1 files changed, 92 insertions, 5 deletions

diff --git a/include/llvm/Support/Allocator.h b/include/llvm/Support/Allocator.h
index c0414f9..4c84878 100644
--- a/include/llvm/Support/Allocator.h
+++ b/include/llvm/Support/Allocator.h
@@ -15,6 +15,8 @@
 #define LLVM_SUPPORT_ALLOCATOR_H
 
 #include "llvm/Support/AlignOf.h"
+#include "llvm/Support/DataTypes.h"
+#include <cassert>
 #include <cstdlib>
 
 namespace llvm {
@@ -41,21 +43,104 @@ public:
   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.
@@ -83,9 +168,11 @@ public:
 
   void Deallocate(const void * /*Ptr*/) {}
 
+  unsigned GetNumSlabs() const;
+
   void PrintStats() const;
 };
 
 }  // end namespace llvm
 
-#endif
+#endif // LLVM_SUPPORT_ALLOCATOR_H