box and val (c2 crash)

Tobias Hartmann tobias.hartmann at oracle.com
Tue Jan 8 16:16:02 UTC 2019


Hi Remi,

I've fixed the issue with:
http://hg.openjdk.java.net/valhalla/valhalla/rev/530ea41023b2

Please let me know if you still see crashes with your benchmarks.

Thanks,
Tobias


On 07.01.19 17:37, Tobias Hartmann wrote:
> Thanks Remi! I've filed https://bugs.openjdk.java.net/browse/JDK-8216270 and will work on a fix.
> 
> Best regards,
> Tobias
> 
> On 07.01.19 14:16, forax at univ-mlv.fr wrote:
>> Hi Tobias,
>> it solves the second issue i've reported but not the first one,
>> (the issue in TypePtr::xmeet_helper(Type const*)),
>> so it still crashes.
>>
>> with 12-valhalla+0-09d9f9085910:
>>
>> Current CompileTask:
>> C2:    325  120             fr.umlv.valuetype.perf.TupleLoopBenchMark::sum (46 bytes)
>>
>> Stack: [0x00007f53541cd000,0x00007f53542ce000],  sp=0x00007f53542ca700,  free space=1013k
>> Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
>> V  [libjvm.so+0xe1a0a6]  VMError::report_and_die(int, char const*, char const*, __va_list_tag*, Thread*, unsigned char*, void*, void*, char const*, int, unsigned long)+0x186
>> V  [libjvm.so+0xe1ae57]  VMError::report_and_die(Thread*, void*, char const*, int, char const*, char const*, __va_list_tag*)+0x47
>> V  [libjvm.so+0x67a7fe]  report_vm_error(char const*, int, char const*, char const*, ...) [clone .constprop.51]+0xee
>> V  [libjvm.so+0xdbc50e]  TypePtr::xmeet_helper(Type const*) const+0x5e
>> V  [libjvm.so+0xdb8250]  TypePtr::xmeet(Type const*) const+0x10
>> V  [libjvm.so+0x556611]  PhiNode::Value(PhaseGVN*) const+0x131
>> V  [libjvm.so+0xc38af6]  PhaseGVN::transform_no_reclaim(Node*)+0x86
>> V  [libjvm.so+0xc00d9d]  Parse::do_exits()+0x4bd
>> V  [libjvm.so+0xc05d86]  Parse::Parse(JVMState*, ciMethod*, float)+0xab6
>> V  [libjvm.so+0x53db98]  ParseGenerator::generate(JVMState*)+0x88
>> V  [libjvm.so+0x70f9ed]  Parse::do_call()+0x2dd
>> V  [libjvm.so+0xc15b08]  Parse::do_one_bytecode()+0x32e8
>> V  [libjvm.so+0xc031e7]  Parse::do_one_block()+0x197
>> V  [libjvm.so+0xc03652]  Parse::do_all_blocks()+0x102
>> V  [libjvm.so+0xc05d40]  Parse::Parse(JVMState*, ciMethod*, float)+0xa70
>> V  [libjvm.so+0x53db98]  ParseGenerator::generate(JVMState*)+0x88
>> V  [libjvm.so+0x61bc28]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool, DirectiveSet*)+0xe98
>> V  [libjvm.so+0x53d096]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0xe6
>> V  [libjvm.so+0x6242f2]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x3a2
>> V  [libjvm.so+0x625738]  CompileBroker::compiler_thread_loop()+0x608
>> V  [libjvm.so+0xda4468]  JavaThread::thread_main_inner()+0xf8
>> V  [libjvm.so+0xda1131]  Thread::call_run()+0x171
>> V  [libjvm.so+0xbd5708]  thread_native_entry(Thread*)+0xf8
>>
>> cheers,
>> Rémi
>>
>> ----- Mail original -----
>>> De: "Tobias Hartmann" <tobias.hartmann at oracle.com>
>>> À: "Remi Forax" <forax at univ-mlv.fr>, "valhalla-dev" <valhalla-dev at openjdk.java.net>
>>> Envoyé: Lundi 7 Janvier 2019 10:55:51
>>> Objet: Re: box and val (c2 crash)
>>
>>> Hi Remi,
>>>
>>> I fixed the issue with JDK-8216260:
>>> http://hg.openjdk.java.net/valhalla/valhalla/rev/09d9f9085910
>>>
>>> The problem was that we tried to scalarize a boxed value type return which
>>> obviously fails if null
>>> is returned. Could you please verify that the fix solves the crashes you were
>>> seeing?
>>>
>>> Thanks,
>>> Tobias
>>>
>>> On 04.01.19 15:25, Tobias Hartmann wrote:
>>>> Hi Remi,
>>>>
>>>> thanks a lot for reporting these issues. I'll have a look!
