There's an AVX-related crash during G1 in a compiler test, unsure if the cause is G1 or C1/C2. The only occurrence of this is a test run in my EnableValhalla -> --enable-preview feature branch without --enable-preview passed. I have not been able to reproduce it again, both on the branch and on lworld with -XX:-EnableValhalla. The crash appears to be unrelated to my changes.

#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007fc3920a53fa, pid=2345918, tid=2346701
#
# JRE version: Java(TM) SE Runtime Environment (26.0) (fastdebug build 26-jep401ea2-2025-12-11-1738491)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 26-jep401ea2-2025-12-11-1738491, mixed mode, tiered, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# C [libc.so.6+0xdf3fa] __memset_avx512_unaligned_erms+0x7a
#
# Core dump will be written. Default location: Core dumps may be processed with "/opt/core.sh %p" (or dumping to testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_compiler/scratch/1/core.2345918)
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#

--------------- S U M M A R Y ------------

Command Line: -Dtest.boot.jdk=jdk/25/37/bundles/linux-x64/jdk-25_linux-x64_bin.tar.gz/jdk-25 -Djava.io.tmpdir=testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_compiler/tmp -Djava.library.path=2025-12-11-1738491/linux-x64-debug.test/hotspot/jtreg/native --patch-module=java.base=testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_compiler/patches/java.base -Djava.security.policy=file:./testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_compiler/jtreg.policy com.sun.javatest.regtest.agent.AgentServer -id 87 -logfile testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_compiler/jtData/agentServer.87.trace -allowSetSecurityManager -port 49623 -timeoutFactor 4.0

Host: , AMD EPYC 9J14 96-Core Processor, 12 cores, 23G, Oracle Linux Server release 8.10
Time: Thu Dec 11 18:32:36 2025 UTC elapsed time: 28.928452 seconds (0d 0h 0m 28s)

--------------- T H R E A D ---------------

Current thread (0x00007fc35c000cc0): WorkerThread "G1 Conc#1" [id=2346701, stack(0x00007fc3598fa000,0x00007fc3599fa000) (1024K)]

Stack: [0x00007fc3598fa000,0x00007fc3599fa000], sp=0x00007fc3599f8d08, free space=1019k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [libc.so.6+0xdf3fa] __memset_avx512_unaligned_erms+0x7a
V [libjvm.so+0x175ee13] MarkBitMap::do_clear(MemRegion, bool)+0x83 (markBitMap.cpp:57)
V [libjvm.so+0xf1d96e] G1ClearBitMapTask::G1ClearBitmapHRClosure::do_heap_region(G1HeapRegion*)+0x4e (markBitMap.hpp:99)
V [libjvm.so+0xf98f5a] G1HeapRegionManager::par_iterate(G1HeapRegionClosure*, G1HeapRegionClaimer*, unsigned int) const+0x6a (g1HeapRegionManager.cpp:581)
V [libjvm.so+0xf1d7ea] G1ClearBitMapTask::work(unsigned int)+0x5a (g1ConcurrentMark.cpp:771)
V [libjvm.so+0x1e49b08] WorkerThread::run()+0x88 (workerThread.cpp:69)
V [libjvm.so+0x1cc5336] Thread::call_run()+0xb6 (thread.cpp:242)
V [libjvm.so+0x18e0c08] thread_native_entry(Thread*)+0x118 (os_linux.cpp:862)