| // -*- C++ -*- |
| //===-- parallel_backend_tbb.h --------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _PSTL_PARALLEL_BACKEND_TBB_H |
| #define _PSTL_PARALLEL_BACKEND_TBB_H |
| |
| #include <algorithm> |
| #include <type_traits> |
| |
| #include "parallel_backend_utils.h" |
| |
| // Bring in minimal required subset of Intel TBB |
| #include <tbb/blocked_range.h> |
| #include <tbb/parallel_for.h> |
| #include <tbb/parallel_reduce.h> |
| #include <tbb/parallel_scan.h> |
| #include <tbb/parallel_invoke.h> |
| #include <tbb/task_arena.h> |
| #include <tbb/tbb_allocator.h> |
| |
| #if TBB_INTERFACE_VERSION < 10000 |
| # error Intel(R) Threading Building Blocks 2018 is required; older versions are not supported. |
| #endif |
| |
| namespace __pstl |
| { |
| namespace __par_backend |
| { |
| |
| //! Raw memory buffer with automatic freeing and no exceptions. |
| /** Some of our algorithms need to start with raw memory buffer, |
| not an initialize array, because initialization/destruction |
| would make the span be at least O(N). */ |
| // tbb::allocator can improve performance in some cases. |
| template <typename _Tp> |
| class __buffer |
| { |
| tbb::tbb_allocator<_Tp> _M_allocator; |
| _Tp* _M_ptr; |
| const std::size_t _M_buf_size; |
| __buffer(const __buffer&) = delete; |
| void |
| operator=(const __buffer&) = delete; |
| |
| public: |
| //! Try to obtain buffer of given size to store objects of _Tp type |
| __buffer(std::size_t n) : _M_allocator(), _M_ptr(_M_allocator.allocate(n)), _M_buf_size(n) {} |
| //! True if buffer was successfully obtained, zero otherwise. |
| operator bool() const { return _M_ptr != NULL; } |
| //! Return pointer to buffer, or NULL if buffer could not be obtained. |
| _Tp* |
| get() const |
| { |
| return _M_ptr; |
| } |
| //! Destroy buffer |
| ~__buffer() { _M_allocator.deallocate(_M_ptr, _M_buf_size); } |
| }; |
| |
| // Wrapper for tbb::task |
| inline void |
| __cancel_execution() |
| { |
| tbb::task::self().group()->cancel_group_execution(); |
| } |
| |
| //------------------------------------------------------------------------ |
| // parallel_for |
| //------------------------------------------------------------------------ |
| |
| template <class _Index, class _RealBody> |
| class __parallel_for_body |
| { |
| public: |
| __parallel_for_body(const _RealBody& __body) : _M_body(__body) {} |
| __parallel_for_body(const __parallel_for_body& __body) : _M_body(__body._M_body) {} |
| void |
| operator()(const tbb::blocked_range<_Index>& __range) const |
| { |
| _M_body(__range.begin(), __range.end()); |
| } |
| |
| private: |
| _RealBody _M_body; |
| }; |
| |
| //! Evaluation of brick f[i,j) for each subrange [i,j) of [first,last) |
| // wrapper over tbb::parallel_for |
| template <class _ExecutionPolicy, class _Index, class _Fp> |
| void |
| __parallel_for(_ExecutionPolicy&&, _Index __first, _Index __last, _Fp __f) |
| { |
| tbb::this_task_arena::isolate([=]() { |
| tbb::parallel_for(tbb::blocked_range<_Index>(__first, __last), __parallel_for_body<_Index, _Fp>(__f)); |
| }); |
| } |
| |
| //! Evaluation of brick f[i,j) for each subrange [i,j) of [first,last) |
| // wrapper over tbb::parallel_reduce |
| template <class _ExecutionPolicy, class _Value, class _Index, typename _RealBody, typename _Reduction> |
| _Value |
| __parallel_reduce(_ExecutionPolicy&&, _Index __first, _Index __last, const _Value& __identity, |
| const _RealBody& __real_body, const _Reduction& __reduction) |
