Re: [Flightgear-devel] gnu linker question (don't optimize unused variables)
It's not optimizing the variable, it's optimizing the entire .o file out of the linkage, as nothing external is explicitly using any of the symbols in the .o. Ah - that explains a lot! No. Either build gnucap as a shared library or add some dummy references to symbols in the file(s) that are referenced, perhaps indirectly, by code outside of the library. Ok, thanks, at least I have a clue now where to look. I'll think about it... Torsten -- Download Intel#174; Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] gnu linker question (don't optimize unused variables)
Hi,
this is a question for the gnu linker geek:
I am trying to add gnucap to FlightGear as posted before. It compiles cleanly
and links fine, but there is one issue. Gnucap uses commands which are
implemented in separate files. These commands get registered into a global
command registry. Here is a code snipped for the clear command:
class CMD_CLEAR : public CMD {
public:
void do_it(CS, CARD_LIST* Scope) {
// .. do something fancy here
}
} p0;
DISPATCHERCMD::INSTALL d0(command_dispatcher, clear, p0);
The class CMD_CLEAR implements the CMD interface which requires the do_it()
function.
The DISPATCHER template contains a INSTALL class, it's constructor performs
the registration into the registry. In theory, when the INSTALL class is
instantiated as d0, the actions in the constructor are performed.
Unfortunately, this does not happen when linked against FlightGear.
I tried to rename d0 into something more uniqe and grep'ed the created object
and library for the variable which were found there, but not in the fgfs
executable. This lead me to the conclusion, that the linker optimizes the
unused variable from the executable.
Is there any magic switch to pass to the g++ linker telling him not to
optimize unused variables, preferably for a certain set of files or a single
library?
Torsten
--
Download Intel#174; Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev
___
Flightgear-devel mailing list
Flightgear-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] gnu linker question (don't optimize unused variables)
On Thu, Apr 15, 2010 at 10:59 PM, Torsten Dreyer tors...@t3r.de wrote:
Hi,
this is a question for the gnu linker geek:
I am trying to add gnucap to FlightGear as posted before. It compiles
cleanly
and links fine, but there is one issue. Gnucap uses commands which are
implemented in separate files. These commands get registered into a global
command registry. Here is a code snipped for the clear command:
class CMD_CLEAR : public CMD {
public:
void do_it(CS, CARD_LIST* Scope) {
// .. do something fancy here
}
} p0;
DISPATCHERCMD::INSTALL d0(command_dispatcher, clear, p0);
The class CMD_CLEAR implements the CMD interface which requires the do_it()
function.
The DISPATCHER template contains a INSTALL class, it's constructor performs
the registration into the registry. In theory, when the INSTALL class is
instantiated as d0, the actions in the constructor are performed.
Unfortunately, this does not happen when linked against FlightGear.
I tried to rename d0 into something more uniqe and grep'ed the created
object
and library for the variable which were found there, but not in the fgfs
executable. This lead me to the conclusion, that the linker optimizes the
unused variable from the executable.
It's not optimizing the variable, it's optimizing the entire .o file out of
the linkage, as nothing external is explicitly using any of the symbols in
the .o. This is a major weakness of the registration pattern when statically
linking.
Is there any magic switch to pass to the g++ linker telling him not to
optimize unused variables, preferably for a certain set of files or a
single
library?
No. Either build gnucap as a shared library or add some dummy references to
symbols in the file(s) that are referenced, perhaps indirectly, by code
outside of the library.
Tim
--
Download Intel#174; Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev___
Flightgear-devel mailing list
Flightgear-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/flightgear-devel
