[PATCH] x86: Don't display eiz with no scale

[H.J. Lu]

On Tue, Jul 21, 2020 at 2:40 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 15.07.2020 15:57, H.J. Lu wrote:
> > On Tue, Jul 14, 2020 at 11:14 PM Jan Beulich <jbeulich@suse.com> wrote:
> >>
> >> On 14.07.2020 18:54, H.J. Lu wrote:
> >>> On Tue, Jul 14, 2020 at 5:55 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>>>
> >>>> On Tue, Jul 14, 2020 at 5:51 AM Jan Beulich <jbeulich@suse.com> wrote:
> >>>>>
> >>>>> On 14.07.2020 14:43, H.J. Lu wrote:
> >>>>>> On Mon, Jul 13, 2020 at 11:12 PM Jan Beulich <jbeulich@suse.com> wrote:
> >>>>>>> Nevertheless, I've meanwhile thought of a (contrived) case that was
> >>>>>>> broken with the code present:
> >>>>>>>
> >>>>>>>         addr32 mov $0x89abcdef, %rax
> >>>>>>>
> >>>>>>> would have got the immediate sign-extended from 32 to 64 bits.
> >>>>>>>
> >>>>>>
> >>>>>> I opened:
> >>>>>>
> >>>>>> https://sourceware.org/bugzilla/show_bug.cgi?id=26237
> >>>>>>
> >>>>>> There are multiple issues.
> >>>>>
> >>>>> Hmm, the former two lines there look correct to me, while the latter
> >>>>> two lines look to have been translated with a gas that didn't have
> >>>>> yesterday's change yet. IOW - I'm somewhat confused.
> >>>>
> >>>> The bug is against binutils 2.35, not master.
> >>>>
> >>>
> >>> Here is the patch for master branch.
> >>
> >> Ah, so your issue was just with disassembly. Yet then why not go a step
> >> further and (at least in 64-bit mode) print
> >>
> >> [       ]*[a-f0-9]+:    67 48 89 1c 25 ef cd ab 89      mov[ ]+%rbx,0x89abcdef
> >> [       ]*[a-f0-9]+:    67 89 04 25 11 22 33 ff         mov[ ]+%eax,0xff332211
> >>
> >> instead of
> >>
> >> [       ]*[a-f0-9]+:    67 48 89 1c 25 ef cd ab 89      mov[ ]+%rbx,0x89abcdef\(,%eiz,1\)
> >> [       ]*[a-f0-9]+:    67 89 04 25 11 22 33 ff         mov[ ]+%eax,0xff332211\(,%eiz,1\)
> >>
> >> and keep the () part only for
> >>
> >> [       ]*[a-f0-9]+:    67 89 04 65 11 22 33 ff         mov[ ]+%eax,0xff332211\(,%eiz,2\)
> >>
> >> , as there's no SIB-less way to express a base-and-index-less address?
> >>
> >
> > Done.
> >
> > I am checking in this.
>
> Having only now noticed the collision with my change to
> evex-no-scale-64.d, I wonder whether we want to revert your change,
> and hence whether my underlying suggestion was a bad one: There's
> now no sign left that these insns use 32-bit address mode. The
> alternative would be to ensure that an addr32 prefix gets emitted.
> I'd personally favor this alternative, but I could live with the
> revert. (When making the suggestion I didn't realize this is a
> 32-bit-addressing-specific output mode.)
>

Can you revert it for me?

Thanks.

-- 
H.J.