[libc] [llvm] [libc] add basic arena allocator (PR #121173)

[Daniel Thornburgh via llvm-commits]

https://github.com/mysterymath commented:

Can you speak a bit more as to how this particular allocation approach helps for baremetal systems? These tend to be more space-constrained than time-constrained. AFAICT, this allocator can never free, which prioritizes time over space. (It also is likely less code, but the existing allocator is relatively small for what it does, and RAM is usually more expensive than ROM.)

Minimizing time and ROM usage and maximizing RAM usage may be a reasonable trade-off to support, but just to double-check, is there a specific use-case that exists to drive those requirements?

https://github.com/llvm/llvm-project/pull/121173