rustc_mir_transform/
required_consts.rs

1use rustc_middle::mir::visit::Visitor;
2use rustc_middle::mir::{Body, ConstOperand, Location, traversal};
3
4pub(super) struct RequiredConstsVisitor<'tcx> {
5    required_consts: Vec<ConstOperand<'tcx>>,
6}
7
8impl<'tcx> RequiredConstsVisitor<'tcx> {
9    pub(super) fn compute_required_consts(body: &mut Body<'tcx>) {
10        let mut visitor = RequiredConstsVisitor { required_consts: Vec::new() };
11        for (bb, bb_data) in traversal::reverse_postorder(&body) {
12            visitor.visit_basic_block_data(bb, bb_data);
13        }
14        body.set_required_consts(visitor.required_consts);
15    }
16}
17
18impl<'tcx> Visitor<'tcx> for RequiredConstsVisitor<'tcx> {
19    fn visit_const_operand(&mut self, constant: &ConstOperand<'tcx>, _: Location) {
20        if constant.const_.is_required_const() {
21            self.required_consts.push(*constant);
22        }
23    }
24}