From: Ulf Carlsson <ulfc@calypso.engr.sgi.com>
To: Andrew Cagney <ac131313@cygnus.com>
Cc: Alan Modra <alan@linuxcare.com.au>,
BINUTILS Patches <binutils@sourceware.cygnus.com>,
GDB Patches <gdb-patches@sourceware.cygnus.com>
Subject: Re: [rfc] For mips, sign-extended ecoff offsets
Date: Mon, 19 Jun 2000 18:47:00 -0000 [thread overview]
Message-ID: <14670.52424.697477.308492@calypso.engr.sgi.com> (raw)
In-Reply-To: <394EC637.24300B87@cygnus.com>
Hi Andrew,
> > > The attatched patch changes the MIPS ELF32 backend so that it is more
> > > likely to return a sign-extended offset. At present the ELF backend
> > > returns sign-extended symbol table values but not sign extended debug
> > > information.
> >
> > Hi Andrew,
> > Would it be better to just change ecoff_swap_sym_in? It seems like
> > this would achieve what you want, and not risk breaking quite so much.
> > I'm worried about what happens if things like PDR.adr get changed from
> > 0xa0000000 to 0xffffffffa0000000.
>
> Thats why I'm asking :-) Remember though, on the MIPS platform, if
> ``PDR.adr'' is an address then, the canonical form of the value
> ``0xa0000000'' obtained from an elf32 binary is 0xffffffffa00000000.
> GDB and BFD have, for too many years, been bribed and cajoled into
> perpetuated the lie that MIPS doesn't sign extend addresses. GDB's now
> decided to come clean on this matter (and purge an amazing amount of
> bogus code :-).
On a 64-bit MIPS processor 32-bit addresses are of course sign
extended, but this shouldn't concern the 32-bit BFD backend for MIPS
in any way. Whether we sign extend the addresses or not shouldn't
make any difference except in our internal representation of the
bfd_vma. I may be wrong though!
Ulf
next prev parent reply other threads:[~2000-06-19 18:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-06-19 5:14 Andrew Cagney
2000-06-19 8:48 ` Alan Modra
2000-06-19 18:18 ` Andrew Cagney
2000-06-19 18:47 ` Ulf Carlsson [this message]
2000-06-19 18:57 ` Alan Modra
2000-06-19 19:16 ` Andrew Cagney
2000-06-19 20:08 ` Geoff Keating
2000-06-19 20:41 ` Ian Lance Taylor
2000-06-25 14:13 ` Ralf Baechle
[not found] ` <14670.59816.517716.492387@calypso.engr.sgi.com>
2000-06-19 21:30 ` Geoff Keating
2000-06-19 18:50 ` Alan Modra
2000-06-19 19:23 ` Andrew Cagney
2000-06-19 20:39 ` Ian Lance Taylor
2000-06-23 0:28 ` Andrew Cagney
2000-06-23 9:48 ` Ian Lance Taylor
2000-07-03 23:47 ` Andrew Cagney
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