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RE: 3.0.1 PATCH: Avoid non-PIC code in boehm-gc for Solaris 2/Intel
- To: "'Rainer Orth'" <ro at TechFak dot Uni-Bielefeld dot DE>, gcc-patches at gcc dot gnu dot org, java-patches at gcc dot gnu dot org
- Subject: RE: 3.0.1 PATCH: Avoid non-PIC code in boehm-gc for Solaris 2/Intel
- From: "Boehm, Hans" <hans_boehm at hp dot com>
- Date: Tue, 26 Jun 2001 09:56:55 -0700
- Cc: "Hans-J. Boehm" <boehm at acm dot org>
Thanks for pointing this out. I'd also like to fix it in version 6.0 of the
GC.
The patch seems a bit brittle to me. You're inserting compiler generated
code in a position at which the stack pointer is 4 bytes displaced from
where the compiler thinks it is. This strikes me as dangerous, particularly
since this should also compile with non-gcc compilers. You're also counting
on the compiler not to push anything on the stack between the argument push
and the call.
Is there a way to fix this entirely in assembly code, possibly in a separate
file? At least in the gcc case, it would be safer to combine each call into
a single asm. If this is hard, we can also look at using the generic
setjmp-based code.
Hans
> -----Original Message-----
> From: Rainer Orth [mailto:ro@TechFak.Uni-Bielefeld.DE]
> Sent: Tuesday, June 26, 2001 5:30 AM
> To: gcc-patches@gcc.gnu.org; java-patches@gcc.gnu.org
> Cc: Hans-J. Boehm
> Subject: 3.0.1 PATCH: Avoid non-PIC code in boehm-gc for
> Solaris 2/Intel
>
>
> An initial attempt to bootstrap GCC 3.0 on Solaris 8/Intel with
> --enable-libgcj failed when trying to link the shared libgcjgc:
>
> /vol/gcc/obj/gcc-3.0/8-cc-gas/gcc/xgcc
> -B/vol/gcc/obj/gcc-3.0/8-cc-gas/gcc/
> -B/vol/gcc/share/i386-pc-solaris2.8/bin/
> -B/vol/gcc/share/i386-pc-solaris2.8/lib/ -isystem
> /vol/gcc/share/i386-pc-solaris2.8/include -shared -Wl,-h
> -Wl,libgcjgc.so.1 -o .libs/libgcjgc.so.1.0.1
> .libs/allchblk.o .libs/alloc.o .libs/blacklst.o
> .libs/checksums.o .libs/dbg_mlc.o .libs/dyn_load.o
> .libs/finalize.o .libs/gcj_mlc.o .libs/headers.o
> .libs/hpux_irix_threads.o .libs/linux_threads.o
> .libs/malloc.o .libs/mallocx.o .libs/mark.o .libs/mark_rts.o
> .libs/misc.o .libs/new_hblk.o .libs/obj_map.o .libs/os_dep.o
> .libs/pcr_interface.o .libs/ptr_chck.o .libs/real_malloc.o
> .libs/reclaim.o .libs/solaris_pthreads.o
> .libs/solaris_threads.o .libs/stubborn.o .libs/typd_mlc.o
> .libs/mach_dep.o -lpthread -lc
> Text relocation remains referenced
> against symbol offset in file
> GC_push_one 0x5 .libs/mach_dep.o
> GC_push_one 0xe .libs/mach_dep.o
> GC_push_one 0x17 .libs/mach_dep.o
> GC_push_one 0x20 .libs/mach_dep.o
> GC_push_one 0x29 .libs/mach_dep.o
> GC_push_one 0x32 .libs/mach_dep.o
> GC_push_one 0x3b .libs/mach_dep.o
> ld: fatal: relocations remain against allocatable but
> non-writable sections
>
> I.e. the current code required text relocations, making the
> text section
> non-sharable. The patch below fixes this. Bootstrapped with no
> regressions on i386-pc-solaris2.8.
>
> Ok for branch and mainline?
>
> Rainer
>
> --------------------------------------------------------------
> ---------------
> Rainer Orth, Faculty of Technology, Bielefeld University
>
> Email: ro@TechFak.Uni-Bielefeld.DE
>
>
> Tue Jun 26 14:22:59 2001 Rainer Orth <ro@TechFak.Uni-Bielefeld.DE>
>
> * mach_dep.c (GC_push_regs) [I386 && SVR4 || SCO ||
> SCO_ELF]: Call
> GC_push_one in C to allow for PIC code.
>
> ===================================================================
> RCS file: boehm-gc/RCS/mach_dep.c,v
> retrieving revision 1.1
> diff -up -r1.1 boehm-gc/mach_dep.c
> --- boehm-gc/mach_dep.c 2000/04/27 00:43:33 1.1
> +++ boehm-gc/mach_dep.c 2000/04/26 22:43:33
> @@ -281,13 +281,13 @@ void GC_push_regs()
>
> # if defined(I386) && (defined(SVR4) || defined(SCO)
> || defined(SCO_ELF))
> /* I386 code, SVR4 variant, generic code does not
> appear to work */
> - asm("pushl %eax"); asm("call GC_push_one");
> asm("addl $4,%esp");
> - asm("pushl %ebx"); asm("call GC_push_one");
> asm("addl $4,%esp");
> - asm("pushl %ecx"); asm("call GC_push_one");
> asm("addl $4,%esp");
> - asm("pushl %edx"); asm("call GC_push_one");
> asm("addl $4,%esp");
> - asm("pushl %ebp"); asm("call GC_push_one");
> asm("addl $4,%esp");
> - asm("pushl %esi"); asm("call GC_push_one");
> asm("addl $4,%esp");
> - asm("pushl %edi"); asm("call GC_push_one");
> asm("addl $4,%esp");
> + asm("pushl %eax"); GC_push_one (); asm("addl $4,%esp");
> + asm("pushl %ebx"); GC_push_one (); asm("addl $4,%esp");
> + asm("pushl %ecx"); GC_push_one (); asm("addl $4,%esp");
> + asm("pushl %edx"); GC_push_one (); asm("addl $4,%esp");
> + asm("pushl %ebp"); GC_push_one (); asm("addl $4,%esp");
> + asm("pushl %esi"); GC_push_one (); asm("addl $4,%esp");
> + asm("pushl %edi"); GC_push_one (); asm("addl $4,%esp");
> # endif
>
> # ifdef NS32K
>