From: "Jiang, Haochen" <haochen.jiang@intel.com>
To: "Beulich, Jan" <JBeulich@suse.com>, "H.J. Lu" <hjl.tools@gmail.com>
Cc: Binutils <binutils@sourceware.org>
Subject: RE: [RFC] x86: proposal for a new .insn directive
Date: Fri, 20 Jan 2023 01:25:29 +0000 [thread overview]
Message-ID: <SA1PR11MB59460D8BACA23AC5AFD6DEE0ECC59@SA1PR11MB5946.namprd11.prod.outlook.com> (raw)
In-Reply-To: <8ed80af6-b36b-46d4-de64-530331bd4e4d@suse.com>
> >>
> >> # TBD: How to specify the Disp8 scaling factor here? (In Intel syntax we can
> simply
> >> # use memory operand size.)
> >> .insn EVEX.66.0F38.W0 0x88, 4(%eax), %ymm1 # vexpandps
> 4(%eax), %ymm1
One of the way I think is to add a field at encoding
{VEX,XOP,EVEX}[.<len>][.<prefix>][.<space>][.<w>][.<memory>]
<memory> could be x or y.
If <memory> is omitted, it is implied by register size or it is in Intel syntax.
But the potential problem is that if we have to add a field every time we meet
something special, the directive will turn out to be longer and longer and more
and more complicated. I don't know whether everyone like this.
BRs,
Haochen
> >
> > I think it is a nice feature. But it will be very difficult to
> > support all complex
> > x86 encoding schemes which change over time.
>
> Of course, and especially also if yet new schemes would appear. We can
> only possibly encode what we're aware of; but even that may help with
> unknown (or further extended) schemes, compared to today's need of
> resorting to .byte.
>
> > We can start with the regular encoding schemes first.
>
> Well, at the very least immediates need dealing with in some sensible way.
> So at least those two TBDs will need addressing up front (or maybe while
> I'm starting with some initial work here, which I may have time for in
> about two weeks).
>
> Jan
next prev parent reply other threads:[~2023-01-20 1:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-13 11:58 Jan Beulich
2023-01-17 15:56 ` H.J. Lu
2023-01-17 16:16 ` Jan Beulich
2023-01-20 1:25 ` Jiang, Haochen [this message]
2023-01-20 9:07 ` Jan Beulich
2023-02-03 11:39 ` Jan Beulich
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