[compiler-rt] [compiler-rt][rtsan] pathconf/fpathconf interception. (PR #134495)

[via llvm-commits]

davidtrevelyan wrote:

> depends on the query. Ideally, most of them ought to be called at initialisation time. For non deterministic queries, e.g. _PC_NAME_MAX, mount points and metadata, it might not be safe to call can be flagged in rtsan context. wdyt ?

Thanks for the info! For me it depends on whether these functions would realistically ever be accidentally called in a real-time context by someone doing real-time programming. Unfortunately there are many non-deterministic system functions and we're unlikely to be able to intercept them all, at least in the near term, until we have a better implementation with (perhaps) code generation to make it maintainable. I believe we should concentrate on the functions for which interception delivers most value to the real-time programmer.

Your helpful point about them being mostly initialisation-time use-cases is good - this makes me lean towards not intercepting them in this case. But I don't have strong feelings about it. 

https://github.com/llvm/llvm-project/pull/134495