RFR (XL): 8152664 - Support non-continuous CodeBlobs in HotSpot
Volker Simonis
volker.simonis at gmail.com
Mon Apr 11 14:16:33 UTC 2016
Rickard, Dean,
I'm afraid all this hacks can not work. It doesn't help to make
CompiledMethod::consts_begin() non-virtual and then calling a virtual
function from it. The problem ist that at the point where you call
consts_begin_v(), the vtable of 'this' is still the one of CodeBlob and
this results in calling yet another arbitrary function:
#0 CodeBlob::is_locked_by_vm (this=0x3fff607d0c10) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/codeBlob.hpp:168
#1 0x00003fffb6e38048 in CompiledMethod::consts_begin
(this=0x3fff607d0c10) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/compiledMethod.hpp:255
#2 0x00003fffb758d658 in RelocIterator::initialize (this=0x3ffdfd3fc9a8,
nm=0x3fff607d0c10, begin=0x3fff607d0fac "\001", limit=0x0) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.cpp:142
#3 0x00003fffb6ace56c in RelocIterator::RelocIterator
(this=0x3ffdfd3fc9a8, nm=0x3fff607d0c10, begin=0x3fff607d0fac "\001",
limit=0x0) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.hpp:1378
#4 0x00003fffb7591afc in trampoline_stub_Relocation::get_trampoline_for
(call=0x3fff607d0fac "\001", code=0x3fff607d0c10) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.cpp:849
#5 0x00003fffb741ba4c in NativeCall::get_trampoline (this=0x3fff607d0fac)
at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/cpu/ppc/vm/nativeInst_ppc.cpp:146
#6 0x00003fffb7596a34 in Relocation::pd_call_destination
(this=0x3ffdfd3fcd10, orig_addr=0x3fff6033482c "\001") at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/cpu/ppc/vm/relocInfo_ppc.cpp:87
#7 0x00003fffb758f71c in CallRelocation::fix_relocation_after_move
(this=0x3ffdfd3fcd10, src=0x3ffdfd3fdbc0, dest=0x3ffdfd3fcdd8) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.cpp:506
#8 0x00003fffb6c48914 in CodeBuffer::relocate_code_to
(this=0x3ffdfd3fdbc0, dest=0x3ffdfd3fcdd8) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/asm/codeBuffer.cpp:812
#9 0x00003fffb6c48480 in CodeBuffer::copy_code_to (this=0x3ffdfd3fdbc0,
dest_blob=0x3fff607d0c10) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/asm/codeBuffer.cpp:748
#10 0x00003fffb6c426ec in CodeBuffer::copy_code_and_locs_to
(this=0x3ffdfd3fdbc0, blob=0x3fff607d0c10) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/asm/codeBuffer.hpp:607
#11 0x00003fffb6c3f8b0 in CodeBlob::CodeBlob (this=0x3fff607d0c10,
name=0x3fffb7a760f8 "nmethod", layout=..., cb=0x3ffdfd3fdbc0,
frame_complete_offset=20, frame_size=14, oop_maps=0x3ffe0001ed00,
caller_must_gc_arguments=false, subtype=8) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/codeBlob.cpp:117
#12 0x00003fffb6ce5360 in CompiledMethod::CompiledMethod
(this=0x3fff607d0c10, method=0x3ffe1ddce568, name=0x3fffb7a760f8 "nmethod",
size=1768, header_size=392, cb=0x3ffdfd3fdbc0, frame_complete_offset=20,
frame_size=14, oop_maps=0x3ffe0001ed00, caller_must_gc_arguments=false) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/compiledMethod.cpp:42
#13 0x00003fffb7422198 in nmethod::nmethod (this=0x3fff607d0c10,
method=0x3ffe1ddce568, nmethod_size=1768, compile_id=4, entry_bci=-1,
offsets=0x3ffdfd3fdb98, orig_pc_offset=104, debug_info=0x3fffb03f2dc0,
dependencies=0x3ffe0001ed70, code_buffer=0x3ffdfd3fdbc0, frame_size=14,
oop_maps=0x3ffe0001ed00, handler_table=0x3ffdfd3fdb50,
nul_chk_table=0x3ffdfd3fdb70, compiler=0x3fffb03d0cd0, comp_level=3) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/nmethod.cpp:706
#14 0x00003fffb7421850 in nmethod::new_nmethod (method=..., compile_id=4,
entry_bci=-1, offsets=0x3ffdfd3fdb98, orig_pc_offset=104,
debug_info=0x3fffb03f2dc0, dependencies=0x3ffe0001ed70,
code_buffer=0x3ffdfd3fdbc0, frame_size=14, oop_maps=0x3ffe0001ed00,
handler_table=0x3ffdfd3fdb50, nul_chk_table=0x3ffdfd3fdb70,
compiler=0x3fffb03d0cd0, comp_level=3) at
/usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/nmethod.cpp:548
I think we really need to rework this as proposed by Andrew in his last
mail. I'm working on such a fix.
