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Re: mips gas is horribly broken
- To: hjl at lucon dot org
- Subject: Re: mips gas is horribly broken
- From: Geoff Keating <geoffk at geoffk dot org>
- Date: Wed, 6 Jun 2001 12:32:15 -0700
- CC: binutils at sourceware dot cygnus dot com, linux-mips at oss dot sgi dot com
- References: <20010606091846.A21652@lucon.org>
- Reply-to: Geoff Keating <geoffk at redhat dot com>
> Date: Wed, 6 Jun 2001 09:18:46 -0700
> From: "H . J . Lu" <hjl@lucon.org>
> Cc: linux-mips@oss.sgi.com
> Content-Disposition: inline
> User-Agent: Mutt/1.2.5i
>
> Around line 9544 in gas/config/tc-mips.c, there are
>
> if (value != 0 && ! fixP->fx_pcrel)
> {
> /* In this case, the bfd_install_relocation routine will
> incorrectly add the symbol value back in. We just want
> the addend to appear in the object file.
> FIXME: If this makes VALUE zero, we're toast. */
> value -= S_GET_VALUE (fixP->fx_addsy);
> }
>
> I spent several days trying to figure out why libstdc++ was miscompiled
> on Linux/mipsel. That was because value was zero. That is totally
> unacceptable for gas to knowingly generate incorrect binaries. At
> least, we should do
>
> value -= S_GET_VALUE (fixP->fx_addsy);
> assert (value != 0);
>
> But I'd like to fix it once for all. Does anyone have any suggestions?
There is no easy fix. This has been a longstanding problem, but any
change to bfd_install_relocation would require modifying every port in
a corresponding way, see for instance the FIXME at line 4816 or so in
tc-ppc.c.
--
- Geoffrey Keating <geoffk@geoffk.org>