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extract polonius move fact generation
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@lqd
lqd committed Nov 26, 2023
1 parent eca2789 commit 3de68e0
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Showing 2 changed files with 91 additions and 85 deletions.
92 changes: 7 additions & 85 deletions compiler/rustc_borrowck/src/nll.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,28 +2,25 @@
#![deny(rustc::diagnostic_outside_of_impl)]
//! The entry point of the NLL borrow checker.

use polonius_engine::{Algorithm, Output};
use rustc_data_structures::fx::FxIndexMap;
use rustc_hir::def_id::LocalDefId;
use rustc_index::IndexSlice;
use rustc_middle::mir::{create_dump_file, dump_enabled, dump_mir, PassWhere};
use rustc_middle::mir::{
Body, ClosureOutlivesSubject, ClosureRegionRequirements, LocalKind, Location, Promoted,
START_BLOCK,
};
use rustc_middle::mir::{Body, ClosureOutlivesSubject, ClosureRegionRequirements, Promoted};
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::{self, OpaqueHiddenType, TyCtxt};
use rustc_mir_dataflow::impls::MaybeInitializedPlaces;
use rustc_mir_dataflow::move_paths::MoveData;
use rustc_mir_dataflow::ResultsCursor;
use rustc_span::symbol::sym;
use std::env;
use std::io;
use std::path::PathBuf;
use std::rc::Rc;
use std::str::FromStr;

use polonius_engine::{Algorithm, Output};

use rustc_mir_dataflow::impls::MaybeInitializedPlaces;
use rustc_mir_dataflow::move_paths::{InitKind, InitLocation, MoveData};
use rustc_mir_dataflow::ResultsCursor;
mod polonius;

use crate::{
borrow_set::BorrowSet,
Expand Down Expand Up @@ -78,81 +75,6 @@ pub(crate) fn replace_regions_in_mir<'tcx>(
universal_regions
}

// This function populates an AllFacts instance with base facts related to
// MovePaths and needed for the move analysis.
fn populate_polonius_move_facts(
all_facts: &mut AllFacts,
move_data: &MoveData<'_>,
location_table: &LocationTable,
body: &Body<'_>,
) {
all_facts
.path_is_var
.extend(move_data.rev_lookup.iter_locals_enumerated().map(|(l, r)| (r, l)));

for (child, move_path) in move_data.move_paths.iter_enumerated() {
if let Some(parent) = move_path.parent {
all_facts.child_path.push((child, parent));
}
}

let fn_entry_start =
location_table.start_index(Location { block: START_BLOCK, statement_index: 0 });

// initialized_at
for init in move_data.inits.iter() {
match init.location {
InitLocation::Statement(location) => {
let block_data = &body[location.block];
let is_terminator = location.statement_index == block_data.statements.len();

if is_terminator && init.kind == InitKind::NonPanicPathOnly {
// We are at the terminator of an init that has a panic path,
// and where the init should not happen on panic

for successor in block_data.terminator().successors() {
if body[successor].is_cleanup {
continue;
}

// The initialization happened in (or rather, when arriving at)
// the successors, but not in the unwind block.
let first_statement = Location { block: successor, statement_index: 0 };
all_facts
.path_assigned_at_base
.push((init.path, location_table.start_index(first_statement)));
}
} else {
// In all other cases, the initialization just happens at the
// midpoint, like any other effect.
all_facts
.path_assigned_at_base
.push((init.path, location_table.mid_index(location)));
}
}
// Arguments are initialized on function entry
InitLocation::Argument(local) => {
assert!(body.local_kind(local) == LocalKind::Arg);
all_facts.path_assigned_at_base.push((init.path, fn_entry_start));
}
}
}

for (local, path) in move_data.rev_lookup.iter_locals_enumerated() {
if body.local_kind(local) != LocalKind::Arg {
// Non-arguments start out deinitialised; we simulate this with an
// initial move:
all_facts.path_moved_at_base.push((path, fn_entry_start));
}
}

// moved_out_at
// deinitialisation is assumed to always happen!
all_facts
.path_moved_at_base
.extend(move_data.moves.iter().map(|mo| (mo.path, location_table.mid_index(mo.source))));
}

/// Computes the (non-lexical) regions from the input MIR.
///
/// This may result in errors being reported.
Expand Down Expand Up @@ -206,7 +128,7 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
if let Some(all_facts) = &mut all_facts {
let _prof_timer = infcx.tcx.prof.generic_activity("polonius_fact_generation");
all_facts.universal_region.extend(universal_regions.universal_regions());
populate_polonius_move_facts(all_facts, move_data, location_table, body);
polonius::emit_move_facts(all_facts, move_data, location_table, body);

// Emit universal regions facts, and their relations, for Polonius.
//
Expand Down
84 changes: 84 additions & 0 deletions compiler/rustc_borrowck/src/nll/polonius.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,84 @@
//! Functions dedicated to fact generation for the `-Zpolonius=legacy` datalog implementation.
//!
//! Will be removed in the future, once the in-tree `-Zpolonius=next` implementation reaches feature
//! parity.

use rustc_middle::mir::{Body, LocalKind, Location, START_BLOCK};
use rustc_mir_dataflow::move_paths::{InitKind, InitLocation, MoveData};

use crate::facts::AllFacts;
use crate::location::LocationTable;

/// Emit polonius facts needed for move/init analysis: moves and assignments.
pub(crate) fn emit_move_facts(
all_facts: &mut AllFacts,
move_data: &MoveData<'_>,
location_table: &LocationTable,
body: &Body<'_>,
) {
all_facts
.path_is_var
.extend(move_data.rev_lookup.iter_locals_enumerated().map(|(l, r)| (r, l)));

for (child, move_path) in move_data.move_paths.iter_enumerated() {
if let Some(parent) = move_path.parent {
all_facts.child_path.push((child, parent));
}
}

let fn_entry_start =
location_table.start_index(Location { block: START_BLOCK, statement_index: 0 });

// initialized_at
for init in move_data.inits.iter() {
match init.location {
InitLocation::Statement(location) => {
let block_data = &body[location.block];
let is_terminator = location.statement_index == block_data.statements.len();

if is_terminator && init.kind == InitKind::NonPanicPathOnly {
// We are at the terminator of an init that has a panic path,
// and where the init should not happen on panic

for successor in block_data.terminator().successors() {
if body[successor].is_cleanup {
continue;
}

// The initialization happened in (or rather, when arriving at)
// the successors, but not in the unwind block.
let first_statement = Location { block: successor, statement_index: 0 };
all_facts
.path_assigned_at_base
.push((init.path, location_table.start_index(first_statement)));
}
} else {
// In all other cases, the initialization just happens at the
// midpoint, like any other effect.
all_facts
.path_assigned_at_base
.push((init.path, location_table.mid_index(location)));
}
}
// Arguments are initialized on function entry
InitLocation::Argument(local) => {
assert!(body.local_kind(local) == LocalKind::Arg);
all_facts.path_assigned_at_base.push((init.path, fn_entry_start));
}
}
}

for (local, path) in move_data.rev_lookup.iter_locals_enumerated() {
if body.local_kind(local) != LocalKind::Arg {
// Non-arguments start out deinitialised; we simulate this with an
// initial move:
all_facts.path_moved_at_base.push((path, fn_entry_start));
}
}

// moved_out_at
// deinitialisation is assumed to always happen!
all_facts
.path_moved_at_base
.extend(move_data.moves.iter().map(|mo| (mo.path, location_table.mid_index(mo.source))));
}

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