LCSSA preserves dom info.

llvm-svn: 40604

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/LCSSA.cpp b/llvm/lib/Transforms/Utils/LCSSA.cpp
index 3f4bad5c513..466136dea7d 100644
--- a/llvm/lib/Transforms/Utils/LCSSA.cpp
+++ b/llvm/lib/Transforms/Utils/LCSSA.cpp
@@ -73,6 +73,14 @@ namespace {
       AU.addPreserved<LoopInfo>();
       AU.addRequired<DominatorTree>();
       AU.addPreserved<ScalarEvolution>();
+      AU.addPreserved<DominatorTree>();
+
+      // Request DominanceFrontier now, even though LCSSA does
+      // not use it. This allows Pass Manager to schedule Dominance
+      // Frontier early enough such that one LPPassManager can handle
+      // multiple loop transformation passes.
+      AU.addRequired<DominanceFrontier>(); 
+      AU.addPreserved<DominanceFrontier>();
     }
   private:
     void getLoopValuesUsedOutsideLoop(Loop *L,