[clang] [PAC][clang][Driver] Add signed GOT flag (PR #96160)

[Daniil Kovalev via cfe-commits]

kovdan01 wrote:

@ahmedbougacha 

> I should mention that in our world we generally don't expect these to be common (other than in cc1 invocations), and they're generally used for overriding default ABI behavior inferred from triples and deployment targets and whatnot.

We also don't expect usage of these options to be common - instead, we propose `-mbranch-protection=pauthabi` option which enables a pre-defined set of ptrauth flags, see #97237.

I think that the main rationale for using comma-separated flags instead of a bunch of different flags is that it'll reduce unneeded `-fptrauth-` duplication - such duplication is probably undesirable even in cc1 invocations.

> and it should be doable to support the long spellings on top of these.

Regarding that: I'm not sure if it's a good idea to support both `-fptrauth-xxx -fptrauth-yyy` and `-fptrauth=xxx,yyy`. It'll result in additional logic for handling conflicts if the same flags are defined in different ways. It's probably not too complex, but it'll make things more messy, and I don't think it's what we are trying to achive.

https://github.com/llvm/llvm-project/pull/96160