| { |
| return tbb::this_task_arena::isolate([__first, __last, &__identity, &__real_body, &__reduction]() -> _Value { |
| return tbb::parallel_reduce( |
| tbb::blocked_range<_Index>(__first, __last), __identity, |
| [__real_body](const tbb::blocked_range<_Index>& __r, const _Value& __value) -> _Value { |
| return __real_body(__r.begin(), __r.end(), __value); |
| }, |
| __reduction); |
| }); |
| } |
| |
| //------------------------------------------------------------------------ |
| // parallel_transform_reduce |
| // |
| // Notation: |
| // r(i,j,init) returns reduction of init with reduction over [i,j) |
| // u(i) returns f(i,i+1,identity) for a hypothetical left identity element of r |
| // c(x,y) combines values x and y that were the result of r or u |
| //------------------------------------------------------------------------ |
| |
| template <class _Index, class _Up, class _Tp, class _Cp, class _Rp> |
| struct __par_trans_red_body |
| { |
| alignas(_Tp) char _M_sum_storage[sizeof(_Tp)]; // Holds generalized non-commutative sum when has_sum==true |
| _Rp _M_brick_reduce; // Most likely to have non-empty layout |
| _Up _M_u; |
| _Cp _M_combine; |
| bool _M_has_sum; // Put last to minimize size of class |
| _Tp& |
| sum() |
| { |
| _PSTL_ASSERT_MSG(_M_has_sum, "sum expected"); |
| return *(_Tp*)_M_sum_storage; |
| } |
| __par_trans_red_body(_Up __u, _Tp __init, _Cp __c, _Rp __r) |
| : _M_brick_reduce(__r), _M_u(__u), _M_combine(__c), _M_has_sum(true) |
| { |
| new (_M_sum_storage) _Tp(__init); |
| } |
| |
| __par_trans_red_body(__par_trans_red_body& __left, tbb::split) |
| : _M_brick_reduce(__left._M_brick_reduce), _M_u(__left._M_u), _M_combine(__left._M_combine), _M_has_sum(false) |
| { |
| } |
| |
| ~__par_trans_red_body() |
| { |
| // 17.6.5.12 tells us to not worry about catching exceptions from destructors. |
| if (_M_has_sum) |
| sum().~_Tp(); |
| } |
| |
| void |
| join(__par_trans_red_body& __rhs) |
| { |
| sum() = _M_combine(sum(), __rhs.sum()); |
| } |
| |
| void |
| operator()(const tbb::blocked_range<_Index>& __range) |
| { |
| _Index __i = __range.begin(); |
| _Index __j = __range.end(); |
| if (!_M_has_sum) |
| { |
| _PSTL_ASSERT_MSG(__range.size() > 1, "there should be at least 2 elements"); |
| new (&_M_sum_storage) |
| _Tp(_M_combine(_M_u(__i), _M_u(__i + 1))); // The condition i+1 < j is provided by the grain size of 3 |
| _M_has_sum = true; |
| std::advance(__i, 2); |
| if (__i == __j) |
| return; |
| } |
| sum() = _M_brick_reduce(__i, __j, sum()); |
| } |
| }; |
| |
| template <class _ExecutionPolicy, class _Index, class _Up, class _Tp, class _Cp, class _Rp> |
| _Tp |
| __parallel_transform_reduce(_ExecutionPolicy&&, _Index __first, _Index __last, _Up __u, _Tp __init, _Cp __combine, |
| _Rp __brick_reduce) |
| { |
| __par_backend::__par_trans_red_body<_Index, _Up, _Tp, _Cp, _Rp> __body(__u, __init, __combine, __brick_reduce); |
| // The grain size of 3 is used in order to provide mininum 2 elements for each body |
| tbb::this_task_arena::isolate( |
| [__first, __last, &__body]() { tbb::parallel_reduce(tbb::blocked_range<_Index>(__first, __last, 3), __body); }); |
| return __body.sum(); |
| } |
| |
| //------------------------------------------------------------------------ |
| // parallel_scan |
| //------------------------------------------------------------------------ |
| |
| template <class _Index, class _Up, class _Tp, class _Cp, class _Rp, class _Sp> |
| class __trans_scan_body |
