[Support] Split MallocAllocator out of Allocator.h

StringMap.h is very popular (4K uses), and it doesn't need to see
BumpPtrAllocator, which is relatively expensive according to
ClangBuildAnalyzer. StringMap only needs MallocAllocator, so split that
into AllocatorBase.h and use it instead.

Here is the change in header uses:
$ diff -u thedeps-before.txt thedeps-after.txt | \
    grep '^[-+] ' |  sort | uniq -c | sort -nr
   3993 +    ../llvm/include/llvm/Support/AllocatorBase.h
    758 -    ../llvm/include/llvm/Support/Allocator.h
    270 -    ../llvm/include/llvm/Support/Alignment.h
     13 -    ../llvm/include/llvm/Support/Host.h
      6 -    ../llvm/include/llvm/ADT/StringMap.h
      4 -    ../llvm/include/llvm/Support/SwapByteOrder.h
      4 -    ../llvm/include/llvm/Support/MathExtras.h
      4 -    ../llvm/include/llvm/Support/AlignOf.h
      4 -    ../llvm/include/llvm/ADT/SmallVector.h
      1 -    ../llvm/include/llvm/Support/PointerLikeTypeTraits.h

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D73392

include/llvm/ADT/ScopedHashTable.h

@@ -32,7 +32,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseMapInfo.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include <cassert>
 #include <new>
 

include/llvm/ADT/SparseSet.h

@@ -21,7 +21,7 @@
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include <cassert>
 #include <cstdint>
 #include <cstdlib>

include/llvm/ADT/StringMap.h

@@ -16,9 +16,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
-#include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>

include/llvm/ADT/StringSet.h

@@ -15,7 +15,7 @@
 
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include <cassert>
 #include <initializer_list>
 #include <utility>

include/llvm/BinaryFormat/MachO.h

@@ -15,7 +15,7 @@
 
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DataTypes.h"
-#include "llvm/Support/Host.h"
+#include "llvm/Support/SwapByteOrder.h"
 
 namespace llvm {
 namespace MachO {

include/llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h

@@ -18,7 +18,6 @@
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeRecordMapping.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
-#include "llvm/Support/Allocator.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Error.h"

include/llvm/DebugInfo/PDB/Native/SymbolCache.h

@@ -14,7 +14,6 @@
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/PDB/Native/NativeRawSymbol.h"
-#include "llvm/Support/Allocator.h"
 
 #include <memory>
 #include <vector>

include/llvm/Object/IRSymtab.h

@@ -28,6 +28,7 @@
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/Object/SymbolicFile.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cassert>

include/llvm/ProfileData/SampleProf.h

@@ -22,6 +22,7 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/MathExtras.h"

include/llvm/Remarks/RemarkStringTable.h

@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Remarks/Remark.h"
+#include "llvm/Support/Allocator.h"
 #include <vector>
 
 namespace llvm {

include/llvm/Support/Allocator.h

@@ -23,6 +23,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Alignment.h"
+#include "llvm/Support/AllocatorBase.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
@@ -38,81 +39,6 @@
 
 namespace llvm {
 
-/// CRTP base class providing obvious overloads for the core \c
-/// Allocate() methods of LLVM-style allocators.
-///
-/// This base class both documents the full public interface exposed by all
-/// LLVM-style allocators, and redirects all of the overloads to a single core
-/// set of methods which the derived class must define.
-template <typename DerivedT> class AllocatorBase {
-public:
-  /// Allocate \a Size bytes of \a Alignment aligned memory. This method
-  /// must be implemented by \c DerivedT.
-  void *Allocate(size_t Size, size_t Alignment) {
-#ifdef __clang__
-    static_assert(static_cast<void *(AllocatorBase::*)(size_t, size_t)>(
-                      &AllocatorBase::Allocate) !=
-                      static_cast<void *(DerivedT::*)(size_t, size_t)>(
-                          &DerivedT::Allocate),
-                  "Class derives from AllocatorBase without implementing the "
-                  "core Allocate(size_t, size_t) overload!");
-#endif
-    return static_cast<DerivedT *>(this)->Allocate(Size, Alignment);
-  }
-
-  /// Deallocate \a Ptr to \a Size bytes of memory allocated by this
-  /// allocator.
-  void Deallocate(const void *Ptr, size_t Size) {
-#ifdef __clang__
-    static_assert(static_cast<void (AllocatorBase::*)(const void *, size_t)>(
-                      &AllocatorBase::Deallocate) !=
-                      static_cast<void (DerivedT::*)(const void *, size_t)>(
-                          &DerivedT::Deallocate),
-                  "Class derives from AllocatorBase without implementing the "
-                  "core Deallocate(void *) overload!");
-#endif
-    return static_cast<DerivedT *>(this)->Deallocate(Ptr, Size);
-  }
-
-  // The rest of these methods are helpers that redirect to one of the above
-  // core methods.
-
-  /// Allocate space for a sequence of objects without constructing them.
-  template <typename T> T *Allocate(size_t Num = 1) {
-    return static_cast<T *>(Allocate(Num * sizeof(T), alignof(T)));
-  }
-
-  /// Deallocate space for a sequence of objects without constructing them.
-  template <typename T>
-  typename std::enable_if<
-      !std::is_same<typename std::remove_cv<T>::type, void>::value, void>::type
-  Deallocate(T *Ptr, size_t Num = 1) {
-    Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T));
-  }
-};
-
-class MallocAllocator : public AllocatorBase<MallocAllocator> {
-public:
-  void Reset() {}
-
-  LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size,
-                                                size_t /*Alignment*/) {
-    return safe_malloc(Size);
-  }
-
-  // Pull in base class overloads.
-  using AllocatorBase<MallocAllocator>::Allocate;
-
-  void Deallocate(const void *Ptr, size_t /*Size*/) {
-    free(const_cast<void *>(Ptr));
-  }
-
-  // Pull in base class overloads.
-  using AllocatorBase<MallocAllocator>::Deallocate;
-
-  void PrintStats() const {}
-};
-
 namespace detail {
 
