Bug 2156679

Summary: Build Clang with PGO
Product: [Fedora] Fedora Reporter: Alexander Zaitsev <zamazan4ik>
Component: clangAssignee: Tom Stellard <tstellar>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 38CC: airlied, jchecahi, kkleine, npopov, sbergman, serge.guelton, siddharth.kde, tstellar, tuliom
Target Milestone: ---   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Fixed In Version: Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Alexander Zaitsev 2022-12-28 06:22:01 UTC
Description of problem:

Clang supports (https://llvm.org/docs/HowToBuildWithPGO.html) bootstrapping with PGO. It increases Clang performance. The same thing is already enabled for GCC in Fedora (profiledbootstrap option). I think the same thing could be done for Clang since in the current build script I don't see that Clang is built with PGO.

Expected results:
Provided Clang binaries with Fedora are built with PGO.

Additional option:
Also you could try to build binary with LLVM BOLT (https://github.com/facebookincubator/BOLT/blob/main/bolt/docs/OptimizingClang.md) but I guess it's another question and it's much more complicated topic.

Comment 1 Ben Cotton 2023-02-07 15:04:14 UTC
This bug appears to have been reported against 'rawhide' during the Fedora Linux 38 development cycle.
Changing version to 38.