fixed test for avx2 in cmake

cmake/modules/FindSSE.cmake

@@ -40,10 +40,20 @@ if (ENABLE_SSE)
             set(CMAKE_REQUIRED_FLAGS "-mavx")
             check_c_source_runs("
             #include <immintrin.h>
-
             int main()
             {
-            __m256i a = _mm256_setzero_si256();
+              __m256 a, b, c;
+              const float src[8] = { 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f, 7.0f, 8.0f };
+              float dst[8];
+              a = _mm256_loadu_ps( src );
+              b = _mm256_loadu_ps( src );
+              c = _mm256_add_ps( a, b );
+              _mm256_storeu_ps( dst, c );
+              for( int i = 0; i < 8; i++ ){
+                if( ( src[i] + src[i] ) != dst[i] ){
+                  return -1;
+                }
+              }
               return 0;
             }"
             HAVE_AVX)
@@ -63,11 +73,20 @@ if (ENABLE_SSE)
           set(CMAKE_REQUIRED_FLAGS "-mavx2")
           check_c_source_runs("
           #include <immintrin.h>
-
           int main()
           {
-            __m256i a = _mm256_setzero_si256();
-            __m256i b = _mm256_abs_epi16(a);
+            __m256i a, b, c;
+            const int src[8] = { 1, 2, 3, 4, 5, 6, 7, 8 };
+            int dst[8];
+            a =  _mm256_loadu_si256( (__m256i*)src );
+            b =  _mm256_loadu_si256( (__m256i*)src );
+            c = _mm256_add_epi32( a, b );
+            _mm256_storeu_si256( (__m256i*)dst, c );
+            for( int i = 0; i < 8; i++ ){
+              if( ( src[i] + src[i] ) != dst[i] ){
+                return -1;
+              }
+            }
             return 0;
           }"
           HAVE_AVX2)