[PATCH] D104556: [InstrProfiling] Make CountersPtr in __profd_ relative

Mon Jun 21 16:14:23 PDT 2021

davidxl added a comment.

In D104556#2831800 <https://reviews.llvm.org/D104556#2831800>, @nickdesaulniers wrote:

> In D104556#2831757 <https://reviews.llvm.org/D104556#2831757>, @vsk wrote:
>
>> llvm has had a long-standing policy of keeping details of the .profraw format private between libprofile and InstrProfReader, opting to only commit to backwards-compat for the indexed .profdata format. I'm concerned that breaking with that practice would send the wrong message and commit llvm to maintaining an extra compat layer for a long time.
>>
>> Why/how does the Linux PGO patch "care" about the .profraw format?
>
> Because the Linux kernel cannot statically link against compiler-rt; we MUST emulate the interfaces provided by compiler-rt within the Linux kernel's runtime.

One way to solve this is to use a matching version of llvm-profdata tool and export indexed profile data only.

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https://reviews.llvm.org/D104556