[compiler-rt] [llvm] [RFC][Transforms][IPO] Add func suffix in ArgumentPromotion and DeadArgumentElimination (PR #109899)

[via llvm-commits]

yonghong-song wrote:

> 
> Wouldn't it be more desirable to disable argument promotion on functions you may want to enable tracing? Alternatively, if you had the actual signature of the function (post-argpromotion) available, would that enable a user write a correct probe?

We cannot disable argument promotion when building the kernel. Typically the kernel is built by some distro (ubuntu, fedora, etc.) or by a kernel team in google, meta, etc. for their inside-company use case. Once a kernel is built, it will be deployed to thousands or millions of machines. From user perspective, rebuilding the kernel by themself is not an option since the actual tracing happens in production system and it is typically not allowed for you to install your own kernel to production machine as there could be many services running on the machine and you do not want to disrupt those services.

If we indeed have actual signatures if the func signature got changed, that will be even better. We need to record this info in the binary so people can use that. Dwarf somehow had some information, but not always.

https://github.com/llvm/llvm-project/pull/109899