
fn apply_before_statement_effect(
&mut self,
state: &mut Self::Domain,
stmt: &mir::Statement<'tcx>,
loc: Location,
) {
self.borrows.analysis.apply_before_statement_effect(&mut state.borrows, stmt, loc);
self.uninits.analysis.apply_before_statement_effect(&mut state.uninits, stmt, loc);
self.ever_inits.analysis.apply_before_statement_effect(&mut state.ever_inits, stmt, loc);
self.borrows.apply_before_statement_effect(&mut state.borrows, stmt, loc);
self.uninits.apply_before_statement_effect(&mut state.uninits, stmt, loc);
self.ever_inits.apply_before_statement_effect(&mut state.ever_inits, stmt, loc);
}

fn reconstruct_statement_effect(
fn apply_statement_effect(
&mut self,
state: &mut Self::Domain,
stmt: &mir::Statement<'tcx>,
loc: Location,
) {
self.borrows.analysis.apply_statement_effect(&mut state.borrows, stmt, loc);
self.uninits.analysis.apply_statement_effect(&mut state.uninits, stmt, loc);
self.ever_inits.analysis.apply_statement_effect(&mut state.ever_inits, stmt, loc);
self.borrows.apply_statement_effect(&mut state.borrows, stmt, loc);
self.uninits.apply_statement_effect(&mut state.uninits, stmt, loc);
self.ever_inits.apply_statement_effect(&mut state.ever_inits, stmt, loc);
}

fn reconstruct_before_terminator_effect(
fn apply_before_terminator_effect(
&mut self,
state: &mut Self::Domain,
term: &mir::Terminator<'tcx>,
loc: Location,
) {
self.borrows.analysis.apply_before_terminator_effect(&mut state.borrows, term, loc);
self.uninits.analysis.apply_before_terminator_effect(&mut state.uninits, term, loc);
self.ever_inits.analysis.apply_before_terminator_effect(&mut state.ever_inits, term, loc);
self.borrows.apply_before_terminator_effect(&mut state.borrows, term, loc);
self.uninits.apply_before_terminator_effect(&mut state.uninits, term, loc);
self.ever_inits.apply_before_terminator_effect(&mut state.ever_inits, term, loc);
}

fn reconstruct_terminator_effect(
fn apply_terminator_effect<'mir>(
&mut self,
state: &mut Self::Domain,
term: &mir::Terminator<'tcx>,
term: &'mir mir::Terminator<'tcx>,
loc: Location,
) -> TerminatorEdges<'mir, 'tcx> {
self.borrows.apply_terminator_effect(&mut state.borrows, term, loc);
self.uninits.apply_terminator_effect(&mut state.uninits, term, loc);
self.ever_inits.apply_terminator_effect(&mut state.ever_inits, term, loc);

// This return value doesn't matter. It's only used by `iterate_to_fixpoint`, which this
// analysis doesn't use.
TerminatorEdges::None
}

fn apply_call_return_effect(
&mut self,
_state: &mut Self::Domain,
_block: BasicBlock,
_return_places: CallReturnPlaces<'_, 'tcx>,
) {
// This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
unreachable!();
}

fn apply_switch_int_edge_effects(
&mut self,
_block: BasicBlock,
_discr: &mir::Operand<'tcx>,
_apply_edge_effects: &mut impl SwitchIntEdgeEffects<Self::Domain>,
) {
self.borrows.analysis.apply_terminator_effect(&mut state.borrows, term, loc);
self.uninits.analysis.apply_terminator_effect(&mut state.uninits, term, loc);
self.ever_inits.analysis.apply_terminator_effect(&mut state.ever_inits, term, loc);
// This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
unreachable!();
}
}

impl JoinSemiLattice for BorrowckDomain<'_, '_> {
fn join(&mut self, _other: &Self) -> bool {
// This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
unreachable!();
}
}

impl<'tcx, C> DebugWithContext<C> for BorrowckDomain<'_, 'tcx>
where
C: rustc_mir_dataflow::move_paths::HasMoveData<'tcx>,
{
fn fmt_with(&self, ctxt: &C, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("borrows: ")?;
self.borrows.fmt_with(ctxt, f)?;
f.write_str(" uninits: ")?;
self.uninits.fmt_with(ctxt, f)?;
f.write_str(" ever_inits: ")?;
self.ever_inits.fmt_with(ctxt, f)?;
Ok(())
}

