From: Jan Beulich <jbeulich@suse.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Binutils <binutils@sourceware.org>
Subject: Re: [PATCH 5/7] x86: re-work insn/suffix recognition
Date: Fri, 19 Aug 2022 10:28:46 +0200 [thread overview]
Message-ID: <de1e7338-d374-6636-ec29-e6e3a1a05313@suse.com> (raw)
In-Reply-To: <CAMe9rOoQakP9XcmY843ozC-MEQYpvQdy-aG4CivpVdcwFEt5Jw@mail.gmail.com>
On 18.08.2022 17:14, H.J. Lu wrote:
> On Wed, Aug 17, 2022 at 11:24 PM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 17.08.2022 22:29, H.J. Lu wrote:
>>> On Tue, Aug 16, 2022 at 12:32 AM Jan Beulich <jbeulich@suse.com> wrote:
>>>>
>>>> x86: re-work insn/suffix recognition
>>>>
>>>> Having templates with a suffix explicitly present has always been
>>>> quirky. Introduce a 2nd matching pass in case the 1st one couldn't find
>>>
>>> I don't like the second pass. What problem does it solve?
>>
>> It addresses the reasons we have various pretty odd (and confusing by
>> their mere presence) insn templates which better would never have been
>> there. If you have a better suggestion to eliminate those, I'm all ears.
>>
>> You can also easily see the issues this solves by looking at the
>> testsuite changes. Among other things this once again is a matter of
>> providing consistent and hence predictable behavior.
>
> Did you mean the error reporting behavior? I don't think we should add
> a second pass just for it.
No. Certain insns simply were not accepted previously (this is actually
what finally made me think of a solution here; prior observations
weren't severe enough to try to get past your possible opposition which
was to be expected based on past discussions). And certain other ones
were wrongly accepted.
>> Further this sets the stage for the subsequent two changes, which I
>> don't think are easily possible without this 2nd pass.
>
> Does it indicate that the second pass is used quite often?
No, what I did say ...
>> And finally you've likely spotted that this is actually a reduction in
>> code size, first and foremost because the odd maybe_adjust_templates()
>> can now go away. Plus I think you realize that the 2nd pass wouldn't
>> be engaged in many cases - it requires a template match failure in the
>> 1st pass, after all, which isn't going to happen very often.
... here will continue to be the case with those later changes.
Jan
next prev parent reply other threads:[~2022-08-19 8:28 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 7:27 [PATCH 0/7] x86: suffix handling changes Jan Beulich
2022-08-16 7:30 ` [PATCH 1/7] x86/Intel: restrict suffix derivation Jan Beulich
2022-08-17 19:19 ` H.J. Lu
2022-08-18 6:07 ` Jan Beulich
2022-08-18 14:46 ` H.J. Lu
2022-08-19 8:19 ` Jan Beulich
2022-08-19 14:23 ` H.J. Lu
2022-08-19 14:49 ` Jan Beulich
2022-08-19 17:00 ` H.J. Lu
2022-08-22 9:34 ` Jan Beulich
2022-08-22 14:38 ` H.J. Lu
2022-08-16 7:30 ` [PATCH 2/7] x86: insert "no error" enumerator in i386_error enumeration Jan Beulich
2022-08-17 19:19 ` H.J. Lu
2022-08-16 7:31 ` [PATCH 3/7] x86: move / quiesce pre-386 non-16-bit warning Jan Beulich
2022-08-17 19:21 ` H.J. Lu
2022-08-18 7:21 ` Jan Beulich
2022-08-18 15:30 ` H.J. Lu
2022-08-19 6:13 ` Jan Beulich
2022-08-19 14:18 ` H.J. Lu
2022-08-16 7:32 ` [PATCH 4/7] x86: improve match_template()'s diagnostics Jan Beulich
2022-08-17 20:24 ` H.J. Lu
2022-08-18 6:14 ` Jan Beulich
2022-08-18 14:51 ` H.J. Lu
2022-08-16 7:32 ` [PATCH 5/7] x86: re-work insn/suffix recognition Jan Beulich
2022-08-17 20:29 ` H.J. Lu
2022-08-18 6:24 ` Jan Beulich
2022-08-18 15:14 ` H.J. Lu
2022-08-19 8:28 ` Jan Beulich [this message]
2022-08-23 2:00 ` H.J. Lu
2022-08-26 9:26 ` Jan Beulich
2022-08-26 18:46 ` H.J. Lu
2022-09-06 6:40 ` Jan Beulich
2022-09-06 21:53 ` H.J. Lu
2022-09-07 7:17 ` Jan Beulich
2022-09-26 23:52 ` H.J. Lu
2022-09-28 12:49 ` Jan Beulich
2022-09-28 19:33 ` H.J. Lu
2022-09-29 8:08 ` Jan Beulich
2022-09-29 16:00 ` H.J. Lu
2022-09-29 16:06 ` Jan Beulich
2022-09-29 16:20 ` H.J. Lu
2022-08-16 7:33 ` [PATCH 6/7] x86-64: further re-work insn/suffix recognition to also cover MOVSL Jan Beulich
2022-08-16 7:34 ` [PATCH 7/7] ix86: don't recognize/derive Q suffix in the common case Jan Beulich
2022-08-17 20:36 ` H.J. Lu
2022-08-18 6:29 ` Jan Beulich
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