[Pixman] [PATCH] SIMD: Try without any CFLAGS before forcing -mcpu=

Loïc Minier lool at dooz.org
Sun Mar 14 10:25:10 PDT 2010

On Wed, Mar 10, 2010, Siarhei Siamashka wrote:
> I would prefer a bit more descriptive comment (with the details copied
> from that launchpad page).

 I see you pushed this now; thanks!  Yeah, it's not obvious why one
 needs to try with the toolchain defaults first.  I'm attaching a patch
 to update the comments.

> Patch looks mostly OK to me and improves arm simd support a bit. It still
> fails with CFLAGS="-O2 -mthumb" (and toolchain configured to compile for armv4
> by default)

 This is unfortunate, but even if I could change the configure test to
 succeed here, the actual build would place CFLAGS last
 (user-overrides); it's perhaps best if the build fails at this point.
 The other option would be to munge the user-specific CFLAGS in
 configure, but I'm not sure I'm confortable with that, plus these can
 be overriden during the build as well.

 So I guess people forcing Thumb in CFLAGS with a default of an old CPU
 will have a bit more pain here.  I think it also fails if you force
 -mcpu=oldcpu in CFLAGS.

> But that was also happening earlier, so it is not a regression.


> In my opinion the best solution overall would be to move all the assembly
> optimizations into separate .S files also for legacy ARM processors and
> get rid of these compiler option hacks. I think that bringing support for
> legacy ARM processors into a better shape is quite realistic even for 0.18.0
> stable release, which is due to be released this month. But it can only happen
> if enough people are interested in this, and more importantly, are ready to
> actively participate in testing.

 I think this should be kept as an open bug against pixman that the
 inline asm()s would better be written as separate .S files (thanks for
 the idea).

Loïc Minier

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