JDK-8315088 : C2: assert(wq.size() - before == EMPTY_LOOP_SIZE) failed: expect the EMPTY_LOOP_SIZE nodes of this body if empty
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 21,22
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2023-08-28
  • Updated: 2023-10-23
  • Resolved: 2023-09-05
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JDK 22
22 b14Fixed
Related Reports
Relates :  
JDK-8297724 - Loop strip mining prevents some empty loops from being eliminated
Description
The following Java Fuzzer test starts to fail after JDK-8297724:

To reproduce:
$ java -XX:CompileCommand=compileonly,Test::* -XX:-TieredCompilation Test.java
$ java -Xbatch -XX:CompileCommand=compileonly,Reduced::* -XX:-TieredCompilation Reduced.java

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/opt/mach5/mesos/work_dir/slaves/cd627e65-f015-4fb1-a1d2-b6c9b8127f98-S141865/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/8a11c2a6-dc3b-42a8-a1bf-5f4afa468e45/runs/9fc53209-cfb4-45ef-bad1-2b89080d866c/workspace/open/src/hotspot/share/opto/loopTransform.cpp:3540), pid=1765465, tid=1765479
#  assert(wq.size() - before == EMPTY_LOOP_SIZE) failed: expect the EMPTY_LOOP_SIZE nodes of this body if empty
#
# JRE version: Java(TM) SE Runtime Environment (22.0) (fastdebug build 22-internal-2023-08-25-1459578.christian.hagedorn.jdk)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 22-internal-2023-08-25-1459578.christian.hagedorn.jdk, mixed mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0x126fb18]  IdealLoopTree::collect_loop_core_nodes(PhaseIdealLoop*, Unique_Node_List&) const+0x348
.............
Command Line: -XX:CompileCommand=quiet -XX:-TieredCompilation Test
.............
Stack: [0x00007f123d399000,0x00007f123d499000],  sp=0x00007f123d493a40,  free space=1002k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0x126fb18]  IdealLoopTree::collect_loop_core_nodes(PhaseIdealLoop*, Unique_Node_List&) const+0x348  (loopTransform.cpp:3540)
V  [libjvm.so+0x126fbbf]  IdealLoopTree::enqueue_data_nodes(PhaseIdealLoop*, Unique_Node_List&, Unique_Node_List&) const+0x1f
V  [libjvm.so+0x126fe23]  IdealLoopTree::process_safepoint(PhaseIdealLoop*, Unique_Node_List&, Unique_Node_List&, Node*) const+0x113
V  [libjvm.so+0x1270310]  IdealLoopTree::empty_loop_with_data_nodes(PhaseIdealLoop*) const [clone .part.0]+0x490
V  [libjvm.so+0x12710f5]  IdealLoopTree::do_remove_empty_loop(PhaseIdealLoop*) [clone .part.0]+0x9b5
V  [libjvm.so+0x12a3411]  PhaseIdealLoop::build_and_optimize()+0xec1
V  [libjvm.so+0x9ef5d9]  PhaseIdealLoop::optimize(PhaseIterGVN&, LoopOptsMode)+0x3b9
V  [libjvm.so+0x9ea590]  Compile::Optimize()+0x820
V  [libjvm.so+0x9ee3a0]  Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x1bb0
V  [libjvm.so+0x84949b]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x13b
V  [libjvm.so+0x9fa2b7]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x977
V  [libjvm.so+0x9faff8]  CompileBroker::compiler_thread_loop()+0x5f8
V  [libjvm.so+0xeb65cc]  JavaThread::thread_main_inner()+0xcc
V  [libjvm.so+0x17a09fa]  Thread::call_run()+0xba
V  [libjvm.so+0x149fe9a]  thread_native_entry(Thread*)+0x12a
Comments
[jdk21u-fix-request] Approval Request from Aleksey Shipilëv Clean backport to fix JDK 21 regression. The change was in mainline for 1.5 months, and there is no recorded bugtail.
20-10-2023
A pull request was submitted for review. URL: https://git.openjdk.org/jdk21u/pull/275 Date: 2023-10-20 08:34:18 +0000
20-10-2023
Changeset: fe4f9002 Author: Roland Westrelin <roland@openjdk.org> Date: 2023-09-05 07:32:51 +0000 URL: https://git.openjdk.org/jdk/commit/fe4f90021ffd44cb0af34f39d4ca0a7e44605c92
05-09-2023
A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/15520 Date: 2023-08-31 15:54:50 +0000
31-08-2023
[~roland] can you have a look?
28-08-2023
ILW = Assertion failure when removing an empty loop, single Java Fuzzer test, possibly disable compilation of affected method = HLM = P3
28-08-2023