[NFC][APInt][DenseMapInfo] Move DenseMapAPIntKeyInfo into DenseMap.h as DenseMapInfo<APInt>

`DenseMapAPIntKeyInfo` is now located in `lib/IR/LLVMContextImpl.h`.
Moved it into `include/ADT/DenseMapInfo.h` to use it.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D85131

llvm/include/llvm/ADT/APInt.h

@@ -31,6 +31,7 @@ class raw_ostream;
 template <typename T> class SmallVectorImpl;
 template <typename T> class ArrayRef;
 template <typename T> class Optional;
+template <typename T> struct DenseMapInfo;
 
 class APInt;
 
@@ -96,7 +97,7 @@ private:
 
   unsigned BitWidth; ///< The number of bits in this APInt.
 
-  friend struct DenseMapAPIntKeyInfo;
+  friend struct DenseMapInfo<APInt>;
 
   friend class APSInt;
 

llvm/include/llvm/ADT/DenseMapInfo.h

@@ -13,6 +13,7 @@
 #ifndef LLVM_ADT_DENSEMAPINFO_H
 #define LLVM_ADT_DENSEMAPINFO_H
 
+#include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringRef.h"
@@ -347,6 +348,29 @@ template <> struct DenseMapInfo<hash_code> {
   static bool isEqual(hash_code LHS, hash_code RHS) { return LHS == RHS; }
 };
 
+/// Provide DenseMapInfo for APInt.
+template <> struct DenseMapInfo<APInt> {
+  static inline APInt getEmptyKey() {
+    APInt V(nullptr, 0);
+    V.U.VAL = 0;
+    return V;
+  }
+
+  static inline APInt getTombstoneKey() {
+    APInt V(nullptr, 0);
+    V.U.VAL = 1;
+    return V;
+  }
+
+  static unsigned getHashValue(const APInt &Key) {
+    return static_cast<unsigned>(hash_value(Key));
+  }
+
+  static bool isEqual(const APInt &LHS, const APInt &RHS) {
+    return LHS.getBitWidth() == RHS.getBitWidth() && LHS == RHS;
+  }
+};
+
 } // end namespace llvm
 
 #endif // LLVM_ADT_DENSEMAPINFO_H

llvm/lib/IR/LLVMContextImpl.h

@@ -57,27 +57,7 @@ class Type;
 class Value;
 class ValueHandleBase;
 
-struct DenseMapAPIntKeyInfo {
-  static inline APInt getEmptyKey() {
-    APInt V(nullptr, 0);
-    V.U.VAL = 0;
-    return V;
-  }
-
-  static inline APInt getTombstoneKey() {
-    APInt V(nullptr, 0);
-    V.U.VAL = 1;
-    return V;
-  }
-
-  static unsigned getHashValue(const APInt &Key) {
-    return static_cast<unsigned>(hash_value(Key));
-  }
-
-  static bool isEqual(const APInt &LHS, const APInt &RHS) {
-    return LHS.getBitWidth() == RHS.getBitWidth() && LHS == RHS;
-  }
-};
+using DenseMapAPIntKeyInfo = DenseMapInfo<APInt>;
 
 struct DenseMapAPFloatKeyInfo {
   static inline APFloat getEmptyKey() { return APFloat(APFloat::Bogus(), 1); }