[llvm] r278028 - [MemorySSA] Ensure address stability of MemorySSA object.

[Geoff Berry via llvm-commits]

Author: gberry
Date: Mon Aug  8 12:52:01 2016
New Revision: 278028

URL: http://llvm.org/viewvc/llvm-project?rev=278028&view=rev
Log:
[MemorySSA] Ensure address stability of MemorySSA object.

Summary:
Ensure that the MemorySSA object never changes address when using the
new pass manager since the walkers contained by MemorySSA cache pointers
to it at construction time.  This is achieved by wrapping the
MemorySSAAnalysis result in a unique_ptr.  Also add some asserts that
check for this bug.

Reviewers: george.burgess.iv, dberlin

Subscribers: mcrosier, hfinkel, chandlerc, silvas, llvm-commits

Differential Revision: https://reviews.llvm.org/D23171

Modified:
    llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h
    llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp

Modified: llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h?rev=278028&r1=278027&r2=278028&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/MemorySSA.h Mon Aug  8 12:52:01 2016
@@ -494,7 +494,6 @@ class MemorySSAWalker;
 class MemorySSA {
 public:
   MemorySSA(Function &, AliasAnalysis *, DominatorTree *);
-  MemorySSA(MemorySSA &&);
   ~MemorySSA();
 
   MemorySSAWalker *getWalker();
@@ -676,9 +675,9 @@ class MemorySSAAnalysis : public Analysi
   static char PassID;
 
 public:
-  typedef MemorySSA Result;
+  typedef std::unique_ptr<MemorySSA> Result;
 
-  MemorySSA run(Function &F, AnalysisManager<Function> &AM);
+  Result run(Function &F, AnalysisManager<Function> &AM);
 };
 
 /// \brief Printer pass for \c MemorySSA.
@@ -786,6 +785,8 @@ public:
   /// the walker it uses or returns.
   virtual void invalidateInfo(MemoryAccess *) {}
 
+  virtual void verify(const MemorySSA *MSSA) { assert(MSSA == this->MSSA); }
+
 protected:
   friend class MemorySSA; // For updating MSSA pointer in MemorySSA move
                           // constructor.

Modified: llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp?rev=278028&r1=278027&r2=278028&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp Mon Aug  8 12:52:01 2016
@@ -1025,6 +1025,8 @@ public:
 #endif
     return Result;
   }
+
+  void verify(const MemorySSA *MSSA) { assert(MSSA == &this->MSSA); }
 };
 
 struct RenamePassData {
@@ -1104,6 +1106,11 @@ public:
   /// earliest-MemoryAccess-we-can-optimize-to". This is necessary if we're
   /// going to have DT updates, if we remove MemoryAccesses, etc.
   void resetClobberWalker() { Walker.reset(); }
+
+  void verify(const MemorySSA *MSSA) override {
+    MemorySSAWalker::verify(MSSA);
+    Walker.verify(MSSA);
+  }
 };
 
 /// \brief Rename a single basic block into MemorySSA form.
@@ -1231,19 +1238,6 @@ MemorySSA::MemorySSA(Function &Func, Ali
   buildMemorySSA();
 }
 
-MemorySSA::MemorySSA(MemorySSA &&MSSA)
-    : AA(MSSA.AA), DT(MSSA.DT), F(MSSA.F),
-      ValueToMemoryAccess(std::move(MSSA.ValueToMemoryAccess)),
-      PerBlockAccesses(std::move(MSSA.PerBlockAccesses)),
-      LiveOnEntryDef(std::move(MSSA.LiveOnEntryDef)),
-      BlockNumberingValid(std::move(MSSA.BlockNumberingValid)),
-      BlockNumbering(std::move(MSSA.BlockNumbering)),
-      Walker(std::move(MSSA.Walker)), NextID(MSSA.NextID) {
-  // Update the Walker MSSA pointer so it doesn't point to the moved-from MSSA
-  // object any more.
-  Walker->MSSA = this;
-}
-
 MemorySSA::~MemorySSA() {
   // Drop all our references
   for (const auto &Pair : PerBlockAccesses)
@@ -1818,6 +1812,7 @@ void MemorySSA::verifyMemorySSA() const
   verifyDefUses(F);
   verifyDomination(F);
   verifyOrdering(F);
+  Walker->verify(this);
 }
 
 /// \brief Verify that the order and existence of MemoryAccesses matches the
@@ -2083,23 +2078,24 @@ bool MemorySSAPrinterLegacyPass::runOnFu
 
 char MemorySSAAnalysis::PassID;
 
-MemorySSA MemorySSAAnalysis::run(Function &F, AnalysisManager<Function> &AM) {
+std::unique_ptr<MemorySSA>
+MemorySSAAnalysis::run(Function &F, AnalysisManager<Function> &AM) {
   auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
   auto &AA = AM.getResult<AAManager>(F);
-  return MemorySSA(F, &AA, &DT);
+  return make_unique<MemorySSA>(F, &AA, &DT);
 }
 
 PreservedAnalyses MemorySSAPrinterPass::run(Function &F,
                                             FunctionAnalysisManager &AM) {
   OS << "MemorySSA for function: " << F.getName() << "\n";
-  AM.getResult<MemorySSAAnalysis>(F).print(OS);
+  AM.getResult<MemorySSAAnalysis>(F)->print(OS);
 
   return PreservedAnalyses::all();
 }
 
 PreservedAnalyses MemorySSAVerifierPass::run(Function &F,
                                              FunctionAnalysisManager &AM) {
-  AM.getResult<MemorySSAAnalysis>(F).verifyMemorySSA();
+  AM.getResult<MemorySSAAnalysis>(F)->verifyMemorySSA();
 
   return PreservedAnalyses::all();
 }