X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=include%2Fllvm%2FSupport%2FAllocator.h;h=ff08622eee548a76c96da4dab6a4725409bd0111;hp=eb6c2d1e25a76b3a776ec97adc82507fb0b6b569;hb=4f240010fdea1fcbe7dac3c8e9ebad082e4036c2;hpb=86bfd34ece523d863282ef2a2e4cf451c387c559

diff --git a/include/llvm/Support/Allocator.h b/include/llvm/Support/Allocator.h
index eb6c2d1e25a..ff08622eee5 100644
--- a/include/llvm/Support/Allocator.h
+++ b/include/llvm/Support/Allocator.h
@@ -6,234 +6,428 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This file defines the MallocAllocator and BumpPtrAllocator interfaces.
-//
+/// \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_ALLOCATOR_H
 #define LLVM_SUPPORT_ALLOCATOR_H
 
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/AlignOf.h"
+#include "llvm/Support/DataTypes.h"
 #include "llvm/Support/MathExtras.h"
-#include "llvm/System/DataTypes.h"
+#include "llvm/Support/Memory.h"
 #include <algorithm>
 #include <cassert>
-#include <cstdlib>
 #include <cstddef>
+#include <cstdlib>
 
 namespace llvm {
 
-class MallocAllocator {
+/// \brief 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:
-  MallocAllocator() {}
-  ~MallocAllocator() {}
+  /// \brief 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);
+  }
 
-  void Reset() {}
+  /// \brief 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);
+  }
 
-  void *Allocate(size_t Size, size_t /*Alignment*/) { return malloc(Size); }
+  // The rest of these methods are helpers that redirect to one of the above
+  // core methods.
 
-  template <typename T>
-  T *Allocate() { return static_cast<T*>(malloc(sizeof(T))); }
+  /// \brief 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>::Alignment));
+  }
 
+  /// \brief Deallocate space for a sequence of objects without constructing them.
   template <typename T>
-  T *Allocate(size_t Num) {
-    return static_cast<T*>(malloc(sizeof(T)*Num));
+  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 malloc(Size);
+  }
+
+  // Pull in base class overloads.
+  using AllocatorBase<MallocAllocator>::Allocate;
+
+  void Deallocate(const void *Ptr, size_t /*Size*/) {
+    free(const_cast<void *>(Ptr));
   }
 
-  void Deallocate(const void *Ptr) { free(const_cast<void*>(Ptr)); }
+  // Pull in base class overloads.
+  using AllocatorBase<MallocAllocator>::Deallocate;
 
   void PrintStats() const {}
 };
 
-/// MemSlab - This structure lives at the beginning of every slab allocated by
-/// the bump allocator.
-class MemSlab {
+namespace detail {
+
+// We call out to an external function to actually print the message as the
+// printing code uses Allocator.h in its implementation.
+void printBumpPtrAllocatorStats(unsigned NumSlabs, size_t BytesAllocated,
+                                size_t TotalMemory);
+} // End namespace detail.
+
+/// \brief Allocate memory in an ever growing pool, as if by bump-pointer.
+///
+/// This isn't strictly a bump-pointer allocator as it uses backing slabs of
+/// memory rather than relying on boundless contiguous heap. However, it has
+/// bump-pointer semantics in that is a monotonically growing pool of memory
+/// where every allocation is found by merely allocating the next N bytes in
+/// the slab, or the next N bytes in the next slab.
+///
+/// Note that this also has a threshold for forcing allocations above a certain
+/// size into their own slab.
+///
+/// The BumpPtrAllocatorImpl template defaults to using a MallocAllocator
+/// object, which wraps malloc, to allocate memory, but it can be changed to
+/// use a custom allocator.
+template <typename AllocatorT = MallocAllocator, size_t SlabSize = 4096,
+          size_t SizeThreshold = SlabSize>
+class BumpPtrAllocatorImpl
+    : public AllocatorBase<
+          BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold>> {
 public:
-  size_t Size;
-  MemSlab *NextPtr;
-};
+  static_assert(SizeThreshold <= SlabSize,
+                "The SizeThreshold must be at most the SlabSize to ensure "
+                "that objects larger than a slab go into their own memory "
+                "allocation.");
 
