Hi,
I've heard that the cost of implementing a register is more.
In ARMv8 there is a Zero register XZR/WZR, so what is the benefit of implementing such a register over the cost of implementing it?
If you check out the AArch64 ISA you see the advantage: You can reduce the number of real opcodes if you have a dedicated register which returns 0 or discards the data written. I suspect the implementation is rather simple.
From ARMv8-A Architecture Reference Manual:
"This indicates that the argument takes the value zero, but does not indicate that the ZR is implemented as a physical register.