Regards,
Volker
On Mon, Apr 11, 2016 at 1:55 PM, Rickard Bäckman <rickard.backman at oracle.com
> wrote:
> Volker,
>
> here is the patch if you want to try it.
> http://cr.openjdk.java.net/~rbackman/8152664/virtual.patch
>
> /R
>
> On 04/11, Rickard Bäckman wrote:
> > Volker,
> >
> > thanks for finding this issue.
> >
> > I think that maybe the easiest fix is as follows:
> >
> > create new virtual methods in CompiledMethod:
> >
> > virtual address stub_begin_v() = 0;
> >
> > make the now virtual stub_begin non-virtual like:
> >
> > address stub_begin() { return stub_begin_v(); }
> >
> > in nmethod we override the stub_begin() with the normal this + offset
> > compuation and implement stub_begin_v() to call stub_begin().
> >
> > That will avoid all virtual calls in the case were we are not working on
> > a CompiledMethod.
> >
> > It adds a couple of methods though. What do you think?
> >
> > /R
> >
> > On 04/08, Volker Simonis wrote:
> > > Hi Rickard,
> > >
> > > I found the problem why your change crashes the VM on ppc (and I'm
> pretty
> > > sure it will also crash on ARM - @Andrew, maybe you can try it out?).
> It is
> > > caused by the following code in address NativeCall::get_trampoline()
> which
> > > is also present on arm64:
> > >
> > > address NativeCall::get_trampoline() {
> > > address call_addr = addr_at(0);
> > > CodeBlob *code = CodeCache::find_blob(call_addr);
> > > ...
> > > // If the codeBlob is not a nmethod, this is because we get here
> from the
> > > // CodeBlob constructor, which is called within the nmethod
> constructor.
> > > return trampoline_stub_Relocation::get_trampoline_for(call_addr,
> > > (nmethod*)code);
> > > }
> > >
> > > The comment explains the situation quite well: we're in the CodeBlob
> > > constructor which was called by the CompiledMethod constructor which
> was
> > > called from the nmethod constructor:
> > >
> > > #3 0x00003fffb741b80c in NativeCall::get_trampoline
> (this=0x3fff607d0fac)
> > > at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/cpu/ppc/vm/nativeInst_ppc.cpp:146
> > > #4 0x00003fffb7596914 in Relocation::pd_call_destination
> > > (this=0x3ffdfe3fcc90, orig_addr=0x3fff603b8a2c "\001") at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/cpu/ppc/vm/relocInfo_ppc.cpp:87
> > > #5 0x00003fffb758f5fc in CallRelocation::fix_relocation_after_move
> > > (this=0x3ffdfe3fcc90, src=0x3ffdfe3fdb40, dest=0x3ffdfe3fcd58) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.cpp:506
> > > #6 0x00003fffb6c48898 in CodeBuffer::relocate_code_to
> > > (this=0x3ffdfe3fdb40, dest=0x3ffdfe3fcd58) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/asm/codeBuffer.cpp:812
> > > #7 0x00003fffb6c48404 in CodeBuffer::copy_code_to
> (this=0x3ffdfe3fdb40,
> > > dest_blob=0x3fff607d0c10) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/asm/codeBuffer.cpp:748
> > > #8 0x00003fffb6c42670 in CodeBuffer::copy_code_and_locs_to
> > > (this=0x3ffdfe3fdb40, blob=0x3fff607d0c10) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/asm/codeBuffer.hpp:607
> > > #9 0x00003fffb6c3f834 in CodeBlob::CodeBlob (this=0x3fff607d0c10,
> > > name=0x3fffb7a75fd8 "nmethod", layout=..., cb=0x3ffdfe3fdb40,
> > > frame_complete_offset=20, frame_size=14, oop_maps=0x3ffe00049620,
> > > caller_must_gc_arguments=false, subtype=8) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/codeBlob.cpp:117
> > > #10 0x00003fffb6ce52c8 in CompiledMethod::CompiledMethod
> > > (this=0x3fff607d0c10, method=0x3ffe1ddce568, name=0x3fffb7a75fd8
> "nmethod",
> > > size=1768, header_size=392, cb=0x3ffdfe3fdb40,
> frame_complete_offset=20,
