Add AVX checks (#20)

Co-authored-by: mancini <mancini@astron.nl>

cmake/FindAVX.cmake

@@ -0,0 +1,42 @@
+include(CheckCXXSourceRuns)
+
+set(SUPPORTED_COMPILERS Clang;GNU;Intel;IntelLLVM)
+
+if(CMAKE_CXX_COMPILER_ID IN_LIST SUPPORTED_COMPILERS)
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
+    set(CMAKE_REQUIRED_FLAGS "-xHost") # ICC
+  elseif(CMAKE_CXX_COMPILER_ID STREQUAL "IntelLLVM")
+    set(CMAKE_REQUIRED_FLAGS "-march=native") # ICX
+  else()
+    set(CMAKE_REQUIRED_FLAGS "-march=native") # GCC/Clang
+  endif()
+else()
+  message(FATAL_ERROR "Unsupported compiler: ${CMAKE_CXX_COMPILER_ID}.")
+endif()
+
+# AVX check
+check_cxx_source_runs(
+  "
+#include <immintrin.h>
+int main() {
+    __m256 a = _mm256_setzero_ps(); // AVX
+    (void) a;
+    return 0;
+}
+"
+  HAVE_AVX)
+
+if(HAVE_AVX)
+  # AVX2 check
+  check_cxx_source_runs(
+    "
+#include <immintrin.h>
+int main() {
+    __m256i a = _mm256_set1_epi32(-1);
+    __m256i b = _mm256_abs_epi32(a); // AVX2
+    (void) b;
+    return 0;
+}
+"
+    HAVE_AVX2)
+endif()