As the compiler analyzes loops explicitly marked for parallelization with directives, it issues warning messages about certain data dependencies it detects; but the loop will still be parallelized.
Example: Verbose parallelization warnings:
demo% f95 -explicitpar -vpara any.f any.f: MAIN any: "any.f", line 11: Warning: the loop may have parallelization inhibiting reference
Use with -xopenmp and OpenMP API directives, or with -explicitpar and C$MIC DOALL legacy parallelization directives.
Warnings are issued with the compiler detects the following situations:
Problematic use of OpenMP data sharing attributes clauses, such as declaring a variable shared whose accesses in an OpenMP parallel region may cause data race, or declaring a variable private whose value in a parallel region is used after the parallel region.
C$MIC DOALL parallelized loops with data dependencies between different loop iterations.
No warnings appear if all parallelization directives are processed without issues.
Sun Studio compilers support the OpenMP API parallelization model. Consequently, C$MIC parallelization directives are deprecated. See the OpenMP API User’s Guide for information on migrating to the OpenMP API.