[PATCH video-intel] config: add -fno-strict-aliasing now that it is out of $CWARNFLAGS

[Dan Nicholson]

On Mon, Feb 22, 2010 at 6:44 AM, Gaetan Nadon <memsize at videotron.ca> wrote:
> On Mon, 2010-02-22 at 06:20 -0800, Dan Nicholson wrote:
>
> On Mon, Feb 22, 2010 at 5:36 AM, Gaetan Nadon <memsize at videotron.ca> wrote:
>> This patch will ensure the modules continues to suppress the
>> optimization, based on strict aliasing rules, after the option
>> is removed from $CWARNFLAGS. There is no change in the object
>> code produced.
>>
>> There is no attempt to determine if the module should or should not
>> have such an optimization. A new warning (-Wstrict-aliasing=2)
>> has been added to the XORG_CWARNFLAGS macro to help  find code
>> that may interfere with optimization.
>> ---
>>  src/Makefile.am      |   11 +++++++++--
>>  src/xvmc/Makefile.am |   12 ++++++++++--
>>  uxa/Makefile.am      |    6 +++++-
>>  3 files changed, 24 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/Makefile.am b/src/Makefile.am
>> index b4bafbd..54c86fa 100644
>> --- a/src/Makefile.am
>> +++ b/src/Makefile.am
>> @@ -26,8 +26,15 @@ SUBDIRS = xvmc render_program
>>  # _ladir passes a dummy rpath to libtool so the thing will actually link
>>  # TODO: -nostdlib/-Bstatic/-lgcc platform magic, not installing the .a,
>> etc.
>>
>> -AM_CFLAGS = @CWARNFLAGS@ @XORG_CFLAGS@ @DRM_CFLAGS@ @DRI_CFLAGS@ \
>> -       @PCIACCESS_CFLAGS@ -I$(top_srcdir)/uxa
>> -I$(top_srcdir)/src/render_program
>> +AM_CFLAGS = \
>> +       $(CWARNFLAGS) \
>> +       -fno-strict-aliasing \
>> +       $(XORG_CFLAGS) \
>> +       $(DRM_CFLAGS) \
>> +       $(DRI_CFLAGS) \
>> +       $(PCIACCESS_CFLAGS) \
>> +       -I$(top_srcdir)/uxa \
>> +       -I$(top_srcdir)/src/render_program
>
> I think you need to test for gcc in configure like CWARNFLAGS did
> instead of shoving it into the Makefile. This will just make other
> compilers bomb on the unrecognized option.
>
> I checked the case statement but I totally missed this line:
> if  test "x$GCC" = xyes ; then
>
> I have to find an elegant way of doing it.

configure.ac:
ALIASING_CFLAGS=
if test "x$GCC" = xyes; then
    ALIASING_CFLAGS=-fno-strict-aliasing
fi
AC_SUBST([ALIASING_CFLAGS])

Makefile.am:
AM_CFLAGS = \
    $(CWARNFLAGS) \
    $(ALIASING_CFLAGS) \
    ...

--
Dan