>>>>
>>>> Best regards,
>>>> Tobias
>>>>
>>>>
>>>> On 04.01.19 15:14, Remi Forax wrote:
>>>>> I believe the crash comes from the method "next()" (or indexedElements() because
>>>>> it the same kind of code),
>>>>>
>>>>>   Cursor.box next() {
>>>>>     if (index + 1 == array.length) {
>>>>>       return null;
>>>>>     }
>>>>>     return new Cursor(array, index + 1);
>>>>>   }
>>>>>
>>>>> There is a merge of either null or a Cursor (which is a value type) into a
>>>>> register typed Cursor.box.
>>>>>
>>>>> Trying to insert a local variable in between result in a crash in a different
>>>>> methods
>>>>>   Cursor.box next() {
>>>>>     Cursor.box box;
>>>>>     if (index + 1 == array.length) {
>>>>>       box = null;
>>>>>     } else {
>>>>>       box = new Cursor(array, index + 1);
>>>>>     }
>>>>>     return box;
>>>>>   }
>>>>>
>>>>> Current CompileTask:
>>>>> C2:    308  117
>>>>> fr.umlv.valuetype.perf.TupleLoopBenchMark$Cursor::next (38 bytes)
>>>>>
>>>>> Stack: [0x00007fb3b253c000,0x00007fb3b263d000],  sp=0x00007fb3b2639d00,  free
>>>>> space=1015k
>>>>> Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted,
>>>>> Vv=VM code, C=native code)
>>>>> V  [libjvm.so+0xde246f]  ValueTypeNode::make_from_oop(GraphKit*, Node*,
>>>>> ciValueKlass*)+0x9f
>>>>> V  [libjvm.so+0xc06567]  Parse::return_current(Node*)+0x8d7
>>>>> V  [libjvm.so+0xc14dc4]  Parse::do_one_bytecode()+0x2714
>>>>> V  [libjvm.so+0xc03077]  Parse::do_one_block()+0x197
>>>>> V  [libjvm.so+0xc034e2]  Parse::do_all_blocks()+0x102
>>>>> V  [libjvm.so+0xc05bd0]  Parse::Parse(JVMState*, ciMethod*, float)+0xa70
>>>>> V  [libjvm.so+0x53da48]  ParseGenerator::generate(JVMState*)+0x88
>>>>> V  [libjvm.so+0x61bab8]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int,
>>>>> bool, bool, bool, DirectiveSet*)+0xe98
>>>>> V  [libjvm.so+0x53cf46]  C2Compiler::compile_method(ciEnv*, ciMethod*, int,
>>>>> DirectiveSet*)+0xe6
>>>>> V  [libjvm.so+0x624182]
>>>>> CompileBroker::invoke_compiler_on_method(CompileTask*)+0x3a2
>>>>> V  [libjvm.so+0x6255c8]  CompileBroker::compiler_thread_loop()+0x608
>>>>> V  [libjvm.so+0xda42f8]  JavaThread::thread_main_inner()+0xf8
>>>>> V  [libjvm.so+0xda0fc1]  Thread::call_run()+0x171
>>>>> V  [libjvm.so+0xbd5598]  thread_native_entry(Thread*)+0xf8
>>>>>
>>>>> Rémi
>>>>>
>>>>> ----- Mail original -----
>>>>>> De: "Remi Forax" <forax at univ-mlv.fr>
>>>>>> À: "valhalla-dev" <valhalla-dev at openjdk.java.net>
>>>>>> Envoyé: Jeudi 3 Janvier 2019 16:14:22
>>>>>> Objet: box and val (c2 crash)
>>>>>
>>>>>> Now, i've tried to play with the .box/.val trying to implement the clojure
>>>>>> Cursor protocol,
>>>>>> which iterate like it's an abstract linked list, so at each step either you
>>>>>> return a new Cursor (a value type) or null at the end (which seems to be a good
>>>>>> test for a nullable value type).
>>>>>>
>>>>>> The following code compiles !
>>>>>> I had to had the fix method because the compier refuse to find any methods on
>>>>>> Cursor.box and
>>>>>>  Cursor.box boxed = ...
>>>>>>  ((Cursor)boxed).next
>>>>>> doesn't compile too.
>>>>>>
>>>>>> If you try to execute the code, it crashes the VM (in the C2 compiler thread it
>>>>>> seems)
>>>>>>
>>>>>> Current CompileTask:
>>>>>> C2:    338  119             fr.umlv.valuetype.perf.TupleLoopBenchMark::sum (46
>>>>>> bytes)
>>>>>>
>>>>>> Stack: [0x00007ff4c0a37000,0x00007ff4c0b38000],  sp=0x00007ff4c0b34700,  free
>>>>>> space=1013k
>>>>>> Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted,
>>>>>> Vv=VM code, C=native code)
