Re: Exporting new libgomp functions

[Amittai Aviram <amittai dot aviram at yale dot edu>]

On Jan 12, 2011, at 1:57 PM, Ian Lance Taylor wrote:

> Amittai Aviram <amittai.aviram@yale.edu> writes:
> 
>> I would like to define some new functions in libgomp and make these
>> available to applications compiled with GCC with the -fopenmp flag.
>> Suppose I want to export function void foo(void).  I had thought that
>> I could just define it in, say, foo.c, include foo.c into my build of
>> libgomp, and provide a header file in my application with foo's
>> signature.  However, when I do this, I get a linker error that the
>> application uses an "undefined function."  I have verified that foo.o
>> and foo.lo are in my gcc_obj build directory tree, and that the
>> definition of "foo" does indeed occur in foo.o (i.e., I can see its
>> disassembly using objdump -d).  Now, libgomp already exports a bunch
>> of functions, such as omp_get_thread_num, etc.  How can I do the same
>> with my new functions?  Thanks!
> 
> You need to edit libgomp/libgomp.map to assign an appropriate version to
> your new symbol.  All libgomp symbols not mentioned in that file are
> hidden in libgomp.so.
> 
> Ian


Thank you!  Unfortunately, this didn't work.  I added my function names to the end of the list for OMP_1.0 "global," i.e.,

OMP_1.0 {
	global:
		omp_set_num_threads;
		[...]
		foo;
	local:
		*;
};

I rebuilt GCC and again tried to build my application, which makes a call to foo from inside an OpenMP parallel block:

#pragma omp parallel
{
	foo();
}

And I get the same linker error, an "undefined reference to 'foo'."

I also tried putting my function names into the GOMP_1.0 global list, with the same results. :-(

Is there something else I need to do?  Thanks!




Amittai Aviram
PhD Student in Computer Science
Yale University
646 483 2639
amittai.aviram@yale.edu
http://www.amittai.com