Only somewhat true. There is register renaming which increases the size of the virtual register set. rax assigned to in line 1 can be a different virtual regist

Only somewhat true. There is register renaming which increases the size of the virtual register set. rax assigned to in line 1 can be a different virtual register from rax assigned to in line 5. AMD and Intel should both be very good at exploiting it to the limits, they had to in their superscalar 32 bit x86 designs :)