Re: rex.W prefix in jumps on x86_64

[Marc Nieper-Wißkirchen]

Hi Paul,

> >>  look at the disassembly, I see things like
> >>
> >>  rex.W jmpq *%rax
> >>
> >>  when an instruction like `jmpr R0' is jitted. I am wondering about
> >> the
> >>  REX prefix, which doesn't seem to be necessary. In 64 bit-mode,
> >> where
> >>  the operand size is fixed for jumps and calls.
> >>
>
> Was that introduced by commit 8dc376f?. This one introduced a bug but I
> can't exactly put my finger on what's going on.

I am using the git head version, so that commit is included in my test
code. But that commit has something to do with jmpi's, not jmpr's.

Which (other) bug has been introduced by that commit?

Marc