[PATCH] D103988: SampleFDO] place the discriminator flag variable into the used list.

Tue Jun 15 16:58:54 PDT 2021

xur added a comment.

In D103988#2820735 <https://reviews.llvm.org/D103988#2820735>, @MaskRay wrote:

> CommonLinkage doesn't work.
>
> Whether `appendToUsed` is needed depends on whether the runtime has a live section referencing `__llvm_fs_discriminator__`.
> If the runtime has the guarantee, no need for `appendToUsed`.
>
> Otherwise, the first revision `appendToUsed` with `WeakODRLinkage` looks good to me.
>
> `appendToUsed` with `ExternalLinkage` in a comdat works as well, but comdat will need extra code when Mach-O wants this feature.

Fangri, thanks for reviewing this. This variable will NOT be referenced by compiler runtime library -- only be referenced by AutoFDO offline tool (to generate AFDO profile).

It seems that Fangri (as a linker expert) prefers my first implementation.

I'm OK either way. Hoy: what is your thought?

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D103988/new/

https://reviews.llvm.org/D103988