Re: [pcre-dev] JIT fails with NEON instructions

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Autor: Sebastian Pop
Data:  
A: Zoltán Herczeg
CC: pcre-dev@exim.org
Assumpte: Re: [pcre-dev] JIT fails with NEON instructions
The problem occurs on Ubuntu 18.04 and A-72 as well
when configuring with --enable-pcre2-16 and --enable-pcre2-32
each exposes one fail.
I will send a patch to fix these issues.

Sebastian

On Wed, Oct 30, 2019 at 3:47 PM Sebastian Pop <sebpop@???> wrote:

> A previous email to the pcre-dev list shows the log output:
> https://lists.exim.org/lurker/message/20191030.143840.c1a0847b.en.html
>
> My testing for the patch was on both Ubuntu 18.04 and 19.04 on A1 instance
> based on A-72. I will try to see if I can reproduce the bug on A1 with a
> Fedora
> distribution.
>
> Sebastian
>
> On Wed, Oct 30, 2019 at 3:37 PM Sebastian Pop <sebpop@???> wrote:
>
>> Thanks Zoltán for the heads up.
>> I can work on fixing the reported issues.
>> Is there a log of the output and instructions on how to reproduce the
>> problems?
>> I would need the configure or cmake line and the make command.
>>
>> Thanks,
>> Sebastian
>>
>> On Wed, Oct 30, 2019 at 1:28 PM Zoltán Herczeg <hzmester@???>
>> wrote:
>>
>>> Hi Sebastian,
>>>
>>> could you check this failure?
>>>
>>> Regards,
>>> Zoltan
>>>
>>> -------- Eredeti levél --------
>>> Feladó: Petr Pisar via Pcre-dev < pcre-dev@??? (Link -> mailto:
>>> pcre-dev@???) >
>>> Dátum: 2019 október 30 18:25:42
>>> Tárgy: Re: [pcre-dev] JIT fails with NEON instructions
>>> Címzett: pcre-dev@??? (Link -> mailto:pcre-dev@exim.org)
>>> On Wed, Oct 30, 2019 at 03:38:45PM +0100, Petr Pisar via Pcre-dev wrote:
>>> > On Thu, Oct 17, 2019 at 05:54:08PM +0100, ph10@??? wrote:
>>> > > I have just made available a Release Candidate for PCRE2 10.34 here:
>>> > >
>>> > > https://ftp.pcre.org/pub/pcre/Testing/pcre2-10.34-RC1.tar.gz
>>> > > https://ftp.pcre.org/pub/pcre/Testing/pcre2-10.34-RC1.tar.bz2
>>> > > https://ftp.pcre.org/pub/pcre/Testing/pcre2-10.34-RC1.tar.zip
>>> > >
>>> > > NOTE: this is a different FTP site than was used for previous
>>> releases.
>>> > >
>>> > I experience two test failures on 64-bit ARM with Fedora 32
>>> distribution:
>>> >
>>> Both failures are triggered by this PCRE2 commit:
>>> commit a6b4b9c7f9e3d20966de682487ee575cba053a20
>>> Author: zherczeg <zherczeg@6239d852-aaf2-0410-a92c-79f79f948069>
>>> Date: Tue Sep 17 06:59:45 2019 +0000
>>> Support NEON based fast forward character search in ARM64. Patch by
>>> Sebastian Pop.
>>> git-svn-id: svn://vcs.exim.org/pcre2/code/trunk@1172
>>> 6239d852-aaf2-0410-a92c-79f79f948
>>> 069
>>> I verified it on this machine:
>>> # lscpu
>>> Architecture: aarch64
>>> CPU op-mode(s): 64-bit
>>> Byte Order: Little Endian
>>> CPU(s): 4
>>> On-line CPU(s) list: 0-3
>>> Thread(s) per core: 1
>>> Core(s) per socket: 4
>>> Socket(s): 1
>>> NUMA node(s): 1
>>> Vendor ID: Cavium
>>> Model: 1
>>> Model name: ThunderX2 99xx
>>> Stepping: 0x1
>>> BogoMIPS: 400.00
>>> NUMA node0 CPU(s): 0-3
>>> Vulnerability L1tf: Not affected
>>> Vulnerability Mds: Not affected
>>> Vulnerability Meltdown: Not affected
>>> Vulnerability Spec store bypass: Vulnerable
>>> Vulnerability Spectre v1: Mitigation; __user pointer sanitization
>>> Vulnerability Spectre v2: Vulnerable
>>> Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics cpuid
>>> asimdrdm
>>> using Fedora 31 (gcc-9.2.1, binutils-2.32).
>>> The compiler defines __ARM_NEON macro on that machine.
>>> getauxval(AT_HWCAP) sets
>>> HWCAP_ASIMD bit. So I believe the machine supports NEON.
>>> When I disable the
>>> #if (defined SLJIT_CONFIG_ARM_64 && SLJIT_CONFIG_ARM_64 && (defined
>>> __ARM_NEON || defined
>>> __ARM_NEON__))
>>> branch in src/pcre2_jit_compile.c not to emit NEON instructions, all
>>> tests
>>> pass on that machine.
>>> This I conclude something is wrong in the NEON support in sljit.
>>> -- Petr
>>>
>>
>>