From: Alan Modra <amodra@gmail.com>
To: Mark Mitchell <mark@codesourcery.com>
Cc: binutils@sourceware.org
Subject: Re: RFC: COMDAT group names become anonymouse local symbols
Date: Thu, 21 Oct 2010 02:12:00 -0000 [thread overview]
Message-ID: <20101021021150.GS26553@bubble.grove.modra.org> (raw)
In-Reply-To: <4CBF89DF.5070509@codesourcery.com>
On Wed, Oct 20, 2010 at 05:31:27PM -0700, Mark Mitchell wrote:
> The concern here is indeed about compatibility with other linkers. At
> least one linker does not treat the name of the group as "B" in this
> case -- and therefore does not correctly collapse COMDAT groups
> generated by GAS.
Hmm, OK.
> I don't see anything that says that the symbol name is implicitly the
> name of the associated section; in other words, I don't see how to
> justify your statement that "the name of such a symbol is given by the
> section sn_name".
Correct, but this is how GNU ld and other binutils have behaved for a
long time. For example, gas allows access to a section symbol (having
st_name zero) with
.data
.long .data
for which readelf shows:
Relocation section '.rel.data' at offset 0x1ec contains 1 entries:
Offset Info Type Sym. Value Symbol's Name
00000000 00000201 R_386_32 00000000 .data
There are no unwind sections in this file.
Symbol table '.symtab' contains 4 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000 0 SECTION LOCAL DEFAULT 1
2: 00000000 0 SECTION LOCAL DEFAULT 2
3: 00000000 0 SECTION LOCAL DEFAULT 4
Note the symbol index on the reloc, the zero st_name in .symtab,
but the reloc is said to be against ".data".
It would be reasonable to say that this behaviour is a GNU extension
to the ELF spec. We do quite a lot of that. :-)
As far as changing this to suit some other linker, I'm definitely not
motivated to do the work myself as I don't see this as a bug in gas.
It's a bug in the other linker!
--
Alan Modra
Australia Development Lab, IBM
prev parent reply other threads:[~2010-10-21 2:12 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-19 20:08 Mark Mitchell
2010-10-20 18:05 ` Cary Coutant
2010-10-20 18:19 ` Mark Mitchell
2010-10-21 6:12 ` Cary Coutant
2010-10-21 0:18 ` Alan Modra
2010-10-21 0:31 ` Mark Mitchell
2010-10-21 1:04 ` Ian Lance Taylor
2010-10-21 4:41 ` Mark Mitchell
2010-10-21 5:19 ` H.J. Lu
2010-10-21 5:27 ` Mark Mitchell
2010-10-21 5:41 ` H.J. Lu
2010-10-21 5:42 ` Mark Mitchell
2010-10-21 6:24 ` Alan Modra
2010-10-21 16:41 ` Mark Mitchell
2010-10-21 18:50 ` Daniel Jacobowitz
2010-10-21 20:22 ` Mark Mitchell
2010-10-21 22:19 ` Alan Modra
2010-10-21 22:41 ` Mark Mitchell
2010-10-21 23:11 ` Alan Modra
2010-10-22 3:23 ` Mark Mitchell
2010-10-22 4:33 ` Alan Modra
2010-10-22 6:10 ` Mark Mitchell
2010-10-22 7:16 ` Alan Modra
2010-10-22 15:34 ` Mark Mitchell
2010-10-23 8:16 ` Alan Modra
2010-10-23 18:05 ` Mark Mitchell
2010-10-24 1:15 ` Hans-Peter Nilsson
2010-10-24 1:43 ` Mark Mitchell
2010-10-24 3:50 ` Hans-Peter Nilsson
2010-10-24 4:34 ` Mark Mitchell
2010-10-25 11:45 ` Hans-Peter Nilsson
2010-10-25 12:39 ` Alan Modra
2010-10-25 15:22 ` Mark Mitchell
2010-10-26 3:45 ` Alan Modra
2010-10-26 15:48 ` Dave Korn
2010-10-26 15:49 ` Mark Mitchell
2010-10-26 15:59 ` Dave Korn
2010-10-26 16:12 ` Dave Korn
2010-10-21 2:12 ` Alan Modra [this message]
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