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

[okura]

Summary

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

[jdoerfert]

LGTM, thx

[kuter]

llvm/include/llvm/ADT/DenseMapInfo.h

352

It seems that, it is possible to specify arbitrary key info traits for DenseSet.
This was what DenseMapAPIntKeyInfo in LLVMContextImpl.h was dong.
It would declare a DenseSet like this:
DenseSet<APInt, DenseMapAPIntKeyInfo>

This specialization might not be desirable for every use case since static_cast<unsigned> discards information.

Maybe we want to do this in the Attributor like the way LLVMContextImpl.h was doing it ?

[okura]

llvm/include/llvm/ADT/DenseMapInfo.h

352

Sorry, I didn't understand what you mean.

This specialization might not be desirable for every use case since static_cast<unsigned> discards information.

This specialization has already been in LLVMContextImpl.h and I didn't change anything.

I want to use it in Attributor, but it exists under /lib directory and we were not able to include it directly.
So I moved it into here.

[kuter]

llvm/include/llvm/ADT/DenseMapInfo.h

352

What I was saying is that you made this the default for APInt.
I wasn't exactly sure that this should be the default.

I was talking about keeping it as DenseMapAPIntKeyInfo.
I wrote this before this revision got accepted.

[okura]

llvm/include/llvm/ADT/DenseMapInfo.h

352

What I was saying is that you made this the default for APInt.
I wasn't exactly sure that this should be the default.

I understood the point. I'm sorry for my misunderstanding.

TBH, I'm also not sure whether making it the default is appropriate or not.
(I made this change based on my interpretation that it was implemented as the default.)

Hmm..., I feel we should hear from others on this issue.

I wrote this before this revision got accepted.

I'm sorry, I noticed your comment after landing this patch.

[jdoerfert]

llvm/include/llvm/ADT/DenseMapInfo.h

352

I'm sorry, I noticed your comment after landing this patch.

Post review comments are not cause for grief. Git is flexible and we can augment and change things even after a commit. So no worries :)

TBH, I'm also not sure whether making it the default is appropriate or not.

I think this is appropriate. We had one APInt DenseMapInfo specialization, now we have two, both using the same technique. If you don't like the default, people can specify a different one, but not making the only used one the default seems unhelpful as people then will reimplement something without knowing there is a version available.

[okura]

llvm/include/llvm/ADT/DenseMapInfo.h

352

Thank you for giving a comment on this! I will leave this as is.

llvm/include/llvm/ADT/APInt.h

 class FoldingSetNodeID;
 class StringRef;
 class hash_code;
 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;
 
 inline APInt operator-(APInt);
 
 //===----------------------------------------------------------------------===//
 //                              APInt Class
 //===----------------------------------------------------------------------===//
private:
   /// integer bit-width <= 64, it uses VAL, otherwise it uses pVal.
   union {
     uint64_t VAL;   ///< Used to store the <= 64 bits integer value.
     uint64_t *pVal; ///< Used to store the >64 bits integer value.
   } U;
 
   unsigned BitWidth; ///< The number of bits in this APInt.
 
-  friend struct DenseMapAPIntKeyInfo;
+  friend struct DenseMapInfo<APInt>;
 
   friend class APSInt;
 
   /// Fast internal constructor
   ///
   /// This constructor is used only internally for speed of construction of
   /// temporaries. It is unsafe for general use so it is not public.
   APInt(uint64_t *val, unsigned bits) : BitWidth(bits) {

llvm/include/llvm/ADT/DenseMapInfo.h

 //===- llvm/ADT/DenseMapInfo.h - Type traits for DenseMap -------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines DenseMapInfo traits for DenseMap.
 //
 //===----------------------------------------------------------------------===//
 
 #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"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <utility>
 

 
 template <> struct DenseMapInfo<hash_code> {
   static inline hash_code getEmptyKey() { return hash_code(-1); }
   static inline hash_code getTombstoneKey() { return hash_code(-2); }
   static unsigned getHashValue(hash_code val) { return val; }
   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

 
 namespace llvm {
 
 class StringRef;
 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); }
   static inline APFloat getTombstoneKey() { return APFloat(APFloat::Bogus(), 2); }
 
   static unsigned getHashValue(const APFloat &Key) {
     return static_cast<unsigned>(hash_value(Key));
   }