Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2

[Andrew Johnson <anj@aps.anl.gov>]

Hi Lewis,

On 2012-03-02 J. Lewis Muir wrote:
> The build host is running RHEL Client 5.7.  The VxWorks Tornado
> 2.0.2 environment is from the APS.

Wind River have never officially supported compiling code for vxWorks 5.x on a 
linux-x86 system, and I don't do test builds on version 5.4.2 very often, 
although I do use 5.5.2 quite a bit.  Note that EPICS 3.15 will not support 
vxWorks 5.4.2 because the C++ compiler is too old; you will have to upgrade to 
vxWorks 5.5.2 to run that.  I recently published a linux-x86 toolset built on 
RHEL 5.6 for vxWorks 5.5.2 using the very latest Wind River GCC sources.

I have just built the tip of the 3.14 branch for ppc604 on vxWorks 5.4.2 using 
my RHEL 6.2 x86_64 workstation without getting those warnings.  I don't know 
if I'm using exactly the same tools as you though.  This is the log from 
compiling the src/db/test/O.vxWorks-ppc604 directory:

/usr/local/vw/tornado202p1/host/x86-linux/bin/ccppc -c -DCPU=PPC604 -
DvxWorks=vxWorks -include /usr/local/vw/tornado202p1/target/h/vxWorks.h -O2   
-Wall -mcpu=604 -mstrict-align -mno-implicit-fp -fno-builtin -MMD -I. -
I../O.Common -I. -I.. -I../../../../include/os/vxWorks -I../../../../include       
-I/usr/local/vw/tornado202p1/target/h ../callbackTest.c 
/usr/local/vw/tornado202p1/host/x86-linux/bin/ldppc -r -o callbackTest  -
L../../../../lib/vxWorks-ppc604/          -
L/usr/local/vw/tornado202p1/host/x86-linux/powerpc-wrs-vxworks/lib           
callbackTest.o -ldbIoc -ldbStaticIoc -lca -lCom
/usr/local/vw/tornado202p1/host/x86-linux/bin/nmppc callbackTest > 
callbackTest.nm
perl ../../../../bin/linux-x86_64/munch.pl -o callbackTest_ctdt.c 
callbackTest.nm
/usr/local/vw/tornado202p1/host/x86-linux/bin/ccppc -c -DCPU=PPC604  -
DvxWorks=vxWorks -include /usr/local/vw/tornado202p1/target/h/vxWorks.h -O2 -
Wall -mcpu=604 -mstrict-align -mno-implicit-fp -fno-builtin -MMD -fdollars-in-
identifiers -I. -I../O.Common -I. -I.. -I../../../../include/os/vxWorks -
I../../../../include -I/usr/local/vw/tornado202p1/target/h  
callbackTest_ctdt.c
/usr/local/vw/tornado202p1/host/x86-linux/bin/ldppc -r -o callbackTest.munch 
callbackTest_ctdt.o callbackTest
Installing created file ../../../../bin/vxWorks-ppc604/callbackTest.munch

> Searching the web I found this:
> 
>   http://gcc.gnu.org/ml/gcc-help/2001-03/msg00167.html
> 
> I don't know if that helps.

A little...

> Are these warnings a problem?

I suspect not, but I don't know for sure.

> I happened to be compiling with -O0.  I tried compiling with -O2
> and these "size of symbol changed" warnings went away.  Strange.

Hmm, -O0 turns them on for me too.  This appears to be something to do with 
template instantiation.  If I recompile just the two files it's complaining 
about (cac.o and udpiiu.o) with -O0 then I get even more warnings from the 
later ldppc runs.  It feels like the linker is comparing the sizes of the 
instantiated template in the named .o file with another one, and warning if 
they're different.  Maybe the new one isn't being compiled with the same 
optimization level?

HTH.  I would encourage you to look at upgrading to vxWorks 5.5.2 though, I 
have a lot more confidence in its compiler.

- Andrew
-- 
Never interrupt your enemy when he is making a mistake.
-- Napoleon Bonaparte