Avoid overly large SmallPtrSet/SmallSet

These sets perform linear searching in small mode so it is never a good
idea to use SmallSize/N bigger than 32.

llvm-svn: 259283
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 6918360..9492801 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -854,7 +854,7 @@
   // isReadonlyCall - If this is a read-only call, we can be more aggressive.
   bool isReadonlyCall = AA->onlyReadsMemory(QueryCS);
 
-  SmallPtrSet<BasicBlock*, 64> Visited;
+  SmallPtrSet<BasicBlock*, 32> Visited;
 
   unsigned NumSortedEntries = Cache.size();
   DEBUG(AssertSorted(Cache));