================ @@ -0,0 +1,155 @@ +<!--===- docs/DoConcurrentMappingToOpenMP.md + + Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. + See https://llvm.org/LICENSE.txt for license information. + SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception + +--> + +# `DO CONCURRENT` mapping to OpenMP + +```{contents} +--- +local: +--- +``` + +This document seeks to describe the effort to parallelize `do concurrent` loops +by mapping them to OpenMP worksharing constructs. The goals of this document +are: +* Describing how to instruct `flang` to map `DO CONCURRENT` loops to OpenMP + constructs. +* Tracking the current status of such mapping. +* Describing the limitations of the current implementation. +* Describing next steps. +* Tracking the current upstreaming status (from the AMD ROCm fork). + +## Usage + +In order to enable `do concurrent` to OpenMP mapping, `flang` adds a new +compiler flag: `-fdo-concurrent-to-openmp`. This flag has 3 possible values: +1. `host`: this maps `do concurrent` loops to run in parallel on the host CPU. + This maps such loops to the equivalent of `omp parallel do`. +2. `device`: this maps `do concurrent` loops to run in parallel on a target device. + This maps such loops to the equivalent of + `omp target teams distribute parallel do`. +3. `none`: this disables `do concurrent` mapping altogether. In that case, such + loops are emitted as sequential loops. + +The `-fdo-concurrent-to-openmp` compiler switch is currently available only when +OpenMP is also enabled. So you need to provide the following options to flang in +order to enable it: +``` +flang ... -fopenmp -fdo-concurrent-to-openmp=[host|device|none] ... +``` +For mapping to device, the target device architecture must be specified as well. +See `-fopenmp-targets` and `-foffload-arch` for more info. ---------------- skatrak wrote:
```suggestion See `-fopenmp-targets` and `--offload-arch` for more info. ``` https://github.com/llvm/llvm-project/pull/126026 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
