[NFCI][SimplifyCFG] Prefer to add Insert edges before Delete edges into DomTreeUpdater, if reasonable

This has a measurable impact on the number of DomTree recalculations.
While this doesn't handle all the cases,
it deals with the most obvious ones.

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 0b3a259..bfad88f 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -1395,11 +1395,11 @@ BasicBlock *llvm::CreateControlFlowHub(
   SmallVector<DominatorTree::UpdateType, 16> Updates;
   if (DTU) {
     for (auto In : Incoming) {
+      Updates.push_back({DominatorTree::Insert, In, FirstGuardBlock});
       for (auto Succ : successors(In)) {
         if (Outgoing.count(Succ))
           Updates.push_back({DominatorTree::Delete, In, Succ});
       }
-      Updates.push_back({DominatorTree::Insert, In, FirstGuardBlock});
     }
   }