RFR: 8305189: C2 failed "assert(_outcnt==1) failed: not unique" [v2]

[Roland Westrelin]

On Mon, 15 May 2023 13:39:12 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   review
>
> I see the following failure with `TestMissingMulLOptimization` from JDK-8299546 and `-XX:StressLongCountedLoop=2000000`:
> 
> 
> # A fatal error has been detected by the Java Runtime Environment:
> #
> #  Internal Error (c:\sb\prod\1684151031\workspace\open\src\hotspot\share\opto\loopnode.cpp:4157), pid=5368, tid=836
> #  Error: assert(loop == nullptr) failed
> 
> Current CompileTask:
> C2:    267   15    b  4       compiler.ccp.TestMissingMulLOptimization::test (101 bytes)
> 
> Stack: [0x0000002f4f600000,0x0000002f4f700000]
> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
> V  [jvm.dll+0xc53091]  os::win32::platform_print_native_stack+0xf1  (os_windows_x86.cpp:236)
> V  [jvm.dll+0xee2a99]  VMError::report+0x1019  (vmError.cpp:815)
> V  [jvm.dll+0xee4775]  VMError::report_and_die+0x645  (vmError.cpp:1596)
> V  [jvm.dll+0xee4e84]  VMError::report_and_die+0x64  (vmError.cpp:1361)
> V  [jvm.dll+0x55053b]  report_vm_error+0x5b  (debug.cpp:191)
> V  [jvm.dll+0xadcab2]  PhaseIdealLoop::eliminate_useless_zero_trip_guard+0x2f2  (loopnode.cpp:4157)
> V  [jvm.dll+0xad0fb1]  PhaseIdealLoop::build_and_optimize+0x971  (loopnode.cpp:4455)
> V  [jvm.dll+0x4ebc51]  Compile::optimize_loops+0x1d1  (compile.cpp:2155)
> V  [jvm.dll+0x4de2e8]  Compile::Optimize+0xef8  (compile.cpp:2391)
> V  [jvm.dll+0x4db378]  Compile::Compile+0x1458  (compile.cpp:840)
> V  [jvm.dll+0x3f05ba]  C2Compiler::compile_method+0x11a  (c2compiler.cpp:121)
> V  [jvm.dll+0x4f6a81]  CompileBroker::invoke_compiler_on_method+0x881  (compileBroker.cpp:2268)
> V  [jvm.dll+0x4f3ea6]  CompileBroker::compiler_thread_loop+0x396  (compileBroker.cpp:1945)
> V  [jvm.dll+0x7f2ff9]  JavaThread::thread_main_inner+0x279  (javaThread.cpp:720)
> V  [jvm.dll+0xe5434d]  Thread::call_run+0x1cd  (thread.cpp:222)
> V  [jvm.dll+0xc519c2]  os::win32::thread_native_entry+0xa2  (os_windows.cpp:551)

@TobiHartmann thanks for the review

-------------

PR Comment: https://git.openjdk.org/jdk/pull/13901#issuecomment-1564060406