Your message dated Sun, 23 Nov 2025 21:41:56 +0000
with message-id <[email protected]>
and subject line Bug#1116636: fixed in llvm-toolchain-21 1:21.1.6-2
has caused the Debian Bug report #1116636,
regarding llvm-toolchain-21: unsoundness/miscompilations on i386
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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--
1116636: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1116636
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Source: rustc
Version: 1.84.0+dfsg1-1
Severity: serious
Tags: upstream
Justification: Policy 2.2.1
X-Debbugs-Cc: [email protected], [email protected]
Filing this bug to have a record in BTS - I'll file a separate one for
release.debian.org about the broader baseline question.
This issue came up back in November on debian-devel/-release:
https://lists.debian.org/debian-release/2024/11/msg00443.html
My original mail, partially wrongly summarizing the issue.
https://lists.debian.org/debian-release/2024/11/msg00445.html
My reponse linking to more upstream details, including why downgrading to i586
in LLVM/rustc doesn't work.
It boils down to the following:
- Debian's i386 baseline is currently 32-bit x86 without MMX or SSE (i686)
- Debian's LLVM and rustc packages accordingly patch their i686 targets to
remove SSE support, which would be part of that target's baseline upstream
otherwise [0,1]
- Upstream LLVM and rustc consider this combination unsound and unfixable (for
IMHO valid reasons) because it can cause subtle miscompilations leading to
runtime crashes, in addition to the (usual, expected) different semantics of
x87 and SSE2 floating point implementations [2,3]
I see the following options:
A) bump i386 baseline for Trixie to match LLVM/rustc's upstream i686 target,
i.e. Pentium 4 *with* MMX and SSE2 (separate RT bug will be filed shortly)
B) RC-ignore this bug and implications for Trixie, bump baseline for Trixie+1
C) remove LLVM and rustc and all their transitive rdeps (this includes Firefox
and Chromium, most major Desktop environments, sequoia, and probably a bit
more) on i386 from Trixie, further reducing the usefulness of this arch
Personally (with my rustc maintainer hat on) I have a strong preference for A).
Please keep responses on details of A) to the corresponding release.debian.org
bug!
Fabian
0:
https://salsa.debian.org/rust-team/rust/-/blob/debian/sid/debian/patches/behaviour/d-rustc-i686-baseline.patch?ref_type=heads
1:
https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/blob/19/debian/patches/clang-baseline-fix-i386.patch
2: https://github.com/rust-lang/compiler-team/issues/808
3: https://github.com/rust-lang/rust/issues/114479#issuecomment-2072052116
--- End Message ---
--- Begin Message ---
Source: llvm-toolchain-21
Source-Version: 1:21.1.6-2
Done: Samuel Thibault <[email protected]>
We believe that the bug you reported is fixed in the latest version of
llvm-toolchain-21, which is due to be installed in the Debian FTP archive.
A summary of the changes between this version and the previous one is
attached.
Thank you for reporting the bug, which will now be closed. If you
have further comments please address them to [email protected],
and the maintainer will reopen the bug report if appropriate.
Debian distribution maintenance software
pp.
Samuel Thibault <[email protected]> (supplier of updated llvm-toolchain-21
package)
(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing [email protected])
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Format: 1.8
Date: Sun, 23 Nov 2025 14:28:16 +0100
Source: llvm-toolchain-21
Architecture: source
Version: 1:21.1.6-2
Distribution: unstable
Urgency: medium
Maintainer: LLVM Packaging Team <[email protected]>
Changed-By: Samuel Thibault <[email protected]>
Closes: 1116636 1121222
Changes:
llvm-toolchain-21 (1:21.1.6-2) unstable; urgency=medium
.
[ Samuel Thibault ]
* Enable compiler-rt and disable liborc on hurd-amd64.
(Closes: #1121222)
.
[ Sylvestre Ledru ]
* Enable sse2 back on i386 (closes: #1116636)
https://lists.debian.org/debian-devel/2025/01/msg00034.html
(remove the two patches that we are applying for disable sse2)
It is now the same as upstream
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