runtime check of CPU AVX capabilities

testAVX.cpp

#include <iostream>
#include <immintrin.h>

// Verify CPU capabilities:
bool bAVXok = false;
int cpuInfo[4] = { 0,0,0,0 };
__cpuid(cpuInfo, 0);
if (cpuInfo[0] != 0) {
	__cpuid(cpuInfo, 1);
	if (cpuInfo[2] & (1 << 28)) {
		bAVXok = true; // Note: this test only confirms CPU AVX capability, and does not check OS capability.
		// to-do: check for AVX2 ...
	}
}
if (bAVXok)
	std::cout << "CPU supports AVX (ok)";
else {
	std::cout << "Your CPU doesn't support AVX - please try a non-AVX build on this machine" << std::endl;
	exit(EXIT_FAILURE);
}