[PATCH] D136698: [SampleFDO] Persist profile staleness metrics into binary

[Mircea Trofin via Phabricator via llvm-commits]

mtrofin added a comment.

In D136698#3883961 <https://reviews.llvm.org/D136698#3883961>, @wenlei wrote:

> In D136698#3883954 <https://reviews.llvm.org/D136698#3883954>, @davidxl wrote:
>
>> For incremental build, are the artifacts (build logs) also cached?
>>
>> Anyway, I can see the usefulness of the post-build analysis case. However should we consider more general mechanism for message persistence? I will copy some folks in the review.
>
> Yes, this should be more general than profile staleness. Actually the other use case we have in mind is for persisting static performance proxy, which can also be used as full reward function for MLGO.

(sorry for the delay) SGTM, I assume, if we want the values to be more complex, we can base64-encode them or something like that (i.e. we can evolve the format to not assume the values are ints); also, we may want to allow, at a later stage, the section to be populated with values available to the assembler - like exact MBB sizes - I don't think that'd be difficult to fit in at a later stage (some sort of callback to TargetLoweringObjectFileImpl.cpp or something like that). I'm listing these to check if there's any assumptions that such later evolution might invalidate.


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