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Louis Dionne 1b6d6e595b [pstl] Allow customizing whether per-TU insulation is provided 
Like we do in libc++, PSTL needs the ability to constrain
ABI-unstable symbols to each translation unit. This is OFF by
default (like for libc++), because most people don't care about
this and there is a cost associated to enabling the option (code
bloat because templates are not deduped across TUs).

I'm using '#pragma clang attribute push' to avoid marking each
declaration with an attribute, which quickly becomes difficult
to maintain.

llvm-svn: 368684
 		2019-08-13 12:49:00 +00:00
..
cmake [pstl] Rename PARALLELSTL_BACKEND to PSTL_PARALLEL_BACKEND 2019-08-13 11:50:26 +00:00
docs Bump the trunk version to 10.0.0svn 2019-07-18 11:51:05 +00:00
include [pstl] Allow customizing whether per-TU insulation is provided 2019-08-13 12:49:00 +00:00
test [libc++] Take 2: Integrate the PSTL into libc++ 2019-08-05 18:29:14 +00:00
.arcconfig
…
.clang-format [pstl] Indent preprocessor directives as part of the clang-format rules 2019-04-01 15:21:46 +00:00
CMakeLists.txt [pstl] Allow customizing whether per-TU insulation is provided 2019-08-13 12:49:00 +00:00
CREDITS.txt
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LICENSE.txt
…
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.