fn fmt_diff_with(&self, old: &Self, ctxt: &C, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if self == old {
return Ok(());
}

if self.borrows != old.borrows {
f.write_str("borrows: ")?;
self.borrows.fmt_diff_with(&old.borrows, ctxt, f)?;
f.write_str("\n")?;
}

if self.uninits != old.uninits {
f.write_str("uninits: ")?;
self.uninits.fmt_diff_with(&old.uninits, ctxt, f)?;
f.write_str("\n")?;
}

if self.ever_inits != old.ever_inits {
f.write_str("ever_inits: ")?;
self.ever_inits.fmt_diff_with(&old.ever_inits, ctxt, f)?;
f.write_str("\n")?;
}

Ok(())
}
}

/// The transient state of the dataflow analyses used by the borrow checker.
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) struct BorrowckDomain<'a, 'tcx> {
pub(crate) borrows: <Borrows<'a, 'tcx> as Analysis<'tcx>>::Domain,
pub(crate) uninits: <MaybeUninitializedPlaces<'a, 'tcx> as Analysis<'tcx>>::Domain,
pub(crate) ever_inits: <EverInitializedPlaces<'a, 'tcx> as Analysis<'tcx>>::Domain,
}

rustc_index::newtype_index! {
#[orderable]
#[debug_format = "bw{}"]
Expand Down
93 changes: 54 additions & 39 deletions compiler/rustc_borrowck/src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -36,21 +36,21 @@ use rustc_middle::mir::*;
use rustc_middle::query::Providers;
use rustc_middle::ty::{self, ParamEnv, RegionVid, TyCtxt, TypingMode};
use rustc_middle::{bug, span_bug};
use rustc_mir_dataflow::Analysis;
use rustc_mir_dataflow::impls::{
EverInitializedPlaces, MaybeInitializedPlaces, MaybeUninitializedPlaces,
};
use rustc_mir_dataflow::move_paths::{
InitIndex, InitLocation, LookupResult, MoveData, MoveOutIndex, MovePathIndex,
};
use rustc_mir_dataflow::{Analysis, EntrySets, Results, ResultsVisitor, visit_results};
use rustc_session::lint::builtin::UNUSED_MUT;
use rustc_span::{Span, Symbol};
use smallvec::SmallVec;
use tracing::{debug, instrument};

use crate::borrow_set::{BorrowData, BorrowSet};
use crate::consumers::{BodyWithBorrowckFacts, ConsumerOptions};
use crate::dataflow::{BorrowIndex, BorrowckDomain, BorrowckResults, Borrows};
use crate::dataflow::{BorrowIndex, Borrowck, BorrowckDomain, Borrows};
use crate::diagnostics::{AccessKind, IllegalMoveOriginKind, MoveError, RegionName};
use crate::location::LocationTable;
use crate::nll::PoloniusOutput;
Expand Down Expand Up @@ -221,6 +221,10 @@ fn do_mir_borrowck<'tcx>(
consumer_options,
);

// `flow_inits` is large, so we drop it as soon as possible. This reduces
// peak memory usage significantly on some benchmarks.
drop(flow_inits);

// Dump MIR results into a file, if that is enabled. This let us
// write unit-tests, as well as helping with debugging.
nll::dump_nll_mir(&infcx, body, &regioncx, &opt_closure_req, &borrow_set);
Expand All @@ -229,27 +233,6 @@ fn do_mir_borrowck<'tcx>(
// information.
nll::dump_annotation(&infcx, body, &regioncx, &opt_closure_req, &opaque_type_values, diags);

