Bug 508456

Summary:	Illegal instruction detected (SIGILL) at pcmpistrm
Product:	[Developer tools] valgrind	Reporter:	Salis <salis.joshi>
Component:	memcheck	Assignee:	Julian Seward <jseward>
Status:	REPORTED ---
Severity:	normal	CC:	pjfloyd
Priority:	NOR
Version First Reported In:	3.18.1
Target Milestone:	---
Platform:	Ubuntu
OS:	Other
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

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?