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.
v2: Clean the #includes. Suggested by Ilia, Matt & Siavash.
Cc: Siavash Eliasi <siavashser...@gmail.com>
Cc: Matt Turner <matts...@gmail.com>
Tested-by: David Heidelberg <da...@ixit.cz>
Tested-by: Siavash Eliasi <siavashser...@gmail.com>
Reviewed-by: Matt Turner <matts...@gmail.com>
Signed-off-by: Emil Velikov <emil.l.veli...@gmail.com>
---
configure.ac | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/configure.ac b/configure.ac
index 91e111b..8aa070d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -252,7 +252,16 @@ 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 $CFLAGS"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <smmintrin.h>
+int main () {
+ __m128i a = _mm_set1_epi32 (0), b = _mm_set1_epi32 (0), c;
+ c = _mm_max_epu32(a, b);
+ return 0;
+}]])], SSE41_SUPPORTED=1)
+CFLAGS="$save_CFLAGS"
if test "x$SSE41_SUPPORTED" = x1; then
DEFINES="$DEFINES -DUSE_SSE41"
fi
--
2.1.3
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