[NFC] add anonymous namespace to a couple classes (#121511)

This ensures these classes are visible only to the appropriate
translation unit and allows for more optimizations.

Author: AlexMaclean

llvm/lib/IR/SafepointIRVerifier.cpp

@@ -289,6 +289,7 @@ static void PrintValueSet(raw_ostream &OS, IteratorTy Begin, IteratorTy End) {
 
 using AvailableValueSet = DenseSet<const Value *>;
 
+namespace {
 /// State we compute and track per basic block.
 struct BasicBlockState {
   // Set of values available coming in, before the phi nodes
@@ -305,6 +306,7 @@ struct BasicBlockState {
   // contribute to AvailableOut.
   bool Cleared = false;
 };
+} // namespace
 
 /// A given derived pointer can have multiple base pointers through phi/selects.
 /// This type indicates when the base pointer is exclusively constant

llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp

@@ -181,6 +181,7 @@ static bool foldGuardedFunnelShift(Instruction &I, const DominatorTree &DT) {
 /// the bit indexes (Mask) needed by a masked compare. If we're matching a chain
 /// of 'and' ops, then we also need to capture the fact that we saw an
 /// "and X, 1", so that's an extra return value for that case.
+namespace {
 struct MaskOps {
   Value *Root = nullptr;
   APInt Mask;
@@ -190,6 +191,7 @@ struct MaskOps {
   MaskOps(unsigned BitWidth, bool MatchAnds)
       : Mask(APInt::getZero(BitWidth)), MatchAndChain(MatchAnds) {}
 };
+} // namespace
 
 /// This is a recursive helper for foldAnyOrAllBitsSet() that walks through a
 /// chain of 'and' or 'or' instructions looking for shift ops of a common source