-fno-strict-aliasing in CWARNFLAGS?
Jeremy Huddleston
jeremyhu at apple.com
Tue Feb 2 14:00:15 PST 2010
On Feb 2, 2010, at 13:18, Gaetan Nadon wrote:
> I have not seen any compelling reasons to turn off this optimization.
> Maybe 10 years ago when it was first introduced. I have seen reports of
> large number of warnings, but from older gcc versions. As it is today,
> we are losing some optimization that could be beneficial.
>
> This option has been there for so long (most likely copied along), I
> doubt you will will get a clear answer for each of the 240 xorg modules.
> It would take a few modules to try it out first.
I see it in libX11 has historically used -fno-strict-aliasing:
http://cgit.freedesktop.org/xorg/lib/libX11/commit/?id=db7c6fdeeaef9475458498e4cf09d6b1329e9aa3
but adding XORG_CWARNFLAGS to XORG_DEFAULT_OPTIONS has caused this to change for other modules.
Looking at historic versions of modules, I see it present in:
libICE
libSM
libX11
libXau
libXfont
libXft
libXpm
libXres
xorg-server
of course most of these seem to have just copied the entire GCC_WARNINGS block and probably didn't actually need -fno-strict-aliasing
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