[ADT] Remove KeyInfoT forwarders in DenseMap.h (NFC) (#165102)

This patch removes getEmptyKey, getTombstoneKey, and getHashValue from
DenseMapBase.  These forwarder methods do not really encapsulate
KeyInfoT.  Many of their callers already mention KeyInfoT::isEqual for
example.

An existing static_assert is moved to another method.  Note that it
must live in a method for type completeness reasons.

Author: kazutakahirata

llvm/include/llvm/ADT/DenseMap.h

@@ -130,13 +130,13 @@ class DenseMapBase : public DebugEpochBase {
       return;
     }
 
-    const KeyT EmptyKey = getEmptyKey();
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
     if constexpr (std::is_trivially_destructible_v<ValueT>) {
       // Use a simpler loop when values don't need destruction.
       for (BucketT &B : buckets())
         B.getFirst() = EmptyKey;
     } else {
-      const KeyT TombstoneKey = getTombstoneKey();
+      const KeyT TombstoneKey = KeyInfoT::getTombstoneKey();
       unsigned NumEntries = getNumEntries();
       for (BucketT &B : buckets()) {
         if (!KeyInfoT::isEqual(B.getFirst(), EmptyKey)) {
@@ -314,15 +314,15 @@ class DenseMapBase : public DebugEpochBase {
       return false; // not in map.
 
     TheBucket->getSecond().~ValueT();
-    TheBucket->getFirst() = getTombstoneKey();
+    TheBucket->getFirst() = KeyInfoT::getTombstoneKey();
     decrementNumEntries();
     incrementNumTombstones();
     return true;
   }
   void erase(iterator I) {
     BucketT *TheBucket = &*I;
     TheBucket->getSecond().~ValueT();
-    TheBucket->getFirst() = getTombstoneKey();
+    TheBucket->getFirst() = KeyInfoT::getTombstoneKey();
     decrementNumEntries();
     incrementNumTombstones();
   }
@@ -362,7 +362,8 @@ class DenseMapBase : public DebugEpochBase {
     if (getNumBuckets() == 0) // Nothing to do.
       return;
 
-    const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
+    const KeyT TombstoneKey = KeyInfoT::getTombstoneKey();
     for (BucketT &B : buckets()) {
       if (!KeyInfoT::isEqual(B.getFirst(), EmptyKey) &&
           !KeyInfoT::isEqual(B.getFirst(), TombstoneKey))
@@ -372,12 +373,14 @@ class DenseMapBase : public DebugEpochBase {
   }
 
   void initEmpty() {
+    static_assert(std::is_base_of_v<DenseMapBase, DerivedT>,
+                  "Must pass the derived type to this template!");
     setNumEntries(0);
     setNumTombstones(0);
 
     assert((getNumBuckets() & (getNumBuckets() - 1)) == 0 &&
            "# initial buckets must be a power of two!");
-    const KeyT EmptyKey = getEmptyKey();
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
     for (BucketT &B : buckets())
       ::new (&B.getFirst()) KeyT(EmptyKey);
   }
@@ -397,8 +400,8 @@ class DenseMapBase : public DebugEpochBase {
     initEmpty();
 
     // Insert all the old elements.
-    const KeyT EmptyKey = getEmptyKey();
-    const KeyT TombstoneKey = getTombstoneKey();
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
+    const KeyT TombstoneKey = KeyInfoT::getTombstoneKey();
     for (BucketT &B : OldBuckets) {
       if (!KeyInfoT::isEqual(B.getFirst(), EmptyKey) &&
           !KeyInfoT::isEqual(B.getFirst(), TombstoneKey)) {
@@ -442,8 +445,8 @@ class DenseMapBase : public DebugEpochBase {
       memcpy(reinterpret_cast<void *>(Buckets), OtherBuckets,
              NumBuckets * sizeof(BucketT));
     } else {
-      const KeyT EmptyKey = getEmptyKey();
-      const KeyT TombstoneKey = getTombstoneKey();
+      const KeyT EmptyKey = KeyInfoT::getEmptyKey();
+      const KeyT TombstoneKey = KeyInfoT::getTombstoneKey();
       for (size_t I = 0; I < NumBuckets; ++I) {
         ::new (&Buckets[I].getFirst()) KeyT(OtherBuckets[I].getFirst());
         if (!KeyInfoT::isEqual(Buckets[I].getFirst(), EmptyKey) &&
@@ -453,19 +456,6 @@ class DenseMapBase : public DebugEpochBase {
     }
   }
 
