fixed test for avx2 in cmake

cmake/modules/FindSSE.cmake

@@ -40,11 +40,21 @@ if (ENABLE_SSE)
             set(CMAKE_REQUIRED_FLAGS "-mavx")
             check_c_source_runs("
             #include <immintrin.h>
-
             int main()
             {
-            __m256i a = _mm256_setzero_si256();
-            return 0;
+              __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)
         endif()
@@ -54,29 +64,38 @@ if (ENABLE_SSE)
         endif()
     endif()
     
-     if (ENABLE_AVX2)
+    if (ENABLE_AVX2)
 
-        #
-        # Check compiler for AVX intrinsics
-        #
-        if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG )
-            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);
+      #
+      # Check compiler for AVX intrinsics
+      #
+      if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG )
+          set(CMAKE_REQUIRED_FLAGS "-mavx2")
+          check_c_source_runs("
+          #include <immintrin.h>
+          int main()
+          {
+            __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)
-        endif()
+          }"
+          HAVE_AVX2)
+      endif()
 
-        if (HAVE_AVX2)
-            message(STATUS "AVX2 is enabled - target CPU must support it")
-        endif()
-    endif()
+      if (HAVE_AVX2)
+          message(STATUS "AVX2 is enabled - target CPU must support it")
+      endif()
+  endif()
 
 endif()