[LLVMdev] -O4 -fvisibility=hidden

[Jack Howarth]

   After trying the recommended use of -O4 -fvisibility=hidden to
compile xplor-nih with full LTO optimizations, I discovered three
symbols become undefined...

llvm-gcc-4 -O4 -fvisibility=hidden -o xplor xplor.o  \
	   \
	  -L. -lxplorCmd -lxplor -L/Users/howarth/xplor-nih-2.21/bin.Darwin_9_x86/ -lfft -lintVar -lvmd -lpy -lswigpy-xplor -ltclXplor -lswigtcl8-xplor -lnmrPot -lcommon -lmarvin  \
	     -lcrypto  -L/sw/lib/llvm-gcc-4.2/lib -lgfortran -llapack -lblas   -L/Users/howarth/xplor-nih-2.21/bin.Darwin_9_x86/ \
	   
Undefined symbols:
  "_xplorwrapproc_slave_", referenced from:
      llvm bitcode in xplor.o
  "_python_interp_", referenced from:
      llvm bitcode in xplor.o
  "_tcl_interp_", referenced from:
      llvm bitcode in xplor.o
ld: symbol(s) not found

These are all defined as extern as follows...

extern "C" void
FORTRAN(tcl_interp)   (const long&          canReturn,
                             long&          qterm,
                             long&          fd)

extern "C" void
FORTRAN(python_init)(const long&         argc,
                           char**        argv)

extern "C" void FORTRAN(xplorwrapproc_slave)();

The only symbols that become undefined are those extern
symbols which calling fortran routines from c++ code.
I'll look into creating a testcase and opening a PR for
this issue.
               Jack