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Bug 1552915 - Need D43956 to mitigate a Rust compile time regression
Summary: Need D43956 to mitigate a Rust compile time regression
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Fedora
Classification: Fedora
Component: llvm
Version: rawhide
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: ---
Assignee: Tom Stellard
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2018-03-07 22:40 UTC by Josh Stone
Modified: 2018-03-30 12:53 UTC (History)
9 users (show)

Fixed In Version: llvm-6.0.0-3.fc28
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2018-03-30 12:53:16 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
LLVM 36417 0 None None None 2018-03-07 22:40:19 UTC

Description Josh Stone 2018-03-07 22:40:20 UTC
Description of problem:
Upstream rust issue 48226 reported a huge regression in compilation time after the update to LLVM 6.0.  This was reported in LLVM 36417, which bisected to D38229 as the culprit.  D43956 is the upstream LLVM workaround, which Rust has already backported to its own LLVM branch.

https://github.com/rust-lang/rust/issues/48226
https://bugs.llvm.org/show_bug.cgi?id=36417
https://reviews.llvm.org/D38229
https://reviews.llvm.org/D43956


Version-Release number of selected component (if applicable):
llvm-libs-6.0.0-0.4.rc2.fc28.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Create the project in the Rust bug.
2. "cargo build --release" takes a short time -- about 6 seconds for me.
3. set "debug = true", then "cargo build --release" takes several minutes.

Actual results:
long build time

Expected results:
short build time

Additional info:
This culprit D38229 is in the release_60 branch, but not earlier.  I confirmed that using a rust.fc29 build linked to llvm-6 shows the regression, but rust.fc27 linked to llvm-5 is fine.

f29: https://koji.fedoraproject.org/koji/taskinfo?taskID=25507822
f27: https://koji.fedoraproject.org/koji/taskinfo?taskID=25524928

Comment 1 Tom Stellard 2018-03-09 20:39:47 UTC
This should be fixed in rawhide with: llvm-6.0.0-3.fc29

Comment 2 Josh Stone 2018-03-09 23:03:38 UTC
Confirmed!  Just updating to this new llvm package solves the slow build.

Shall we keep the bug open, to be closed by a f28 update?

Comment 3 Tom Stellard 2018-03-09 23:06:29 UTC
Yes, let's keep it open until the f28 update.

Comment 4 Fedora Update System 2018-03-13 22:43:42 UTC
lldb-6.0.0-1.fc28 compiler-rt-6.0.0-1.fc28 libomp-6.0.0-1.fc28 clang-6.0.0-2.fc28 llvm-6.0.0-3.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-689de58112

Comment 5 Fedora Update System 2018-03-14 18:05:27 UTC
clang-6.0.0-2.fc28, compiler-rt-6.0.0-1.fc28, libomp-6.0.0-1.fc28, lldb-6.0.0-1.fc28, llvm-6.0.0-3.fc28 has been pushed to the Fedora 28 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-689de58112

Comment 6 Fedora Update System 2018-03-30 12:53:16 UTC
clang-6.0.0-2.fc28, compiler-rt-6.0.0-1.fc28, libomp-6.0.0-1.fc28, lldb-6.0.0-1.fc28, llvm-6.0.0-3.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.


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