Bug 2238781

Summary: Static function miscompiled at -O1 optimization level with gcc-13.2.1-1.fc39.i686
Product: [Fedora] Fedora Reporter: Petr Pisar <ppisar>
Component: gccAssignee: Jakub Jelinek <jakub>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: rawhideCC: dmalcolm, fweimer, jakub, jlaw, jwakely, mcermak, mpolacek, msebor, nickc, sipoyare
Target Milestone: ---   
Target Release: ---   
Hardware: i686   
OS: Unspecified   
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Fixed In Version: gcc-13.2.1-6.fc39 gcc-13.2.1-7.fc38 Doc Type: If docs needed, set a value
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Last Closed: 2023-12-08 01:39:09 UTC Type: Bug
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reproducer none

Description Petr Pisar 2023-09-13 15:06:09 UTC 
Created attachment 1988683 [details]
reproducer

When packaging zpaqfranz (bug #2238725), I discovered a segfault on i686 <https://github.com/fcorbelli/zpaqfranz/issues/71>. I believe this is caused by GCC which miscompiled a loading of an uint64_t array member passed by a pointer in static function.

If you build an attached reproducer with "gcc -O1 -g -Dunix t2.cc" on i686, and disassemble a HighwayHashReset() function, you can see that loading key[3] at the last line of the function:

  state->v1[3] = state->mul1[3] ^ ((key[3] >> 32) | (key[3] << 32));

is miscompiled like:

        movl    28(%eax), %ecx
        movl    24(%ecx), %ebx

while expected assembly code is:

        movl    28(%eax), %ecx
        movl    24(%eax), %ebx

A trigger is having the HighwayHashReset() function static and compiling with -O1. Lowering the optimization or removing the static keyword fixes the assembly code. This does not happen on other 64-bit architectures.
Comment 1 Marek Polacek 2023-09-15 17:55:23 UTC 
Looks like it was fixed by https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=790c1f60a5662b16eb19eb4b81922995863c7571

commit 790c1f60a5662b16eb19eb4b81922995863c7571
Author: Roger Sayle <roger>
Date:   Thu Aug 3 07:12:04 2023 +0100

    PR target/110792: Early clobber issues with rot32di2_doubleword on i386.

The fix is not yet in GCC 13 but Sam & I asked for it: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110792#c16
Comment 2 Petr Pisar 2023-09-18 08:11:05 UTC 
That indeed looks similar.
Comment 3 Fedora Update System 2023-12-06 11:46:30 UTC 
FEDORA-2023-1c6b112a75 has been submitted as an update to Fedora 39. https://bodhi.fedoraproject.org/updates/FEDORA-2023-1c6b112a75
Comment 4 Fedora Update System 2023-12-07 01:49:00 UTC 
FEDORA-2023-1c6b112a75 has been pushed to the Fedora 39 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2023-1c6b112a75`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2023-1c6b112a75

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 5 Fedora Update System 2023-12-08 01:39:09 UTC 
FEDORA-2023-1c6b112a75 has been pushed to the Fedora 39 stable repository.
If problem still persists, please make note of it in this bug report.
Comment 6 Fedora Update System 2024-03-17 11:34:10 UTC 
FEDORA-2024-a5ef56504d (gcc-13.2.1-7.fc38) has been submitted as an update to Fedora 38.
https://bodhi.fedoraproject.org/updates/FEDORA-2024-a5ef56504d
Comment 7 Fedora Update System 2024-03-18 03:22:04 UTC 
FEDORA-2024-a5ef56504d has been pushed to the Fedora 38 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2024-a5ef56504d`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2024-a5ef56504d

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 8 Fedora Update System 2024-03-24 01:35:43 UTC 
FEDORA-2024-a5ef56504d (gcc-13.2.1-7.fc38) has been pushed to the Fedora 38 stable repository.
If problem still persists, please make note of it in this bug report.