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

Davide Italiano via llvm-dev
2016-12-18T02:32:54Z

On Sat, Dec 17, 2016 at 1:35 PM, Davide Italiano <davide at freebsd.org>
wrote:
[...]

> I don't have an infrastructure to measure the runtime performance
> benefits/regression of clang, but I have for `game7`.
> I wasn't able to notice any fundamental speedup (at least, not
> something that justifies a 2x build-time).
>

Just to provide numbers (using Sean's Mathematica template, thanks),
here's a plot of the CDF of the frames in a particular level/scene.
The curves pretty much match, and the picture in the middle shows a
relative difference of 0.4% between Jun and Dec (which could be very
possibly be in the noise).
On the same scene, the difference between -O3 and -flto is 12%, FWIW.
So it seems that at least for this particular case all the compile
time didn't buy any runtime improvement.

--
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare
-------------- next part --------------
A non-text attachment was scrubbed...
Name: flto_regression.png
Type: image/png
Size: 131534 bytes
Desc: not available
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20161217/12c8a067/attachment-0001.png>