a minor tweak to my previous patch, handle the invalidation case
when there are multiple iterations of the loop.  This fixes PR3375.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62822 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index ddfb26e..c84a51f 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -751,9 +751,10 @@
         // cache remains sorted.  Sort it now (if needed) so that recursive
         // invocations of getNonLocalPointerDepFromBB that could reuse the cache
         // value will only see properly sorted cache arrays.
-        if (NumSortedEntries != Cache->size()) {
+        if (Cache && NumSortedEntries != Cache->size()) {
           std::sort(Cache->begin(), Cache->end());
           NumSortedEntries = Cache->size();
+          Cache = 0;
         }
         
         // FIXME: it is entirely possible that PHI translating will end up with
@@ -767,12 +768,12 @@
                                         Result, Visited))
           goto PredTranslationFailure;
       }
-      
+
       // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
       CacheInfo = &NonLocalPointerDeps[CacheKey];
       Cache = &CacheInfo->second;
       NumSortedEntries = Cache->size();
-
+      
       // Since we did phi translation, the "Cache" set won't contain all of the
       // results for the query.  This is ok (we can still use it to accelerate
       // specific block queries) but we can't do the fastpath "return all