JDK-8372274 : [lworld] C2: assert(_inputs.at(alias_idx) == nullptr) failed: did not yet touch this slice
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: repo-valhalla
  • Priority: P3
  • Status: In Progress
  • Resolution: Unresolved
  • Submitted: 2025-11-20
  • Updated: 2025-11-24
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repo-valhallaUnresolved
Related Reports
Relates :  
JDK-8371603 - assert(_inputs.at(alias_idx) == nullptr || _inputs.at(alias_idx) == load->in(1)) failed
Description
The attached Java Fuzzer test fails with the following assertion. It could be related to JDK-8371603 which is currently also failing in mainline. However, the reproducer does not trigger in mainline.

To reproduce:
$ java -XX:CompileCommand=compileonly,*Test*::mainTest* -XX:-TieredCompilation -Xcomp -XX:+StressIGVN -XX:+StressCCP -XX:+StressLoopPeeling -XX:RepeatCompilation=500 Test.java
$ java -XX:CompileOnly=Reduced::test -XX:-TieredCompilation -Xcomp -XX:+StressIGVN -XX:+StressCCP -XX:+StressLoopPeeling -XX:RepeatCompilation=500 Reduced.java

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/opt/mach5/mesos/work_dir/slaves/526fbd26-20de-495c-9a19-a04adc16f7d1-S25912/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/e0a93070-fe55-4f3e-900d-17459a379e58/runs/1314d7e8-2d48-4d43-aac9-59676eeab5b4/workspace/open/src/hotspot/share/opto/vectorization.cpp:222), pid=268681, tid=268700
#  assert(_inputs.at(alias_idx) == nullptr) failed: did not yet touch this slice
#
# JRE version: Java(TM) SE Runtime Environment (26.0+1) (fastdebug build 26-valhalla+1-125)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 26-valhalla+1-125, compiled mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0x1d16a3a]  VLoopMemorySlices::find_memory_slices()+0x41a
..............
Command Line: -XX:CompileOnly=Reduced::test -XX:-TieredCompilation -Xcomp -XX:+StressIGVN -XX:+StressCCP -XX:+StressLoopPeeling -XX:RepeatCompilation=500 --add-modules=ALL-DEFAULT jdk.compiler/com.sun.tools.javac.launcher.SourceLauncher Reduced.java
..............
Current CompileTask:
C2:1098  107    b        Reduced::test (84 bytes)

Stack: [0x00007f61a31f3000,0x00007f61a32f3000],  sp=0x00007f61a32ed5e0,  free space=1001k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0x1d16a3a]  VLoopMemorySlices::find_memory_slices()+0x41a  (vectorization.cpp:222)
V  [libjvm.so+0x1d1eac4]  VLoopAnalyzer::setup_submodules_helper()+0x74
V  [libjvm.so+0x1d1eb54]  VLoopAnalyzer::setup_submodules()+0x44
V  [libjvm.so+0x166d689]  PhaseIdealLoop::auto_vectorize(IdealLoopTree*, VSharedData&)+0x999
V  [libjvm.so+0x164bd90]  PhaseIdealLoop::build_and_optimize()+0xf40
V  [libjvm.so+0xbe6850]  PhaseIdealLoop::optimize(PhaseIterGVN&, LoopOptsMode)+0x4c0
V  [libjvm.so+0xbdd3d4]  Compile::optimize_loops(PhaseIterGVN&, LoopOptsMode)+0xb4
V  [libjvm.so+0xbe0814]  Compile::Optimize()+0x10b4
V  [libjvm.so+0xbe3505]  Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x1da5
V  [libjvm.so+0x9dcf50]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x4e0
V  [libjvm.so+0xbf2e34]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x854
V  [libjvm.so+0xbf45c0]  CompileBroker::compiler_thread_loop()+0x530
V  [libjvm.so+0x1190c3b]  JavaThread::thread_main_inner()+0x13b
V  [libjvm.so+0x1c69f26]  Thread::call_run()+0xb6
V  [libjvm.so+0x18957c8]  thread_native_entry(Thread*)+0x128