> > > frame_size=14, oop_maps=0x3ffe00049620,
> caller_must_gc_arguments=false) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/compiledMethod.cpp:42
> > > #11 0x00003fffb7421f58 in nmethod::nmethod (this=0x3fff607d0c10,
> > > method=0x3ffe1ddce568, nmethod_size=1768, compile_id=4, entry_bci=-1,
> > > offsets=0x3ffdfe3fdb18, orig_pc_offset=104, debug_info=0x3fffb03d55f0,
> > > dependencies=0x3ffe00049690, code_buffer=0x3ffdfe3fdb40, frame_size=14,
> > > oop_maps=0x3ffe00049620, handler_table=0x3ffdfe3fdad0,
> > > nul_chk_table=0x3ffdfe3fdaf0, compiler=0x3fffb03bc270, comp_level=3) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/nmethod.cpp:706
> > >
> > > Now we cast 'code' to 'nmethod' but at this point in time 'code' is
> still a
> > > CodeBlob from the C++ point of view (i.e. it still has a CodeBlob
> vtable
> > > (see [1] for an explanation)).
> > >
> > > Later on, in RelocIterator::initialize() we call virtual methods on the
> > > nmethod which still has the vtable of a "CodeBlob" and this fails
> badly:
> > >
> > > #0 SingletonBlob::print_on (this=0x3fff607d0c10, st=0x0) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/codeBlob.cpp:584
> > > #1 0x00003fffb758d51c in RelocIterator::initialize
> (this=0x3ffdfe3fc928,
> > > nm=0x3fff607d0c10, begin=0x3fff607d0fac "\001", limit=0x0) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.cpp:144
> > > #2 0x00003fffb6ace56c in RelocIterator::RelocIterator
> > > (this=0x3ffdfe3fc928, nm=0x3fff607d0c10, begin=0x3fff607d0fac "\001",
> > > limit=0x0) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.hpp:1378
> > > #3 0x00003fffb75919dc in
> trampoline_stub_Relocation::get_trampoline_for
> > > (call=0x3fff607d0fac "\001", code=0x3fff607d0c10) at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/share/vm/code/relocInfo.cpp:849
> > > #4 0x00003fffb741b80c in NativeCall::get_trampoline
> (this=0x3fff607d0fac)
> > > at
> > >
> /usr/work/d046063/OpenJDK/jdk9-hs-comp/hotspot/src/cpu/ppc/vm/nativeInst_ppc.cpp:146
> > >
> > > As you can see, we actually want to call nmethod::stub_begin() at
> > > relocInfo.cpp:144
> > >
> > > 142 _section_start[CodeBuffer::SECT_CONSTS] = nm->consts_begin();
> > > 143 _section_start[CodeBuffer::SECT_INSTS ] = nm->insts_begin() ;
> > > 144 _section_start[CodeBuffer::SECT_STUBS ] = nm->stub_begin() ;
> > >
> > > but we actually end up in SingletonBlob::print_on() which is a
> completely
> > > different method. Notice that the call to nm->consts_begin() before
> also
> > > fails, but it doesn't crash the VM because it happens to call
> > > SingletonBlob::verify() which has no bad side effect. The call to
> > > nm->insts_begin() in line 143 is non-virtual and thus works fine. Here
> are
> > > the corresponding vtable slots in the CodeBlob vtable for
> consts_begin()
> > > and stub_begin()
> > >
> > > (gdb) p &nmethod::consts_begin
> > > $76 = &virtual table offset 42
> > > (gdb) p &nmethod::stub_begin
> > > $77 = &virtual table offset 44
> > > (gdb) p ((*(void ***)nm) + 1)[42]
> > > $86 = (void *) 0x3fffb6c41df8 <SingletonBlob::verify()>
> > > (gdb) p ((*(void ***)nm) + 1)[44]
> > > $87 = (void *) 0x3fffb6c41e64 <SingletonBlob::print_on(outputStream*)
> const>
> > >
> > > As you can see, 'nm' is indeed a "CodeBlob" at this point:
> > >
> > > (gdb) p *(void ***)nm
> > > $91 = (void **) 0x3fffb7befa00 <vtable for CodeBlob+16>
> > > (gdb) p nm->print()
> > > [CodeBlob (0x00003fff607d1090)]
> > > Framesize: 14
> > >
> > > The offending calls succeeded before your change, because they where
> not
> > > virtual. Any idea how we can fix this with the new class hierarchy?
