[PATCH] D25277: [test-suite] Run FP tests twice with -ffp-contract=off/on

[Sebastian Pop via llvm-commits]

On Fri, Oct 7, 2016 at 10:53 PM, Matthias Braun <matze at braunis.de> wrote:
>
>> On Oct 6, 2016, at 7:30 AM, Sebastian Pop via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>>
>>> I don't plan big changes in the near future except for an additionol plugin to collect the llvm statistics generated by the new -save-stats clang flag...
>>
>> I like this: I had also thought adding a test-suite mode to collect at
>> compile time the output of -mllvm -stats.
>> Please point me to your patches, keep me in the review loop, and let
>> me know how I can help ;-)
>
> I put a first version of this into the test-suite now (r283649). You can enable it with -DTEST_SUITE_COLLECT_STATS at cmake time (make sure your clang is new enough to understand -save-stats and has asserts enabled).
>

Thanks, I'll give it a try!

> Future Work:
> - We may want to add some filtering mechanism to not flood the output with too many values.

Collecting more data does not harm.

> - LLVM should put the pass timings into the stats as well. At least when we output the .json file.

Yes, that would be a good addition.

> - Figure out how expensive the stats are and either always compile them into clang or provide a release build configuration with stats enabled.

As far as I know, stats are pretty cheap to collect.
IMO it is not worth modifying the compiler to always collect stats.
Maybe we can add a cmake check to verify whether the compiler has stats.

Thanks,
Sebastian