From: Robert Lipe <robertl@dgii.com>
To: law@cygnus.com
Cc: egcs@cygnus.com
Subject: Re: disturbing g++ 971031 results. defer-pop to blame?
Date: Mon, 03 Nov 1997 02:06:00 -0000 [thread overview]
Message-ID: <19971103011246.03918@dgii.com> (raw)
In-Reply-To: <16196.878533936@hurl.cygnus.com>
> > Now is when I notice that GDB is not playing nice with EGCS ELF output.
> > When it rains...
> Sigh. More likely it's not playing nice with dwarf2 more so than
> ELF.
GDB that I built from 4.14-95q4 (i486-unknown-sco3.2v5.0.0elf) handles
the binaries in question just fine. GDB 4.16 built from virgin FSF
sources isn't useful on my ELF binaries. I'll chase this later...
I build the binary in question.
./negcs -O0 -g /tmp/net34.C -lstdc++ && ./a.out
I then step through it:
(gdb)
13 int get_k() {return k;}
(gdb)
bar_1::get_k() -> 1
bar_2::get_k() -> 2
Program received signal SIGSEGV, Segmentation fault.
0x8059187 in .fini ()
If I look at the tail end of the object, the reason for our
crash is more apparent:
Disassembly of section .fini:
0805917c <_fini>:
805917c: e8 c7 f9 fe ff call 8048b48 <__do_global_dtors_aux>
8059181: 90 nop
8059182: 90 nop
8059183: 90 nop
08059184 <.fini>:
8059184: 4c decl %esp
8059185: cd 04 int $0x4
8059187: 08 c2 orb %al,%dl
08059188 <.fini>:
8059188: c2 00 00 ret $0x0
805918b: 90 nop
The entry in the middle looks like mush to me.
Roaming through the objects that are linked, I can see that crtn.o gives
us the return. crtbegin.o gives us the call to __do_global_dtors_aux().
Where does the strange sequence in th emiddle come from?
If I take hte final link line:
/play/negcs/gcc/ld -b elf -Ra,XPG4PLUS,ELF -YP,/usr/ccs/lib:/lib:/usr/lib \
-Qn /usr/ccs/lib/crt1.o /usr/ccs/lib/values-Xa.o \
/play/negcs/gcc/crtbegin.o -L/play/negcs/gcc -L/usr/ccs/bin \
-L/usr/ccs/lib -L/usr/local/lib net34.o -lstdc++ \
-lgcc -lcrypt -lgen -lc -lgcc /play/negcs/gcc/crtend.o \
/usr/ccs/lib/crtn.o
and play with the order (add crtn.o before or after -lstdc++) I have
reason to think that it's from something in libstdc++. If I just
hoist -lstdc++ down to the very last (and stick another -lgcc after
it) I get a functioning executable.
Objdump --all-headers on libstdc++.a and all the .o's that go into
it shows nothing in the .fini section.
How can I find out what this is and where it's coming from?
next prev parent reply other threads:[~1997-11-03 2:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-11-01 20:49 GCC 971031 on OpenServer Robert Lipe
1997-11-02 12:48 ` disturbing g++ 971031 results. defer-pop to blame? Robert Lipe
1997-11-02 19:06 ` Jeffrey A Law
1997-11-02 20:47 ` Robert Lipe
1997-11-02 22:44 ` Jeffrey A Law
1997-11-02 23:32 ` Robert Lipe
1997-11-03 2:06 ` Jeffrey A Law
1997-11-03 2:06 ` Robert Lipe [this message]
1997-11-03 1:51 ` Jeffrey A Law
1997-11-03 3:21 ` Andreas Schwab
1997-11-03 9:43 ` Robert Lipe
[not found] ` <16810.878541954.cygnus.egcs@hurl.cygnus.com>
1997-11-03 2:28 ` Jason Merrill
1997-11-03 9:43 ` disturbing g++ 971031 results. defer-pop not to blame Robert Lipe
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