#define LLVM_SUPPORT_ALLOCATOR_H
#include "llvm/Support/AlignOf.h"
+#include "llvm/System/DataTypes.h"
+#include <cassert>
#include <cstdlib>
namespace llvm {
-
+
class MallocAllocator {
public:
MallocAllocator() {}
~MallocAllocator() {}
-
+
void Reset() {}
void *Allocate(size_t Size, size_t /*Alignment*/) { return malloc(Size); }
-
+
template <typename T>
T *Allocate() { return static_cast<T*>(malloc(sizeof(T))); }
-
- void Deallocate(void *Ptr) { free(Ptr); }
+
+ template <typename T>
+ T *Allocate(size_t Num) {
+ return static_cast<T*>(malloc(sizeof(T)*Num));
+ }
+
+ void Deallocate(const void *Ptr) { free(const_cast<void*>(Ptr)); }
void PrintStats() const {}
};
-/// BumpPtrAllocator - This allocator is useful for containers that need very
-/// simple memory allocation strategies. In particular, this just keeps
+/// MemSlab - This structure lives at the beginning of every slab allocated by
+/// the bump allocator.
+class MemSlab {
+public:
+ size_t Size;
+ MemSlab *NextPtr;
+};
+
+/// 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;
+};
+
+/// 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;
+
+public:
+ MallocSlabAllocator() : Allocator() { }
+ virtual ~MallocSlabAllocator();
+ virtual MemSlab *Allocate(size_t Size);
+ virtual void Deallocate(MemSlab *Slab);
+};
+
+/// 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
- void *TheMemory;
+ /// SlabSize - Allocate data into slabs of this size unless we get an
+ /// allocation above SizeThreshold.
+ size_t SlabSize;
+
+ /// SizeThreshold - For any allocation larger than this threshold, we should
+ /// allocate a separate slab.
+ size_t SizeThreshold;
+
+ /// 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;
+
+ /// CurSlab - The slab that we are currently allocating into.
+ ///
+ MemSlab *CurSlab;
+
+ /// CurPtr - The current pointer into the current slab. This points to the
+ /// next free byte in the slab.
+ char *CurPtr;
+
+ /// End - The end of the current slab.
+ ///
+ char *End;
+
+ /// BytesAllocated - This field tracks how many bytes we've allocated, so
+ /// that we can compute how much space was wasted.
+ size_t BytesAllocated;
+
+ /// 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);
+
+ /// StartNewSlab - Allocate a new slab and move the bump pointers over into
+ /// the new slab. Modifies CurPtr and End.
+ void StartNewSlab();
+
+ /// DeallocateSlabs - Deallocate all memory slabs after and including this
+ /// one.
+ void DeallocateSlabs(MemSlab *Slab);
+
+ static MallocSlabAllocator DefaultSlabAllocator;
+
public:
- BumpPtrAllocator();
+ BumpPtrAllocator(size_t size = 4096, size_t threshold = 4096,
+ SlabAllocator &allocator = DefaultSlabAllocator);
~BumpPtrAllocator();
-
+
+ /// 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();
+ /// Allocate - Allocate space at the specified alignment.
+ ///
void *Allocate(size_t Size, size_t Alignment);
+ /// Allocate space, but do not construct, one object.
+ ///
template <typename T>
- T *Allocate() {
+ T *Allocate() {
return static_cast<T*>(Allocate(sizeof(T),AlignOf<T>::Alignment));
}
-
- void Deallocate(void * /*Ptr*/) {}
+
+ /// 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));
+ }
+
+ /// 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));
+ }
+
+ void Deallocate(const void * /*Ptr*/) {}
+
+ unsigned GetNumSlabs() const;
void PrintStats() const;
};
} // end namespace llvm
-#endif
+#endif // LLVM_SUPPORT_ALLOCATOR_H
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