-/// SlabAllocator - This class can be used to parameterize the underlying
-/// allocation strategy for the bump allocator.  In particular, this is used
-/// by the JIT to allocate contiguous swathes of executable memory.  The
-/// interface uses MemSlab's instead of void *'s so that the allocator
-/// doesn't have to remember the size of the pointer it allocated.
-class SlabAllocator {
-public:
-  virtual ~SlabAllocator();
-  virtual MemSlab *Allocate(size_t Size) = 0;
-  virtual void Deallocate(MemSlab *Slab) = 0;
-};
+  BumpPtrAllocatorImpl()
+      : CurPtr(nullptr), End(nullptr), BytesAllocated(0), Allocator() {}
+  template <typename T>
+  BumpPtrAllocatorImpl(T &&Allocator)
+      : CurPtr(nullptr), End(nullptr), BytesAllocated(0),
+        Allocator(std::forward<T &&>(Allocator)) {}
+
+  // Manually implement a move constructor as we must clear the old allocators
+  // slabs as a matter of correctness.
+  BumpPtrAllocatorImpl(BumpPtrAllocatorImpl &&Old)
+      : CurPtr(Old.CurPtr), End(Old.End), Slabs(std::move(Old.Slabs)),
+        CustomSizedSlabs(std::move(Old.CustomSizedSlabs)),
+        BytesAllocated(Old.BytesAllocated),
+        Allocator(std::move(Old.Allocator)) {
+    Old.CurPtr = Old.End = nullptr;
+    Old.BytesAllocated = 0;
+    Old.Slabs.clear();
+    Old.CustomSizedSlabs.clear();
+  }
 
-/// MallocSlabAllocator - The default slab allocator for the bump allocator
-/// is an adapter class for MallocAllocator that just forwards the method
-/// calls and translates the arguments.
-class MallocSlabAllocator : public SlabAllocator {
-  /// Allocator - The underlying allocator that we forward to.
-  ///
-  MallocAllocator Allocator;
+  ~BumpPtrAllocatorImpl() {
+    DeallocateSlabs(Slabs.begin(), Slabs.end());
+    DeallocateCustomSizedSlabs();
+  }
 
-public:
-  MallocSlabAllocator() : Allocator() { }
-  virtual ~MallocSlabAllocator();
-  virtual MemSlab *Allocate(size_t Size);
-  virtual void Deallocate(MemSlab *Slab);
-};
+  BumpPtrAllocatorImpl &operator=(BumpPtrAllocatorImpl &&RHS) {
+    DeallocateSlabs(Slabs.begin(), Slabs.end());
+    DeallocateCustomSizedSlabs();
+
+    CurPtr = RHS.CurPtr;
+    End = RHS.End;
+    BytesAllocated = RHS.BytesAllocated;
+    Slabs = std::move(RHS.Slabs);
+    CustomSizedSlabs = std::move(RHS.CustomSizedSlabs);
+    Allocator = std::move(RHS.Allocator);
+
+    RHS.CurPtr = RHS.End = nullptr;
+    RHS.BytesAllocated = 0;
+    RHS.Slabs.clear();
+    RHS.CustomSizedSlabs.clear();
+    return *this;
+  }
 
-/// BumpPtrAllocator - This allocator is useful for containers that need
-/// very simple memory allocation strategies.  In particular, this just keeps
-/// allocating memory, and never deletes it until the entire block is dead. This
-/// makes allocation speedy, but must only be used when the trade-off is ok.
-class BumpPtrAllocator {
-  BumpPtrAllocator(const BumpPtrAllocator &); // do not implement
-  void operator=(const BumpPtrAllocator &);   // do not implement
+  /// \brief Deallocate all but the current slab and reset the current pointer
+  /// to the beginning of it, freeing all memory allocated so far.
+  void Reset() {
+    if (Slabs.empty())
+      return;
+
+    // Reset the state.
+    BytesAllocated = 0;
+    CurPtr = (char *)Slabs.front();
+    End = CurPtr + SlabSize;
+
+    // Deallocate all but the first slab, and all custome sized slabs.
+    DeallocateSlabs(std::next(Slabs.begin()), Slabs.end());
+    Slabs.erase(std::next(Slabs.begin()), Slabs.end());
+    DeallocateCustomSizedSlabs();
+    CustomSizedSlabs.clear();
+  }
 
-  /// SlabSize - Allocate data into slabs of this size unless we get an
-  /// allocation above SizeThreshold.
-  size_t SlabSize;
+  /// \brief Allocate space at the specified alignment.
+  LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size, size_t Alignment) {
+    assert(Alignment > 0 && "0-byte alignnment is not allowed. Use 1 instead.");
+
+    // Keep track of how many bytes we've allocated.
+    BytesAllocated += Size;
+
+    size_t Adjustment = alignmentAdjustment(CurPtr, Alignment);
+    assert(Adjustment + Size >= Size && "Adjustment + Size must not overflow");
+
+    // Check if we have enough space.
+    if (Adjustment + Size <= size_t(End - CurPtr)) {
+      char *AlignedPtr = CurPtr + Adjustment;
+      CurPtr = AlignedPtr + Size;
+      // Update the allocation point of this memory block in MemorySanitizer.
+      // Without this, MemorySanitizer messages for values originated from here
+      // will point to the allocation of the entire slab.
+      __msan_allocated_memory(AlignedPtr, Size);
+      return AlignedPtr;
+    }
 
