[sim/ppc] Fix printf_filtered reference

[sim/ppc] Fix printf_filtered reference

Building a gdb that includes the PPC sim in C++ mode fails to link with:

(...)s.o compile-object-load.o compile-object-run.o compile-loc2c.o compile-c-support.o inflow.o    init.o \
          ../sim/ppc/libsim.a ../readline/libreadline.a ../opcodes/libopcodes.a ../bfd/libbfd.a -lz  ../libiberty/libiberty.a ../libdecnumber/libdecnumber.a    -ldl -ldl -lncurses -lm -ldl  -lguile-2.0 -lgc  -lpthread -ldl -lutil -lm -lpython2.7 -Xlinker -export-dynamic -lexpat -llzma -lbabeltrace -lbabeltrace-ctf  ../libiberty/libiberty.a  build-gnulib/import/libgnu.a
../sim/ppc/libsim.a(sim_calls.o): In function `sim_open':
/home/pedro/gdb/mygit/cxx-convertion/src/sim/ppc/sim_calls.c:73: undefined reference to `printf_filtered'
/home/pedro/gdb/mygit/cxx-convertion/src/sim/ppc/sim_calls.c:73: undefined reference to `printf_filtered'
../sim/ppc/libsim.a(sim_calls.o): In function `sim_close':
/home/pedro/gdb/mygit/cxx-convertion/src/sim/ppc/sim_calls.c:93: undefined reference to `printf_filtered'
/home/pedro/gdb/mygit/cxx-convertion/src/sim/ppc/sim_calls.c:93: undefined reference to `printf_filtered'
../sim/ppc/libsim.a(sim_calls.o): In function `sim_load':
/home/pedro/gdb/mygit/cxx-convertion/src/sim/ppc/sim_calls.c:102: undefined reference to `printf_filtered'
../sim/ppc/libsim.a(sim_calls.o):/home/pedro/gdb/mygit/cxx-convertion/src/sim/ppc/sim_calls.c:102: more undefined references to `printf_filtered' follow
collect2: error: ld returned 1 exit status

The undefined references come from TRACE macro calls, which expand to
calls to printf_filtered.

But note that the sim's 'printf_filtered' is actually a #define to
'sim_io_printf_filtered', in sim_callbacks.h :

 #define printf_filtered sim_io_printf_filtered

AFAICS, this is not meant to call gdb's printf_filtered function.  The
ChangeLog entry that added the printf_filtered macro reads:

 Tue Jul 30 21:12:24 1996  Andrew Cagney  <cagney@kremvax.highland.com.au>

	 * sim_callbacks.h (sim_io_printf_filtered): Replace
	 printf_filtered with a local simulator specific version.  Add
	 #define printf_filtered to simplify updating of existing code.

That is, just another incomplete/partial transition.  Maybe prior to
1996 this was really meant to call gdb's printf_filtered version.

The reference to printf_filtered appears because sim_calls.c, the
compilation unit that fails to link, has this at the top:

 #undef printf_filtered /* blow away the mapping */

presumably so that this further below:

 void
 sim_io_printf_filtered(const char *fmt,
			...)
 {
   (...)
   callbacks->printf_filtered(callbacks, "%s", message);
 }

works.  So those TRACE macros instances in sim_calls.c just happen to
work because gdb is linked in, which satisfies the 'printf_filtered'
reference, when GDB is built in C mode.  When built in C++ mode, the
problem is exposed, as GDB's printf_filtered is mangled.

The fix here is to make the TRACE macro call sim_io_printf_filtered
directly.

(Standalone "run" doesn't fail to link simply because the offending
routines are not part of its link.)

sim/ppc/ChangeLog
2015-11-17  Pedro Alves  <palves@redhat.com>

	* debug.h (TRACE, ITRACE, DTRACE, DITRACE, PTRACE): Call
	sim_io_printf_filtered instead of printf_filtered.