[PATCH util-macros 1/2] Don't disable strict aliasing (-fno-strict-aliasing) globally
Gaetan Nadon
memsize at videotron.ca
Mon Nov 1 12:59:08 PDT 2010
On Mon, 2010-11-01 at 12:17 -0700, Jeremy Huddleston wrote:
> 1) It is *NOT* a warning flag. Using CWARNFLAGS should *only* enable
> warnings, not change the resulting assembly.
>
> 2) It was never intended to be in all of the modules. It landed there
> by accident when the code was copy/pasted from one configure.ac to
> another and then into util-macros.
>
> 3) Performance gains are not in consideration here.
>
I totally agree, but it does not justify simply removing the offending
flag as if it had never existed. It does have an impact on the binaries,
some modules need it, other don't, but we don't know which ones for
sure. That's my understanding, I could be wrong.
I have made a concrete proposal:
1. It preserves backward compatibility so previous versions are
unaffected when configured with the latest util-macros
2. It provides a low risk approach which I believe will be
supported by reviewers.
3. It gets you where you want to be, but perhaps not in "one go"
I'd like to hear how this proposal will not provide the end result you
are looking for. There must be a misunderstand somewhere, so we have to
keep working hard to find it.
===============================================================================
This is what I had found at the time:
Modules which had CWARNFLAGS added a year ago *and* did not have -fno-strict-aliasing option prior to that:
font= "util"
app= "appres bdftopcf beforelight bitmap editres fonttosfnt fslsfonts fstobdf iceauth \
ico listres luit mkcomposecache mkfontscale oclock rendercheck rgb rstart sessreg setxkbmap \
showfont smproxy viewres x11perf xauth xbacklight xbiff xcalc xclipboard xclock xcmsdb xconsole \
xcursorgen xdbedizzy xdm xdpyinfo xdriinfo xedit xev xeyes xf86dga xfd xfontsel xfs xfsinfo \
xgamma xgc xhost xinit xkbcomp xkbevd xkbprint xkbutils xkill xload xlogo xlsatoms xlsclients \
xlsfonts xmag xman xmessage xmh xmodmap xmore xprop xrandr xrdb xrefresh xscope xset xsetmode \
xsetpointer xsetroot xsm xstdcmap xvidtune xvinfo xwd xwininfo xwud"
lib=" libAppleWM libdmx libfontenc libFS libpciaccess libWindowsWM \
libXaw libXcomposite libXcursor libXdamage libXdmcp libXext \
libXfixes libXi libXinerama libxkbfile libXmu libXrandr \
libXrender libXScrnSaver libXt libXtst libXv libXvMC \
libXxf86dga"
driver="xf86-input-acecad xf86-input-aiptek xf86-input-evdev \
xf86-input-joystick xf86-input-keyboard xf86-input-mouse \
xf86-input-wacom xf86-video-cirrus xf86-video-mach64 \
xf86-video-qxl xf86-video-siliconmotion"
Modules which never had -fno-strict-aliasing nor any warning flags of any kind and still don't today:
app="mkfontdir scripts twm xditview xinput"
lib="libXxf86vm"
driver="xf86-input-synaptics xf86-input-vmmouse \
xf86-input-void xf86-video-apm xf86-video-ark \
xf86-video-ast xf86-video-ati xf86-video-chips \
xf86-video-dummy xf86-video-fbdev\
xf86-video-glint xf86-video-i128 xf86-video-i740 \
xf86-video-mga xf86-video-neomagic xf86-video-newport \
xf86-video-nv xf86-video-r128 \
xf86-video-rendition xf86-video-s3 xf86-video-s3virge \
xf86-video-savage xf86-video-sis xf86-video-sisusb \
xf86-video-suncg14 xf86-video-suncg3 xf86-video-suncg6 \
xf86-video-sunffb xf86-video-sunleo xf86-video-suntcx \
xf86-video-tdfx xf86-video-tga xf86-video-trident \
xf86-video-tseng xf86-video-v4l xf86-video-vesa \
xf86-video-vmware xf86-video-voodoo xf86-video-wsfb \
xf86-video-xgi xf86-video-xgixp "
Modules which had -fno-strict-aliasing for a long time (prior to CWARNFLAGS era)
lib="libICE libSM libX11 libXau libXfont libXft libXpm libXres"
driver="xf86-video-intel xf86-video-geode xf86-video-radeonhd"
xserver
========================================================================
Gaetan
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