diff options
| -rw-r--r-- | llvm/include/llvm/Support/GenericDomTree.h | 4 | ||||
| -rw-r--r-- | llvm/include/llvm/Support/GenericDomTreeConstruction.h | 16 |
2 files changed, 19 insertions, 1 deletions
diff --git a/llvm/include/llvm/Support/GenericDomTree.h b/llvm/include/llvm/Support/GenericDomTree.h index 8d9640f76fd..635c87a106f 100644 --- a/llvm/include/llvm/Support/GenericDomTree.h +++ b/llvm/include/llvm/Support/GenericDomTree.h @@ -522,7 +522,9 @@ class DominatorTreeBase { /// /// Batch updates should be generally faster when performing longer sequences /// of updates than calling insertEdge/deleteEdge manually multiple times, as - /// they can reorder the updates and remove redundant ones internally. + /// it can reorder the updates and remove redundant ones internally. + /// The batch updater is also able to detect sequences of zero and exactly one + /// update -- it's optimized to do less work in these cases. /// /// Note that for postdominators it automatically takes care of applying /// updates on reverse edges internally (so there's no need to swap the diff --git a/llvm/include/llvm/Support/GenericDomTreeConstruction.h b/llvm/include/llvm/Support/GenericDomTreeConstruction.h index 34c1fe6800a..460110eb70b 100644 --- a/llvm/include/llvm/Support/GenericDomTreeConstruction.h +++ b/llvm/include/llvm/Support/GenericDomTreeConstruction.h @@ -1122,6 +1122,22 @@ struct SemiNCAInfo { //~~ static void ApplyUpdates(DomTreeT &DT, ArrayRef<UpdateT> Updates) { + const size_t NumUpdates = Updates.size(); + if (NumUpdates == 0) + return; + + // Take the fast path for a single update and avoid running the batch update + // machinery. + if (NumUpdates == 1) { + const auto &Update = Updates.front(); + if (Update.getKind() == UpdateKind::Insert) + DT.insertEdge(Update.getFrom(), Update.getTo()); + else + DT.deleteEdge(Update.getFrom(), Update.getTo()); + + return; + } + BatchUpdateInfo BUI; LegalizeUpdates(Updates, BUI.Updates); |