-  template <typename LookupKeyT>
-  static unsigned getHashValue(const LookupKeyT &Val) {
-    return KeyInfoT::getHashValue(Val);
-  }
-
-  static const KeyT getEmptyKey() {
-    static_assert(std::is_base_of_v<DenseMapBase, DerivedT>,
-                  "Must pass the derived type to this template!");
-    return KeyInfoT::getEmptyKey();
-  }
-
-  static const KeyT getTombstoneKey() { return KeyInfoT::getTombstoneKey(); }
-
 private:
   DerivedT &derived() { return *static_cast<DerivedT *>(this); }
   const DerivedT &derived() const {
@@ -573,7 +563,7 @@ class DenseMapBase : public DebugEpochBase {
     incrementNumEntries();
 
     // If we are writing over a tombstone, remember this.
-    const KeyT EmptyKey = getEmptyKey();
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
     if (!KeyInfoT::isEqual(TheBucket->getFirst(), EmptyKey))
       decrementNumTombstones();
 
@@ -587,8 +577,8 @@ class DenseMapBase : public DebugEpochBase {
     if (NumBuckets == 0)
       return nullptr;
 
-    const KeyT EmptyKey = getEmptyKey();
-    unsigned BucketNo = getHashValue(Val) & (NumBuckets - 1);
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
+    unsigned BucketNo = KeyInfoT::getHashValue(Val) & (NumBuckets - 1);
     unsigned ProbeAmt = 1;
     while (true) {
       const BucketT *Bucket = BucketsPtr + BucketNo;
@@ -625,13 +615,13 @@ class DenseMapBase : public DebugEpochBase {
 
     // FoundTombstone - Keep track of whether we find a tombstone while probing.
     BucketT *FoundTombstone = nullptr;
-    const KeyT EmptyKey = getEmptyKey();
-    const KeyT TombstoneKey = getTombstoneKey();
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
+    const KeyT TombstoneKey = KeyInfoT::getTombstoneKey();
     assert(!KeyInfoT::isEqual(Val, EmptyKey) &&
            !KeyInfoT::isEqual(Val, TombstoneKey) &&
            "Empty/Tombstone value shouldn't be inserted into map!");
 
-    unsigned BucketNo = getHashValue(Val) & (NumBuckets - 1);
+    unsigned BucketNo = KeyInfoT::getHashValue(Val) & (NumBuckets - 1);
     unsigned ProbeAmt = 1;
     while (true) {
       BucketT *ThisBucket = BucketsPtr + BucketNo;
@@ -930,8 +920,8 @@ class SmallDenseMap
     NumEntries = TmpNumEntries;
     std::swap(NumTombstones, RHS.NumTombstones);
 
-    const KeyT EmptyKey = this->getEmptyKey();
-    const KeyT TombstoneKey = this->getTombstoneKey();
+    const KeyT EmptyKey = KeyInfoT::getEmptyKey();
+    const KeyT TombstoneKey = KeyInfoT::getTombstoneKey();
     if (Small && RHS.Small) {
       // If we're swapping inline bucket arrays, we have to cope with some of
       // the tricky bits of DenseMap's storage system: the buckets are not
@@ -1125,8 +1115,8 @@ class SmallDenseMap
 
       // Loop over the buckets, moving non-empty, non-tombstones into the
       // temporary storage. Have the loop move the TmpEnd forward as it goes.
-      const KeyT EmptyKey = this->getEmptyKey();
-      const KeyT TombstoneKey = this->getTombstoneKey();
+      const KeyT EmptyKey = KeyInfoT::getEmptyKey();
+      const KeyT TombstoneKey = KeyInfoT::getTombstoneKey();
       for (BucketT &B : inlineBuckets()) {
         if (!KeyInfoT::isEqual(B.getFirst(), EmptyKey) &&
             !KeyInfoT::isEqual(B.getFirst(), TombstoneKey)) {