DiscoPoP - Discovery of Potential Parallelism

DiscoPoP is an open-source tool that helps software developers parallelize their programs with threads. It is a joint project of Technical University of Darmstadt and Iowa State University.

In a nutshell, DiscoPoP performs the following steps:

• detect parts of the code (computational units or CUs) with little to no internal parallelization potential,
• find data dependences among them,
• identify parallel patterns that can be used to parallelize a code region,
• and finally suggest corresponding OpenMP parallelization constructs and clauses to programmers.

DiscoPoP is built on top of LLVM. Therefore, DiscoPoP can perform the above-mentioned steps on any source code which can be transferred into the LLVM IR.

A more comprehensive overview of DiscoPoP can be found on our project website.

Wiki

Detailed information about each execution step, the setup as well as the functionality of DiscoPoP and how to contribute can be found on the wiki page.

Quick Links

• Quickstart guide

Example

DiscoPoP creates parallelization suggestions for sequential source code. Implementing these suggestions results in a parallel program. A simple example for the results of the assisted parallelization on the basis of the created parallelization suggestions can be found below.

Original Source Code

Let's assume the original source code looks as follows:

int foo(int in, int d){
    return in * d;
}

int bar(int in, int d){
    return in + d;
}

int delta(int in, int d){
    return in -d;
}

int main( void)
{
    int i;
    int d=20,a=22, b=44,c=90;
    for (i=0; i<100; i++) {
        a = foo(i, d);
        b = bar(a, d);
        c = delta(b, d);
    }
    a = b;
    return 0;
}

Applying DiscoPop to this program will result in a set of parallelization suggestions.

Parallel Source Code

For demonstration purposes we have applied the identified and suggested pipeline pattern to the original source code, which resulted in the following parallel source code. Please refer to the parallel patterns page of the DiscoPoP wiki for a complete overview of the supported parallel patterns.

int foo(int in, int d){
    return in * d;
}

int bar(int in, int d){
    return in + d;
}

int delta(int in, int d){
    return in -d;
}

int main( void)
{
    int i;
    int d=20,a=22, b=44,c=90;
    for (i=0; i<100; i++) {
        #pragma omp task firsprivate(i) shared(d, in) depend(out:a)
        a = foo(i, d);
        #pragma omp task shared(d, in) depend(in:a) depend(out:b)
        b = bar(a, d);
        #pragma omp task private(c) shared(d, in) depend(in: b)
        c = delta(b, d);
    }
    a = b;
    return 0;
}

License

© DiscoPoP is available under the terms of the BSD-3-Clause license, as specified in the LICENSE file.