diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src/coverage/graph.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/coverage/graph.rs | 24 |
1 files changed, 9 insertions, 15 deletions
diff --git a/compiler/rustc_mir_transform/src/coverage/graph.rs b/compiler/rustc_mir_transform/src/coverage/graph.rs index bf57a99224d..743aa679058 100644 --- a/compiler/rustc_mir_transform/src/coverage/graph.rs +++ b/compiler/rustc_mir_transform/src/coverage/graph.rs @@ -165,21 +165,15 @@ impl CoverageGraph { self.dominators.as_ref().unwrap().cmp_in_dominator_order(a, b) } - /// Returns true if the given node has 2 or more in-edges, i.e. 2 or more - /// predecessors. - /// - /// This property is interesting to code that assigns counters to nodes and - /// edges, because if a node _doesn't_ have multiple in-edges, then there's - /// no benefit in having a separate counter for its in-edge, because it - /// would have the same value as the node's own counter. - #[inline(always)] - pub(crate) fn bcb_has_multiple_in_edges(&self, bcb: BasicCoverageBlock) -> bool { - // Even though bcb0 conceptually has an extra virtual in-edge due to - // being the entry point, we've already asserted that it has no _other_ - // in-edges, so there's no possibility of it having _multiple_ in-edges. - // (And since its virtual in-edge doesn't exist in the graph, that edge - // can't have a separate counter anyway.) - self.predecessors[bcb].len() > 1 + /// Returns the source of this node's sole in-edge, if it has exactly one. + /// That edge can be assumed to have the same execution count as the node + /// itself (in the absence of panics). + pub(crate) fn sole_predecessor( + &self, + to_bcb: BasicCoverageBlock, + ) -> Option<BasicCoverageBlock> { + // Unlike `simple_successor`, there is no need for extra checks here. + if let &[from_bcb] = self.predecessors[to_bcb].as_slice() { Some(from_bcb) } else { None } } /// Returns the target of this node's sole out-edge, if it has exactly |