[PATCH] D21405: [PGO] IRPGO pre-cleanup pass changes

[Xinliang David Li via llvm-commits]

On Fri, Jul 29, 2016 at 9:32 PM, Mehdi AMINI <mehdi.amini at apple.com> wrote:
> mehdi_amini added a comment.
>
> In https://reviews.llvm.org/D21405#501428, @chandlerc wrote:
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>> I would be much more in favor of a design which instead of changing the pipeline to optimize differently (and thus having PGO vs. normal divergence) either:
>>
>> - Teaches the instrumentation pass to do the necessary (possibly interprocedural) analysis to instrument only in places it will be cheap, or
>> - Teach the existing pipeline to actually optimize and transform the instrumentation code to remove the overhead as necessary.
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>
> I totally agree that this would be much better,

See my reply -- I don't agree this is better.

> however there is something that was mentioned that I don't know how to address: the counters can get actually more precise due to the split context after inlining.

yes, this is the added benefit post cleanup just won't get.

David
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> Repository:
>   rL LLVM
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> https://reviews.llvm.org/D21405
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