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Directly modify the used_locals vec

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Fixes perf regression in `optimized_mir` query
This commit is contained in:
Wesley Wiser 2020-04-13 21:02:03 -04:00
parent de3cf6e8a4
commit da8f3bbf32
1 changed files with 12 additions and 14 deletions
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26
src/librustc_mir/transform/simplify.rs
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@ -438,13 +438,16 @@ impl<'a, 'tcx> Visitor<'tcx> for DeclMarker<'a, 'tcx> {
}
struct StatementDeclMarker<'a, 'tcx> {
used_locals: IndexVec<Local, usize>,
used_locals: &'a mut IndexVec<Local, usize>,
statement: &'a Statement<'tcx>,
}
impl<'a, 'tcx> StatementDeclMarker<'a, 'tcx> {
pub fn new(local_count: usize, statement: &'a Statement<'tcx>) -> Self {
Self { used_locals: IndexVec::from_elem_n(0, local_count), statement }
pub fn new(
used_locals: &'a mut IndexVec<Local, usize>,
statement: &'a Statement<'tcx>,
) -> Self {
Self { used_locals, statement }
}
}
@ -457,7 +460,11 @@ impl<'a, 'tcx> Visitor<'tcx> for StatementDeclMarker<'a, 'tcx> {
}
}
self.used_locals[*local] += 1;
let use_count = &mut self.used_locals[*local];
// If this is the local we're removing...
if *use_count != 0 {
*use_count -= 1;
}
}
}
@ -504,17 +511,8 @@ impl<'a, 'tcx> MutVisitor<'tcx> for RemoveStatements<'a, 'tcx> {
trace!("removing statement {:?}", stmt);
self.modified = true;
let mut visitor = StatementDeclMarker::new(self.used_locals.len(), stmt);
let mut visitor = StatementDeclMarker::new(self.used_locals, stmt);
visitor.visit_statement(stmt, Location { block, statement_index: i });
for (local, count) in visitor.used_locals.iter_enumerated() {
let used_count = &mut self.used_locals[local];
// If this is the local we're removing...
if *used_count != 0 {
*used_count -= count;
}
}
}
i += 1;