[OPENMP] Current status of OpenMP support.

[ABataev]

Summary

Some info about supported features of OpenMP 4.5-5.0.

[Hahnfeld]

Do we want to add documentation about which target devices Clang can generate code for?

docs/OpenMPSupport.rst

47

I think that's also a combined directive?

[ABataev]

In D39457#911950, @Hahnfeld wrote:

Do we want to add documentation about which target devices Clang can generate code for?

Ok

docs/OpenMPSupport.rst

47

No, it is not. It is part of device constructs

[ABataev]

Added info about supported devices.

[ABataev]

Update status.

[ABataev]

Fixed version of OpenMP standard

[ABataev]

Updated info about supported constructs.

[ABataev]

Added codegen for target teams construct.

[ABataev]

Added codegen for distribute parallel for simd construct.

[ABataev]

Update

[ABataev]

Status update.

[ABataev]

Status update

[ABataev]

Status update

[Hahnfeld]

@hfinkel I think you requested this documentation on the mailing list. Can you take a look if it matches your expectations so we can get this bundled in the 6.0 release?

docs/OpenMPSupport.rst

18

We should probably say that current trunk is not able to compile for Cuda devices yet.

[ABataev]

Updated status of target (update|enter data|exit data) directives.
Marked that support for cuda devices is not ready yet.

[hfinkel]

In D39457#961824, @Hahnfeld wrote:

@hfinkel I think you requested this documentation on the mailing list. Can you take a look if it matches your expectations so we can get this bundled in the 6.0 release?

Yes, this looks good. Thank you.

docs/OpenMPSupport.rst

+.. 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, PPC64[LE] and Cuda devices.
+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:`Mostly complete`.  Some rework is
+  required for better stability.
+
+* #pragma omp target update: :good:`Mostly complete`.  Some rework is
+  required for better stability.
+
+* #pragma omp target: :partial:`Partial`.  No support for the `reduction`,
+  `nowait` and `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]: :partial:`Partial`. No full codegen support.
+
+Combined directives
+===================
+
+* #pragma omp parallel for simd: :good:`Complete`.
+
+* #pragma omp target parallel: :partial:`Partial`.  No support for the `reduction`,
+  `nowait` and `depend` clauses.
+
+* #pragma omp target parallel for [simd]: :partial:`Partial`.  No support for the `reduction`,
+  `nowait` and `depend` clauses.
+
+* #pragma omp target simd: :partial:`Partial`.  No support for the `reduction`,
+  `nowait` and `depend` clauses.
+
+* #pragma omp target teams: :partial:`Partial`.  No support for the `reduction`,
+  `nowait` and `depend` clauses.
+
+* #pragma omp teams distribute [simd]: :partial:`Partial`.  No full codegen support.
+
+* #pragma omp target teams distribute [simd]: :partial:`Partial`.  No full codegen support.
+
+* #pragma omp teams distribute parallel for [simd]: :partial:`Partial`.  No full codegen support.
+
+* #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`-based directives.
+

docs/index.rst

.. toctree::
    SanitizerStats
    SanitizerSpecialCaseList
    ControlFlowIntegrity
    LTOVisibility
    SafeStack
    SourceBasedCodeCoverage
    Modules
    MSVCCompatibility
+   OpenMPSupport
    ThinLTO
    CommandGuide/index
    FAQ
 
 Using Clang as a Library
 ========================
 
 .. toctree::