Re: RISC-V animals sporadically produce weird memory-related failures

From: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>
To: Alexander Lakhin <exclusion(at)gmail(dot)com>
Cc: Tom Turelinckx <pgbf(at)twiska(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: RISC-V animals sporadically produce weird memory-related failures
Date: 2024-12-02 19:51:31
Message-ID: CA+hUKGLr_wz=y5QWtk=L_+wmr0x1r_YfmgMt6wy1=a6HH=8dmQ@mail.gmail.com
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On Tue, Dec 3, 2024 at 7:00 AM Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:
> A build made with clang-19 without llvm passed `make check` successfully.

We heard in another thread[1] that we'd need to use the JITLink API
for RISCV, instead of the RuntimeDyld API we're using. I have a newer
patch to use JITLink on all architectures, starting at some LLVM
version, but it needs a bit more polish and research before sharing.
I'm surprised it's segfaulting instead of producing an error of some
sort, though. I wonder why. It would be nice if we could fail
gracefully instead.

Hmm, from a quick look in the LLVM main branch, it looks like a bunch
of RISCV stuff just landed in recent months under
llvm/lib/ExecutionEngine/RuntimeDyld, so maybe that's not true anymore
on bleeding-edge LLVM (20-devel), I have no idea what state that's in,
but IIUC there is no way RuntimeDyld could work on LLVM 16 or 19.

[1] https://www.postgresql.org/message-id/flat/20220829074622.2474104-1-alex.fan.q%40gmail.com

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