[llvm][DenseMapInfo] Add an info specialization for std::tuple

This revision adds a DenseMapInfo overload for std::tuples whose elements all have a DenseMapInfo. The implementation is similar to that of std::pair, and has been used within MLIR for over a year.

Differential Revision: https://reviews.llvm.org/D78057

Author: River707

llvm/include/llvm/ADT/DenseMapInfo.h

@@ -23,6 +23,24 @@
 
 namespace llvm {
 
+namespace detail {
+
+/// Simplistic combination of 32-bit hash values into 32-bit hash values.
+static inline unsigned combineHashValue(unsigned a, unsigned b) {
+  uint64_t key = (uint64_t)a << 32 | (uint64_t)b;
+  key += ~(key << 32);
+  key ^= (key >> 22);
+  key += ~(key << 13);
+  key ^= (key >> 8);
+  key += (key << 3);
+  key ^= (key >> 15);
+  key += ~(key << 27);
+  key ^= (key >> 31);
+  return (unsigned)key;
+}
+
+} // end namespace detail
+
 template<typename T>
 struct DenseMapInfo {
   //static inline T getEmptyKey();
@@ -206,17 +224,8 @@ struct DenseMapInfo<std::pair<T, U>> {
   }
 
   static unsigned getHashValue(const Pair& PairVal) {
-    uint64_t key = (uint64_t)FirstInfo::getHashValue(PairVal.first) << 32
-          | (uint64_t)SecondInfo::getHashValue(PairVal.second);
-    key += ~(key << 32);
-    key ^= (key >> 22);
-    key += ~(key << 13);
-    key ^= (key >> 8);
-    key += (key << 3);
-    key ^= (key >> 15);
-    key += ~(key << 27);
-    key ^= (key >> 31);
-    return (unsigned)key;
+    return detail::combineHashValue(FirstInfo::getHashValue(PairVal.first),
+                                    SecondInfo::getHashValue(PairVal.second));
   }
 
   static bool isEqual(const Pair &LHS, const Pair &RHS) {
@@ -225,6 +234,56 @@ struct DenseMapInfo<std::pair<T, U>> {
   }
 };
 
+// Provide DenseMapInfo for all tuples whose members have info.
+template <typename... Ts> struct DenseMapInfo<std::tuple<Ts...>> {
+  using Tuple = std::tuple<Ts...>;
+
+  static inline Tuple getEmptyKey() {
+    return Tuple(DenseMapInfo<Ts>::getEmptyKey()...);
+  }
+
+  static inline Tuple getTombstoneKey() {
+    return Tuple(DenseMapInfo<Ts>::getTombstoneKey()...);
+  }
+
+  template <unsigned I>
+  static unsigned getHashValueImpl(const Tuple &values, std::false_type) {
+    using EltType = typename std::tuple_element<I, Tuple>::type;
+    std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
+    return detail::combineHashValue(
+        DenseMapInfo<EltType>::getHashValue(std::get<I>(values)),
+        getHashValueImpl<I + 1>(values, atEnd));
+  }
+
+  template <unsigned I>
+  static unsigned getHashValueImpl(const Tuple &values, std::true_type) {
+    return 0;
+  }
+
+  static unsigned getHashValue(const std::tuple<Ts...> &values) {
+    std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
+    return getHashValueImpl<0>(values, atEnd);
+  }
+
+  template <unsigned I>
+  static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs, std::false_type) {
+    using EltType = typename std::tuple_element<I, Tuple>::type;
+    std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
+    return DenseMapInfo<EltType>::isEqual(std::get<I>(lhs), std::get<I>(rhs)) &&
+           isEqualImpl<I + 1>(lhs, rhs, atEnd);
+  }
+
+  template <unsigned I>
+  static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs, std::true_type) {
+    return true;
+  }
+
+  static bool isEqual(const Tuple &lhs, const Tuple &rhs) {
+    std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
+    return isEqualImpl<0>(lhs, rhs, atEnd);
+  }
+};
+
 // Provide DenseMapInfo for StringRefs.
 template <> struct DenseMapInfo<StringRef> {
   static inline StringRef getEmptyKey() {

mlir/include/mlir/Support/STLExtras.h

@@ -399,74 +399,4 @@ struct FunctionTraits<ReturnType (&)(Args...), false>
     : public FunctionTraits<ReturnType (*)(Args...)> {};
 } // end namespace mlir
 
-// Allow tuples to be usable as DenseMap keys.
-// TODO: Move this to upstream LLVM.
-
-/// Simplistic combination of 32-bit hash values into 32-bit hash values.
-/// This function is taken from llvm/ADT/DenseMapInfo.h.
-static inline unsigned llvm_combineHashValue(unsigned a, unsigned b) {
-  uint64_t key = (uint64_t)a << 32 | (uint64_t)b;
-  key += ~(key << 32);
-  key ^= (key >> 22);
-  key += ~(key << 13);
-  key ^= (key >> 8);
-  key += (key << 3);
-  key ^= (key >> 15);
-  key += ~(key << 27);
-  key ^= (key >> 31);
-  return (unsigned)key;
-}
-
-namespace llvm {
-template <typename... Ts> struct DenseMapInfo<std::tuple<Ts...>> {
-  using Tuple = std::tuple<Ts...>;
-
-  static inline Tuple getEmptyKey() {
-    return Tuple(DenseMapInfo<Ts>::getEmptyKey()...);
-  }
-
-  static inline Tuple getTombstoneKey() {
-    return Tuple(DenseMapInfo<Ts>::getTombstoneKey()...);
-  }
-
-  template <unsigned I>
-  static unsigned getHashValueImpl(const Tuple &values, std::false_type) {
-    using EltType = typename std::tuple_element<I, Tuple>::type;
-    std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
-    return llvm_combineHashValue(
-        DenseMapInfo<EltType>::getHashValue(std::get<I>(values)),
-        getHashValueImpl<I + 1>(values, atEnd));
-  }
-
-  template <unsigned I>
-  static unsigned getHashValueImpl(const Tuple &values, std::true_type) {
-    return 0;
-  }
-
-  static unsigned getHashValue(const std::tuple<Ts...> &values) {
-    std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
-    return getHashValueImpl<0>(values, atEnd);
-  }
-
-  template <unsigned I>
-  static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs, std::false_type) {
-    using EltType = typename std::tuple_element<I, Tuple>::type;
-    std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
-    return DenseMapInfo<EltType>::isEqual(std::get<I>(lhs), std::get<I>(rhs)) &&
-           isEqualImpl<I + 1>(lhs, rhs, atEnd);
-  }
-
-  template <unsigned I>
-  static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs, std::true_type) {
-    return true;
-  }
-
-  static bool isEqual(const Tuple &lhs, const Tuple &rhs) {
-    std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
-    return isEqualImpl<0>(lhs, rhs, atEnd);
-  }
-};
-
-} // end namespace llvm
-
 #endif // MLIR_SUPPORT_STLEXTRAS_H