[lld] [llvm] [lld][MachO] Follow-up to use madvise() for threaded file page-in. (PR #157917)

[Richard Smith via llvm-commits]

zygoloid wrote:

> @drodriguez I wondered about .tbd files. Basically, the new code in the commit I mention, prevents most input files from using mmap() to solve an obscure clang problem on Linux.

Can you explain how it prevents most input files from using mmap? I would expect that for most input files either the file is binary (in which case `RequiresNullTerminator` should be false), or there is a null terminator produced by mmap (in which case you get to use mmap), or you're hitting an OS bug like the Linux one.

https://github.com/llvm/llvm-project/pull/157917