On Fri, Nov 04, 2016 at 01:33:36PM -0400, Lennart Sorensen wrote:
> And of course I made a typo while copying things into the patch.
>
> Doing another build test of it now.
>
> --- vlc-2.2.4.orig/configure.ac 2016-05-31 12:11:07.000000000 -0400
> +++ vlc-2.2.4/configure.ac 2016-11-04 12:22:02.543265439 -0400
> @@ -1422,25 +1422,24 @@
> VLC_SAVE_FLAGS
> AC_CACHE_CHECK([if \$CC groks AltiVec C extensions],
> [ac_cv_c_altivec], [
> - CFLAGS="${CFLAGS} -maltivec"
> + CFLAGS="${CFLAGS} -maltivec -fno-tree-vectorize"
> AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
> [#include <altivec.h>]], [
> [vec_ld(0, (unsigned char *)0);]])], [
> - ac_cv_c_altivec="-maltivec"
> + ac_cv_c_altivec="-maltivec -fno-tree-vectorize"
> ], [
> ac_cv_c_altivec="no"
> ])
> ])
> - VLC_RESTORE_FLAGS
> AS_IF([test "${ac_cv_c_altivec}" != "no"], [
> CPPFLAGS="${CPPFLAGS} ${ac_cv_c_altivec}"
> AC_DEFINE(CAN_COMPILE_C_ALTIVEC, 1, [Define to 1 if C AltiVec extensions
> are available.])
> - VLC_ADD_CFLAGS([libvlccore],[${ac_cv_c_altivec}])
> - ALTIVEC_CFLAGS="$ALTIVEC_FLAGS ${ac_cv_c_altivec} ${ac_cv_c_altivec_abi}"
> - VLC_ADD_CFLAGS([deinterlace],[${ac_cv_c_altivec} ${ac_cv_c_altivec_abi}])
> + ALTIVEC_CFLAGS="$ALTIVEC_CFLAGS ${ac_cv_c_altivec}
> ${ac_cv_c_altivec_abi}"
> + VLC_ADD_CFLAGS([libdeinterlace],[${ac_cv_c_altivec}
> ${ac_cv_c_altivec_abi}])
> have_altivec="yes"
> ])
> AC_CHECK_HEADERS(altivec.h)
> + VLC_RESTORE_FLAGS
>
> VLC_SAVE_FLAGS
> LDFLAGS="${LDFLAGS} -Wl,-framework,vecLib"
That did not quite work, so I had to try the slightly more complicated
patch.
This patch works:
--- vlc-2.2.4.orig/configure.ac 2016-05-31 12:11:07.000000000 -0400
+++ vlc-2.2.4/configure.ac 2016-11-08 10:28:54.763640362 -0500
@@ -1422,25 +1422,23 @@
VLC_SAVE_FLAGS
AC_CACHE_CHECK([if \$CC groks AltiVec C extensions],
[ac_cv_c_altivec], [
- CFLAGS="${CFLAGS} -maltivec"
+ CFLAGS="${CFLAGS} -maltivec -fno-tree-vectorize"
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
[#include <altivec.h>]], [
[vec_ld(0, (unsigned char *)0);]])], [
- ac_cv_c_altivec="-maltivec"
+ ac_cv_c_altivec="-maltivec -fno-tree-vectorize"
], [
ac_cv_c_altivec="no"
])
])
- VLC_RESTORE_FLAGS
AS_IF([test "${ac_cv_c_altivec}" != "no"], [
CPPFLAGS="${CPPFLAGS} ${ac_cv_c_altivec}"
AC_DEFINE(CAN_COMPILE_C_ALTIVEC, 1, [Define to 1 if C AltiVec extensions
are available.])
- VLC_ADD_CFLAGS([libvlccore],[${ac_cv_c_altivec}])
- ALTIVEC_CFLAGS="$ALTIVEC_FLAGS ${ac_cv_c_altivec} ${ac_cv_c_altivec_abi}"
- VLC_ADD_CFLAGS([deinterlace],[${ac_cv_c_altivec} ${ac_cv_c_altivec_abi}])
+ ALTIVEC_CFLAGS="$ALTIVEC_CFLAGS ${ac_cv_c_altivec} ${ac_cv_c_altivec_abi}"
have_altivec="yes"
])
AC_CHECK_HEADERS(altivec.h)
+ VLC_RESTORE_FLAGS
VLC_SAVE_FLAGS
LDFLAGS="${LDFLAGS} -Wl,-framework,vecLib"
--- vlc-2.2.4.orig/modules/video_filter/Modules.am 2015-02-02
14:42:29.000000000 -0500
+++ vlc-2.2.4/modules/video_filter/Modules.am 2016-11-08 10:28:31.391639060
-0500
@@ -29,6 +29,7 @@
libdeinterlace_plugin_la_SOURCES += deinterlace/merge_arm.S
libdeinterlace_plugin_la_CFLAGS += -DCAN_COMPILE_ARM
endif
+libdeinterlace_plugin_la_CFLAGS += $(ALTIVEC_CFLAGS)
video_filter_LTLIBRARIES += libdeinterlace_plugin.la
libdynamicoverlay_plugin_la_SOURCES = \
With this patch, only functions inside a CPU feature check for altivec
support has any vector instructions.
And I realized the reason it was broken is that when using -maltivec and
-O4 (which vlc uses), you get -ftree-vectorize automatically enabled
which means gcc starts to automatically generate vector instructions
all over the place, which is not desired in this case. It rather defeats
the purpose of having a cpu feature check after all.
--
Len Sorensen
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