shenandoah c2 compiler crash in jdk8

[Roman Kennke]

Hello Nick,

thanks for reporting the problem!

Yes, it is possible and likely that Shenandoah needs more nodes in C2
than CMS. We will investigate the problem next week.

Thanks and best regards,
Roman

> It stops crashing if I add `-XX:MaxNodeLimit=100000` option.. Is it
> true
> that Shenandoah needs substantially more nodes compared to CMS? If
> so,
> default (75000) probably needs to be adjusted... as crash in release
> version has less than obvious stacktrace
> 
> Pls confirm it's not a bug :)
> 
> On Fri, 30 Oct 2020 at 21:16, Nick Evgeniev <nevgeniev at gmail.com>
> wrote:
> 
> > hi,
> > 
> > pls disregard previous email it's not related to existing jdk bug
> > 
> > #
> > # A fatal error has been detected by the Java Runtime Environment:
> > #
> > #  Internal Error
> > (/home/buildbot/worker/build-jdk8u-redhat-
> > linux/build/hotspot/src/share/vm/opto/node.cpp:75),
> > pid=101496, tid=0x00007fd2b0cb1700
> > #  assert(Compile::current()->live_nodes() <
> > Compile::current()->max_node_limit()) failed: Live Node limit
> > exceeded limit
> > #
> > # JRE version: OpenJDK Runtime Environment (8.0) (build
> > 1.8.0-builds.shipilev.net-openjdk-jdk8-redhat-b175-20201026-debug-
> > testing-b00)
> > # Java VM: OpenJDK 64-Bit Server VM (25.71-b00-debug mixed mode
> > linux-amd64 compressed oops)
> > # Core dump written. Default location:
> > /home/e21170/Downloads/core/segv/core or core.101496
> > #
> > # If you would like to submit a bug report, please visit:
> > #   http://bugreport.java.com/bugreport/crash.jsp
> > #
> > 
> > ---------------  T H R E A D  ---------------
> > 
> > Current thread (0x00007fd2ac204830):  JavaThread "C2
> > CompilerThread0"
> > daemon [_thread_in_native, id=101889,
> > stack(0x00007fd2b0bb2000,0x00007fd2b0cb2000)]
> > 
> > Stack:
> > [0x00007fd2b0bb2000,0x00007fd2b0cb2000],  sp=0x00007fd2b0cab2a0,
> >  free space=996k
> > Native frames: (J=compiled Java code, j=interpreted, Vv=VM code,
> > C=native
> > code)
> > V  [libjvm.so+0xe0a497]  VMError::report(outputStream*)+0xf0d
> > V  [libjvm.so+0xe0b903]  VMError::report_and_die()+0x475
> > V  [libjvm.so+0x68cef0]  report_vm_error(char const*, int, char
> > const*,
> > char const*)+0xa5
> > V  [libjvm.so+0xb92ec3]  Node::verify_construction()+0x155
> > V  [libjvm.so+0xb93d18]  Node::Node(Node*, Node*)+0x62
> > V  [libjvm.so+0x3dc8a1]  CastX2PNode::CastX2PNode(Node*)+0x25
> > V  [libjvm.so+0xd1381f]
> >  ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop*)+0x2629
> > V  [libjvm.so+0xab474c]  PhaseIdealLoop::build_and_optimize(bool,
> > bool)+0xc82
> > V  [libjvm.so+0x61eb88]  PhaseIdealLoop::PhaseIdealLoop(PhaseIterGV
> > N&,
> > bool, bool)+0xac
> > V  [libjvm.so+0xd0b2b9]  ShenandoahBarrierC2Support::expand(Compile
> > *,
> > PhaseIterGVN&)+0x67
> > V  [libjvm.so+0x614694]  Compile::Optimize()+0xf22
> > V  [libjvm.so+0x60dc0e]  Compile::Compile(ciEnv*, C2Compiler*,
> > ciMethod*,
> > int, bool, bool, bool)+0x12ba
> > V  [libjvm.so+0x53f1ad]  C2Compiler::compile_method(ciEnv*,
> > ciMethod*,
> > int)+0x119
> > V  [libjvm.so+0x626c2f]
> >  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x4d3
> > V  [libjvm.so+0x626051]  CompileBroker::compiler_thread_loop()+0x32
> > b
> > V  [libjvm.so+0xdae72c]  compiler_thread_entry(JavaThread*,
> > Thread*)+0x57
> >