[Mesa-dev] [PATCH V2] mesa: use build flag to ensure stack is realigned on x86

[Ian Romanick]

On 12/08/2014 01:56 PM, Matt Turner wrote:
> On Mon, Dec 8, 2014 at 1:54 PM, Ian Romanick <idr at freedesktop.org> wrote:
>>> diff --git a/configure.ac b/configure.ac
>>> index b0df1bb..7dc435a 100644
>>> --- a/configure.ac
>>> +++ b/configure.ac
>>> @@ -253,8 +253,9 @@ AC_SUBST([VISIBILITY_CXXFLAGS])
>>>  dnl
>>>  dnl Optional flags, check for compiler support
>>>  dnl
>>> +SSE41_CFLAGS="-msse4.1"
>>>  save_CFLAGS="$CFLAGS"
>>> -CFLAGS="-msse4.1 $CFLAGS"
>>> +CFLAGS="$SSE41_CFLAGS $CFLAGS"
>>>  AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
>>>  #include <smmintrin.h>
>>>  int main () {
>>> @@ -474,6 +475,12 @@ fi
>>>  dnl
>>>  dnl Arch/platform-specific settings
>>>  dnl
>>> +case "$target_cpu" in
>>> +    i?86)
>>> +        SSE41_CFLAGS="$SSE41_CFLAGS -mstackrealign"
>>> +;;
>>> +esac
>>
>> Should we only add -mstackrealign if SSE41_CFLAGS is not empty?
> 
> It looks like it's unconditionally set.

Right... I'm asking if we should conditionally add it instead.  Is there
any harm in doing -mstackrealign when it's not needed?