cmake: try baseline optimization feature check without extra flags first

cmake/OpenCVCompilerOptimizations.cmake

@@ -171,7 +171,7 @@ elseif(" ${CMAKE_CXX_FLAGS} " MATCHES " -march=native | -xHost | /QxHost ")
 endif()
 
 if(X86 OR X86_64)
-  ocv_update(CPU_KNOWN_OPTIMIZATIONS "SSE;SSE2;SSE3;SSSE3;SSE4_1;POPCNT;SSE4_2;FP16;FMA3;AVX;AVX2;AVX_512F;AVX512_COMMON;AVX512_KNL;AVX512_KNM;AVX512_SKX;AVX512_CNL;AVX512_CLX;AVX512_ICL")
+  ocv_update(CPU_KNOWN_OPTIMIZATIONS "SSE;SSE2;SSE3;SSSE3;SSE4_1;POPCNT;SSE4_2;AVX;FP16;AVX2;FMA3;AVX_512F;AVX512_COMMON;AVX512_KNL;AVX512_KNM;AVX512_SKX;AVX512_CNL;AVX512_CLX;AVX512_ICL")
 
   ocv_update(CPU_AVX512_COMMON_GROUP "AVX_512F;AVX_512CD")
   ocv_update(CPU_AVX512_KNL_GROUP "AVX512_COMMON;AVX512_KNL_EXTRA")
@@ -445,7 +445,7 @@ macro(ocv_check_compiler_optimization OPT)
       set(_varname "")
       if(CPU_${OPT}_TEST_FILE)
         set(__available 0)
-        if(CPU_BASELINE_DETECT)
+        if(__is_from_baseline OR CPU_BASELINE_DETECT)
           set(_varname "HAVE_CPU_${OPT}_SUPPORT")
           ocv_check_compiler_flag(CXX "${CPU_BASELINE_FLAGS}" "${_varname}" "${CPU_${OPT}_TEST_FILE}")
           if(${_varname})

cmake/checks/cpu_sse2.cpp

@@ -1,2 +1,16 @@
 #include <emmintrin.h>
-int main() { return 0; }
+
+inline __m128i _v128_comgt_epu32(const __m128i& a, const __m128i& b)
+{
+    const __m128i delta = _mm_set1_epi32((int)0x80000000);
+    return _mm_cmpgt_epi32(_mm_xor_si128(a, delta), _mm_xor_si128(b, delta));
+}
+
+int main()
+{
+    __m128i a, b, c;
+    a = _mm_set1_epi32(0x00000000);
+    b = _mm_set1_epi32(0x0000ffff);
+    c = _v128_comgt_epu32(a, b);
+    return 0;
+}