JDK-8373569 : C2: assert(is_Call()) failed: invalid node class: Region
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 26
  • Priority: P3
  • Status: Closed
  • Resolution: Duplicate
  • Submitted: 2025-12-12
  • Updated: 2025-12-12
  • Resolved: 2025-12-12
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JDK 26
26Resolved
Related Reports
Causes :  
JDK-8354383 - C2: enable sinking of Type nodes out of loop
Duplicate :  
JDK-8373508 - C2: assert(local == C->top()) failed: LocArray collision
Relates :  
JDK-8370562 - Whitebox Fuzzer for C2
Description
Found by Olivier Mattmann <olivier.mattmann@bluewin.ch> during work on this Master thesis where he is working on a fuzzer for C2 ( JDK-8370562).

The attached reproducer Test.java starts failing after JDK-8354383.

java -Xbatch -XX:-TieredCompilation -XX:CompileCommand=compileonly,Test.test -XX:-UseOnStackReplacement Test.java
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/src/jdk/src/hotspot/share/opto/node.hpp:916), pid=50011, tid=50026
#  assert(is_Call()) failed: invalid node class: Region
#
# JRE version: Java(TM) SE Runtime Environment (27.0) (fastdebug build 27-internal-mhassig.open)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 27-internal-mhassig.open, mixed mode, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0xa2cd54]  CreateExNode::Identity(PhaseGVN*)+0x2e4

Current CompileTask:
C2:1801  102   !b        Test::test (125 bytes)

Stack: [0x00007f71740ca000,0x00007f71741ca000],  sp=0x00007f71741c4d00,  free space=1003k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0xa2cd54]  CreateExNode::Identity(PhaseGVN*)+0x2e4  (node.hpp:916)
V  [libjvm.so+0x189189c]  PhaseIterGVN::transform_old(Node*)+0x3cc  (phaseX.cpp:2178)
V  [libjvm.so+0x18960b5]  PhaseIterGVN::optimize()+0xc5  (phaseX.cpp:1054)
V  [libjvm.so+0xbb50a2]  PhaseIdealLoop::optimize(PhaseIterGVN&, LoopOptsMode)+0x672  (loopnode.hpp:1344)
V  [libjvm.so+0xbabe61]  Compile::optimize_loops(PhaseIterGVN&, LoopOptsMode)+0xb1  (compile.cpp:2266)
V  [libjvm.so+0xbaed8f]  Compile::Optimize()+0xcbf  (compile.cpp:2515)
V  [libjvm.so+0xbb1f33]  Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x2023  (compile.cpp:860)
V  [libjvm.so+0x9cc6e8]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x498  (c2compiler.cpp:147)
V  [libjvm.so+0xbc1420]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x780  (compileBroker.cpp:2345)
V  [libjvm.so+0xbc2c80]  CompileBroker::compiler_thread_loop()+0x530  (compileBroker.cpp:1989)
V  [libjvm.so+0x1124d7b]  JavaThread::thread_main_inner()+0x13b  (javaThread.cpp:776)
V  [libjvm.so+0x1ba9036]  Thread::call_run()+0xb6  (thread.cpp:242)
V  [libjvm.so+0x17fe7d8]  thread_native_entry(Thread*)+0x118  (os_linux.cpp:860)
Comments
This one appears to be a duplicate. Fix for the other issue makes the crash go away.
12-12-2025
Roland, could you please take a look? Thanks.
12-12-2025
ILW = Assert during C2 compilation due to unexpected node type, reproducible with fuzzer generated test, no workaround but disable compilation of affected method = HLM = P3
12-12-2025