From: Sudakshina Das <sudi.das@arm.com>
To: Kyrill Tkachov <kyrylo.tkachov@foss.arm.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Cc: nd <nd@arm.com>,
Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
Richard Earnshaw <Richard.Earnshaw@arm.com>
Subject: Re: [PATCH][ARM] Fix wrong code by arm_final_prescan with fp16 move instructions
Date: Thu, 30 Nov 2017 16:08:00 -0000 [thread overview]
Message-ID: <2662e77b-cf75-8072-d6ef-14e184ce95c1@arm.com> (raw)
In-Reply-To: <5A1C0434.5000109@foss.arm.com>
Hi Kyrill
On 27/11/17 12:25, Kyrill Tkachov wrote:
> Hi Sudi,
>
> On 24/11/17 14:57, Sudi Das wrote:
>> Hi
>>
>> For the following test case:
>> __fp16
>> test_select (__fp16 a, __fp16 b, __fp16 c)
>> {
>> return (a < b) ? b : c;
>> }
>>
>> when compiled with -mfpu=fp-armv8 -march=armv8.2-a+fp16 -marm
>> -mfloat-abi=hard trunk generates wrong code:
>>
>> test_select:
>> @ args = 0, pretend = 0, frame = 0
>> @ frame_needed = 0, uses_anonymous_args = 0
>> @ link register save eliminated.
>> vcvtb.f32.f16 s0, s0
>> vcvtb.f32.f16 s15, s1
>> vcmpe.f32 s0, s15
>> vmrs APSR_nzcv, FPSCR
>> // <------ No conditional branch!
>> vmov s1, s2 @ __fp16
>> .L2:
>> vmov s0, s1 @ __fp16
>> bx lr
>>
>> There should have been a conditional branch there to skip one of the
>> VMOVs.
>> This patch fixes this problem by making *movhf_vfp_fp16 unconditional
>> wherever needed.
>>
>> Testing done: Add a new test case and checked for regressions
>> arm-none-linux-gnueabihf.
>>
>> Is this ok for trunk?
>>
>
> This is ok after assuming a bootstrap on arm-none-linux-gnueabihf passes
> as well.
> Does this bug appear on the GCC 7 branch?
> If so, could you please test this patch on that branch as well if so?
>
I have tested the patch and also sent a new patch request for gcc-7
https://gcc.gnu.org/ml/gcc-patches/2017-11/msg02577.html
Thanks
Sudi
> Thanks,
> Kyrill
>
>> Sudi
>>
>> ChangeLog entry are as follow:
>>
>> *** gcc/ChangeLog ***
>>
>> 2017-11-24 Sudakshina Das <sudi.das@arm.com>
>>
>> * config/arm/vfp.md (*movhf_vfp_fp16): Add conds attribute.
>>
>> *** gcc/testsuite/ChangeLog ***
>>
>> 2017-11-24 Sudakshina Das <sudi.das@arm.com>
>>
>> * gcc.target/arm/armv8_2-fp16-move-2.c: New test.
>
next prev parent reply other threads:[~2017-11-30 16:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-24 15:44 Sudakshina Das
2017-11-27 12:39 ` Kyrill Tkachov
2017-11-30 16:08 ` Sudakshina Das [this message]
2017-11-30 16:28 ` Kyrill Tkachov
2017-12-01 10:18 ` Sudakshina Das
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2662e77b-cf75-8072-d6ef-14e184ce95c1@arm.com \
--to=sudi.das@arm.com \
--cc=Ramana.Radhakrishnan@arm.com \
--cc=Richard.Earnshaw@arm.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=kyrylo.tkachov@foss.arm.com \
--cc=nd@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).