Fix clang 5.0 by using type aliases for LLVM DenseSet/Map

When inlining the declaration for llvm::DenseSet/DenseMap in the mlir
namespace from a forward declaration, clang does not take the default
for the template parameters if their are declared later.

namespace llvm {
  template<typename Foo>
  class DenseMap;
}
namespace mlir {
  using llvm::DenseMap;
}
namespace llvm {
  template<typename Foo = int>
  class DenseMap {};
}

namespace mlir {
  DenseMap<> map;
}

PiperOrigin-RevId: 261495612

mlir/include/mlir/Support/LLVM.h

@@ -73,9 +73,13 @@ using llvm::isa_and_nonnull;
 
 // Containers.
 using llvm::ArrayRef;
-using llvm::DenseMap;
 using llvm::DenseMapInfo;
-using llvm::DenseSet;
+template <typename KeyT, typename ValueT,
+          typename KeyInfoT = DenseMapInfo<KeyT>,
+          typename BucketT = llvm::detail::DenseMapPair<KeyT, ValueT>>
+using DenseMap = llvm::DenseMap<KeyT, ValueT, KeyInfoT, BucketT>;
+template <typename ValueT, typename ValueInfoT = DenseMapInfo<ValueT>>
+using DenseSet = llvm::DenseSet<ValueT, ValueInfoT>;
 using llvm::MutableArrayRef;
 using llvm::None;
 using llvm::Optional;

mlir/lib/Analysis/SliceAnalysis.cpp

@@ -26,6 +26,7 @@
 #include "mlir/IR/Function.h"
 #include "mlir/IR/Operation.h"
 #include "mlir/Support/Functional.h"
+#include "mlir/Support/LLVM.h"
 #include "mlir/Support/STLExtras.h"
 #include "llvm/ADT/SetVector.h"
 
@@ -35,7 +36,6 @@
 
 using namespace mlir;
 
-using llvm::DenseSet;
 using llvm::SetVector;
 
 static void getForwardSliceImpl(Operation *op,

mlir/lib/Transforms/MaterializeVectors.cpp

@@ -143,7 +143,6 @@
 /// ```
 
 using llvm::dbgs;
-using llvm::DenseSet;
 using llvm::SetVector;
 
 using namespace mlir;

mlir/lib/Transforms/Vectorize.cpp

@@ -539,7 +539,6 @@ using namespace mlir;
 using functional::makePtrDynCaster;
 using functional::map;
 using llvm::dbgs;
-using llvm::DenseSet;
 using llvm::SetVector;
 
 static llvm::cl::OptionCategory clOptionsCategory("vectorize options");