Open MPI compilation error - parallel-processing

Question

I am trying to compile open MPI (release 1.5.4) from the source code on a Macbook Pro (OS X Lion) with Xcode 4.1 installed. I configure the openmpi with the following options;
../configure CFLAGS=-m64 CXXFLAGS=-m64 FFLAGS=-m64 FCFLAGS=-m64 --with-wrapper-cflags=-m64 --with-wrapper-cxxflags=-m64
in a new/clean directory. When I try make it gives me the following error;
Making all in otfprofile
CXX otfprofile-otfprofile.o
CXX otfprofile-CSVParse.o
CXX otfprofile-DataStructure.o
CXX otfprofile-Handler.o
CXX otfprofile-Prodtex.o
CXX otfprofile-Summary.o
CXXLD otfprofile
Undefined symbols for architecture x86_64:
"___builtin_expect", referenced from:
_main.omp_fn.0 in otfprofile-otfprofile.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
make[9]: *** [otfprofile] Error 1
make[8]: *** [all-recursive] Error 1
make[7]: *** [all-recursive] Error 1
make[6]: *** [all] Error 2
make[5]: *** [all-recursive] Error 1
make[4]: *** [all-recursive] Error 1
make[3]: *** [all] Error 2
make[2]: *** [all-recursive] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all-recursive] Error 1
I have gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00), gfortran GNU Fortran (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3)
I heard that I can use MacPorts for an easy installation but I want to compile it myself from the source. Can someone suggest me if I need to set some extra flags or what is causing this error? Please let me know if you need any further information. Thanks.

Answer 1

__builtin_expect is a gcc extension. I'd guess the clang/LLVM move from Apple doesn't support that but thinks it's gcc still.
There's a macro in OpenMPI which is set conditionally, but most likely incorrectly here. Since __builtin_expect is just an optimisation to hint about branch prediction you can probably fix the build by forcing the macro OMPI_CXX_HAVE_BUILTIN_EXPECT to be undefined during build.