[PhiValues] Use SetVector to avoid non-determinism

I'm not sure whether this can cause actual non-determinism in the
compiler output, but at least it causes non-determinism in the
statistics collected by BasicAA.

Use SetVector to have a predictable iteration order.

Author: nikic

llvm/include/llvm/Analysis/PhiValues.h

@@ -21,7 +21,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/ValueHandle.h"
@@ -40,7 +40,7 @@ class Function;
 /// it is queried.
 class PhiValues {
 public:
-  using ValueSet = SmallPtrSet<Value *, 4>;
+  using ValueSet = SmallSetVector<Value *, 4>;
 
   /// Construct an empty PhiValues.
   PhiValues(const Function &F) : F(F) {}
@@ -70,8 +70,7 @@ class PhiValues {
                   FunctionAnalysisManager::Invalidator &);
 
 private:
-  using PhiSet = SmallPtrSet<const PHINode *, 4>;
-  using ConstValueSet = SmallPtrSet<const Value *, 4>;
+  using ConstValueSet = SmallSetVector<const Value *, 4>;
 
   /// The next depth number to be used by processPhi.
   unsigned int NextDepthNumber = 1;

llvm/lib/Analysis/PhiValues.cpp

@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/PhiValues.h"
-#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/InitializePasses.h"