BumpPtrAllocator::BumpPtrAllocator(size_t size, size_t threshold,
SlabAllocator &allocator)
: SlabSize(size), SizeThreshold(threshold), Allocator(allocator),
- CurSlab(0), BytesAllocated(0) {
- StartNewSlab();
-}
+ CurSlab(0), BytesAllocated(0) { }
BumpPtrAllocator::~BumpPtrAllocator() {
DeallocateSlabs(CurSlab);
/// StartNewSlab - Allocate a new slab and move the bump pointers over into
/// the new slab. Modifies CurPtr and End.
void BumpPtrAllocator::StartNewSlab() {
+ // If we allocated a big number of slabs already it's likely that we're going
+ // to allocate more. Increase slab size to reduce mallocs and possibly memory
+ // overhead. The factors are chosen conservatively to avoid overallocation.
+ if (BytesAllocated >= SlabSize * 128)
+ SlabSize *= 2;
+
MemSlab *NewSlab = Allocator.Allocate(SlabSize);
NewSlab->NextPtr = CurSlab;
CurSlab = NewSlab;
/// Reset - Deallocate all but the current slab and reset the current pointer
/// to the beginning of it, freeing all memory allocated so far.
void BumpPtrAllocator::Reset() {
+ if (!CurSlab)
+ return;
DeallocateSlabs(CurSlab->NextPtr);
CurSlab->NextPtr = 0;
CurPtr = (char*)(CurSlab + 1);
/// Allocate - Allocate space at the specified alignment.
///
void *BumpPtrAllocator::Allocate(size_t Size, size_t Alignment) {
+ if (!CurSlab) // Start a new slab if we haven't allocated one already.
+ StartNewSlab();
+
// Keep track of how many bytes we've allocated.
BytesAllocated += Size;