[PATCH] BumpPtr allocate SimpleReferences

[colinl at codeaurora.org]

It doesn't seem like there's any memory different between the linked list version and the bumpvector version.  The linked list version requires 2*(pointer_size)*N memory and if a bumpvector is resized to double each time, the sum of all intermediate backing allocations comes out the same.

16 Items in a linked list requires 2*16*pointer
16 Items in a bumpvector requires (1+2+4+8+16)*pointer

http://reviews.llvm.org/D6518