-  /// SizeThreshold - For any allocation larger than this threshold, we should
-  /// allocate a separate slab.
-  size_t SizeThreshold;
+    // If Size is really big, allocate a separate slab for it.
+    size_t PaddedSize = Size + Alignment - 1;
+    if (PaddedSize > SizeThreshold) {
+      void *NewSlab = Allocator.Allocate(PaddedSize, 0);
+      CustomSizedSlabs.push_back(std::make_pair(NewSlab, PaddedSize));
+
+      uintptr_t AlignedAddr = alignAddr(NewSlab, Alignment);
+      assert(AlignedAddr + Size <= (uintptr_t)NewSlab + PaddedSize);
+      char *AlignedPtr = (char*)AlignedAddr;
+      __msan_allocated_memory(AlignedPtr, Size);
+      return AlignedPtr;
+    }
 
-  /// Allocator - The underlying allocator we use to get slabs of memory.  This
-  /// defaults to MallocSlabAllocator, which wraps malloc, but it could be
-  /// changed to use a custom allocator.
-  SlabAllocator &Allocator;
+    // Otherwise, start a new slab and try again.
+    StartNewSlab();
+    uintptr_t AlignedAddr = alignAddr(CurPtr, Alignment);
+    assert(AlignedAddr + Size <= (uintptr_t)End &&
+           "Unable to allocate memory!");
+    char *AlignedPtr = (char*)AlignedAddr;
+    CurPtr = AlignedPtr + Size;
+    __msan_allocated_memory(AlignedPtr, Size);
+    return AlignedPtr;
+  }
 
-  /// CurSlab - The slab that we are currently allocating into.
-  ///
-  MemSlab *CurSlab;
+  // Pull in base class overloads.
+  using AllocatorBase<BumpPtrAllocatorImpl>::Allocate;
 
-  /// CurPtr - The current pointer into the current slab.  This points to the
-  /// next free byte in the slab.
-  char *CurPtr;
+  void Deallocate(const void * /*Ptr*/, size_t /*Size*/) {}
 
-  /// End - The end of the current slab.
-  ///
-  char *End;
+  // Pull in base class overloads.
+  using AllocatorBase<BumpPtrAllocatorImpl>::Deallocate;
 
-  /// BytesAllocated - This field tracks how many bytes we've allocated, so
-  /// that we can compute how much space was wasted.
-  size_t BytesAllocated;
+  size_t GetNumSlabs() const { return Slabs.size() + CustomSizedSlabs.size(); }
 
-  /// AlignPtr - Align Ptr to Alignment bytes, rounding up.  Alignment should
-  /// be a power of two.  This method rounds up, so AlignPtr(7, 4) == 8 and
-  /// AlignPtr(8, 4) == 8.
-  static char *AlignPtr(char *Ptr, size_t Alignment);
+  size_t getTotalMemory() const {
+    size_t TotalMemory = 0;
+    for (auto I = Slabs.begin(), E = Slabs.end(); I != E; ++I)
+      TotalMemory += computeSlabSize(std::distance(Slabs.begin(), I));
+    for (auto &PtrAndSize : CustomSizedSlabs)
+      TotalMemory += PtrAndSize.second;
+    return TotalMemory;
+  }
 
-  /// StartNewSlab - Allocate a new slab and move the bump pointers over into
-  /// the new slab.  Modifies CurPtr and End.
-  void StartNewSlab();
+  void PrintStats() const {
+    detail::printBumpPtrAllocatorStats(Slabs.size(), BytesAllocated,
+                                       getTotalMemory());
+  }
 
-  /// DeallocateSlabs - Deallocate all memory slabs after and including this
-  /// one.
-  void DeallocateSlabs(MemSlab *Slab);
+private:
+  /// \brief The current pointer into the current slab.
+  ///
+  /// This points to the next free byte in the slab.
+  char *CurPtr;
 
-  static MallocSlabAllocator DefaultSlabAllocator;
+  /// \brief The end of the current slab.
+  char *End;
 
