| Message ID | yddzkaus4my.fsf@manam.CeBiTec.Uni-Bielefeld.DE |
|---|---|
| State | New |
| Headers | show |
On Mon, Apr 2, 2012 at 2:24 PM, Rainer Orth <ro@cebitec.uni-bielefeld.de> wrote: > Steven Bosscher <stevenb.gcc@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 <ro@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 >
# HG changeset patch # Parent ae1fe58e699b5ec26f0ad31675d3915eef63d963 Fix .jcr alignment diff --git a/gcc/java/class.c b/gcc/java/class.c --- a/gcc/java/class.c +++ b/gcc/java/class.c @@ -2815,10 +2815,11 @@ emit_register_classes_in_jcr_section (vo DECL_SECTION_NAME (cdecl) = build_string (strlen (JCR_SECTION_NAME), JCR_SECTION_NAME); DECL_ALIGN (cdecl) = POINTER_SIZE; + DECL_USER_ALIGN (cdecl) = 1; DECL_INITIAL (cdecl) = build_constructor (class_array_type, init); TREE_CONSTANT (DECL_INITIAL (cdecl)) = 1; TREE_STATIC (cdecl) = 1; - TREE_READONLY (cdecl) = 1; + TREE_READONLY (cdecl) = 0; TREE_CONSTANT (cdecl) = 1; DECL_ARTIFICIAL (cdecl) = 1; DECL_IGNORED_P (cdecl) = 1;