Determine device architecture (ARM/ARM64/x86) with 'adb getprop' Using adb getprop, I've found a few values that I think are pertinent, but I don't have any idea what an ARM64 device's value would like, much less an x86 one. 

For my ARM device, the values are:

ro.product.cpu.abi       armeabi-v7a
ro.product.cpu.abi2      armeabi
ro.product.cpu.abilist32 armeabi-v7a,armeabi
ro.product.cpu.abilist64


I though armabi-v8a would mean ARM64, but Wikipedia says 


  most chips support 32-bit AArch32 for legacy applications


So, I'm wondering if an ARMv8 chip could possibly be loaded with 32-bit Android which would further complicate things

Is there any way I can determine my device architecture with adb?
I did some poking around in some custom ROMs for x86 devices, and along with the info provided by @Izzy I think I've figured it out.

Example ARM64 device

ro.product.cpu.abilist32  armeabi-v7a,armeabi
ro.product.cpu.abilist64  arm64-v8a


Example ARM device

ro.product.cpu.abilist32  armeabi-v7a,armeabi
ro.product.cpu.abilist64


Example x86 device

ro.product.cpu.abilist32  x86,armeabi-v7a,armeabi
ro.product.cpu.abilist64


So, to figure out what kind of device you have:

ro.product.cpu.abilist64 not empty = ARM64

ro.product.cpu.abilist32 contains x86 = x86

If none of these conditions match, you have an ARM device