[LLVMdev] Recent compile time performance regressions

[Yi Kong]

On 1 August 2014 21:33, Chandler Carruth <chandlerc at google.com> wrote:
>> Note, this patch is actually the smaller culprit, around 209801 there is
>> another performance regression, but I have no idea if/where this is coming
>> from or if this for some reason is a false positive.
>
>
> I'm having to question the results on this bot. The range of commits which
> cause the larger compile time regression is 209797 - 209799... But those
> commits are totally innocuous. The closest to a something that could go
> poorly would be r209798, but that commit doesn't seem plausible for a huge
> slowdown.
>
> I wonder if there is something weird going on with the bot...

209797-209799 regression is false positive, due to reverting perf back
to original timeit tool.(r209797)

However the multithreading stuff is real regression and I'm able to
reproduce same regression on my local build bots.

-Yi