[clang] [llvm] [ARM][AArch64] BTI, GCS, PAC Module flag update. (PR #86212)

[Daniel Kiss via cfe-commits]

DanielKristofKiss wrote:

> > @DanielKristofKiss, thanks a lot for updating the patch! I see some cases where PAC-RET flags are not upgraded well, and they might be related to the points we discussed above. I will post an update later and provide a reproducer.
> 
> I have confirmed that the root cause of the issues I see is not what we discussed above. It only occurs for some cases of ThinLTO:
> 
> * a module has no functions when `CopyModuleAttrToFunctions` is called the first time
> * we set module flags to 2, because there are no functions to upgrade
> * some functions are added later, `CopyModuleAttrToFunctions` is called again, but it does nothing because module flags are already set to 2.
> 
> I think it is an edge case. I can send a separate patch to not gate this one.

Thanks for the feedback, if you have a reproduced happy to take a look.

https://github.com/llvm/llvm-project/pull/86212