Only passes that preserve MemorySSA must mark it as preserved.

Summary:
The method `getLoopPassPreservedAnalyses` should not mark MemorySSA as
preserved, because it's being called in a lot of passes that do not
preserve MemorySSA.
Instead, mark the MemorySSA analysis as preserved by each pass that does
preserve it.
These changes only affect the new pass mananger.

Reviewers: chandlerc

Subscribers: mehdi_amini, jlebar, Prazek, george.burgess.iv, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62536

llvm-svn: 363091

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
index 06d65b55890..9fba159495b 100644
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -2861,7 +2861,11 @@ PreservedAnalyses SimpleLoopUnswitchPass::run(Loop &L, LoopAnalysisManager &AM,
   // Historically this pass has had issues with the dominator tree so verify it
   // in asserts builds.
   assert(AR.DT.verify(DominatorTree::VerificationLevel::Fast));
-  return getLoopPassPreservedAnalyses();
+
+  auto PA = getLoopPassPreservedAnalyses();
+  if (EnableMSSALoopDependency)
+    PA.preserve<MemorySSAAnalysis>();
+  return PA;
 }
 
 namespace {