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Dvorskiy, Mikhail 0b2e0e80d9 [pstl] Support Threading Building Blocks 2020 (oneTBB) for "tbb" parallel backend. 
After the changes the "tbb" parallel backend will work with old TBB versions(TBB_INTERFACE_VERSION <= 12000) and new ones (TBB 2020 and greater)

More about oneTBB:
https://github.com/oneapi-src/oneTBB

Phabricator Review:
https://reviews.llvm.org/D87380
 		2020-09-14 14:21:54 +03:00
..
cmake [pstl] Rename PARALLELSTL_BACKEND to PSTL_PARALLEL_BACKEND 2019-08-13 11:50:26 +00:00
docs Bump the trunk major version to 12 2020-07-15 12:05:05 +02:00
include [pstl] Support Threading Building Blocks 2020 (oneTBB) for "tbb" parallel backend. 2020-09-14 14:21:54 +03:00
test [libc++][pstl] Remove c++98 from UNSUPPORTED annotations 2020-07-29 14:17:32 -04:00
.clang-format [pstl] Indent preprocessor directives as part of the clang-format rules 2019-04-01 15:21:46 +00:00
CMakeLists.txt [CMake] Bump CMake minimum version to 3.13.4 2020-07-22 14:25:07 -04:00
CREDITS.txt
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LICENSE.txt Fix typos throughout the license files that somehow I and my reviewers 2019-01-21 09:52:34 +00:00
README.md A test commit from Mikhail Dvorskiy (blank line, to pstl/trunk) according 'Obtaining Commit Access' rules (https://llvm.org/docs/DeveloperPolicy.html#obtaining-commit-access) 2019-06-03 08:23:30 +00:00

README.md

Parallel STL

Parallel STL is an implementation of the C++ standard library algorithms with support for execution policies, as specified in ISO/IEC 14882:2017 standard, commonly called C++17. The implementation also supports the unsequenced execution policy specified in Parallelism TS version 2 and proposed for the next version of the C++ standard in the C++ working group paper P1001. Parallel STL offers efficient support for both parallel and vectorized execution of algorithms. For sequential execution, it relies on an available implementation of the C++ standard library.

Prerequisites

To use Parallel STL, you must have the following software installed:

  • C++ compiler with:
    • Support for C++11
    • Support for OpenMP* 4.0 SIMD constructs
  • Threading Building Blocks (TBB) which is available for download at https://github.com/01org/tbb/

Known issues and limitations

  • unseq and par_unseq policies only have effect with compilers that support #pragma omp simd or #pragma simd.
  • Parallel and vector execution is only supported for the algorithms if random access iterators are provided, while for other iterator types the execution will remain serial.
  • The following algorithms do not allow efficient SIMD execution: includes, inplace_merge, merge, nth_element, partial_sort, partial_sort_copy, set_difference, set_intersection, set_symmetric_difference, set_union, sort, stable_partition, stable_sort, unique.
  • The initial value type for exclusive_scan, inclusive_scan, transform_exclusive_scan, transform_inclusive_scan shall be DefaultConstructible. A default constructed-instance of the initial value type shall be the identity element for the specified binary operation.
  • For max_element, min_element, minmax_element, partial_sort, partial_sort_copy, sort, stable_sort the dereferenced value type of the provided iterators shall be DefaultConstructible.
  • For remove, remove_if, unique the dereferenced value type of the provided iterators shall be MoveConstructible.
  • The following algorithms require additional O(n) memory space for parallel execution: copy_if, inplace_merge, partial_sort, partial_sort_copy, partition_copy, remove, remove_if, rotate, sort, stable_sort, unique, unique_copy.