Latest revision as of 17:56, 9 December 2022

LLVM 16

Summary

Update all llvm sub-projects in Fedora Linux to version 16.

Owner

Name: Tom Stellard
Email: <tstellar@redhat.com>

Current status

Targeted release: Fedora Linux 38
Last updated: 2022-12-09
devel thread
FESCo issue: #2909
Tracker bug: #2152199
Release notes tracker: #935

Detailed Description

All llvm sub-projects in Fedora will be updated to version 16, and there will be a soname version change for the llvm libraries. Compatibility packages clang15 and llvm15 will be added to ensure that packages that currently depend on clang and llvm version 15 libraries will continue to work.

In addition, the default LTO mode for Fedora packages compiling with clang will be changed from "Full LTO" to "Thin LTO". "Thin LTO" uses much less compiler resources than "Full LTO", and is better tested and supported by upstream. Note that this will not be a change to clang itself, but rather a change to the compiler flags for clang in redhat-rpm-config.

Feedback

Benefit to Fedora

New features and bug fixes provided by the latest version of LLVM.

Scope

Proposal owners:
- Review existing llvm and clang compatibility packages and orphan any packages that are no longer used.
- Build release candidates into @fedora-llvm-team/llvm16 COPR.
- Build final release (March 2023) into Rawhide and F38 branches.

Other developers:
- Maintainers of packages that depend on clang-libs or llvm-libs will need to update their spec files to depend on the clang15 and llvm15 compatibility packages if they want to rebuild their package and it does not work with LLVM 16 yet. The key point here is that spec file changes are only needed if a package is going to be rebuilt after LLVM 16 is added to Fedora. The compatibility packages will ensure that already built packages continue to work.

Release engineering: [1]

Policies and guidelines: N/A (not needed for this Change)

Trademark approval: N/A (not needed for this Change)

Alignment with Objectives:

Upgrade/compatibility impact

This change should not impact upgradeability.

How To Test

The CI tests for the llvm sub-packages in Fedora will be used to catch regressions that might be potentially introduced by the update to LLVM 16.

User Experience

Dependencies

This change can be made without updating any other packages. However, as mention before, packages that need to use LLVM 15 will need to update their spec file on their first rebuild after this change.

Contingency Plan

Contingency mechanism: (What to do? Who will do it?) Contingency mechanism: (What to do? Who will do it?): If there are major problems with LLVM 16, the compatibility package provide a way for other packages to continue using LLVM 15.
Contingency deadline: Final Freeze
Blocks release? No

Documentation

Release notes will be added for this change.

Release Notes

LLVM sub-projects in Fedora have been updated to version 16:

   llvm
   clang
   lld
   lldb
   compiler-rt
   libomp
   llvm-test-suite
   libcxx
   libcxxabi
   python-lit
   flang
   mlir
   polly
   libclc
   llvm-unwind
   llvm-bolt