| { |
| alignas(_Tp) char _M_sum_storage[sizeof(_Tp)]; // Holds generalized non-commutative sum when has_sum==true |
| _Rp _M_brick_reduce; // Most likely to have non-empty layout |
| _Up _M_u; |
| _Cp _M_combine; |
| _Sp _M_scan; |
| bool _M_has_sum; // Put last to minimize size of class |
| public: |
| __trans_scan_body(_Up __u, _Tp __init, _Cp __combine, _Rp __reduce, _Sp __scan) |
| : _M_brick_reduce(__reduce), _M_u(__u), _M_combine(__combine), _M_scan(__scan), _M_has_sum(true) |
| { |
| new (_M_sum_storage) _Tp(__init); |
| } |
| |
| __trans_scan_body(__trans_scan_body& __b, tbb::split) |
| : _M_brick_reduce(__b._M_brick_reduce), _M_u(__b._M_u), _M_combine(__b._M_combine), _M_scan(__b._M_scan), |
| _M_has_sum(false) |
| { |
| } |
| |
| ~__trans_scan_body() |
| { |
| // 17.6.5.12 tells us to not worry about catching exceptions from destructors. |
| if (_M_has_sum) |
| sum().~_Tp(); |
| } |
| |
| _Tp& |
| sum() const |
| { |
| _PSTL_ASSERT_MSG(_M_has_sum, "sum expected"); |
| return *const_cast<_Tp*>(reinterpret_cast<_Tp const*>(_M_sum_storage)); |
| } |
| |
| void |
| operator()(const tbb::blocked_range<_Index>& __range, tbb::pre_scan_tag) |
| { |
| _Index __i = __range.begin(); |
| _Index __j = __range.end(); |
| if (!_M_has_sum) |
| { |
| new (&_M_sum_storage) _Tp(_M_u(__i)); |
| _M_has_sum = true; |
| ++__i; |
| if (__i == __j) |
| return; |
| } |
| sum() = _M_brick_reduce(__i, __j, sum()); |
| } |
| |
| void |
| operator()(const tbb::blocked_range<_Index>& __range, tbb::final_scan_tag) |
| { |
| sum() = _M_scan(__range.begin(), __range.end(), sum()); |
| } |
| |
| void |
| reverse_join(__trans_scan_body& __a) |
| { |
| if (_M_has_sum) |
| { |
| sum() = _M_combine(__a.sum(), sum()); |
| } |
| else |
| { |
| new (&_M_sum_storage) _Tp(__a.sum()); |
| _M_has_sum = true; |
| } |
| } |
| |
| void |
| assign(__trans_scan_body& __b) |
| { |
| sum() = __b.sum(); |
| } |
| }; |
| |
| template <typename _Index> |
| _Index |
| __split(_Index __m) |
| { |
| _Index __k = 1; |
| while (2 * __k < __m) |
| __k *= 2; |
| return __k; |
| } |
| |
| //------------------------------------------------------------------------ |
| // __parallel_strict_scan |
| //------------------------------------------------------------------------ |
| |
| template <typename _Index, typename _Tp, typename _Rp, typename _Cp> |
| void |
| __upsweep(_Index __i, _Index __m, _Index __tilesize, _Tp* __r, _Index __lastsize, _Rp __reduce, _Cp __combine) |
| { |
| if (__m == 1) |
| __r[0] = __reduce(__i * __tilesize, __lastsize); |
| else |
| { |
| _Index __k = __split(__m); |
| tbb::parallel_invoke( |
| [=] { __par_backend::__upsweep(__i, __k, __tilesize, __r, __tilesize, __reduce, __combine); }, |
| [=] { |
| __par_backend::__upsweep(__i + __k, __m - __k, __tilesize, __r + __k, __lastsize, __reduce, __combine); |
| }); |
| if (__m == 2 * __k) |
| __r[__m - 1] = __combine(__r[__k - 1], __r[__m - 1]); |
| } |
| } |
| |
| template <typename _Index, typename _Tp, typename _Cp, typename _Sp> |
| void |
| __downsweep(_Index __i, _Index __m, _Index __tilesize, _Tp* __r, _Index __lastsize, _Tp __initial, _Cp __combine, |
| _Sp __scan) |
| { |
| if (__m == 1) |
| __scan(__i * __tilesize, __lastsize, __initial); |
| else |
| { |
| const _Index __k = __split(__m); |
| tbb::parallel_invoke( |
| [=] { __par_backend::__downsweep(__i, __k, __tilesize, __r, __tilesize, __initial, __combine, __scan); }, |
| // Assumes that __combine never throws. |
