On 15/11/14 18:21, Matt Turner wrote:
> On Sat, Nov 15, 2014 at 9:04 AM, Emil Velikov <emil.l.veli...@gmail.com>
> wrote:
>> So when checking/building sse code we have three possibilities:
>> 1 Old compiler, throws an error when using -msse*
>> 2 New compiler, user disables sse* (-mno-sse*)
>> 3 New compiler, user doesn't disable sse
>>
>> The original code, added code for #1 but not #2. Later on we patched
>> around the lack of handling #2 by wrapping the code in __SSE4_1__.
>> Yet it lead to a missing/undefined symbol in case of #1 or #2, which
>> might cause an issue for #2 when using the i965 driver.
>>
>> A bit later we "fixed" the undefined symbol by using #1, rather than
>> updating it to handle #2. With this commit we set things straight :)
>>
>> To top it all up, conventions state that in case of conflicting
>> (-enable-foo -disable-foo) options, the latter one takes precedence.
>> Thus we need to make sure to prepend -msse4.1 to CFLAGS in our test.
>>
>> Cc: Siavash Eliasi <siavashser...@gmail.com>
>> Cc: Matt Turner <matts...@gmail.com>
>> Signed-off-by: Emil Velikov <emil.l.veli...@gmail.com>
>> ---
>>
>> Man this thing is _very_ messy.
>> Matt from the last hunk it seems that pixman might need fixing. Should
>> be bother with that, or let people have fun when they hit it :P
>
> I don't know what you mean, specifically.
>
configure.ac (in pixman) does:
CFLAGS="$CFLAGS -msse4.1"
AC_COMPILE_IFELSE(...)
Which overwrites the cflags set by the user. I.e. it will not honour
-mno-sse4.1. At build time things will "blow up", as CFLAGS, are placed
after AM_CFLAGS. I.e. in the makefiles the user knows best while in
configure it's the opposite.
>> -Emil
>>
>> configure.ac | 14 +++++++++++++-
>> 1 file changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/configure.ac b/configure.ac
>> index 91e111b..9d1835e 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -252,7 +252,19 @@ AC_SUBST([VISIBILITY_CXXFLAGS])
>> dnl
>> dnl Optional flags, check for compiler support
>> dnl
>> -AX_CHECK_COMPILE_FLAG([-msse4.1], [SSE41_SUPPORTED=1], [SSE41_SUPPORTED=0])
>> +save_CFLAGS="$CFLAGS"
>> +CFLAGS="-msse4.1 $CFLAGS"
>> +AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
>> +#include <mmintrin.h>
>> +#include <xmmintrin.h>
>> +#include <emmintrin.h>
>> +#include <smmintrin.h>
>
> I think all you need to include is smmintrin.h.
>
True, blame pixman for the rest :P
-Emil
>> +int main () {
>> + __m128i a = _mm_set1_epi32 (0), b = _mm_set1_epi32 (0), c;
>> + c = _mm_max_epu32(a, b);
>> + return 0;
>> +}]])], SSE41_SUPPORTED=1)
>> +CFLAGS="$save_CFLAGS"
>> if test "x$SSE41_SUPPORTED" = x1; then
>> DEFINES="$DEFINES -DUSE_SSE41"
>> fi
>> --
>> 2.1.3
>>
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