[PATCH] D156715: [CSSPGO] Fix issues with post-link function checksum check

Thu Aug 24 09:51:06 PDT 2023

wenlei added a comment.

In D156715#4562026 <https://reviews.llvm.org/D156715#4562026>, @wlei wrote:

> In D156715#4561996 <https://reviews.llvm.org/D156715#4561996>, @hoy wrote:
>
>> In D156715#4558585 <https://reviews.llvm.org/D156715#4558585>, @wlei wrote:
>>
>>> In D156715#4550679 <https://reviews.llvm.org/D156715#4550679>, @hoy wrote:
>>>
>>>> How does perf look like after disabling annotating imported functions?
>>>
>>> So far from what I tested, there is no perf change if only disabling annotating imported functions. Note that this also disables the profile matching for the  imported functions, so it could cause perf issue, depending on if the imported functions is stale.
>>
>> Discussed offline. This effect of this change is potentially two-fold :
>>
>> 1. positive impact of disabling unnecessary matching for non-stale profiles
>> 2. negative impact of disabling matching for to-be-inlined imported functions with a stale profile.
>>
>> Currently they are not tested separately. With a solution of #1, allowing matching for #2  might be a win. Suggesting to hold on this change until we have a good solution for #1.
>>
>> Thoughts?
>
> Yeah, as we discussed offline, sounds good to hold on this, will work on a proper solution for #1 or #2 (alternatively we can pass the metadata or a mismatch flag for the imported function)

Sounds reasonable. Hope we can make progress on #1.

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