// The various `flow_*` structures can be large. We drop `flow_inits` here
// so it doesn't overlap with the others below. This reduces peak memory
// usage significantly on some benchmarks.
drop(flow_inits);

let flow_borrows = Borrows::new(tcx, body, &regioncx, &borrow_set).iterate_to_fixpoint(
tcx,
body,
Some("borrowck"),
);
let flow_uninits = MaybeUninitializedPlaces::new(tcx, body, &move_data).iterate_to_fixpoint(
tcx,
body,
Some("borrowck"),
);
let flow_ever_inits = EverInitializedPlaces::new(body, &move_data).iterate_to_fixpoint(
tcx,
body,
Some("borrowck"),
);

let movable_coroutine =
// The first argument is the coroutine type passed by value
if let Some(local) = body.local_decls.raw.get(1)
Expand Down Expand Up @@ -334,16 +317,11 @@ fn do_mir_borrowck<'tcx>(
// Compute and report region errors, if any.
mbcx.report_region_errors(nll_errors);

let mut results = BorrowckResults {
ever_inits: flow_ever_inits,
uninits: flow_uninits,
borrows: flow_borrows,
};

rustc_mir_dataflow::visit_results(
let mut flow_results = get_flow_results(tcx, body, &move_data, &borrow_set, &regioncx);
visit_results(
body,
traversal::reverse_postorder(body).map(|(bb, _)| bb),
&mut results,
&mut flow_results,
&mut mbcx,
);

Expand Down Expand Up @@ -426,6 +404,47 @@ fn do_mir_borrowck<'tcx>(
(result, body_with_facts)
}

fn get_flow_results<'a, 'tcx>(
tcx: TyCtxt<'tcx>,
body: &'a Body<'tcx>,
move_data: &'a MoveData<'tcx>,
borrow_set: &'a BorrowSet<'tcx>,
regioncx: &RegionInferenceContext<'tcx>,
) -> Results<'tcx, Borrowck<'a, 'tcx>> {
// We compute these three analyses individually, but them combine them into
// a single results so that `mbcx` can visit them all together.
let borrows = Borrows::new(tcx, body, regioncx, borrow_set).iterate_to_fixpoint(
tcx,
body,
Some("borrowck"),
);
let uninits = MaybeUninitializedPlaces::new(tcx, body, move_data).iterate_to_fixpoint(
tcx,
body,
Some("borrowck"),
);
let ever_inits = EverInitializedPlaces::new(body, move_data).iterate_to_fixpoint(
tcx,
body,
Some("borrowck"),
);

let analysis = Borrowck {
borrows: borrows.analysis,
uninits: uninits.analysis,
ever_inits: ever_inits.analysis,
};

assert_eq!(borrows.entry_sets.len(), uninits.entry_sets.len());
assert_eq!(borrows.entry_sets.len(), ever_inits.entry_sets.len());
let entry_sets: EntrySets<'_, Borrowck<'_, '_>> =
itertools::izip!(borrows.entry_sets, uninits.entry_sets, ever_inits.entry_sets)
.map(|(borrows, uninits, ever_inits)| BorrowckDomain { borrows, uninits, ever_inits })
.collect();

Results { analysis, entry_sets }
}

pub(crate) struct BorrowckInferCtxt<'tcx> {
pub(crate) infcx: InferCtxt<'tcx>,
pub(crate) reg_var_to_origin: RefCell<FxIndexMap<ty::RegionVid, RegionCtxt>>,
Expand Down Expand Up @@ -588,14 +607,10 @@ struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
// 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<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>
for MirBorrowckCtxt<'a, '_, 'tcx>
{
type Domain = BorrowckDomain<'a, 'tcx>;

impl<'a, 'tcx> ResultsVisitor<'a, 'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<'a, '_, 'tcx> {
fn visit_statement_before_primary_effect(
&mut self,
_results: &mut R,
_results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
state: &BorrowckDomain<'a, 'tcx>,
stmt: &'a Statement<'tcx>,
location: Location,
Expand Down Expand Up @@ -667,7 +682,7 @@ impl<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>

fn visit_terminator_before_primary_effect(
&mut self,
_results: &mut R,
_results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
state: &BorrowckDomain<'a, 'tcx>,
term: &'a Terminator<'tcx>,
loc: Location,
Expand Down Expand Up @@ -780,7 +795,7 @@ impl<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>

fn visit_terminator_after_primary_effect(
&mut self,
_results: &mut R,
_results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
state: &BorrowckDomain<'a, 'tcx>,
term: &'a Terminator<'tcx>,
loc: Location,
Expand Down
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