From: Jan Hubicka <hubicka@ucw.cz>
To: Richard Guenther <rguenther@suse.de>
Cc: Jan Hubicka <hubicka@ucw.cz>, "H.J. Lu" <hjl.tools@gmail.com>,
gcc-patches@gcc.gnu.org
Subject: Re: varpool alias reorg
Date: Mon, 27 Jun 2011 09:50:00 -0000 [thread overview]
Message-ID: <20110627091629.GB22865@kam.mff.cuni.cz> (raw)
In-Reply-To: <alpine.LNX.2.00.1106271050010.810@zhemvz.fhfr.qr>
> > There are two problems here
> > 1) We do not stream builtin decls and merge them outside lto-symtab (by just
> > streaming references to builtins with their asm names). There is at least
> > one extra PR related to this and on my TODO is to simply remove the code.
> > 2) Aliases within single unit works only when both the alias and the target use
> > asm name. This is because internally we store mangled DECL_ASSEMBLER_NAME and the
> > alias_pair code.
> > With LTO this breaks existing code simply because what used to be multiple units
> > and thus safe is now single LTO unit.
> >
> > Dave Korn fixed part of the problem by introducing mangling code into lto-symtab
> > His code solve similar problems with aliases from the asm code, but it
> > did not solve the problem with aliases from LTO units, like here, simply
> > because alias pair code bypass the lto-symtab. One of goals of the incorrect patch
> > above is to make lto-symtab to do the merging and thus fix this issue (for now at
> > all decls except for builtins).
> >
> > Still it would be good to solve the problem on non-LTO compilation, too.
> > We discussed introduction of proper symbol table into GCC at the GCC gathering last
> > weekend. It is where I am heading but it will take some time.
> >
> > Until that happens, I suggest fixing the testcase same was as we already fixed
> > the memops-asm-lib.c in 4.6 timeframe.
> >
> > Bootstrapped/regtested x86_64-linux, OK?
>
> Ok.
Hi,
thanks! Could you, please, also consider the second two variants I sent? In
general attribute used is needed when implementing libfuncs since we never know
when folding will intoduce new libcall (like in memops-asm). However this
particular case don't need use because the builtin is called directly.
They also solve the problem of BLOCK lists being messed up.
In meantime I tested both variants and they pass. I will add a changelog, of course.
Honza
next prev parent reply other threads:[~2011-06-27 9:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-18 9:11 Jan Hubicka
2011-06-18 14:49 ` H.J. Lu
2011-06-23 14:34 ` H.J. Lu
2011-06-23 16:44 ` Jan Hubicka
2011-06-24 12:30 ` Jan Hubicka
2011-06-24 12:33 ` Jan Hubicka
2011-06-27 14:08 ` Richard Guenther
2011-06-27 16:13 ` Jan Hubicka
2011-06-27 16:22 ` Michael Matz
2011-06-28 8:34 ` Richard Guenther
2011-06-27 9:43 ` Richard Guenther
2011-06-27 9:50 ` Jan Hubicka [this message]
2011-06-22 8:17 ` Regression with "varpool alias reorg" Hans-Peter Nilsson
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