Re: Intel vs AMD x86-64

Timothy Miller
2004-02-25T23:39:11Z

Nakajima, Jun wrote:
> For near branches (CALL, RET, JCC, JCXZ, JMP, etc.), the operand size is
> forced to 64 bits on both processors in 64-bit mode, basically meaning
> RIP is updated.
>
> Compilers would typically use a JMP short for "intraprocedural jumps",
> which requires just an 8-bit displacement relative to RIP.

I see. It's too bad you can't have a 16-bit displacement.

Ummm... so if 66H were used with a near branch, would that affect the
size of the immediate operand which gets added to RIP, or would that
affect the the portion of IP/EIP/RIP affected? If it's the latter,
that's pretty silly.