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[PATCH] x86: Warn .insn instruction with length

Jan Beulich jbeulich@suse.com
Wed Feb 7 16:59:03 GMT 2024 
On 07.02.2024 17:53, H.J. Lu wrote:
> On Wed, Feb 7, 2024 at 7:32 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 07.02.2024 16:24, H.J. Lu wrote:
>>> On Tue, Feb 6, 2024 at 11:51 PM Jan Beulich <jbeulich@suse.com> wrote:
>>>>
>>>> On 06.02.2024 19:06, H.J. Lu wrote:
>>>>> On Tue, Feb 6, 2024 at 9:05 AM Jan Beulich <jbeulich@suse.com> wrote:
>>>>>>
>>>>>> On 06.02.2024 17:28, H.J. Lu wrote:
>>>>>>> With as_bad, assembler will continue to assemble, just not generate
>>>>>>> an object file.   We ran into this with APX.  Not everyone checks
>>>>>>> assembler warnings closely.  It led to mysterious crashes.   I am
>>>>>>> not against it if someone else implements an assembler option to
>>>>>>> turn this error into a warning.
>>>>>>
>>>>>> But it should be the other way around: The compiler could pass an
>>>>>> option to promote the (default) warning to an error. And if you
>>>>>> don#t pay attention to warning for assembly files, you could pass
>>>>>> the same option as well. Without harming anyone else with anything
>>>>>
>>>>> People who use/need instructions > 15 bytes belong to a very small
>>>>> minority.  If they want to do it, they can use .insn or use binutlls 2.41
>>>>> or older.  The default assembler isn't for them.
>>>>
>>>> No, staying on an old assembler isn't viable. And minority or not, you
>>>> have to face it: In the present discussion it is you who represents a
>>>> minority. As such I'm even inclined to suggest that your earlier patch
>>>> wants reverting, on the basis that it was put in despite there being
>>>> disagreement. Unless you soon come forward with an incremental change
>>>> undoing at least the worst of its effects ...
>>>
>>> Please tell me exactly which projects are negatively impacted by
>>> disallowing > 15 byte instructions.
>>
>> I already told you: I'm using such in testing of my personal disassembler
>> library.
> 
> So, it is only you.  You can either use .insn or add a switch to turn
> this error to warning.

I has been a warning until 2.42, which you've regressed for my use case.
This is why I expect you to at least soften the regression, in allowing
people like me to simply add a command line option to the gas invocations.

Plus, as you have learnt from Michael's responses, I'm not the only one
to think that this diagnostic ought to continue to be a warning by
default.

Jan
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