Tests:
compiler/unsafe/GetUnsafeObjectG1PreBarrier.java
compiler/c2/TestNPEHeapBased.java
java/lang/instrument/GetObjectSizeIntrinsicsTest.java#id7
java/lang/instrument/GetObjectSizeIntrinsicsTest.java#id6

Product tested: JDK-21.0.1+2 (ATR run), regression happening from jdk-21+23
OS/architecture: Linux-x64-debug, not seen in product build
Reproducible: Always with below jvm-args
Is it a Regression: yes, started from jdk-21+23 with the introduction of ZGenerational ZGC
Is it a platform-specific issue: Not sure, currently seen only with linux-x64-debug.


Error:
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/opt/mach5/mesos/work_dir/slaves/cd627e65-f015-4fb1-a1d2-b6c9b8127f98-S75332/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/9f54ee97-f028-4eeb-8d9f-e71282916f83/runs/7a6c13e7-18c4-47c0-803f-9564e908be6a/workspace/open/src/hotspot/cpu/x86/gc/z/zAddress_x86.inline.hpp:35), pid=2718529, tid=2718532
# assert(index == 0 || is_power_of_2(index)) failed: Incorrect load shift: 11
#
# JRE version: Java(TM) SE Runtime Environment (21.0.1+2) (fastdebug build 21.0.1-ea+2-LTS-6)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 21.0.1-ea+2-LTS-6, compiled mode, tiered, compressed class ptrs, z gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x5f0841] ZPointer::load_shift_lookup(unsigned long)+0x61
#
# Core dump will be written. Default location: Core dumps may be processed with "/opt/core.sh %p" (or dumping to /opt/mach5/mesos/work_dir/slaves/cd627e65-f015-4fb1-a1d2-b6c9b8127f98-S75487/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b5a7a9b7-646f-4048-af4e-631e65e44fe7/runs/511c385e-5ad4-464a-81d8-dea39b7f0e83/testoutput/test-support/jtreg_open_test_hotspot_jtreg_hotspot_compiler_all_gcs/scratch/4/core.2718529)
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#