> > >
> > > Regards,
> > > Volker
> > >
> > > [1]
> > >
> http://stackoverflow.com/questions/6591859/when-does-the-vptr-pointing-to-vtable-get-initialized-for-a-polymorphic-class
> > >
> > >
> > >
> > > On Thu, Apr 7, 2016 at 5:50 PM, Volker Simonis <
> volker.simonis at gmail.com>
> > > wrote:
> > >
> > > > Hi Rickard,
> > > >
> > > > I'd also like to know what's the rational behind this quite large
> > > > change. Do you expect some performance or memory consumption
> > > > improvements or is this a prerequisite for another change which is
> > > > still to come?
> > > >
> > > > The change itself currently doesn't work on ppc64 (neither on Linux
> > > > nor on AIX). I get the following crash during the build when the
> newly
> > > > built Hotspot is JIT-compiling java.lang.String::charAt on C1 :
> > > >
> > > > #
> > > > # A fatal error has been detected by the Java Runtime Environment:
> > > > #
> > > > # SIGSEGV (0xb) at pc=0x00001000012a44d0, pid=35331, tid=35404
> > > > #
> > > > # JRE version: OpenJDK Runtime Environment (9.0) (slowdebug build
> > > > 9-internal+0-2016-04-07-162501.d046063.jdk9-hs-comp)
> > > > # Java VM: OpenJDK 64-Bit Server VM (slowdebug
> > > > 9-internal+0-2016-04-07-162501.d046063.jdk9-hs-comp, mixed mode,
> > > > tiered, compressed oo
> > > > ps, serial gc, linux-ppc64le)
> > > > # Problematic frame:
> > > > # V [libjvm.so+0xf744d0] outputStream::do_vsnprintf_and_write(char
> > > > const*, char*, bool)+0x40
> > > > #
> > > > # No core dump will be written. Core dumps have been disabled. To
> > > > enable core dumping, try "ulimit -c unlimited" before starting Java
> > > > again
> > > > #
> > > > # If you would like to submit a bug report, please visit:
> > > > # http://bugreport.java.com/bugreport/crash.jsp
> > > > #
> > > >
> > > > --------------- S U M M A R Y ------------
> > > >
> > > > Command Line:
> > > >
> -Dapplication.home=/sapmnt/ld9510/a/d046063/output-jdk9-hs-comp-dbg/jdk
> > > > -Xms8m -XX:+UseSerialGC -Xms32M -Xmx512M -Djdk.
> > > > module.main=jdk.jlink jdk.jlink/jdk.tools.jmod.Main create
> > > > --module-version 9-internal --os-name Linux --os-arch ppc64le
> > > > --os-version
> > > > 2.6 --modulepath /priv/d046063/output-jdk9-hs-comp-dbg/images/jmods
> > > > --hash-dependencies .* --exclude **_the.* --libs
> > > >
> > > >
> /priv/d046063/output-jdk9-hs-comp-dbg/support/modules_libs-stripped/java.base
> > > > --cmds
> > > >
> /priv/d046063/output-jdk9-hs-comp-dbg/support/modules_cmds-stripped/java.base
> > > > --config
> > > > /priv/d046063/output-jdk9-hs-comp-dbg/support/modules_conf/java.base
> > > > --class-path
> /priv/d046063/output-jdk9-hs-comp-dbg/jdk/modules/java.base
> > > > /priv/d046063/output-jdk9-hs-comp-dbg/support/jmods/java.base.jmod
> > > >
> > > > Host: ld9510, POWER8E (raw), altivec supported, 48 cores, 61G, #
> > > > Please check /etc/os-release for details about this release.
