This patch adds support for translation of the OpenMP barrier construct to LLVM IR. The OpenMP IRBuilder is used for this translation. In this patch the code for translation is added to the existing LLVM dialect translation to LLVM IR. A new flag (enable-openmp) is added to invoke this translation.
The patch includes code changes and a testcase.
Note: This patch requires the under review patch (https://reviews.llvm.org/D72400) by @DavidTruby which adds the barrier construct to the OpenMP dialect.