Thanks! It had been so long since I’d submitted the patch that I’d forgotten on which machine I’d done the work and what I needed to do to get set up to modify it. I’m glad you found it easy to do for me.
> On Sep 18, 2017, at 9:54 AM, Siarhei Siamashka <siarhei.siamas...@gmail.com> > wrote: > > On Mon, 18 Sep 2017 07:24:49 -0700 > Rob Tsuk <r...@tsuk.com> wrote: > >>> On Sep 17, 2017, at 6:40 AM, Siarhei Siamashka >>> <siarhei.siamas...@gmail.com> wrote: >>> >>> On Mon, 7 Aug 2017 07:52:29 -0700 >>> Rob Tsuk <r...@tsuk.com <mailto:r...@tsuk.com>> wrote: >>> >>>> From 662b17d0d691b567a3343af3439f5fbefe989584 Mon Sep 17 00:00:00 2001 >>>> From: Rob Tsuk <robt...@google.com> >>>> Date: Mon, 7 Aug 2017 07:11:10 -0700 >>>> Subject: [PATCH 1/1] Fix test for GCC vector extensions >>>> >>>> The previous test was getting a false positive for >>>> clang version 4. >>>> --- >>>> configure.ac | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/configure.ac b/configure.ac >>>> index e833e45..cbebc82 100644 >>>> --- a/configure.ac >>>> +++ b/configure.ac >>>> @@ -1101,7 +1101,7 @@ support_for_gcc_vector_extensions=no >>>> AC_MSG_CHECKING(for GCC vector extensions) >>>> AC_LINK_IFELSE([AC_LANG_SOURCE([[ >>>> unsigned int __attribute__ ((vector_size(16))) e, a, b; >>>> -int main (void) { e = a - ((b << 27) + (b >> (32 - 27))) + 1; return >>>> e[0]; } >>>> +int main (void) { __builtin_shuffle(a,b);e = a - ((b << 27) + (b >> (32 - >>>> 27))) + 1; return e[0]; } >>>> ]])], support_for_gcc_vector_extensions=yes) >>>> >>>> if test x$support_for_gcc_vector_extensions = xyes; then >>> >>> Thanks, the patch looks mostly good. We indeed have to add >>> the use of __builtin_shuffle() to the configure check code >>> snippet because it is used by pixman and Clang implements >>> this functionality in a different and incompatible way. >>> >>> We did not see this problem with older versions of Clang >>> because it did not support the shift vector by scalar operation >>> in its vector extensions. >>> >>> Too bad that GCC and Clang parted their ways and we can't have >>> a single unified implementation. The whole reason to use GCC >>> vector extension was that we could avoid platform-dependent >>> intrinsics in this code. >>> >>> About the patch. It would be great to use the result of >>> __builtin_shuffle() in the intermediate calculations just in >>> case. See >>> >>> https://cgit.freedesktop.org/pixman/commit/?id=a566f627dbd6ea8f2cba70a446e62caaa2ecbd26 >>> >>> <https://cgit.freedesktop.org/pixman/commit/?id=a566f627dbd6ea8f2cba70a446e62caaa2ecbd26> >> >> Your proposed modification to my patch makes sense. I’m not certain when >> I”ll have time to perform it. > > It does not really require much time. I just did that for you: > https://lists.freedesktop.org/archives/pixman/2017-September/004680.html > > -- > Best regards, > Siarhei Siamashka _______________________________________________ Pixman mailing list Pixman@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/pixman
