Argonne National Laboratory

Experimental Physics and
Industrial Control System

1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  <20122013  2014  2015  2016  2017  2018  2019  Index 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  <20122013  2014  2015  2016  2017  2018  2019 
<== Date ==> <== Thread ==>

Subject: Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2
From: Dirk Zimoch <dirk.zimoch@psi.ch>
To: Andrew Johnson <anj@aps.anl.gov>
Cc: tech-talk@aps.anl.gov
Date: Tue, 13 Mar 2012 11:07:04 +0100
Andrew, Lewis,

If the C++ template instantiation is the problem, then the -fno-implicit-templates command line option may help. If that is used, the compiler will not create any code "behind the scenes".

Instead it requires that for each template, you explicitly specify in which file you want to have the implementation. See section "Where's the Template?" in the gcc info pages.

In exactly one source code file one has to write a line like
template class epicsSingleton<localHostName>::reference;

Dirk

Andrew Johnson wrote:
Hi Dirk,

On 3/7/12 2:50 AM, Dirk Zimoch wrote:
These two functions,
epicsSingleton<localHostName>::reference::~reference(void) and
epicsSingleton<localHostName>::reference::operator->(void) both
contain 'assert' (see src/libCom/cxxTemplates/epicsSingleton.h).

'assert' is a macro:
#   define assert(exp) ((exp) ? (void)0 : \
        epicsAssert(__FILE__, __LINE__, #exp, epicsAssertAuthor))

Depending on the optimization level, '(void)0' may be eliminated
and the code becomes shorter (by 4 bytes = 1 PPC instruction).

Try to 'make clean' in the epics base top directory and compile
again.

The problem is more subtle than that, although I suspect that different optimization levels is probably the underlying cause.

Remember Lewis is using a very old version of g++, from back when C++ templates were new; my guess is that ldppc is recompiling the template instances it needs to link the code behind the scenes, but it wasn't told the optimization level that g++ppc used to compile the instances that appear in the .o files it's linking with so it doesn't get the same length code and generates that warning. There may be a flag we could turn on to show more about what's going on inside ldppc, but it's really not worth looking into IMHO; better to spend the time upgrading to vxWorks 5.5.

- Andrew


Replies:
Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2 J. Lewis Muir
References:
"Size of symbol changed" warnings building EPICS Base 3.14.12.2 J. Lewis Muir
Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2 Dirk Zimoch
Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2 J. Lewis Muir
Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2 Andrew Johnson

Navigate by Date:
Prev: RE: Invitation to test cothread.catools release candidate michael.abbott
Next: RE: SmarAct / SmarPod ronaldo.mercado
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  <20122013  2014  2015  2016  2017  2018  2019 
Navigate by Thread:
Prev: Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2 Andrew Johnson
Next: Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2 J. Lewis Muir
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  <20122013  2014  2015  2016  2017  2018  2019 
ANJ, 18 Nov 2013 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·