Should the CPU_FLAGS suggested on this page include "lzcnt"? As listed here  lzcnt was adopted in Intel Haswell.
Or is there a special reason that LZCNT was not listed on this page?
LZCNT is indeed listed on the CPU_FLAGS page.
LZCNT is not listed within the flags of the XEON E5-2660 at server, that i rent
root # cat /proc/cpuinfo | head -n5 processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 63 model name : Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz root # cat /proc/cpuinfo | grep LZCNT | wc -l 0
I'm not sure if that information is absolutely reliable, since this is a QEMU based VPS and i don't know if the guest has full access to all the host CPU instructions. When i asked the provider about that, he answered "You have access to all instructions except for hyperthreading".