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Remove duplicated implementations of borrowed locals analysis

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This commit is contained in:
Tomasz Miąsko 2022-06-06 00:00:00 +00:00
parent 37a42258ff
commit 915f091819
4 changed files with 29 additions and 133 deletions
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20
compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
View File

@ -145,3 +145,23 @@ fn visit_terminator(&mut self, terminator: &mir::Terminator<'tcx>, location: Loc
}
}
}
/// The set of locals that are borrowed at some point in the MIR body.
pub fn borrowed_locals(body: &Body<'_>) -> BitSet<Local> {
struct Borrowed(BitSet<Local>);
impl GenKill<Local> for Borrowed {
#[inline]
fn gen(&mut self, elem: Local) {
self.0.gen(elem)
}
#[inline]
fn kill(&mut self, _: Local) {
// Ignore borrow invalidation.
}
}
let mut borrowed = Borrowed(BitSet::new_empty(body.local_decls.len()));
TransferFunction { trans: &mut borrowed }.visit_body(body);
borrowed.0
}

1
compiler/rustc_mir_dataflow/src/impls/mod.rs
View File

@ -23,6 +23,7 @@
mod liveness;
mod storage_liveness;
pub use self::borrowed_locals::borrowed_locals;
pub use self::borrowed_locals::MaybeBorrowedLocals;
pub use self::init_locals::MaybeInitializedLocals;
pub use self::liveness::MaybeLiveLocals;

74
compiler/rustc_mir_transform/src/dead_store_elimination.rs
View File

@ -13,16 +13,15 @@
//!
use rustc_index::bit_set::BitSet;
use rustc_middle::{
mir::{visit::Visitor, *},
ty::TyCtxt,
};
use rustc_mir_dataflow::{impls::MaybeTransitiveLiveLocals, Analysis};
use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt;
use rustc_mir_dataflow::impls::{borrowed_locals, MaybeTransitiveLiveLocals};
use rustc_mir_dataflow::Analysis;
/// Performs the optimization on the body
///
/// The `borrowed` set must be a `BitSet` of all the locals that are ever borrowed in this body. It
/// can be generated via the [`get_borrowed_locals`] function.
/// can be generated via the [`borrowed_locals`] function.
pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitSet<Local>) {
let mut live = MaybeTransitiveLiveLocals::new(borrowed)
.into_engine(tcx, body)
@ -73,67 +72,6 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitS
}
}
pub fn get_borrowed_locals(body: &Body<'_>) -> BitSet<Local> {
let mut b = BorrowedLocals(BitSet::new_empty(body.local_decls.len()));
b.visit_body(body);
b.0
}
struct BorrowedLocals(BitSet<Local>);
impl<'tcx> Visitor<'tcx> for BorrowedLocals {
fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, loc: Location) {
self.super_rvalue(rvalue, loc);
match rvalue {
Rvalue::AddressOf(_, borrowed_place) | Rvalue::Ref(_, _, borrowed_place) => {
if !borrowed_place.is_indirect() {
self.0.insert(borrowed_place.local);
}
}
Rvalue::Cast(..)
| Rvalue::ShallowInitBox(..)
| Rvalue::Use(..)
| Rvalue::Repeat(..)
| Rvalue::Len(..)
| Rvalue::BinaryOp(..)
| Rvalue::CheckedBinaryOp(..)
| Rvalue::NullaryOp(..)
| Rvalue::UnaryOp(..)
| Rvalue::Discriminant(..)
| Rvalue::Aggregate(..)
| Rvalue::ThreadLocalRef(..) => {}
}
}
fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
self.super_terminator(terminator, location);
match terminator.kind {
TerminatorKind::Drop { place: dropped_place, .. } => {
if !dropped_place.is_indirect() {
self.0.insert(dropped_place.local);
}
}
TerminatorKind::Abort
| TerminatorKind::DropAndReplace { .. }
| TerminatorKind::Assert { .. }
| TerminatorKind::Call { .. }
| TerminatorKind::FalseEdge { .. }
| TerminatorKind::FalseUnwind { .. }
| TerminatorKind::GeneratorDrop
| TerminatorKind::Goto { .. }
| TerminatorKind::Resume
| TerminatorKind::Return
| TerminatorKind::SwitchInt { .. }
| TerminatorKind::Unreachable
| TerminatorKind::Yield { .. }
| TerminatorKind::InlineAsm { .. } => {}
}
}
}
pub struct DeadStoreElimination;
impl<'tcx> MirPass<'tcx> for DeadStoreElimination {
@ -142,7 +80,7 @@ fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
}
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let borrowed = get_borrowed_locals(body);
let borrowed = borrowed_locals(body);
eliminate(tcx, body, &borrowed);
}
}

