bjoernager/rust
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Auto merge of #81440 - tmiasko:always-live-locals, r=matthewjasper

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Visit only statements in always live locals

No functional changes intended.
This commit is contained in:
bors 2021-01-29 06:56:29 +00:00
commit 099f27b6cb
1 changed files with 11 additions and 18 deletions
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29
compiler/rustc_mir/src/util/storage.rs
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@ -1,6 +1,5 @@
use rustc_index::bit_set::BitSet; use rustc_index::bit_set::BitSet;
use rustc_middle::mir::visit::Visitor; use rustc_middle::mir::{self, Local};
use rustc_middle::mir::{self, Local, Location};
/// The set of locals in a MIR body that do not have `StorageLive`/`StorageDead` annotations. /// The set of locals in a MIR body that do not have `StorageLive`/`StorageDead` annotations.
/// ///
@ -13,12 +12,18 @@ pub struct AlwaysLiveLocals(BitSet<Local>);
impl AlwaysLiveLocals { impl AlwaysLiveLocals {
pub fn new(body: &mir::Body<'tcx>) -> Self { pub fn new(body: &mir::Body<'tcx>) -> Self {
let mut ret = AlwaysLiveLocals(BitSet::new_filled(body.local_decls.len())); let mut always_live_locals = AlwaysLiveLocals(BitSet::new_filled(body.local_decls.len()));
let mut vis = StorageAnnotationVisitor(&mut ret); for block in body.basic_blocks() {
vis.visit_body(body); for statement in &block.statements {
use mir::StatementKind::{StorageDead, StorageLive};
if let StorageLive(l) | StorageDead(l) = statement.kind {
always_live_locals.0.remove(l);
}
}
}
ret always_live_locals
} }
pub fn into_inner(self) -> BitSet<Local> { pub fn into_inner(self) -> BitSet<Local> {
@ -33,15 +38,3 @@ impl std::ops::Deref for AlwaysLiveLocals {
&self.0 &self.0
} }
} }
/// Removes locals that have `Storage*` annotations from `AlwaysLiveLocals`.
struct StorageAnnotationVisitor<'a>(&'a mut AlwaysLiveLocals);
impl Visitor<'tcx> for StorageAnnotationVisitor<'_> {
fn visit_statement(&mut self, statement: &mir::Statement<'tcx>, _location: Location) {
use mir::StatementKind::{StorageDead, StorageLive};
if let StorageLive(l) | StorageDead(l) = statement.kind {
(self.0).0.remove(l);
}
}
}