[llvm] [memprof] Make HeapProfileRecords optional (PR #155671)

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

@teresajohnson 

> Right now this section itself requires both AllocSites and CallSites. Does it make sense to change that too? In practice we need not have both in a profile.

Let me take that as a follow-up project.

> Should there be a test for this change to ensure it does something reasonable for an empty memprof yaml?

Yes, and that turns out to be important.  We need to relax the emptiness check in `llvm/include/llvm/ProfileData/MemProfYAML.h`.


https://github.com/llvm/llvm-project/pull/155671