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Re: combination of read/write and earlyclobber constraint modifier
- From: Christophe Lyon <christophe dot lyon at linaro dot org>
- To: Tom de Vries <Tom_deVries at mentor dot com>
- Cc: Marcus Shawcroft <marcus dot shawcroft at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 7 Jul 2014 11:29:47 +0200
- Subject: Re: combination of read/write and earlyclobber constraint modifier
- Authentication-results: sourceware.org; auth=none
- References: <53B30B96 dot 2000603 at mentor dot com> <53B31041 dot 8060608 at redhat dot com> <alpine dot DEB dot 2 dot 10 dot 1407012155000 dot 2640 at laptop-mg dot saclay dot inria dot fr> <53B32D3A dot 1030700 at mentor dot com> <alpine dot DEB dot 2 dot 10 dot 1407020800530 dot 2059 at laptop-mg dot saclay dot inria dot fr> <53B3BC7E dot 3040709 at mentor dot com> <CAFqB+PykGc-8Gstn-c3sPim9FxLpXj9DxmAcwBxLM=A05j=Lvg at mail dot gmail dot com> <53B51590 dot 7030903 at mentor dot com>
On 3 July 2014 10:34, Tom de Vries <Tom_deVries@mentor.com> wrote:
> On 03-07-14 10:20, Marcus Shawcroft wrote:
>>
>> On 2 July 2014 09:02, Tom de Vries <Tom_deVries@mentor.com> wrote:
>>>
>>> On 02-07-14 08:23, Marc Glisse wrote:
>>>>
>>>>
>>>> In the first example you gave, looking at the pattern (no match_dup,
>>>> setting the
>>>> full register), it seems that it may have wanted "=&" instead of "+&".
>>>
>>>
>>>
>>> [ move discussion from gcc ml to gcc-patches ml ]
>>>
>>> Marcus,
>>>
>>> The +& constraint on operand 0 of vec_unpack_trunc_<mode> seems wrong,
>>> since
>>> the template does not use the operand as input.
>>>
>>> This patch fixes that.
>>>
>>> OK for trunk if aarch64 build & regtest succeeds ?
>>
>>
>> Your patch looks fine, operand 0 isn't used for input. OK assuming no
>> regression. Did you find this by inspection or is this the cause of
>> some bug?
>>
>
> Marcus,
>
> I found this by inspection: https://gcc.gnu.org/ml/gcc/2014-07/msg00007.html
> .
>
> Thanks,
> - Tom
>
Hi,
This patch causes gcc.target/aarch64/vmlsq_laneq.c to FAIL on
aarch64_be-none-elf.
Christophe.