> > > > Time: Thu Apr 7 16:28:55 2016 CEST elapsed time: 0 seconds (0d 0h
> 0m 0s)
> > > >
> > > > --------------- T H R E A D ---------------
> > > >
> > > > Current thread (0x000010000429c800): JavaThread "C1
> CompilerThread10"
> > > > daemon [_thread_in_vm, id=35404,
> > > > stack(0x000010006a800000,0x000010006ac00000)]
> > > >
> > > >
> > > > Current CompileTask:
> > > > C1: 761 3 3 java.lang.String::charAt (25 bytes)
> > > >
> > > > Stack: [0x000010006a800000,0x000010006ac00000],
> > > > sp=0x000010006abfc6c0, free space=4081k
> > > > Native frames: (J=compiled Java code, j=interpreted, Vv=VM code,
> C=native
> > > > code)
> > > > V [libjvm.so+0xf744d0] outputStream::do_vsnprintf_and_write(char
> > > > const*, char*, bool)+0x40
> > > > V [libjvm.so+0xf74668] outputStream::print_cr(char const*,
> ...)+0x68
> > > > V [libjvm.so+0x72189c] CodeBlob::print_on(outputStream*) const+0x50
> > > > V [libjvm.so+0x723bdc] RuntimeBlob::print_on(outputStream*)
> const+0x40
> > > > V [libjvm.so+0x721eb0] SingletonBlob::print_on(outputStream*)
> const+0x4c
> > > > V [libjvm.so+0x106d51c] RelocIterator::initialize(CompiledMethod*,
> > > > unsigned char*, unsigned char*)+0x170
> > > > V [libjvm.so+0x5ae56c]
> RelocIterator::RelocIterator(CompiledMethod*,
> > > > unsigned char*, unsigned char*)+0x78
> > > > V [libjvm.so+0x10719dc]
> > > > trampoline_stub_Relocation::get_trampoline_for(unsigned char*,
> > > > nmethod*)+0x78
> > > > V [libjvm.so+0xefb80c] NativeCall::get_trampoline()+0x110
> > > > V [libjvm.so+0x1076914] Relocation::pd_call_destination(unsigned
> > > > char*)+0x150
> > > > V [libjvm.so+0x106f5fc]
> > > > CallRelocation::fix_relocation_after_move(CodeBuffer const*,
> > > > CodeBuffer*)+0x74
> > > > V [libjvm.so+0x728898] CodeBuffer::relocate_code_to(CodeBuffer*)
> > > > const+0x390
> > > > V [libjvm.so+0x728404] CodeBuffer::copy_code_to(CodeBlob*)+0x134
> > > > V [libjvm.so+0x722670]
> CodeBuffer::copy_code_and_locs_to(CodeBlob*)+0x84
> > > > V [libjvm.so+0x71f834] CodeBlob::CodeBlob(char const*,
> > > > CodeBlobLayout const&, CodeBuffer*, int, int, OopMapSet*, bool,
> > > > int)+0x320
> > > > V [libjvm.so+0x7c52c8] CompiledMethod::CompiledMethod(Method*, char
> > > > const*, int, int, CodeBuffer*, int, int, OopMapSet*, bool)+0xd8
> > > > V [libjvm.so+0xf01f58] nmethod::nmethod(Method*, int, int, int,
> > > > CodeOffsets*, int, DebugInformationRecorder*, Dependencies*,
> > > > CodeBuffer*, int, OopMapSet*, ExceptionHandlerTable*,
> > > > ImplicitExceptionTable*, AbstractCompiler*, int)+0xe0
> > > > V [libjvm.so+0xf01610] nmethod::new_nmethod(methodHandle const&,
> > > > int, int, CodeOffsets*, int, DebugInformationRecorder*,
> Dependencies*,
> > > > CodeBuffer*, int, OopMapSet*, ExceptionHandlerTable*,
> > > > ImplicitExceptionTable*, AbstractCompiler*, int)+0x2c4
> > > > V [libjvm.so+0x632970] ciEnv::register_method(ciMethod*, int,
> > > > CodeOffsets*, int, CodeBuffer*, int, OopMapSet*,
> > > > ExceptionHandlerTable*, ImplicitExceptionTable*, AbstractCompiler*,
> > > > bool, bool, RTMState)+0x560
> > > > V [libjvm.so+0x48ee00] Compilation::install_code(int)+0x264
> > > > V [libjvm.so+0x48eff8] Compilation::compile_method()+0x184
> > > > V [libjvm.so+0x48f7a8] Compilation::Compilation(AbstractCompiler*,
> > > > ciEnv*, ciMethod*, int, BufferBlob*, DirectiveSet*)+0x288
> > > > V [libjvm.so+0x4980d0] Compiler::compile_method(ciEnv*, ciMethod*,
