[BasicBlockUtils] Fixup of an assumed typo in MergeBlockIntoPredecessor

The NFC commit e5692a564a73ef63b7b changed the logic for
DomTreeUpdates to use the range [succ_begin, succ_begin) when
looking for SuccsOfPredBB rather than using [succ_begin, succ_end).

As the commit was NFC this is identified as a typo (it has been
discussed briefly in phabricator).

The typo was found when inspecting the code, so I've got no idea if
changing back to the old range has any significant impact (such as
solving any PR:s or causing some new problems). But at least this
restores the code to the originally indented behavior.

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index ee933b6..1a07697 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -230,7 +230,7 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, DomTreeUpdater *DTU,
   if (DTU) {
     SmallPtrSet<BasicBlock *, 2> SuccsOfBB(succ_begin(BB), succ_end(BB));
     SmallPtrSet<BasicBlock *, 2> SuccsOfPredBB(succ_begin(PredBB),
-                                               succ_begin(PredBB));
+                                               succ_end(PredBB));
     Updates.reserve(Updates.size() + 2 * SuccsOfBB.size() + 1);
     // Add insert edges first. Experimentally, for the particular case of two
     // blocks that can be merged, with a single successor and single predecessor