llvm-capstone/openmp/libomptarget
Jon Chesterfield 221ada654b [libomptarget] Implement locks for amdgcn
Summary:
[libomptarget] Implement locks for amdgcn

The nvptx implementation deadlocks on amdgcn. atomic_cas with multiple
active lanes can deadlock - if one lane succeeds, all the others are locked
out. The set_lock implementation therefore runs on a single lane.

Also uses a sleep intrinsic instead of the system clock for a probably
minor performance improvement. The unset/test implementations may be revised
later, based on code size / performance or similar concerns.

This implements the lock at a per-wavefront scope. That's not strictly as
specified, since openmp describes locks in terms of threads. I think the
nvptx implementation provides true per-thread locking on volta and the same
per-warp locking on other architectures.

Reviewers: jdoerfert, ABataev, grokos

Reviewed By: jdoerfert

Subscribers: jvesely, mgorny, jfb, openmp-commits

Tags: #openmp

Differential Revision: https://reviews.llvm.org/D75546
2020-03-05 20:25:31 +00:00
..
cmake/Modules [OpenMP] Switch default C++ standard to C++ 14 2020-02-11 17:11:54 -06:00
deviceRTLs [libomptarget] Implement locks for amdgcn 2020-03-05 20:25:31 +00:00
include [OpenMP][libomptarget] Add support for close map modifier 2019-08-09 21:32:57 +00:00
plugins [OpenMP][Offloading] Added support for multiple streams so that multiple kernels can be executed concurrently 2020-02-11 22:07:14 -06:00
src [LIBOMPTARGET]Lower priority of global constructor/destructor to silence the warning from gcc. 2020-03-02 15:15:11 -05:00
test [LIBOMPTARGET]Fix PR44933: fix crash because of the too early deinitialization of libomptarget. 2020-02-25 15:54:37 -05:00
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 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.