[llvm-dev] llvm (the middle-end) is getting slower, December edition

Davide Italiano via llvm-dev
2016-12-18T19:45:50Z

On Sun, Dec 18, 2016 at 11:10 AM, Philip Reames
<listmail at philipreames.com> wrote:
> On 12/17/2016 01:35 PM, Davide Italiano via llvm-dev wrote:
>>
[...]
>
> I'd really like to see a profile which broke down the time spent in
Value
> Propagation and LVI.  As the person who has touched both most recently, I
am
> probably the responsible party.  At the same time, there are a number of
> known fixes we can apply depending on the way this particular compile time
> problem exhibits.  I'm happy to take a look at this particular issue if
you
> can given me enough information to analyze it.
>

I'll try to reduce the testcase and do some profiling on it, then come
back to you.
Something to keep in mind, please note I'm not pointing fingers. The
main motivation behind this e-mail is showing up that multiple passes
in the compiler seem to have regressed on large testcases. Many people
don't notice because they are (un)lucky enough to not run with LTO.
There are probably/maybe other regressions uncovered by my
non-exahustive analysis. I wasn't particularly pleased after a fair
amount of time working on GVN to clean up technical-debt to realize
that the compiler got slower in other areas.

--
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare