Add assertion on DT availability during LI update in UpdateAnalysisInformation

This came up during discussions in llvm-commits for
rL321653: Check for unreachable preds before updating LI in
UpdateAnalysisInformation

The assert provides hints to passes to require both DT and LI if we plan on
updating LI through this function.

Tests run: make check

llvm-svn: 321805

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 8f59913e14b..056753f7ddb 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -316,6 +316,7 @@ static void UpdateAnalysisInformation(BasicBlock *OldBB, BasicBlock *NewBB,
   if (!LI)
     return;
 
+  assert(DT && "DT should be available to update LoopInfo!");
   Loop *L = LI->getLoopFor(OldBB);
 
   // If we need to preserve loop analyses, collect some information about how