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| 1 | +use rustc_data_structures::fx::FxIndexSet; |
| 2 | +use rustc_data_structures::graph::scc::Sccs; |
| 3 | +use rustc_data_structures::graph::{DirectedGraph, Successors}; |
| 4 | +use rustc_data_structures::unord::UnordMap; |
| 5 | +use rustc_hir::def_id::DefId; |
| 6 | +use rustc_index::{Idx, IndexVec, newtype_index}; |
| 7 | +use rustc_middle::mir::mono::MonoItem; |
| 8 | +use rustc_middle::ty::TyCtxt; |
| 9 | + |
| 10 | +use crate::collector::UsageMap; |
| 11 | +use crate::errors; |
| 12 | + |
| 13 | +#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)] |
| 14 | +struct StaticNodeIdx(usize); |
| 15 | + |
| 16 | +impl Idx for StaticNodeIdx { |
| 17 | + fn new(idx: usize) -> Self { |
| 18 | + Self(idx) |
| 19 | + } |
| 20 | + |
| 21 | + fn index(self) -> usize { |
| 22 | + self.0 |
| 23 | + } |
| 24 | +} |
| 25 | + |
| 26 | +impl From<usize> for StaticNodeIdx { |
| 27 | + fn from(value: usize) -> Self { |
| 28 | + StaticNodeIdx(value) |
| 29 | + } |
| 30 | +} |
| 31 | + |
| 32 | +newtype_index! { |
| 33 | + #[derive(Ord, PartialOrd)] |
| 34 | + struct StaticSccIdx {} |
| 35 | +} |
| 36 | + |
| 37 | +// Adjacency-list graph for statics using [`StaticNodeIdx`] as node type. |
| 38 | +// We cannot use [`DefId`] as the note type directly because each node must be |
| 39 | +// represented by an index in the range `0..num_nodes`. |
| 40 | +struct StaticRefGraph<'a, 'b, 'tcx> { |
| 41 | + // maps from [`StaticNodeIdx`] to [`DefId`] and vice versa |
| 42 | + statics: &'a FxIndexSet<DefId>, |
| 43 | + // contains for each [`MonoItem`] the [`MonoItem`]s it uses |
| 44 | + used_map: &'b UnordMap<MonoItem<'tcx>, Vec<MonoItem<'tcx>>>, |
| 45 | +} |
| 46 | + |
| 47 | +impl<'a, 'b, 'tcx> DirectedGraph for StaticRefGraph<'a, 'b, 'tcx> { |
| 48 | + type Node = StaticNodeIdx; |
| 49 | + |
| 50 | + fn num_nodes(&self) -> usize { |
| 51 | + self.statics.len() |
| 52 | + } |
| 53 | +} |
| 54 | + |
| 55 | +impl<'a, 'b, 'tcx> Successors for StaticRefGraph<'a, 'b, 'tcx> { |
| 56 | + fn successors(&self, node_idx: StaticNodeIdx) -> impl Iterator<Item = StaticNodeIdx> { |
| 57 | + let def_id = self.statics[node_idx.index()]; |
| 58 | + self.used_map[&MonoItem::Static(def_id)].iter().filter_map(|&mono_item| match mono_item { |
| 59 | + MonoItem::Static(def_id) => self.statics.get_index_of(&def_id).map(|idx| idx.into()), |
| 60 | + _ => None, |
| 61 | + }) |
| 62 | + } |
| 63 | +} |
| 64 | + |
| 65 | +pub(super) fn check_static_initializers_are_acyclic<'tcx, 'a, 'b>( |
| 66 | + tcx: TyCtxt<'tcx>, |
| 67 | + mono_items: &'a [MonoItem<'tcx>], |
| 68 | + usage_map: &'b UsageMap<'tcx>, |
| 69 | +) { |
| 70 | + // Collect statics |
| 71 | + let statics: FxIndexSet<DefId> = mono_items |
| 72 | + .iter() |
| 73 | + .filter_map(|&mono_item| match mono_item { |
| 74 | + MonoItem::Static(def_id) => Some(def_id), |
| 75 | + _ => None, |
| 76 | + }) |
| 77 | + .collect(); |
| 78 | + |
| 79 | + // If we don't have any statics the check is not necessary |
| 80 | + if statics.is_empty() { |
| 81 | + return; |
| 82 | + } |
| 83 | + // Create a subgraph from the mono item graph, which only contains statics |
| 84 | + let graph = StaticRefGraph { statics: &statics, used_map: &usage_map.used_map }; |
| 85 | + // Calculate its SCCs |
| 86 | + let sccs: Sccs<StaticNodeIdx, StaticSccIdx> = Sccs::new(&graph); |
| 87 | + // Group statics by SCCs |
| 88 | + let mut members: IndexVec<StaticSccIdx, Vec<StaticNodeIdx>> = |
| 89 | + IndexVec::from_elem_n(Vec::new(), sccs.num_sccs()); |
| 90 | + for i in graph.iter_nodes() { |
| 91 | + members[sccs.scc(i)].push(i); |
| 92 | + } |
| 93 | + // Check each SCC for cycles |
| 94 | + for scc in sccs.all_sccs() { |
| 95 | + let nodes = members[scc].as_mut_slice(); |
| 96 | + let acyclic = match nodes.len() { |
| 97 | + 0 => true, |
| 98 | + 1 => graph.successors(nodes[0]).all(|x| x != nodes[0]), |
| 99 | + 2.. => false, |
| 100 | + }; |
| 101 | + |
| 102 | + if acyclic { |
| 103 | + continue; |
| 104 | + } |
| 105 | + // We sort the nodes by their Span to have consistent error line numbers |
| 106 | + nodes.sort_by_key(|node| tcx.def_span(statics[node.index()])); |
| 107 | + |
| 108 | + let head_def = statics[nodes[0].index()]; |
| 109 | + let head_span = tcx.def_span(head_def); |
| 110 | + |
| 111 | + tcx.dcx().emit_err(errors::StaticInitializerCyclic { |
| 112 | + span: head_span, |
| 113 | + labels: nodes.iter().map(|&n| tcx.def_span(statics[n.index()])).collect(), |
| 114 | + head: &tcx.def_path_str(head_def), |
| 115 | + target: &tcx.sess.target.llvm_target, |
| 116 | + }); |
| 117 | + } |
| 118 | +} |
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