[MemorySSA] Re-enable MemorySSA use.

Differential Revision: https://reviews.llvm.org/D58311

llvm-svn: 370957

2 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/MemorySSA.cpp b/llvm/lib/Analysis/MemorySSA.cpp
index ae1e4b80f13..442d0b45fee 100644
--- a/llvm/lib/Analysis/MemorySSA.cpp
+++ b/llvm/lib/Analysis/MemorySSA.cpp
@@ -84,7 +84,7 @@ bool llvm::VerifyMemorySSA = false;
 #endif
 /// Enables memory ssa as a dependency for loop passes in legacy pass manager.
 cl::opt<bool> llvm::EnableMSSALoopDependency(
-    "enable-mssa-loop-dependency", cl::Hidden, cl::init(false),
+    "enable-mssa-loop-dependency", cl::Hidden, cl::init(true),
     cl::desc("Enable MemorySSA dependency for loop pass manager"));
 
 static cl::opt<bool, true>
diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 4c6c2edc385..b4d7f35d2d9 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/MemorySSA.h"
 #include "llvm/Analysis/MemorySSAUpdater.h"
 #include "llvm/Analysis/MustExecute.h"
 #include "llvm/Analysis/ScalarEvolution.h"
@@ -170,6 +171,8 @@ void llvm::getLoopAnalysisUsage(AnalysisUsage &AU) {
   AU.addPreserved<SCEVAAWrapperPass>();
   AU.addRequired<ScalarEvolutionWrapperPass>();
   AU.addPreserved<ScalarEvolutionWrapperPass>();
+  // FIXME: When all loop passes preserve MemorySSA, it can be required and
+  // preserved here instead of the individual handling in each pass.
 }
 
 /// Manually defined generic "LoopPass" dependency initialization. This is used
@@ -190,6 +193,7 @@ void llvm::initializeLoopPassPass(PassRegistry &Registry) {
   INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(SCEVAAWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
+  INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
 }
 
 /// Create MDNode for input string.