Index: README.md =================================================================== --- README.md +++ README.md @@ -3,38 +3,32 @@ 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 P1001R1. +C++ working group paper [P1001](https://wg21.link/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 to download in the GitHub [repository](https://github.com/01org/tbb/) +* Threading Building Blocks (TBB) which is available for download at https://github.com/01org/tbb/ + +## Known issues and limitations -## Known Issues or 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 satisfy - the DefaultConstructible requirements. A default constructed-instance - of the initial value type shall be the identity element for binary_op. - 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. +* `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`.