> > > > int, DirectiveSet*)+0xc8
> > > > V [libjvm.so+0x7b188c]
> > > > CompileBroker::invoke_compiler_on_method(CompileTask*)+0x590
> > > > V [libjvm.so+0x7b07bc] CompileBroker::compiler_thread_loop()+0x310
> > > > V [libjvm.so+0x11a614c] compiler_thread_entry(JavaThread*,
> Thread*)+0xa0
> > > > V [libjvm.so+0x119f3a8] JavaThread::thread_main_inner()+0x1b4
> > > > V [libjvm.so+0x119f1a4] JavaThread::run()+0x1b8
> > > > V [libjvm.so+0xf53d90] java_start(Thread*)+0x204
> > > > C [libpthread.so.0+0x8a64] start_thread+0xf4
> > > > C [libc.so.6+0x1032a0] clone+0x98
> > > >
> > > > I haven't identified the exact cause (will analyze it tomorrow) but
> > > > the stack trace indicates that it is indeed related to your changes.
> > > >
> > > > Besides that I have some comments:
> > > >
> > > > codeBuffer.hpp:
> > > >
> > > > 472 CodeSection* insts() { return &_insts; }
> > > > 475 const CodeSection* insts() const { return &_insts; }
> > > >
> > > > - do we really need both versions?
> > > >
> > > > codeBlob.hpp:
> > > >
> > > > 135 nmethod* as_nmethod_or_null() const { return
> > > > is_nmethod() ? (nmethod*) this : NULL; }
> > > > 136 nmethod* as_nmethod() const {
> > > > assert(is_nmethod(), "must be nmethod"); return (nmethod*) this; }
> > > > 137 CompiledMethod* as_compiled_method_or_null() const { return
> > > > is_compiled() ? (CompiledMethod*) this : NULL; }
> > > > 138 CompiledMethod* as_compiled_method() const {
> > > > assert(is_compiled(), "must be compiled"); return (CompiledMethod*)
> > > > this; }
> > > > 139 CodeBlob* as_codeblob_or_null() const { return
> > > > (CodeBlob*) this; }
> > > >
> > > > - I don't like this code. You make the getters 'const' which
> > > > implicitely makes 'this' a "pointer to const" but then the returned
> > > > pointer is a normal pointer to a non-const object and therefore you
> > > > have to statically cast away the "pointer to const" (that's why you
> > > > need the cast even in the case where you return a CodeBlob*). So
> > > > either remove the const qualifier from the method declarations or
> make
> > > > them return "pointers to const". And by the way,
> as_codeblob_or_null()
> > > > doesn't seemed to be used anywhere in the code, why do we need it at
> > > > all?
> > > >
> > > > - Why do we need the non-virtual methods is_nmethod() and
> > > > is_compiled() to manually simulate virtual behavior. Why can't we
> > > > simply make them virtual and implement them accordingly in nmathod
> and
> > > > CompiledMethod?
> > > >
> > > > Regards,
> > > > Volker
> > > >
> > > > On Thu, Apr 7, 2016 at 2:12 PM, Rickard Bäckman
> > > > <rickard.backman at oracle.com> wrote:
> > > > > Hi,
> > > > >
> > > > > can I please have review for this patch please?
> > > > >
> > > > > So far CodeBlobs have required all the data (metadata, oops, code,
> etc)
> > > > > to be in one continuous blob With this patch we are looking to
> change
> > > > > that. It's been done by changing offsets in CodeBlob to addresses,
> > > > > making some methods virtual to allow different behavior and also
> > > > > creating a couple of new classes. CompiledMethod now sits inbetween
> > > > > CodeBlob and nmethod.
> > > > >
> > > > > CR: https://bugs.openjdk.java.net/browse/JDK-8152664
> > > > > Webrev: http://cr.openjdk.java.net/~rbackman/8152664/
> > > > >
> > > > > Thanks
> > > > > /R
> > > >
>
More information about the hotspot-dev
mailing list