 // We call out to an external function to actually print the message as the

include/llvm/Support/AllocatorBase.h

@@ -0,0 +1,105 @@
+//===- AllocatorBase.h - Simple memory allocation abstraction -------*- 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file defines the MallocAllocator and BumpPtrAllocator interfaces. Both
+/// of these conform to an LLVM "Allocator" concept which consists of an
+/// Allocate method accepting a size and alignment, and a Deallocate accepting
+/// a pointer and size. Further, the LLVM "Allocator" concept has overloads of
+/// Allocate and Deallocate for setting size and alignment based on the final
+/// type. These overloads are typically provided by a base class template \c
+/// AllocatorBase.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_ALLOCATORBASE_H
+#define LLVM_SUPPORT_ALLOCATORBASE_H
+
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/MemAlloc.h"
+
+namespace llvm {
+
+/// CRTP base class providing obvious overloads for the core \c
+/// Allocate() methods of LLVM-style allocators.
+///
+/// This base class both documents the full public interface exposed by all
+/// LLVM-style allocators, and redirects all of the overloads to a single core
+/// set of methods which the derived class must define.
+template <typename DerivedT> class AllocatorBase {
+public:
+  /// Allocate \a Size bytes of \a Alignment aligned memory. This method
+  /// must be implemented by \c DerivedT.
+  void *Allocate(size_t Size, size_t Alignment) {
+#ifdef __clang__
+    static_assert(static_cast<void *(AllocatorBase::*)(size_t, size_t)>(
+                      &AllocatorBase::Allocate) !=
+                      static_cast<void *(DerivedT::*)(size_t, size_t)>(
+                          &DerivedT::Allocate),
+                  "Class derives from AllocatorBase without implementing the "
+                  "core Allocate(size_t, size_t) overload!");
+#endif
+    return static_cast<DerivedT *>(this)->Allocate(Size, Alignment);
+  }
+
+  /// Deallocate \a Ptr to \a Size bytes of memory allocated by this
+  /// allocator.
+  void Deallocate(const void *Ptr, size_t Size) {
+#ifdef __clang__
+    static_assert(static_cast<void (AllocatorBase::*)(const void *, size_t)>(
+                      &AllocatorBase::Deallocate) !=
+                      static_cast<void (DerivedT::*)(const void *, size_t)>(
+                          &DerivedT::Deallocate),
+                  "Class derives from AllocatorBase without implementing the "
+                  "core Deallocate(void *) overload!");
+#endif
+    return static_cast<DerivedT *>(this)->Deallocate(Ptr, Size);
+  }
+
+  // The rest of these methods are helpers that redirect to one of the above
+  // core methods.
+
+  /// Allocate space for a sequence of objects without constructing them.
+  template <typename T> T *Allocate(size_t Num = 1) {
+    return static_cast<T *>(Allocate(Num * sizeof(T), alignof(T)));
+  }
+
+  /// Deallocate space for a sequence of objects without constructing them.
+  template <typename T>
+  typename std::enable_if<
+      !std::is_same<typename std::remove_cv<T>::type, void>::value, void>::type
+  Deallocate(T *Ptr, size_t Num = 1) {
+    Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T));
+  }
+};
+
+class MallocAllocator : public AllocatorBase<MallocAllocator> {
+public:
+  void Reset() {}
+
+  LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size,
+                                                size_t /*Alignment*/) {
+    return safe_malloc(Size);
+  }
+
+  // Pull in base class overloads.
+  using AllocatorBase<MallocAllocator>::Allocate;
+
+  void Deallocate(const void *Ptr, size_t /*Size*/) {
+    free(const_cast<void *>(Ptr));
+  }
+
+  // Pull in base class overloads.
+  using AllocatorBase<MallocAllocator>::Deallocate;
+
+  void PrintStats() const {}
+};
+
+} // namespace llvm
+
+#endif // LLVM_SUPPORT_ALLOCATORBASE_H

include/llvm/Support/BinaryStreamReader.h

@@ -11,6 +11,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Alignment.h"
 #include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/ConvertUTF.h"

include/llvm/Support/Process.h

@@ -25,7 +25,7 @@
 #define LLVM_SUPPORT_PROCESS_H
 
 #include "llvm/ADT/Optional.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/Error.h"

lib/IR/SafepointIRVerifier.cpp

@@ -45,6 +45,7 @@
 #include "llvm/IR/Statepoint.h"
 #include "llvm/IR/Value.h"
 #include "llvm/InitializePasses.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"

unittests/Support/BinaryStreamTest.cpp

@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/BinaryItemStream.h"
 #include "llvm/Support/BinaryStreamArray.h"