On Sun, Oct 23, 2011 at 10:16 AM, Perry Smith <pedz...@gmail.com> wrote:
> libgomp.so.1 wants libc.a, libpthreads.a, and libgcc_s.a. The first two do > not present a problem. But there are four libgcc_s.a (normal, ppc64, > pthread, and ppc64+pthread). > > Note that there is also four versions of libgomp.so.1 (normal, ppc64, > pthread, ppc64+pthread). > > My question is: which libgcc_s.a should I link to? (this question is for > each of the four versions of libgomp.so.1). > > Setting LIBPATH or whatever I do is going to override the internal path > (since the internal path is broken). So, this may be a question that has > never been asked or answered. > > My knee jerk is that the normal libgomp.so.1 wants the normal libgcc_s.a, the > ppc64 wants the ppc64, etc. But I notice that it will always include pthread > so that is what caused me to pause and ask. > > Part of me wonders if the two non-pthread versions of libgomp make any sense. > I don't really know anything about libgomp. libgomp (-fopenmp) does not make sense without pthreads. -fopenmp implies pthreads. One thing to note: AIX tools default to 32 bit mode, although all systems are 64 bit, unlike GNU/Linux, which defaults to 64 bit mode (on x86-64 and PPC64). Only two of the four libgomp multilibs truly are necessary, but avoiding the non-pthread builds is not worth the trouble. The non-pthread libgomp libraries never will be used, unless GCC is invoked incorrectly. Each library, including libgomp, should list its multilib install directory first, e.g., ppc64 pthread would be -Wl,-blibpath:.../lib/gcc/powerpc-ibm-aix6.1.3.0/4.6.0/pthread/ppc64:.../lib/pthread/ppc64:/usr/lib:/lib and default would be -Wl,-blibpath:.../lib/gcc/powerpc-ibm-aix6.1.3.0/4.6.0:.../lib:/usr/lib:/lib The GCC build process and driver directory search process make a lot of assumptions that the system directories follow a Linux/SVR4/Solaris layout. To follow AIX style, the PPC64 and PPC32 non-reentrant (non-pthreads) libraries should be archived into the same file libgomp.a (which never would be referenced) and the reentrant (pthreads) libraries for PPC64 and PPC32 should be archived into libgomp_r.a. The benefit has not been shown to be worth the effort. - David
