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Very slow link times on debug versions of C++ program on x86_64. Includes oprofile of ld...

Talbot, George Gtalbot@locuspharma.com
Wed Jun 20 14:20:00 GMT 2007 
Thanks for your quick reply.

I'll see if I can come up with a testcase.

Based upon my examination of oprofile results, I can say that ld is
_not_ spending all of its time in I/O, like the previous message
suggests.  Looking at the oprofile results, it's spending it's time
matching wildcards, though of what I'm not exactly sure.

What exactly does the "wild_section"/"match_simple_wild" stuff do in
there?  I'm not sure that I fully understand it.  It appears to be
matching section names, yes?  That seems kinda weird--does a GCC debug
compile have a lot more sections in the .o file?

I will _gladly_ help debug this.

--
George T. Talbot
<gtalbot@locuspharma.com>


> -----Original Message-----
> From: H. J. Lu [mailto:hjl@lucon.org]
> Sent: Wednesday, June 20, 2007 9:47 AM
> To: Talbot, George
> Cc: binutils@sourceware.org
> Subject: Re: Very slow link times on debug versions of C++ program on
> x86_64. Includes oprofile of ld...
> 
> On Wed, Jun 20, 2007 at 09:19:39AM -0400, Talbot, George wrote:
> > Hi all,
> >
> > I've recently upgraded my machine here to an x86_64 box running
Fedora
> > Core 6 (7 came out a week after I installed doh!).  I have a largish
C++
> > program that I compile in both a release (-O3 -DNDEBUG) and debug
(-O0
> > -ggdb3) versions that uses a lot of templates and stuff.  Linking
the
> > release one is pretty quick...on the order of 10-20 seconds or so.
> > However linking the debug version takes many minutes, and the CPU is
> > pegged during the link.
> >
> 
> It may be related to
> 
> http://sourceware.org/ml/binutils/2007-06/msg00064.html
> 
> Please open a bug repprt at
> 
> http://www.sourceware.org/bugzilla/
> 
> with a testcase to reproduce it. If the testcase is too big, you
> can make it available via ftp/http.
> 
> Thanks.
> 
> H.J.
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