RE: Issue with LTO/-fwhole-program

["Bingfeng Mei" <bmei at broadcom dot com>]

> -----Original Message-----
> From: Richard Guenther [mailto:richard.guenther@gmail.com]
> Sent: 11 June 2010 14:08
> To: Bingfeng Mei
> Cc: Dave Korn; Manuel López-Ibáñez; gcc@gcc.gnu.org; Jan Hubicka
> Subject: Re: Issue with LTO/-fwhole-program
> 
> On Fri, Jun 11, 2010 at 3:04 PM, Bingfeng Mei <bmei@broadcom.com> wrote:
> > Well, mixed LTO/non-LTO is quite useful. For example, we have mixed
> C/assembly
> > Application. Gold support for our target is still far away. I found -
> fwhole-program
> > is very important for our size optimization.
> 
> True.  Without symbol resolution information when using GNU ld
> it is hard to do anything reasonable though.  How far has the
> idea of adding resolution output to GNU ld developed?

Not much progress yet. I am not very familiar to structure of GNU LD, and need 
more time crack it. I applied Dave's patch and output lib@offset list from
ld and hacked collect2. It can work if I annotate externally_visible attribute
manually, but it seems quite error-prone process.

So I also try to make sure resolution file is used for automatic annotation
of externally_visible attribute. I will send an updated patch later. 


> 
> Richard.
> 
> > Bingfeng
> >
> >
> >> -----Original Message-----
> >> From: Dave Korn [mailto:dave.korn.cygwin@gmail.com]
> >> Sent: 11 June 2010 14:21
> >> To: Richard Guenther
> >> Cc: Manuel López-Ibáñez; Bingfeng Mei; gcc@gcc.gnu.org; Jan Hubicka
> >> Subject: Re: Issue with LTO/-fwhole-program
> >>
> >> On 11/06/2010 13:59, Richard Guenther wrote:
> >>
> >> > Well, we can't. ?We specifically support mixed LTO/non LTO objects
> >> > (think of shared libraries for example). ?With the linker-plugin
> and
> >> gold
> >> > we can do better, but with just GNU ld and collect2 we can't.
> >>
> >> ? Well then shouldn't we warn if -fwhole-program is used with mixed
> LTO
> >> and
> >> non-LTO objects? ?Or disable it, or both?
> >>
> >> ? ? cheers,
> >> ? ? ? DaveK
> >
> >
> >