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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - GCC memory starvation caused by flatten attribute with LTO"
href="https://bugs.freedesktop.org/show_bug.cgi?id=77580#c8">Comment # 8</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - GCC memory starvation caused by flatten attribute with LTO"
href="https://bugs.freedesktop.org/show_bug.cgi?id=77580">bug 77580</a>
from <span class="vcard"><a class="email" href="mailto:doctorwhoguy@gmail.com" title="Patrick McMunn <doctorwhoguy@gmail.com>"> <span class="fn">Patrick McMunn</span></a>
</span></b>
<pre>(In reply to main.haarp from <a href="show_bug.cgi?id=77580#c6">comment #6</a>)
<span class="quote">> (In reply to Patrick McMunn from <a href="show_bug.cgi?id=77580#c5">comment #5</a>)
> > Created <span class=""><a href="attachment.cgi?id=125089" name="attach_125089" title="Patch to allow LTO optmization of xf86-video-intel">attachment 125089</a> <a href="attachment.cgi?id=125089&action=edit" title="Patch to allow LTO optmization of xf86-video-intel">[details]</a></span> <a href='page.cgi?id=splinter.html&bug=77580&attachment=125089'>[review]</a> [review] [review]
> > Patch to allow LTO optmization of xf86-video-intel
> >
>
> Nice work! This allows building with LTO on gcc-4.9. gcc-5.3.0 however fails
> to build it, throwing a bunch of these around:
>
> /usr/include/bits/string3.h:50:1: error: inlining failed in call to
> always_inline ‘memcpy’: target specific option mismatch
>
>
> Also, unlike your P4, I cannot detect any measurable performance
> improvements (Intel Sandy Bridge). Unfortunate.
>
> All tests done with xf86-video-intel from today's git.</span >
Hmm... You shouldn't be getting that error. That's the error I was getting
before I removed the "always_inline" definitions. If the patch worked properly
for you, the compiler shouldn't be running into a "always_inline" directive.
I don't think I actually tested it with 5.3.0. I only verified that it builds
with 4.9.3, and all my tests with performance involved 6.1.0.
I did do numerous tests involving various compiler flags such as -O2, -O3,
graphite compiler flags, etc, and I found that I actually got reduced
performance with -O3 compared to -O2, and I got reduced performance with using
additional optimizations like graphite. The biggest improvement I got was with
simple -O2 and a proper -march setting.</pre>
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