[OPENMP] Current status of OpenMP support.

Summary: Some info about supported features of OpenMP 4.5-5.0.

Reviewers: hfinkel, rsmith

Subscribers: kkwli0, Hahnfeld, cfe-commits

Differential Revision: https://reviews.llvm.org/D39457

llvm-svn: 322018

clang/docs/OpenMPSupport.rst

@@ -0,0 +1,68 @@
+.. raw:: html
+
+  <style type="text/css">
+    .none { background-color: #FFCCCC }
+    .partial { background-color: #FFFF99 }
+    .good { background-color: #CCFF99 }
+  </style>
+
+.. role:: none
+.. role:: partial
+.. role:: good
+
+==================
+OpenMP Support
+==================
+
+Clang fully supports OpenMP 3.1 + some elements of OpenMP 4.5. Clang supports offloading to X86_64, AArch64 and PPC64[LE] devices.
+Support for Cuda devices is not ready yet.
+The status of major OpenMP 4.5 features support in Clang.
+
+Standalone directives
+=====================
+
+* #pragma omp [for] simd: :good:`Complete`.
+
+* #pragma omp declare simd: :partial:`Partial`.  We support parsing/semantic
+  analysis + generation of special attributes for X86 target, but still
+  missing the LLVM pass for vectorization.
+
+* #pragma omp taskloop [simd]: :good:`Complete`.
+
+* #pragma omp target [enter|exit] data: :good:`Complete`.
+
+* #pragma omp target update: :good:`Complete`.
+
+* #pragma omp target: :partial:`Partial`.  No support for the `depend` clauses.
+
+* #pragma omp declare target: :partial:`Partial`.  No full codegen support.
+
+* #pragma omp teams: :good:`Complete`.
+
+* #pragma omp distribute [simd]: :good:`Complete`.
+
+* #pragma omp distribute parallel for [simd]: :good:`Complete`.
+
+Combined directives
+===================
+
+* #pragma omp parallel for simd: :good:`Complete`.
+
+* #pragma omp target parallel: :partial:`Partial`.  No support for the `depend` clauses.
+
+* #pragma omp target parallel for [simd]: :partial:`Partial`.  No support for the `depend` clauses.
+
+* #pragma omp target simd: :partial:`Partial`.  No support for the `depend` clauses.
+
+* #pragma omp target teams: :partial:`Partial`.  No support for the `depend` clauses.
+
+* #pragma omp teams distribute [simd]: :good:`Complete`.
+
+* #pragma omp target teams distribute [simd]: :partial:`Partial`.  No support for the and `depend` clauses.
+
+* #pragma omp teams distribute parallel for [simd]: :good:`Complete`.
+
+* #pragma omp target teams distribute parallel for [simd]: :partial:`Partial`.  No full codegen support.
+
+Clang does not support any constructs/updates from upcoming OpenMP 5.0 except for `reduction`-based clauses in the `task` and `target`-based directives.
+

clang/docs/index.rst

@@ -39,6 +39,7 @@ Using Clang as a Compiler
    SourceBasedCodeCoverage
    Modules
    MSVCCompatibility
+   OpenMPSupport
    ThinLTO
    CommandGuide/index
    FAQ