-  template<typename T> friend class SpecificBumpPtrAllocator;
-public:
-  BumpPtrAllocator(size_t size = 4096, size_t threshold = 4096,
-                   SlabAllocator &allocator = DefaultSlabAllocator);
-  ~BumpPtrAllocator();
+  /// \brief The slabs allocated so far.
+  SmallVector<void *, 4> Slabs;
 
-  /// Reset - Deallocate all but the current slab and reset the current pointer
-  /// to the beginning of it, freeing all memory allocated so far.
-  void Reset();
+  /// \brief Custom-sized slabs allocated for too-large allocation requests.
+  SmallVector<std::pair<void *, size_t>, 0> CustomSizedSlabs;
 
-  /// Allocate - Allocate space at the specified alignment.
+  /// \brief How many bytes we've allocated.
   ///
-  void *Allocate(size_t Size, size_t Alignment);
+  /// Used so that we can compute how much space was wasted.
+  size_t BytesAllocated;
 
-  /// Allocate space, but do not construct, one object.
-  ///
-  template <typename T>
-  T *Allocate() {
-    return static_cast<T*>(Allocate(sizeof(T),AlignOf<T>::Alignment));
-  }
+  /// \brief The allocator instance we use to get slabs of memory.
+  AllocatorT Allocator;
 
-  /// Allocate space for an array of objects.  This does not construct the
-  /// objects though.
-  template <typename T>
-  T *Allocate(size_t Num) {
-    return static_cast<T*>(Allocate(Num * sizeof(T), AlignOf<T>::Alignment));
+  static size_t computeSlabSize(unsigned SlabIdx) {
+    // Scale the actual allocated slab size based on the number of slabs
+    // allocated. Every 128 slabs allocated, we double the allocated size to
+    // reduce allocation frequency, but saturate at multiplying the slab size by
+    // 2^30.
+    return SlabSize * ((size_t)1 << std::min<size_t>(30, SlabIdx / 128));
   }
 
-  /// Allocate space for a specific count of elements and with a specified
-  /// alignment.
-  template <typename T>
-  T *Allocate(size_t Num, size_t Alignment) {
-    // Round EltSize up to the specified alignment.
-    size_t EltSize = (sizeof(T)+Alignment-1)&(-Alignment);
-    return static_cast<T*>(Allocate(Num * EltSize, Alignment));
+  /// \brief Allocate a new slab and move the bump pointers over into the new
+  /// slab, modifying CurPtr and End.
+  void StartNewSlab() {
+    size_t AllocatedSlabSize = computeSlabSize(Slabs.size());
+
+    void *NewSlab = Allocator.Allocate(AllocatedSlabSize, 0);
+    Slabs.push_back(NewSlab);
+    CurPtr = (char *)(NewSlab);
+    End = ((char *)NewSlab) + AllocatedSlabSize;
   }
 
-  void Deallocate(const void * /*Ptr*/) {}
+  /// \brief Deallocate a sequence of slabs.
+  void DeallocateSlabs(SmallVectorImpl<void *>::iterator I,
+                       SmallVectorImpl<void *>::iterator E) {
+    for (; I != E; ++I) {
+      size_t AllocatedSlabSize =
+          computeSlabSize(std::distance(Slabs.begin(), I));
+#ifndef NDEBUG
+      // Poison the memory so stale pointers crash sooner.  Note we must
+      // preserve the Size and NextPtr fields at the beginning.
+      if (AllocatedSlabSize != 0) {
+        sys::Memory::setRangeWritable(*I, AllocatedSlabSize);
+        memset(*I, 0xCD, AllocatedSlabSize);
+      }
+#endif
+      Allocator.Deallocate(*I, AllocatedSlabSize);
+    }
+  }
 
-  unsigned GetNumSlabs() const;
+  /// \brief Deallocate all memory for custom sized slabs.
+  void DeallocateCustomSizedSlabs() {
+    for (auto &PtrAndSize : CustomSizedSlabs) {
+      void *Ptr = PtrAndSize.first;
+      size_t Size = PtrAndSize.second;
+#ifndef NDEBUG
+      // Poison the memory so stale pointers crash sooner.  Note we must
+      // preserve the Size and NextPtr fields at the beginning.
+      sys::Memory::setRangeWritable(Ptr, Size);
+      memset(Ptr, 0xCD, Size);
+#endif
+      Allocator.Deallocate(Ptr, Size);
+    }
+  }
 
-  void PrintStats() const;
+  template <typename T> friend class SpecificBumpPtrAllocator;
 };
 