@@ Line 20: / Line 20: @@
 == Current status ==
-[[Category:ChangePageIncomplete]]
+[[Category:ChangeAcceptedF38]]
 <!-- When your change proposal page is completed and ready for review and announcement -->
 <!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
@@ Line 27: / Line 27: @@
 <!-- Select proper category, default is Self Contained Change -->
-[[Category:SelfContainedChange]]
+<!-- [[Category:SelfContainedChange]]-->
-<!-- [[Category:SystemWideChange]] -->
+[[Category:SystemWideChange]]
 * Targeted release: [[Releases/38| Fedora Linux 38 ]]
@@ Line 38: / Line 38: @@
 ON_QA -> change is fully code complete
 -->
-* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/EAYAO5E5IWTWZQKM26RHOOYUGSX5PSHV/ devel thread]
+* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/U7R3Q2QJJZIW5MFBCYHWSONXJODBPQYG/ devel thread]
-* FESCo issue: <will be assigned by the Wrangler>
+* FESCo issue: [https://pagure.io/fesco/issue/2909 #2909]
-* Tracker bug: <will be assigned by the Wrangler>
+* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=2152199 #2152199]
-* Release notes tracker: <will be assigned by the Wrangler>
+* Release notes tracker: [https://pagure.io/fedora-docs/release-notes/issue/935 #935]
 == Detailed Description ==
 <!-- Expand on the summary, if appropriate.  A couple sentences suffices to explain the goal, but the more details you can provide the better. -->
-All llvm sub-projects in Fedora will be updated to version 15, and there will be a soname version change for the llvm libraries. Compatibility packages clang14 and llvm14 will be added to ensure that packages that currently depend on clang and llvm version 14 libraries will continue to work.
+All llvm sub-projects in Fedora will be updated to version 16, and there will be a soname version change for the llvm libraries. Compatibility packages clang15 and llvm15 will be added to ensure that packages that currently depend on clang and llvm version 15 libraries will continue to work.
+In addition, the default LTO mode for Fedora packages compiling with clang will be changed from "Full LTO" to "Thin LTO".  "Thin LTO" uses much less compiler resources than "Full LTO", and is better tested and supported by upstream.  Note that this will not be a change to clang itself, but rather a change to the compiler flags for clang in redhat-rpm-config.
 == Feedback ==
@@ Line 83: / Line 85: @@
 * Proposal owners:
 ** Review existing llvm and clang compatibility packages and orphan any packages that are no longer used.
-** Build release candidates into @fedora-llvm-team/llvm15 COPR.
+** Build release candidates into @fedora-llvm-team/llvm16 COPR.
-** Build final release (Sep 2022) into Rawhide and F37 branches.
+** Build final release (March 2023) into Rawhide and F38 branches.
 <!-- What work do the feature owners have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
 * Other developers: <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
-** Maintainers of packages that depend on clang-libs or llvm-libs will need to update their spec files to depend on the clang14 and llvm14 compatibility packages if they want to rebuild their package and it does not work with LLVM 15 yet. The key point here is that spec file changes are only needed if a package is going to be rebuilt after LLVM 15 is added to Fedora. The compatibility packages will ensure that already built packages continue to work.
+** Maintainers of packages that depend on clang-libs or llvm-libs will need to update their spec files to depend on the clang15 and llvm15 compatibility packages if they want to rebuild their package and it does not work with LLVM 16 yet. The key point here is that spec file changes are only needed if a package is going to be rebuilt after LLVM 16 is added to Fedora. The compatibility packages will ensure that already built packages continue to work.
 <!-- What work do other developers have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
-* Release engineering: [https://pagure.io/releng/issues/10820 #10820] <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Release engineering: [https://pagure.io/releng/issues/11150]  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 <!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)?  Is a mass rebuild required?  include a link to the releng issue.
 The issue is required to be filed prior to feature submission, to ensure that someone is on board to do any process development work and testing and that all changes make it into the pipeline; a bullet point in a change is not sufficient communication -->
@@ Line 123: / Line 125: @@
 . What are the expected results of those actions?
 -->
-The CI tests for the llvm sub-packages in Fedora will be used to catch regressions that might be potentially introduced by the update to LLVM 15.
+The CI tests for the llvm sub-packages in Fedora will be used to catch regressions that might be potentially introduced by the update to LLVM 16.
 <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
@@ Line 140: / Line 142: @@
 == Dependencies ==
 <!-- What other packages (RPMs) depend on this package?  Are there changes outside the developers' control on which completion of this change depends?  In other words, completion of another change owned by someone else and might cause you to not be able to finish on time or that you would need to coordinate?  Other upstream projects like the kernel (if this is not a kernel change)? -->
-This change can be made without updating any other packages. However, as mention before, packages that need to use LLVM 14 will need to update their spec file on their first rebuild after this change.
+This change can be made without updating any other packages. However, as mention before, packages that need to use LLVM 15 will need to update their spec file on their first rebuild after this change.
 <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
@@ Line 146: / Line 148: @@
 <!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration".  Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
-* Contingency mechanism: (What to do?  Who will do it?)  Contingency mechanism: (What to do? Who will do it?): If there are major problems with LLVM 15, the compatibility package provide a way for other packages to continue using LLVM 14. <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
+* Contingency mechanism: (What to do?  Who will do it?)  Contingency mechanism: (What to do? Who will do it?): If there are major problems with LLVM 16, the compatibility package provide a way for other packages to continue using LLVM 15. <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 <!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
 * Contingency deadline: Final Freeze  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
@@ Line 164: / Line 166: @@
 Release Notes are not required for initial draft of the Change Proposal but has to be completed by the Change Freeze.
 -->
-LLVM sub-projects in Fedora have been updated to version 15:
+LLVM sub-projects in Fedora have been updated to version 16:
      llvm
@@ Line 181: / Line 183: @@
      libclc
      llvm-unwind
+    llvm-bolt

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