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Re: [PATCH v8 2/2] x86/AT&T: don't default to byte source for ambiguous for MOVSX/MOVZX
- From: Jan Beulich <jbeulich at suse dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: "binutils at sourceware dot org" <binutils at sourceware dot org>
- Date: Fri, 14 Feb 2020 14:13:36 +0100
- Subject: Re: [PATCH v8 2/2] x86/AT&T: don't default to byte source for ambiguous for MOVSX/MOVZX
- References: <92fd2cf8-90a0-98f8-9453-c49d911daec6@suse.com> <c9579c40-5f3f-de90-c666-f110882cf102@suse.com> <CAMe9rOrC1H=VfHH3sgQEMRe0VFzZCb+1CEpRX-f1EWpHRUD38g@mail.gmail.com>
On 14.02.2020 13:28, H.J. Lu wrote:
> On Fri, Feb 14, 2020 at 4:26 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> As pointed out in "x86: replace adhoc (partly wrong) ambiguous operand
>> checking for MOVSX/MOVZX" silently guessing what the programmer may have
>> meant is not helpful, the more that we don't do so elsewhere anymore
>> (except in cases where it is overwhelmingly likely that the other case
>> isn't meant, like here for it meant to be a "sign/zero extension" from
>> 16 bits to 16 bits).
>>
>> gas/
>> 2020-02-XX Jan Beulich <jbeulich@suse.com>
>>
>> PR gas/25438
>> * config/tc-i386.c (process_suffix): Default movsx/movzx to byte
>> suffix only when destination is a word reg.
>> testsuite/gas/i386/noreg16.l, testsuite/gas/i386/noreg32.l,
>> testsuite/gas/i386/noreg64.l: Adjust expectations.
>
> No need for this since this is documented behavior of AT&T syntax.
Well, you know eagerly how people usually look at documentation.
There being an ambiguity still deserves a warning. Documentation
tells us what code to generate (and that we may not change this).
Anyway - I give up here and will maintain the patch in my
private trees. Hopefully there'll be a better time for it later
on.
Jan