Bug 508456 - Illegal instruction detected (SIGILL) at pcmpistrm
Summary: Illegal instruction detected (SIGILL) at pcmpistrm
Status: REPORTED
Alias: None
Product: valgrind
Classification: Developer tools
Component: memcheck (other bugs)
Version First Reported In: 3.18.1
Platform: Ubuntu Other
: NOR normal
Target Milestone: ---
Assignee: Julian Seward
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-08-19 10:31 UTC by Salis
Modified: 2025-08-27 08:30 UTC (History)
1 user (show)

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Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:

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Description Salis 2025-08-19 10:31:02 UTC 
SUMMARY

Illegal instruction detected (SIGILL) when running a test under Valgrind. It is generating an error at following instruction - 

pcmpistrm $72,%%xmm6, %%xmm8;

STEPS TO REPRODUCE
1. The program was run with following Valgrind options- 

valgrind --tool=memcheck --verbose --track-origins=yes --leak-check=full --num-callers=48 --vgdb=yes --read-var-info=yes

OBSERVED RESULT
SIGNALS:Illegal instruction detected (SIGILL). System shutting down.

EXPECTED RESULT


SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Ubuntu 22.04.3 LTS

ADDITIONAL INFORMATION

For reference, similar issue was described in https://bugs.kde.org/show_bug.cgi?id=348574
and handled in https://sourceware.org/git/?p=valgrind.git;a=commitdiff;h=46b6196f0de49ad0e4267989ca5613f907ccfc5f

It seems the control byte being used i.e $72 (i.e. $0x48) is not handled here.
Comment 1 Paul Floyd 2025-08-27 08:30:48 UTC 
Do you have a testcase to reproduce the issue?