Use SmallPtrSet explicitly for SmallSets with pointer types (NFC).

Currently SmallSet<PointerTy> inherits from SmallPtrSet<PointerTy>. This
patch replaces such types with SmallPtrSet, because IMO it is slightly
clearer and allows us to get rid of unnecessarily including SmallSet.h

Reviewers: dblaikie, craig.topper

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D47836

llvm-svn: 334492
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index 1b0e3a7..0057b4b 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -21,7 +21,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/LoopIterator.h"
@@ -765,7 +765,7 @@
   // values from the cloned region. Also update the dominator info for
   // OtherExits and their immediate successors, since we have new edges into
   // OtherExits.
-  SmallSet<BasicBlock*, 8> ImmediateSuccessorsOfExitBlocks;
+  SmallPtrSet<BasicBlock*, 8> ImmediateSuccessorsOfExitBlocks;
   for (auto *BB : OtherExits) {
    for (auto &II : *BB) {