[Mesa-dev] [PATCH] gallium/targets: use c++ compiler for linking

[Marcin Slusarz]

On Mon, Oct 17, 2011 at 05:32:22PM +0200, Michel Dänzer wrote:
> On Son, 2011-10-16 at 18:47 +0200, Marcin Slusarz wrote: 
> > On Sun, Oct 16, 2011 at 04:15:14PM +0200, Michel Dänzer wrote:
> > > On Son, 2011-10-16 at 14:54 +0200, Marcin Slusarz wrote: 
> > > > On Sun, Oct 16, 2011 at 02:03:16PM +0200, Marcin Slusarz wrote:
> > > > > On Fri, Oct 14, 2011 at 08:22:35AM +0200, Michel Dänzer wrote:
> > > > > > On Don, 2011-10-13 at 15:11 -0500, Patrick Baggett wrote:
> > > > > > > Well, trivial answer is that Win32 uses some C/C++ runtime provided by
> > > > > > > Microsoft, usually something like MSVCR90.DLL (v9.0) etc. Solaris uses
> > > > > > > libC.so, for example. As far as I know, only systems where the GNU C/C
> > > > > > > ++ compiler is main system compiler (and generally therefore the GNU C
> > > > > > > ++ runtime) uses anything named "libstdc++". So I'd expect
> > > > > > > Free/Net/OpenBSD + Linux use that naming and probably not much else.
> > > > > > > On other commercial UNIXes, if it does exist, it is just
> > > > > > > for compatibility with C++ programs compiled using g++.
> > > > > > 
> > > > > > gcc -lsdtdc++ doesn't even work on all Linux architectures, as libdstdc
> > > > > > ++ may require other stuff which is only pulled in implicitly by g++. 
> > > > > 
> > > > > Thanks.
> > > > > 
> > > > > > BTW, why does st/xorg need libstdc++ at all without LLVM?
> > > > > 
> > > > > Good question. I assumed it's needed by some mesa/gallium core, but
> > > > > I checked it now and it's only needed by (new) nv50/nvc0 driver code.
> > > > > 
> > > > 
> > > > I found another cases where -lstdc++ was used with gcc.
> > > > Updated patch below.
> > > 
> > > Thanks for tracking these down.
> > > 
> > > However, I wonder if we shouldn't try to only use the C++ compiler for
> > > linking when it's really necessary, e.g. for the nv50/nvc0 drivers.
> > > Otherwise, even assuming the resulting binaries don't depend on things
> > > like libstdc++ unless they're really needed, this creates an artificial
> > > requirement for a C++ compiler. (I realize a C++ compiler is really
> > > required for things like the GLSL compiler, but it should still be
> > > possible to build at least some of these targets without one).
> > 
> > With the attached patch, and with LLVM disabled:
> > 
> > uses c++ symbols | links against libstdc++ | name
> 
> [...]
> 
> These look all good.
> 
> 
> > With LLVM enabled:
> > 
> > uses c++ symbols | links against libstdc++ | name
> 
> [...]
> 
> > 0 1 gallium/libvdpau_r600.so
> 
> [...]
> 
> > 0 1 gallium/libXvMCr600.so
> 
> [...]
> 
> > 0 1 gallium/r600g_drv.so
> 
> [...]
> 
> > 0 1 gbm/pipe_i965.so
> > [...]
> > 0 1 gbm/pipe_r600.so
> 
> These could avoid linking against libstdc++ if they didn't link with g
> ++, right? Anyway, this looks good for now, thanks again.

Right.

I'll commit it today.

Thanks,
Marcin