[SPF:fail] Re: <value optimized out> even with gcc -g -O0

Chuck Anderson cra at WPI.EDU
Tue Feb 2 20:35:48 UTC 2010


On Tue, Feb 02, 2010 at 09:18:07PM +0100, Jan Kratochvil wrote:
> On Mon, 01 Feb 2010 07:18:26 +0100, Chuck Anderson wrote:
> > I'm trying to debug an issue for the upstream author of ocp and am 
> > running into an issue where gdb is showing "<value optimized out>" for 
> > variables even though I've compiled the program with gcc -g -O0.
> [...]
> > Compiler excerpts:
> > 
> > gcc -g -O0 -fPIC -Wall -I.././ -I.././gnulib kickload.c -o kickload.o -c
> > gcc -g -O0 -fPIC -Wall -I.././ -I.././gnulib compdate.c -o compdate.o -c
> > ...
> > gcc -g -O0 -fPIC -Wall -I./ -I./gnulib  -o ocp boot/kickload.o -pthread -ldl  goodies/helpc/ocphhc doc/opencp.dox ocp.hlp
> 
> If you list also the mixasm.c compilation line you would find:
> gcc -g -O0 -fpic -Wall -I.././ -O mixasm.c -o mixasm.o -c
> 
> as there is explicit -O in dev/Makefile there.  After removing it getting
> a valid dump with no <value optimized out>.
> 
> For the -O build found one <value optimized out> as correct and one <value
> optimized out> as some bug in either gdb or gcc but that is out of the scope
> of this mail thread.  -O0 -g works, NOTABUG.

Thanks a bunch for this!


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