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Message-ID: <f1a8853e-b0d4-4e7c-a7b3-b8238dedd272@gmail.com>
Date: Mon, 16 Mar 2026 20:00:00 +0200
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: pgcrypto/des tests fail on riscv64 due to clang's code generation
 anomaly
To: Greg Burd <greg@burd.me>, Tom Lane <tgl@sss.pgh.pa.us>,
 Michael Paquier <michael@paquier.xyz>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>,
 Thomas Munro <thomas.munro@gmail.com>
References: <c64cbda0-7ef2-4762-8e70-9d0dedccc9cf@gmail.com>
 <abdYBpgtoRQV34PX@paquier.xyz> <2284079.1773625237@sss.pgh.pa.us>
 <db01b708-90da-4f52-ae5a-7e9da44ffa7c@app.fastmail.com>
Content-Language: en-US
From: Alexander Lakhin <exclusion@gmail.com>
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 <https://www.postgresql.org/message-id/f1a8853e-b0d4-4e7c-a7b3-b8238dedd272%40gmail.com>
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Hello,

16.03.2026 14:13, Greg Burd wrote:
>> Seems like this might be worth a bug report to the clang people.
> Thanks Alexander for digging and a solid report of the issue, and Michael for spending some time on this, and Tom for chiming in as well.  I agree this looks like a compiler issue.  I know that Thomas (added/CC'ed) you've posted bugs against clang before, any thoughts on this one?
>

Please find attached the reduced test code, which works for me as follows:
$ clang-20 -O2 -march=rv64gcv crypt-des-test.c -o crypt-des-test && ./crypt-des-test
!!!des_init| un_pbox: 15 6 19 20 28 11 27 16 0 14 22 25 4 17 30 9 1 7 23 13 31 26 2 8 18 12 29 5 21 10 3 24

$ clang-20 -O2 -march=rv64gc crypt-des-test.c -o crypt-des-test && ./crypt-des-test
!!!des_init| un_pbox: 8 16 22 30 12 27 1 17 23 15 29 5 25 19 9 0 7 13 24 2 3 28 10 18 31 11 21 6 4 26 14 20

$ clang-20 -O1 -march=rv64gcv crypt-des-test.c -o crypt-des-test && ./crypt-des-test
!!!des_init| un_pbox: 8 16 22 30 12 27 1 17 23 15 29 5 25 19 9 0 7 13 24 2 3 28 10 18 31 11 21 6 4 26 14 20

$ clang-20 --version
Ubuntu clang version 20.1.2 (0ubuntu1~24.04.2)

Best regards,
Alexander
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