[committed, PATCH] Remove Disp16|Disp32 from 64-bit direct branches

[Michael Matz]

Hi,

On Tue, 12 May 2015, H.J. Lu wrote:

> >> 2. Can you speculate what
> >>
> >> " jmpw   4"
> >>
> >> does?
> >
> > It should do a jump to $nextip+offset, of course, just like a 32bit
> > jump.  The disassembly is correct, because with a zero offset, that's
> > indeed '4'.
> 
> I thought it did jump to "(nextip + offset) & 0xffff" on AMD.  Can you 
> verify if it is true?

Sorry, yes, this is true, the 16bit operand size prefix truncates RIP to 
16 bit.  Nevertheless it's a valid instruction and works as documented.


Ciao,
Michael.