-/// SpecificBumpPtrAllocator - Same as BumpPtrAllocator but allows only
-/// elements of one type to be allocated. This allows calling the destructor
-/// in DestroyAll() and when the allocator is destroyed.
-template <typename T>
-class SpecificBumpPtrAllocator {
+/// \brief The standard BumpPtrAllocator which just uses the default template
+/// paramaters.
+typedef BumpPtrAllocatorImpl<> BumpPtrAllocator;
+
+/// \brief A BumpPtrAllocator that allows only elements of a specific type to be
+/// allocated.
+///
+/// This allows calling the destructor in DestroyAll() and when the allocator is
+/// destroyed.
+template <typename T> class SpecificBumpPtrAllocator {
   BumpPtrAllocator Allocator;
-public:
-  SpecificBumpPtrAllocator(size_t size = 4096, size_t threshold = 4096,
-              SlabAllocator &allocator = BumpPtrAllocator::DefaultSlabAllocator)
-    : Allocator(size, threshold, allocator) {}
 
-  ~SpecificBumpPtrAllocator() {
-    DestroyAll();
+public:
+  SpecificBumpPtrAllocator() : Allocator() {}
+  SpecificBumpPtrAllocator(SpecificBumpPtrAllocator &&Old)
+      : Allocator(std::move(Old.Allocator)) {}
+  ~SpecificBumpPtrAllocator() { DestroyAll(); }
+
+  SpecificBumpPtrAllocator &operator=(SpecificBumpPtrAllocator &&RHS) {
+    Allocator = std::move(RHS.Allocator);
+    return *this;
   }
 
   /// Call the destructor of each allocated object and deallocate all but the
   /// current slab and reset the current pointer to the beginning of it, freeing
   /// all memory allocated so far.
   void DestroyAll() {
-    MemSlab *Slab = Allocator.CurSlab;
-    while (Slab) {
-      char *End = Slab == Allocator.CurSlab ? Allocator.CurPtr :
-                                              (char *)Slab + Slab->Size;
-      for (char *Ptr = (char*)(Slab+1); Ptr < End; Ptr += sizeof(T)) {
-        Ptr = Allocator.AlignPtr(Ptr, alignof<T>());
-	if (Ptr + sizeof(T) <= End)
-          reinterpret_cast<T*>(Ptr)->~T();
-      }
-      Slab = Slab->NextPtr;
+    auto DestroyElements = [](char *Begin, char *End) {
+      assert(Begin == (char*)alignAddr(Begin, alignOf<T>()));
+      for (char *Ptr = Begin; Ptr + sizeof(T) <= End; Ptr += sizeof(T))
+        reinterpret_cast<T *>(Ptr)->~T();
+    };
+
+    for (auto I = Allocator.Slabs.begin(), E = Allocator.Slabs.end(); I != E;
+         ++I) {
+      size_t AllocatedSlabSize = BumpPtrAllocator::computeSlabSize(
+          std::distance(Allocator.Slabs.begin(), I));
+      char *Begin = (char*)alignAddr(*I, alignOf<T>());
+      char *End = *I == Allocator.Slabs.back() ? Allocator.CurPtr
+                                               : (char *)*I + AllocatedSlabSize;
+
+      DestroyElements(Begin, End);
     }
+
+    for (auto &PtrAndSize : Allocator.CustomSizedSlabs) {
+      void *Ptr = PtrAndSize.first;
+      size_t Size = PtrAndSize.second;
+      DestroyElements((char*)alignAddr(Ptr, alignOf<T>()), (char *)Ptr + Size);
+    }
+
     Allocator.Reset();
   }
 
-  /// Allocate space for a specific count of elements.
-  T *Allocate(size_t num = 1) {
-    return Allocator.Allocate<T>(num);
-  }
+  /// \brief Allocate space for an array of objects without constructing them.
+  T *Allocate(size_t num = 1) { return Allocator.Allocate<T>(num); }
 };
 
 }  // end namespace llvm
 
-inline void *operator new(size_t Size, llvm::BumpPtrAllocator &Allocator) {
+template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold>
+void *operator new(size_t Size,
+                   llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize,
+                                              SizeThreshold> &Allocator) {
   struct S {
     char c;
-#ifdef __GNUC__
-    char x __attribute__((aligned));
-#else
     union {
       double D;
       long double LD;
       long long L;
       void *P;
     } x;
-#endif
   };
-  return Allocator.Allocate(Size, std::min((size_t)llvm::NextPowerOf2(Size),
-                                           offsetof(S, x)));
+  return Allocator.Allocate(
+      Size, std::min((size_t)llvm::NextPowerOf2(Size), offsetof(S, x)));
+}
+
+template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold>
+void operator delete(
+    void *, llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold> &) {
 }
 
 #endif // LLVM_SUPPORT_ALLOCATOR_H