Execute Openmp program in LLVM-3.0

Question

I generated a .ll file using llvm-gcc for a Openmp program(written in c).
Then Optimized using opt(version 3.0)
But when I try to execute the optimized .ll file using lli or llvm-ld, getting the following errors,

        LLVM ERROR: Program used external function 'GOMP_parallel_start' which could not be resolved!

Here is the step I followed,

   $ llvm-gcc -emit-llvm loop11.c -fopenmp -o loop.ll -S
   $ opt -O3  loop.ll -o loop.opt.ll -S
   $ lli loop.opt.ll
    LLVM ERROR: Program used external function 'GOMP_parallel_start' which could not be resolved!

Please help me to solve this problem.
Thanks in advance.

Anton Korobeynikov · Accepted Answer · 2012-03-06 18:46:44Z

3

You have to link / load the OpenMP runtime, libgomp in this case.

answered Mar 6, 2012 at 18:46

Anton Korobeynikov

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2 Comments

shashikiran Over a year ago

I tried linking OpenMP runtime libgomp, [[$llvm-ld -l="/usr/lib/i386-linux-gnu/gcc/i686-linux-gnu/4.5.2/libgomp.a" op.bc]] getting same error.

Anton Korobeynikov Over a year ago

This will work only if you're using llvm-ld to generate the native code. You will either compile libgomp into LLVM IR and link it in, or load libgomp.so into lli's process. Also, make sure that LLVM was compiled with libffi support.

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