llvm-project/openmp/libomptarget
JonChesterfield 8b6cd15242 [libomptarget][amdgcn] Implement partial barrier
[libomptarget][amdgcn] Implement partial barrier

named_sync is used to coordinate non-spmd kernels. This uses bar.sync on nvptx.
There is no corresponding ISA support on amdgcn, so this is implemented using
shared memory, one word initialized to zero.

Each wave increments the variable by one. Whichever wave is last is responsible
for resetting the variable to zero, at which point it and the others continue.

The race condition on a wave reaching the barrier before another wave has
noticed that it has been released is handled with a generation counter, packed
into the same word.

Uses a shared variable that is not needed on nvptx. Introduces a new hook,
kmpc_impl_target_init, to allow different targets to do extra initialization.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D88602
2020-10-12 21:27:32 +01:00
..
cmake/Modules [OpenMP] Change CMake Configuration to Build for Highest CUDA Architecture by Default 2020-10-08 12:09:34 -04:00
deviceRTLs [libomptarget][amdgcn] Implement partial barrier 2020-10-12 21:27:32 +01:00
include [OpenMP][libomptarget] make omp_get_initial_device 5.1 compliant 2020-10-01 00:51:11 +02:00
plugins [OpenMP][VE plugin] Fixing failure to build VE plugin with consolidated error handling in libomptarget 2020-09-29 17:38:01 +02:00
src [OpenMP][libomptarget] make omp_get_initial_device 5.1 compliant 2020-10-01 00:51:11 +02:00
test [OpenMP] Begin Printing Information Dumps In Libomptarget and Plugins 2020-09-09 12:03:56 -04:00
CMakeLists.txt [OpenMP] build offload plugins before testing them 2019-11-28 17:43:56 -05:00
README.txt Unify build documentation and convert to reStructuredText 2017-12-27 09:15:10 +00:00

README.txt

    README for the LLVM* OpenMP* Offloading Runtime Library (libomptarget)
    ======================================================================

How to Build the LLVM* OpenMP* Offloading Runtime Library (libomptarget)
========================================================================
In-tree build:

$ cd where-you-want-to-live
Check out openmp (libomptarget lives under ./libomptarget) into llvm/projects
$ cd where-you-want-to-build
$ mkdir build && cd build
$ cmake path/to/llvm -DCMAKE_C_COMPILER=<C compiler> -DCMAKE_CXX_COMPILER=<C++ compiler>
$ make omptarget

Out-of-tree build:

$ cd where-you-want-to-live
Check out openmp (libomptarget lives under ./libomptarget)
$ cd where-you-want-to-live/openmp/libomptarget
$ mkdir build && cd build
$ cmake path/to/openmp -DCMAKE_C_COMPILER=<C compiler> -DCMAKE_CXX_COMPILER=<C++ compiler>
$ make

For details about building, please look at README.rst in the parent directory.

Architectures Supported
=======================
The current library has been only tested in Linux operating system and the
following host architectures:
* Intel(R) 64 architecture
* IBM(R) Power architecture (big endian)
* IBM(R) Power architecture (little endian)
* ARM(R) AArch64 architecture (little endian)

The currently supported offloading device architectures are:
* Intel(R) 64 architecture (generic 64-bit plugin - mostly for testing purposes)
* IBM(R) Power architecture (big endian) (generic 64-bit plugin - mostly for testing purposes)
* IBM(R) Power architecture (little endian) (generic 64-bit plugin - mostly for testing purposes)
* ARM(R) AArch64 architecture (little endian) (generic 64-bit plugin - mostly for testing purposes)
* CUDA(R) enabled 64-bit NVIDIA(R) GPU architectures

Supported RTL Build Configurations
==================================
Supported Architectures: Intel(R) 64, IBM(R) Power 7 and Power 8

              ---------------------------
              |   gcc      |   clang    |
--------------|------------|------------|
| Linux* OS   |  Yes(1)    |  Yes(2)    |
-----------------------------------------

(1) gcc version 4.8.2 or later is supported.
(2) clang version 3.7 or later is supported.


Front-end Compilers that work with this RTL
===========================================

The following compilers are known to do compatible code generation for
this RTL:
  - clang (from https://github.com/clang-ykt )
  - clang (development branch at http://clang.llvm.org - several features still
    under development)

-----------------------------------------------------------------------

Notices
=======
This library and related compiler support is still under development, so the
employed interface is likely to change in the future.

*Other names and brands may be claimed as the property of others.