[MemorySSA] Set LoopSimplify to preserve MemorySSA in the NPM, if analysis exists.

Summary:
LoopSimplify is preserved in the legacy pass manager, but not in the new pass manager.
Update LoopSimplify to preserve MemorySSA conditionally when the analysis is available (same behavior as the legacy pass manager).

Reviewers: chandlerc

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65418

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@367594 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/LoopSimplify.cpp b/lib/Transforms/Utils/LoopSimplify.cpp
index 7e6da02d57077bfdab4e05d4513b8ef07ef01272..e202b45208666c9f42d231d5be2e1aed08956089 100644 (file)
--- a/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/lib/Transforms/Utils/LoopSimplify.cpp
@@ -835,12 +835,19 @@ PreservedAnalyses LoopSimplifyPass::run(Function &F,
   DominatorTree *DT = &AM.getResult<DominatorTreeAnalysis>(F);
   ScalarEvolution *SE = AM.getCachedResult<ScalarEvolutionAnalysis>(F);
   AssumptionCache *AC = &AM.getResult<AssumptionAnalysis>(F);
+  auto *MSSAAnalysis = AM.getCachedResult<MemorySSAAnalysis>(F);
+  std::unique_ptr<MemorySSAUpdater> MSSAU;
+  if (MSSAAnalysis) {
+    auto *MSSA = &MSSAAnalysis->getMSSA();
+    MSSAU = make_unique<MemorySSAUpdater>(MSSA);
+  }
+
 
   // Note that we don't preserve LCSSA in the new PM, if you need it run LCSSA
-  // after simplifying the loops. MemorySSA is not preserved either.
+  // after simplifying the loops. MemorySSA is preserved if it exists.
   for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
     Changed |=
-        simplifyLoop(*I, DT, LI, SE, AC, nullptr, /*PreserveLCSSA*/ false);
+        simplifyLoop(*I, DT, LI, SE, AC, MSSAU.get(), /*PreserveLCSSA*/ false);
 
   if (!Changed)
     return PreservedAnalyses::all();
@@ -853,6 +860,8 @@ PreservedAnalyses LoopSimplifyPass::run(Function &F,
   PA.preserve<SCEVAA>();
   PA.preserve<ScalarEvolutionAnalysis>();
   PA.preserve<DependenceAnalysis>();
+  if (MSSAAnalysis)
+    PA.preserve<MemorySSAAnalysis>();
   // BPI maps conditional terminators to probabilities, LoopSimplify can insert
   // blocks, but it does so only by splitting existing blocks and edges. This
   // results in the interesting property that all new terminators inserted are

diff --git a/unittests/Transforms/Scalar/LoopPassManagerTest.cpp b/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
index 5eb8101a3df9417f3f237b628b87651c98e3d6fd..9926396509cede820964acbd0ee5a73f0a15e26a 100644 (file)
--- a/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
+++ b/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
@@ -293,8 +293,7 @@ public:
     // those.
     FAM.registerPass([&] { return AAManager(); });
     FAM.registerPass([&] { return AssumptionAnalysis(); });
-    if (EnableMSSALoopDependency)
-      FAM.registerPass([&] { return MemorySSAAnalysis(); });
+    FAM.registerPass([&] { return MemorySSAAnalysis(); });
     FAM.registerPass([&] { return ScalarEvolutionAnalysis(); });
     FAM.registerPass([&] { return TargetLibraryAnalysis(); });
     FAM.registerPass([&] { return TargetIRAnalysis(); });