DescriptionWhen optimizing or porting HPC applications, it’s common to see numerical differences. This is even more common on heterogeneous systems where execution transitions between CPU and GPU. Finding the exact point where the computations diverge is challenging and labor intensive. We discuss a new PGI Compiler-Assisted Software Testing (PCAST) feature to address this problem. PCAST will allow a programmer to save intermediate and final results of an existing application via API runtime calls or directives that create a reference file. The same runtime calls or directives in the optimized or ported application compare the intermediate and final results to the reference file. For OpenACC applications on a heterogeneous system, dynamic results checking is supported by executing each parallel construct on the CPU as well as the GPU and comparing the results after each construct. We’ll cover these and other potential applications that can simplify HPC application development and tuning.