>>>>>> V  [libjvm.so+0xe19ed6]  VMError::report_and_die(int, char const*, char const*,
>>>>>> __va_list_tag*, Thread*, unsigned char*, void*, void*, char const*, int,
>>>>>> unsigned long)+0x186
>>>>>> V  [libjvm.so+0xe1ac87]  VMError::report_and_die(Thread*, void*, char const*,
>>>>>> int, char const*, char const*, __va_list_tag*)+0x47
>>>>>> V  [libjvm.so+0x67a68e]  report_vm_error(char const*, int, char const*, char
>>>>>> const*, ...) [clone .constprop.51]+0xee
>>>>>> V  [libjvm.so+0xdbc39e]  TypePtr::xmeet_helper(Type const*) const+0x5e
>>>>>> V  [libjvm.so+0xdb80e0]  TypePtr::xmeet(Type const*) const+0x10
>>>>>> V  [libjvm.so+0x5564c1]  PhiNode::Value(PhaseGVN*) const+0x131
>>>>>> V  [libjvm.so+0xc38986]  PhaseGVN::transform_no_reclaim(Node*)+0x86
>>>>>> V  [libjvm.so+0xc00c2d]  Parse::do_exits()+0x4bd
>>>>>> V  [libjvm.so+0xc05c16]  Parse::Parse(JVMState*, ciMethod*, float)+0xab6
>>>>>> V  [libjvm.so+0x53da48]  ParseGenerator::generate(JVMState*)+0x88
>>>>>> V  [libjvm.so+0x70f87d]  Parse::do_call()+0x2dd
>>>>>> V  [libjvm.so+0xc15998]  Parse::do_one_bytecode()+0x32e8
>>>>>> V  [libjvm.so+0xc03077]  Parse::do_one_block()+0x197
>>>>>> V  [libjvm.so+0xc034e2]  Parse::do_all_blocks()+0x102
>>>>>> V  [libjvm.so+0xc05bd0]  Parse::Parse(JVMState*, ciMethod*, float)+0xa70
>>>>>> V  [libjvm.so+0x53da48]  ParseGenerator::generate(JVMState*)+0x88
>>>>>> V  [libjvm.so+0x61bab8]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int,
>>>>>> bool, bool, bool, DirectiveSet*)+0xe98
>>>>>> V  [libjvm.so+0x53cf46]  C2Compiler::compile_method(ciEnv*, ciMethod*, int,
>>>>>> DirectiveSet*)+0xe6
>>>>>> V  [libjvm.so+0x624182]
>>>>>> CompileBroker::invoke_compiler_on_method(CompileTask*)+0x3a2
>>>>>> V  [libjvm.so+0x6255c8]  CompileBroker::compiler_thread_loop()+0x608
>>>>>> V  [libjvm.so+0xda42f8]  JavaThread::thread_main_inner()+0xf8
>>>>>> V  [libjvm.so+0xda0fc1]  Thread::call_run()+0x171
>>>>>> V  [libjvm.so+0xbd5598]  thread_native_entry(Thread*)+0xf8
>>>>>>
>>>>>>
>>>>>> Rémi
>>>>>>
>>>>>> ---
>>>>>>  static value class Tuple {
>>>>>>    private final int index;
>>>>>>    private final int element;
>>>>>>    
>>>>>>    
>>>>>>    private Tuple(int index, int element) {
>>>>>>      this.index = index;
>>>>>>      this.element = element;
>>>>>>    }
>>>>>>  }
>>>>>>  
>>>>>>  static value class Cursor {
>>>>>>    private final int[] array;
>>>>>>    private final int index;
>>>>>>    
>>>>>>    private Cursor(int[] array, int index) {
>>>>>>      this.array = array;
>>>>>>      this.index = index;
>>>>>>    }
>>>>>>    
>>>>>>    Tuple current() {
>>>>>>      return new Tuple(index, array[index]);
>>>>>>    }
>>>>>>    
>>>>>>    Cursor.box next() {
>>>>>>      if (index + 1 == array.length) {
>>>>>>        return null;
>>>>>>      }
>>>>>>      return new Cursor(array, index + 1);
>>>>>>    }
>>>>>>  }
>>>>>>  
>>>>>>  private static Cursor.box indexedElements(int[] array) {
>>>>>>    if (array.length == 0) {
>>>>>>      return null;
>>>>>>    }
>>>>>>    return new Cursor(array, 0);
>>>>>>  }
>>>>>>  
>>>>>>  private static Cursor fix(Cursor.box cursor) {
>>>>>>    return cursor;
>>>>>>  }
>>>>>>  
>>>>>>  @Benchmark
>>>>>>  public int sum() {
>>>>>>    int sum = 0;
>>>>>>    for(Cursor.box cursor = indexedElements(ARRAY); cursor != null; cursor =
>>>>>>    fix(cursor).next()) {
>>>>>>      Tuple tuple = fix(cursor).current();
>>>>>>      sum += tuple.index + tuple.element;
>>>>>>    }
>>>>>>    return sum;
>>>>>>   }


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