From: Jakub Jelinek <jakub@redhat.com>
To: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: archer@sourceware.org, Jason Merrill <jason@redhat.com>
Subject: Re: Inter-CU DWARF size optimizations and gcc -flto
Date: Wed, 01 Feb 2012 13:32:00 -0000 [thread overview]
Message-ID: <20120201133215.GQ18768@tyan-ft48-01.lab.bos.redhat.com> (raw)
In-Reply-To: <20120201132307.GA32578@host2.jankratochvil.net>
On Wed, Feb 01, 2012 at 02:23:09PM +0100, Jan Kratochvil wrote:
> I am sorry if it is clear to everyone but I admit I played with it only
> yesterday.
>
> With
> gcc -flto -flto-partition=none
>
> gcc outputs only single CU (Compilation Unit). With default (omitting)
> -flto-partition there are multiple CUs but still a few compared to the number
> of .o files.
>
> -flto is AFAIK the future for all the compilations. It is well known -flto
> debug info is somehow broken now but that needs to be fixed anyway.
It isn't only somehow broken, it is quite fundamentally broken. And even
with LTO GCC should output CUs matching the original source, one CU per
source IMHO, which is admittedly going to be very difficult though,
especially when partitioning the compilation, because multiple partitions
might need to add stuff to a single CU. IMHO at least for us -flto is a
no-go until these problems are solved though.
Jakub
next prev parent reply other threads:[~2012-02-01 13:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 13:23 Jan Kratochvil
2012-02-01 13:32 ` Jakub Jelinek [this message]
2012-02-22 21:56 ` Tom Tromey
2012-02-26 15:09 ` Daniel Jacobowitz
2012-03-03 2:54 ` Tom Tromey
2012-03-05 0:25 ` Daniel Jacobowitz
2012-03-05 22:03 ` Tom Tromey
2012-03-15 12:51 ` Gary Benson
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