[PATCH] D122930: [Propeller] Promote functions with propeller profiles to .text.hot.

Fri May 13 13:33:10 PDT 2022

rahmanl added a comment.

In D122930#3509769 <https://reviews.llvm.org/D122930#3509769>, @shenhan wrote:

> In D122930#3494676 <https://reviews.llvm.org/D122930#3494676>, @rahmanl wrote:
>
>> In D122930#3492643 <https://reviews.llvm.org/D122930#3492643>, @shenhan wrote:
>>
>>> This looks good to me.  One question, do we have a rough idea, what is the percentage of functions that pgo and propeller disagree about their hotness?
>>
>> Yes. For one example we have 
>> 31% of Propeller functions in .text.hot, 
>> 57% in .text
>> 11% in .text.unlikely
>
> Thanks.
>
>> One questions is whether the promotion should be hidden behind a flag or not.
>
> My thought is that this is a prerequisite for propeller inter-proc layout optimization, so if inter-proc layout optimization is on by default when -fbasic-block-sections=list=<...> is present, then this could also be on by default. On the other hand if we guard inter-proc layout optimization with a flag, then that flag could also cover this.

Thanks. To clarify, this is also needed for function ordering. I went ahead and introduced a flag for this. The feature would also work when `--profile-guided-section-prefix=false`.

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https://reviews.llvm.org/D122930