gcc vs. clang builds of 7.8.3 on OS X

[Johan Tibell]

I thought clang was slower than gcc because clang doesn't support thread
local variables (in some form we need) and therefore GC performance
suffered a lot on clang.


On Sat, Jul 12, 2014 at 9:27 PM, Mark Lentczner <mark.lentczner at gmail.com>
wrote:

> In building the OS X bindist for 7.8.3, I had to choose which of several
> ways to build it. In particular, I could build it with a newere Xcode,
> which uses clang, or an older Xcode which uses gcc. I decided to nofib
> benchmark the variations and see before I released. Here is what I found...
>
> I compared two candidate builds:
>
>    - x86_64 architecture
>    - targeted at OS X 10.7 and later
>    - one built with Xcode 5.1 on 10.9, which uses clang
>    - one built with Xcode 4.5 on 10.8, which uses gcc
>
> I installed both bindists, side-by-side on the same machine: a 10.9
> machine, with Xcode 5.1, which uses clang. The machine is a MacMini, 2.5GHz
> Intel Core i5 (dual core, reports as 4 cpus).
>
>  Summary:
>
>    - clang build was always faster
>       - non-threaded was -3.2% run-time
>       - threaded was -7.3% run-time
>    - clang's improvement in GC run-time was better than -10%
>    - clang builds were significantly bigger
>
> You can find the details here:
>
>    - analysis-Silver-10.9-gcc-vs-clang.html
>    <http://www.ozonehouse.com/mark/platform/analysis-Silver-10.9-gcc-vs-clang.html>
>    - analysis-Silver-10.9-gcc-vs-clang-threaded.html
>    <http://www.ozonehouse.com/mark/platform/analysis-Silver-10.9-gcc-vs-clang-threaded.html>
>
> The only concern is that the binary sizes were significantly bigger: +230%
> - I haven't investigated more, but I'm wondering if nofib doesn't strip the
> binaries before measuring, and perhaps clang's debugging info is much
> greater?
>
> Next up... we are evaluating a bindist built with the HPC Mac OS X gcc
> compiler (based on gcc 4.9)... and preliminary results are looking even
> better! Stay tuned...
>
> - Mark
>
>
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at haskell.org
> http://www.haskell.org/mailman/listinfo/ghc-devs
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/ghc-devs/attachments/20140712/5e74fce2/attachment.html>