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use rustc_index::bit_set::BitSet;
use rustc_middle::mir;
use rustc_mir_dataflow::{AnalysisDomain, CallReturnPlaces, GenKill, GenKillAnalysis};
/// Determines liveness of each local purely based on `StorageLive`/`Dead`.
#[derive(Copy, Clone)]
pub(super) struct MaybeStorageLive;
impl<'tcx> AnalysisDomain<'tcx> for MaybeStorageLive {
type Domain = BitSet<mir::Local>;
const NAME: &'static str = "maybe_storage_live";
fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
// bottom = dead
BitSet::new_empty(body.local_decls.len())
}
fn initialize_start_block(&self, body: &mir::Body<'tcx>, state: &mut Self::Domain) {
for arg in body.args_iter() {
state.insert(arg);
}
}
}
impl<'tcx> GenKillAnalysis<'tcx> for MaybeStorageLive {
type Idx = mir::Local;
fn statement_effect(&self, trans: &mut impl GenKill<Self::Idx>, stmt: &mir::Statement<'tcx>, _: mir::Location) {
match stmt.kind {
mir::StatementKind::StorageLive(l) => trans.gen(l),
mir::StatementKind::StorageDead(l) => trans.kill(l),
_ => (),
}
}
fn terminator_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_terminator: &mir::Terminator<'tcx>,
_loc: mir::Location,
) {
}
fn call_return_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_block: mir::BasicBlock,
_return_places: CallReturnPlaces<'_, 'tcx>,
) {
// Nothing to do when a call returns successfully
}
}
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