RFR: 8261731: shallow copy the internal buffer of a scalar-replaced java.lang.String object

[Volker Simonis]

Thanks for the quick confirmation.

On Thu, Mar 4, 2021 at 11:57 AM Tobias Hartmann
<thartmann at openjdk.java.net> wrote:
>
> On Thu, 4 Mar 2021 10:02:31 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:
>
> >> I didn't look at the code yet but run this through some quick testing. The following tests fail with `-ea -esa -XX:CompileThreshold=100:`
> >> - compiler/codecache/stress/RandomAllocationTest.java
> >> - compiler/codecache/stress/UnexpectedDeoptimizationTest.java
> >> #  Internal Error (open/src/hotspot/share/opto/node.hpp:825), pid=27269, tid=27288
> >> #  assert(is_AllocateArray()) failed: invalid node class: IfTrue
> >>
> >> Current CompileTask:
> >> C2:  12403 2987       4       java.lang.Class::descriptorString (160 bytes)
> >>
> >> Stack: [0x00007fc080bfc000,0x00007fc080cfd000],  sp=0x00007fc080cf8340,  free space=1008k
> >> Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
> >> V  [libjvm.so+0x1302c8c]  PhaseMacroExpand::scalar_replacement(AllocateNode*, GrowableArray<SafePointNode*>&)+0x88c
> >> V  [libjvm.so+0x1303e5e]  PhaseMacroExpand::eliminate_allocate_node(AllocateNode*) [clone .part.0]+0x50e
> >> V  [libjvm.so+0x130447c]  PhaseMacroExpand::eliminate_macro_nodes()+0x57c
> >> V  [libjvm.so+0xa0fbb5]  Compile::Optimize()+0x1235
> >> V  [libjvm.so+0xa11c85]  Compile::Compile(ciEnv*, ciMethod*, int, bool, bool, bool, bool, DirectiveSet*)+0x1905
> >> V  [libjvm.so+0x83d69a]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x1ea
> >> V  [libjvm.so+0xa21aa1]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0xf21
> >> V  [libjvm.so+0xa22748]  CompileBroker::compiler_thread_loop()+0x5a8
> >> V  [libjvm.so+0x18488e1]  JavaThread::thread_main_inner()+0x271
> >> V  [libjvm.so+0x1850b30]  Thread::call_run()+0x100
> >> V  [libjvm.so+0x153b086]  thread_native_entry(Thread*)+0x116
> >
> > java/lang/String/Split.java and java/lang/management/MemoryMXBean/LowMemoryTest2.sh fail with:
> > #  Internal Error (open/src/hotspot/share/opto/macro.cpp:1378), pid=5320, tid=5499
> > #  assert(n->Opcode() == Op_LoadUB || n->Opcode() == Op_LoadB) failed: unknow code shape
> >
> > Current CompileTask:
> > C2:  11623  994   !   4       Split::main (651 bytes)
> >
> > Stack: [0x00007ff1869fe000,0x00007ff186aff000],  sp=0x00007ff186afa2d0,  free space=1008k
> > Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
> > V  [libjvm.so+0x12f8a5f]  PhaseMacroExpand::process_users_of_string_allocation(AllocateArrayNode*, ArrayCopyNode*)+0x83f
> > V  [libjvm.so+0x1303e0e]  PhaseMacroExpand::eliminate_allocate_node(AllocateNode*) [clone .part.0]+0x4be
> > V  [libjvm.so+0x130447c]  PhaseMacroExpand::eliminate_macro_nodes()+0x57c
> > V  [libjvm.so+0xa0fbb5]  Compile::Optimize()+0x1235
> > V  [libjvm.so+0xa11c85]  Compile::Compile(ciEnv*, ciMethod*, int, bool, bool, bool, bool, DirectiveSet*)+0x1905
> > V  [libjvm.so+0x83d69a]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x1ea
> > V  [libjvm.so+0xa21aa1]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0xf21
> > V  [libjvm.so+0xa22748]  CompileBroker::compiler_thread_loop()+0x5a8
> > V  [libjvm.so+0x18488e1]  JavaThread::thread_main_inner()+0x271
> > V  [libjvm.so+0x1850b30]  Thread::call_run()+0x100
> > V  [libjvm.so+0x153b086]  thread_native_entry(Thread*)+0x116
> >
> >
> > And I see some internal testing failing with SIGSEGV in `PhaseMacroExpand::eliminate_allocate_node`
>
> Yes, I've used the latest version for testing.
>
> -------------
>
> PR: https://git.openjdk.java.net/jdk/pull/2570