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

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Autor: Sebastian Pop
Data:  
Dla: Zoltán Herczeg
CC: pcre-dev@exim.org
Temat: Re: [pcre-dev] JIT fails with NEON instructions
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
>>
>
>