Bug 2383037

Summary:	LLVM sometimes fails to correctly spill crbit on power9 and newer
Product:	[Fedora] Fedora	Reporter:	Paul Murphy <paumurph>
Component:	llvm	Assignee:	Tom Stellard <tstellar>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	rawhide	CC:	dmalcolm, fedora-llvm-team, jakub, jchecahi, jistone, kkleine, npopov, scottt.tw, sergesanspaille, siddharth.kde, suraj.ghimire7, tbaeder, tstellar, tuliom
Target Milestone:	---	Flags:	tstellar: mirror+
Target Release:	---
Hardware:	ppc64le
OS:	Linux
Whiteboard:
Fixed In Version:	llvm-20.1.8-3.fc43 llvm-20.1.8-3.fc42	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2025-07-30 13:49:17 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Paul Murphy 2025-07-23 14:04:01 UTC

If building for power9 or newer, and a CR bit is spilled, LLVM may miscompile the code. This bug has been around for quite some time. It was exposed when building the rust toolchain with -mcpu=pwr9 on c9s (see RHEL-88598).

The upstream bug is https://github.com/llvm/llvm-project/issues/143989, a patch is pending with pr https://github.com/llvm/llvm-project/pull/146424.

Reproducible: Always

Steps to Reproduce:
1. Build rust package with a power9 minimum CPU.
2. Observe strange test failures in JSON formatted output.

Comment 1 Fedora Update System 2025-07-29 16:22:20 UTC

FEDORA-2025-18488216e7 (llvm-20.1.8-3.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2025-18488216e7

Comment 2 Fedora Update System 2025-07-30 07:31:36 UTC

FEDORA-2025-dd4673b64d (llvm-20.1.8-3.fc42) has been submitted as an update to Fedora 42.
https://bodhi.fedoraproject.org/updates/FEDORA-2025-dd4673b64d

Comment 3 Fedora Update System 2025-07-30 13:49:17 UTC

FEDORA-2025-18488216e7 (llvm-20.1.8-3.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 4 Fedora Update System 2025-07-31 01:31:59 UTC

FEDORA-2025-dd4673b64d has been pushed to the Fedora 42 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2025-dd4673b64d`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2025-dd4673b64d

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2025-08-03 01:15:18 UTC

FEDORA-2025-dd4673b64d (llvm-20.1.8-3.fc42) has been pushed to the Fedora 42 stable repository.
If problem still persists, please make note of it in this bug report.