67
compiler/rustc_mir_transform/src/dest_prop.rs
View File

@ -104,7 +104,7 @@
Rvalue, Statement, StatementKind, Terminator, TerminatorKind,
};
use rustc_middle::ty::TyCtxt;
use rustc_mir_dataflow::impls::{MaybeInitializedLocals, MaybeLiveLocals};
use rustc_mir_dataflow::impls::{borrowed_locals, MaybeInitializedLocals, MaybeLiveLocals};
use rustc_mir_dataflow::Analysis;
// Empirical measurements have resulted in some observations:
@ -805,7 +805,7 @@ fn find_candidates<'tcx>(body: &Body<'tcx>) -> Vec<CandidateAssignment<'tcx>> {
let mut visitor = FindAssignments {
body,
candidates: Vec::new(),
ever_borrowed_locals: ever_borrowed_locals(body),
ever_borrowed_locals: borrowed_locals(body),
locals_used_as_array_index: locals_used_as_array_index(body),
};
visitor.visit_body(body);
@ -886,69 +886,6 @@ fn is_local_required(local: Local, body: &Body<'_>) -> bool {
}
}
/// Walks MIR to find all locals that have their address taken anywhere.
fn ever_borrowed_locals(body: &Body<'_>) -> BitSet<Local> {
let mut visitor = BorrowCollector { locals: BitSet::new_empty(body.local_decls.len()) };
visitor.visit_body(body);
visitor.locals
}
struct BorrowCollector {
locals: BitSet<Local>,
}
impl<'tcx> Visitor<'tcx> for BorrowCollector {
fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
self.super_rvalue(rvalue, location);
match rvalue {
Rvalue::AddressOf(_, borrowed_place) | Rvalue::Ref(_, _, borrowed_place) => {
if !borrowed_place.is_indirect() {
self.locals.insert(borrowed_place.local);
}
}
Rvalue::Cast(..)
| Rvalue::ShallowInitBox(..)
| Rvalue::Use(..)
| Rvalue::Repeat(..)
| Rvalue::Len(..)
| Rvalue::BinaryOp(..)
| Rvalue::CheckedBinaryOp(..)
| Rvalue::NullaryOp(..)
| Rvalue::UnaryOp(..)
| Rvalue::Discriminant(..)
| Rvalue::Aggregate(..)
| Rvalue::ThreadLocalRef(..) => {}
}
}
fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
self.super_terminator(terminator, location);
match terminator.kind {
TerminatorKind::Drop { place: dropped_place, .. }
| TerminatorKind::DropAndReplace { place: dropped_place, .. } => {
self.locals.insert(dropped_place.local);
}
TerminatorKind::Abort
| TerminatorKind::Assert { .. }
| TerminatorKind::Call { .. }
| TerminatorKind::FalseEdge { .. }
| TerminatorKind::FalseUnwind { .. }
| TerminatorKind::GeneratorDrop
| TerminatorKind::Goto { .. }
| TerminatorKind::Resume
| TerminatorKind::Return
| TerminatorKind::SwitchInt { .. }
| TerminatorKind::Unreachable
| TerminatorKind::Yield { .. }
| TerminatorKind::InlineAsm { .. } => {}
}
}
}
/// `PlaceElem::Index` only stores a `Local`, so we can't replace that with a full `Place`.
///
/// Collect locals used as indices so we don't generate candidates that are impossible to apply