On Mon, Apr 2, 2012 at 2:24 PM, Rainer Orth <r...@cebitec.uni-bielefeld.de>
wrote:
> Steven Bosscher <stevenb....@gmail.com> writes:
>
>> Therefore, an RFA for the attached patch. Bootstrapped&tested on
>> powerpc64-unknown-linux-gnu. OK?
>
> Unfortunately, this patch completely broke libjava testing on
> i386-pc-solaris2* and x86_64-unknown-linux-gnu: all execution tests fail
> with a SEGV:
>
> Program received signal SIGSEGV, Segmentation fault.
> 0xfd0ddf7d in _Jv_Linker::verify_class (klass=klass@entry=0xfe945d80)
> at /vol/gcc/src/hg/trunk/local/libjava/link.cc:1904
> 1904 klass->engine->verify(klass);
>
> klass->engine is NULL at this point. Checking the generated .jcr
> sections, I found that a large number of them have sh_addralign 0x20
> instead of 0x4 before your patch. This caused a massive reduction in
> the number of _Jv_RegisterClassHookDefault calls:
>
> With the following DTrace one-liner
>
> pid$target::_Jv_RegisterClassHookDefault:entry{ @[ustack()] = count(); }
>
> to investigate ArrayStore.exe execution, I find for the unpatched jc1:
>
> libgcj.so.13.0.0`_Jv_RegisterClassHookDefault
> libgcj.so.13.0.0`_Jv_RegisterClasses+0x44
> libgcj.so.13.0.0`_ZN4java4lang9Cloneable6class$E
> 0xe0ec
> 7213
>
> With your patch, I get
>
> libgcj.so.13.0.0`_Jv_RegisterClassHookDefault
> libgcj.so.13.0.0`_Jv_RegisterNewClasses+0xb7
> ArrayStore.exe`_Utf18
> 1
>
> libgcj.so.13.0.0`_Jv_RegisterClassHookDefault
> libgcj.so.13.0.0`_Jv_RegisterClasses+0x44
> libgcj.so.13.0.0`_ZN4java4lang9Cloneable6class$E
> 0xe0ec
> 12
>
> instead.
>
> The alignment change happens because LOCAL_ALIGNMENT overrides
> DECL_ALIGN. This can be avoided by setting DECL_USER_ALIGN (which
> unfortunately is undocumented). The result looks better, but still
> fails in a different way:
>
> Exception in thread "main" java.lang.NoClassDefFoundError: ArrayStore
> at java.lang.Class.initializeClass(libgcj.so.13.0.0)
> Caused by: java.lang.NullPointerException
> at java.lang.Class.initializeClass(libgcj.so.13.0.0)
>
> But the _Jv_RegisterClassHookDefault are almost back to normal:
>
> libgcj.so.13.0.0`_Jv_RegisterClassHookDefault
> libgcj.so.13.0.0`_Jv_RegisterClasses+0x44
> libgcj.so.13.0.0`_ZN4java4lang9Cloneable6class$E
> 0xe0ec
> 7212
>
> I could trace this to a change in .jcr section flags: in ArrayStore.exe,
> I find
>
> Section Header[18]: sh_name: .jcr
> sh_addr: 0x8052058 sh_flags: [ SHF_ALLOC ]
> sh_size: 0x4 sh_type: [ SHT_PROGBITS ]
> sh_offset: 0x2058 sh_entsize: 0
> sh_link: 0 sh_info: 0
> sh_addralign: 0x4
>
> Section Header[26]: sh_name: .jcr
> sh_addr: 0x80625e4 sh_flags: [ SHF_WRITE SHF_ALLOC ]
> sh_size: 0x4 sh_type: [ SHT_PROGBITS ]
> sh_offset: 0x25e4 sh_entsize: 0
> sh_link: 0 sh_info: 0
> sh_addralign: 0x4
>
> The first (without SHF_WRITE set) is from jc1, the second from
> crtbegin.o. The Solaris linker (and probably other ELF linkers which
> don't special-case .jcr) merges sections not just by name, but only if
> name and attributs (flags, type) match. Not marking .jcr read-only
> fixes that part of the failure and restores libjava testsuite results on
> Solaris 11/x86 back to normal (no failures).
>
> Bootstrapped without regressions on i386-pc-solaris2.11.
>
> Ok for mainline?
Ok. I wonder what happens if we mark __JCR_END__ in crtstuff.c
as const?
Thanks,
Richard.
> Rainer
>
>
> 2012-03-31 Rainer Orth <r...@cebitec.uni-bielefeld.de>
>
> * class.c (emit_register_classes_in_jcr_section): Set DECL_USER_ALIGN.
> Clear TREE_READONLY.
>
>
>
> --
> -----------------------------------------------------------------------------
> Rainer Orth, Center for Biotechnology, Bielefeld University
>
