// 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/Support/Memory.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdlib>
namespace llvm {
-template <typename T> struct ReferenceAdder {
- typedef T &result;
-};
-template <typename T> struct ReferenceAdder<T &> {
- typedef T result;
-};
-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));
}
- template <typename T> T *Allocate(size_t Num) {
- return static_cast<T *>(malloc(sizeof(T) * Num));
+ /// \brief 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));
}
-
- void Deallocate(const void *Ptr) { free(const_cast<void *>(Ptr)); }
-
- void PrintStats() const {}
};
-/// MemSlab - This structure lives at the beginning of every slab allocated by
-/// the bump allocator.
-class MemSlab {
+class MallocAllocator : public AllocatorBase<MallocAllocator> {
public:
- size_t Size;
- MemSlab *NextPtr;
-};
+ void Reset() {}
-/// 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;
-};
+ LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size,
+ size_t /*Alignment*/) {
+ return malloc(Size);
+ }
-/// 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;
+ // Pull in base class overloads.
+ using AllocatorBase<MallocAllocator>::Allocate;
-public:
- MallocSlabAllocator() : Allocator() {}
- virtual ~MallocSlabAllocator();
- MemSlab *Allocate(size_t Size) override;
- void Deallocate(MemSlab *Slab) override;
+ 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
+// 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
///
/// Note that this also has a threshold for forcing allocations above a certain
/// size into their own slab.
-class BumpPtrAllocator {
- BumpPtrAllocator(const BumpPtrAllocator &) LLVM_DELETED_FUNCTION;
- void operator=(const BumpPtrAllocator &) LLVM_DELETED_FUNCTION;
+///
+/// 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:
+ 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.");
+
+ 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();
+ }
+
+ ~BumpPtrAllocatorImpl() {
+ DeallocateSlabs(Slabs.begin(), Slabs.end());
+ DeallocateCustomSizedSlabs();
+ }
+
+ 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;
+ }
- /// \brief Allocate at least this many bytes of memory in a slab.
- size_t SlabSize;
+ /// \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();
+ }
- /// \brief Threshold above which allocations to go into a dedicated slab.
- size_t SizeThreshold;
+ /// \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;
+ }
- /// \brief The default allocator used if one is not provided.
- MallocSlabAllocator DefaultSlabAllocator;
+ // 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;
+ }
- /// \brief 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;
+ }
+
+ // Pull in base class overloads.
+ using AllocatorBase<BumpPtrAllocatorImpl>::Allocate;
+
+ void Deallocate(const void * /*Ptr*/, size_t /*Size*/) {}
- /// \brief The slab that we are currently allocating into.
- MemSlab *CurSlab;
+ // Pull in base class overloads.
+ using AllocatorBase<BumpPtrAllocatorImpl>::Deallocate;
+
+ size_t GetNumSlabs() const { return Slabs.size() + CustomSizedSlabs.size(); }
+
+ 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;
+ }
+ void PrintStats() const {
+ detail::printBumpPtrAllocatorStats(Slabs.size(), BytesAllocated,
+ getTotalMemory());
+ }
+
+private:
/// \brief The current pointer into the current slab.
///
/// This points to the next free byte in the slab.
/// \brief The end of the current slab.
char *End;
+ /// \brief The slabs allocated so far.
+ SmallVector<void *, 4> Slabs;
+
+ /// \brief Custom-sized slabs allocated for too-large allocation requests.
+ SmallVector<std::pair<void *, size_t>, 0> CustomSizedSlabs;
+
/// \brief How many bytes we've allocated.
///
/// Used so that we can compute how much space was wasted.
size_t BytesAllocated;
- /// \brief Aligns \c Ptr to \c 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);
+ /// \brief The allocator instance we use to get slabs of memory.
+ AllocatorT Allocator;
+
+ 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));
+ }
/// \brief Allocate a new slab and move the bump pointers over into the new
/// slab, modifying CurPtr and End.
- void StartNewSlab();
-
- /// \brief Deallocate all memory slabs after and including this one.
- void DeallocateSlabs(MemSlab *Slab);
-
- template <typename T> friend class SpecificBumpPtrAllocator;
-
-public:
- BumpPtrAllocator(size_t size = 4096, size_t threshold = 4096);
- BumpPtrAllocator(size_t size, size_t threshold, SlabAllocator &allocator);
- ~BumpPtrAllocator();
-
- /// \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();
+ void StartNewSlab() {
+ size_t AllocatedSlabSize = computeSlabSize(Slabs.size());
- /// \brief Allocate space at the specified alignment.
- void *Allocate(size_t Size, size_t Alignment);
-
- /// \brief Allocate space for one object without constructing it.
- template <typename T> T *Allocate() {
- return static_cast<T *>(Allocate(sizeof(T), AlignOf<T>::Alignment));
+ void *NewSlab = Allocator.Allocate(AllocatedSlabSize, 0);
+ Slabs.push_back(NewSlab);
+ CurPtr = (char *)(NewSlab);
+ End = ((char *)NewSlab) + AllocatedSlabSize;
}
- /// \brief Allocate space for an array of objects without constructing them.
- template <typename T> T *Allocate(size_t Num) {
- return static_cast<T *>(Allocate(Num * sizeof(T), AlignOf<T>::Alignment));
+ /// \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);
+ }
}
- /// \brief Allocate space for an array of objects with the specified alignment
- /// and without constructing them.
- 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 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 Deallocate(const void * /*Ptr*/) {}
-
- unsigned GetNumSlabs() const;
-
- void PrintStats() const;
-
- /// \brief Returns the total physical memory allocated by this allocator.
- size_t getTotalMemory() const;
+ template <typename T> friend 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.
///
BumpPtrAllocator Allocator;
public:
- SpecificBumpPtrAllocator(size_t size = 4096, size_t threshold = 4096)
- : Allocator(size, threshold) {}
- SpecificBumpPtrAllocator(size_t size, size_t threshold,
- SlabAllocator &allocator)
- : Allocator(size, threshold, allocator) {}
-
+ 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();
}
} // 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;
union {
void *P;
} x;
};
- 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)));
}
-inline void operator delete(void *, llvm::BumpPtrAllocator &) {}
+template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold>
+void operator delete(
+ void *, llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold> &) {
+}
#endif // LLVM_SUPPORT_ALLOCATOR_H
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