[PATCH] D19388: [MemorySSA] Fix bug in CachingMemorySSAWalker::invalidateInfo

[Geoff Berry via llvm-commits]

gberry created this revision.
gberry added reviewers: dberlin, george.burgess.iv.
gberry added a subscriber: llvm-commits.
Herald added a subscriber: mcrosier.

CachingMemorySSAWalker::invalidateInfo was using IsCall to determine
which cache map needed to be cleared of entries referring to the invalidated
MemoryAccess, but there could also be entries referring to it in the
other cache map (value entries, not key entries).  This change just
clears both tables to be conservatively correct.

Also add a verifyRemoved() function, called when expensive
checks (i.e. XDEBUG) are enabled to verify that the invalidated
MemoryAccess object is not referenced in any of the caches.

http://reviews.llvm.org/D19388

Files:
  include/llvm/Transforms/Utils/MemorySSA.h
  lib/Transforms/Utils/MemorySSA.cpp

Index: lib/Transforms/Utils/MemorySSA.cpp
===================================================================
--- lib/Transforms/Utils/MemorySSA.cpp
+++ lib/Transforms/Utils/MemorySSA.cpp
@@ -799,19 +799,16 @@
     if (!Q.IsCall)
       Q.StartingLoc = MemoryLocation::get(I);
     doCacheRemove(MA, Q, Q.StartingLoc);
-    return;
-  }
-  // If it is not a use, the best we can do right now is destroy the cache.
-  bool IsCall = false;
-
-  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA)) {
-    Instruction *I = MUD->getMemoryInst();
-    IsCall = bool(ImmutableCallSite(I));
-  }
-  if (IsCall)
+  } else {
+    // If it is not a use, the best we can do right now is destroy the cache.
     CachedUpwardsClobberingCall.clear();
-  else
     CachedUpwardsClobberingAccess.clear();
+  }
+
+#ifdef XDEBUG
+  // Run this only when expensive checks are enabled.
+  verifyRemoved(MA);
+#endif
 }
 
 void CachingMemorySSAWalker::doCacheRemove(const MemoryAccess *M,
@@ -1081,6 +1078,18 @@
   return Result;
 }
 
+#ifdef XDEBUG
+// Verify that MA doesn't exist in any of the caches.
+void CachingMemorySSAWalker::verifyRemoved(MemoryAccess *MA) {
+  for (auto &P : CachedUpwardsClobberingAccess)
+    assert(P.first.first != MA && P.second != MA &&
+           "Found removed MemoryAccess in cache.");
+  for (auto &P : CachedUpwardsClobberingCall)
+    assert(P.first != MA && P.second != MA &&
+           "Found removed MemoryAccess in cache.");
+}
+#endif // XDEBUG
+
 MemoryAccess *
 DoNothingMemorySSAWalker::getClobberingMemoryAccess(const Instruction *I) {
   MemoryAccess *MA = MSSA->getMemoryAccess(I);
Index: include/llvm/Transforms/Utils/MemorySSA.h
===================================================================
--- include/llvm/Transforms/Utils/MemorySSA.h
+++ include/llvm/Transforms/Utils/MemorySSA.h
@@ -756,6 +756,9 @@
   MemoryAccess *getClobberingMemoryAccess(MemoryAccess *, UpwardsMemoryQuery &);
   bool instructionClobbersQuery(const MemoryDef *, UpwardsMemoryQuery &,
                                 const MemoryLocation &Loc) const;
+#ifdef XDEBUG
+  void verifyRemoved(MemoryAccess *);
+#endif
   SmallDenseMap<ConstMemoryAccessPair, MemoryAccess *>
       CachedUpwardsClobberingAccess;
   DenseMap<const MemoryAccess *, MemoryAccess *> CachedUpwardsClobberingCall;


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