The L suffix of the MOVL says it's using 32 bits of the register. You move a byte with MOVB and use CMPQ to compare the full 64 bits. You see this too with AT&

The L suffix of the MOVL says it's using 32 bits of the register. You move a byte with MOVB and use CMPQ to compare the full 64 bits. You see this too with AT&T syntax, sometimes.