| //TODO: Consider adding a requirement for user functors to be constant. |
| [=, &__combine] { |
| __par_backend::__downsweep(__i + __k, __m - __k, __tilesize, __r + __k, __lastsize, |
| __combine(__initial, __r[__k - 1]), __combine, __scan); |
| }); |
| } |
| } |
| |
| // Adapted from Intel(R) Cilk(TM) version from cilkpub. |
| // Let i:len denote a counted interval of length n starting at i. s denotes a generalized-sum value. |
| // Expected actions of the functors are: |
| // reduce(i,len) -> s -- return reduction value of i:len. |
| // combine(s1,s2) -> s -- return merged sum |
| // apex(s) -- do any processing necessary between reduce and scan. |
| // scan(i,len,initial) -- perform scan over i:len starting with initial. |
| // The initial range 0:n is partitioned into consecutive subranges. |
| // reduce and scan are each called exactly once per subrange. |
| // Thus callers can rely upon side effects in reduce. |
| // combine must not throw an exception. |
| // apex is called exactly once, after all calls to reduce and before all calls to scan. |
| // For example, it's useful for allocating a __buffer used by scan but whose size is the sum of all reduction values. |
| // T must have a trivial constructor and destructor. |
| template <class _ExecutionPolicy, typename _Index, typename _Tp, typename _Rp, typename _Cp, typename _Sp, typename _Ap> |
| void |
| __parallel_strict_scan(_ExecutionPolicy&&, _Index __n, _Tp __initial, _Rp __reduce, _Cp __combine, _Sp __scan, |
| _Ap __apex) |
| { |
| tbb::this_task_arena::isolate([=, &__combine]() { |
| if (__n > 1) |
| { |
| _Index __p = tbb::this_task_arena::max_concurrency(); |
| const _Index __slack = 4; |
| _Index __tilesize = (__n - 1) / (__slack * __p) + 1; |
| _Index __m = (__n - 1) / __tilesize; |
| __buffer<_Tp> __buf(__m + 1); |
| _Tp* __r = __buf.get(); |
| __par_backend::__upsweep(_Index(0), _Index(__m + 1), __tilesize, __r, __n - __m * __tilesize, __reduce, |
| __combine); |
| |
| // When __apex is a no-op and __combine has no side effects, a good optimizer |
| // should be able to eliminate all code between here and __apex. |
| // Alternatively, provide a default value for __apex that can be |
| // recognized by metaprogramming that conditionlly executes the following. |
| size_t __k = __m + 1; |
| _Tp __t = __r[__k - 1]; |
| while ((__k &= __k - 1)) |
| __t = __combine(__r[__k - 1], __t); |
| __apex(__combine(__initial, __t)); |
| __par_backend::__downsweep(_Index(0), _Index(__m + 1), __tilesize, __r, __n - __m * __tilesize, __initial, |
| __combine, __scan); |
| return; |
| } |
| // Fewer than 2 elements in sequence, or out of memory. Handle has single block. |
| _Tp __sum = __initial; |
| if (__n) |
| __sum = __combine(__sum, __reduce(_Index(0), __n)); |
| __apex(__sum); |
| if (__n) |
| __scan(_Index(0), __n, __initial); |
| }); |
| } |
| |
| template <class _ExecutionPolicy, class _Index, class _Up, class _Tp, class _Cp, class _Rp, class _Sp> |
| _Tp |
| __parallel_transform_scan(_ExecutionPolicy&&, _Index __n, _Up __u, _Tp __init, _Cp __combine, _Rp __brick_reduce, |
| _Sp __scan) |
| { |
| __trans_scan_body<_Index, _Up, _Tp, _Cp, _Rp, _Sp> __body(__u, __init, __combine, __brick_reduce, __scan); |
| auto __range = tbb::blocked_range<_Index>(0, __n); |
| tbb::this_task_arena::isolate([__range, &__body]() { tbb::parallel_scan(__range, __body); }); |
| return __body.sum(); |
| } |
| |
| //------------------------------------------------------------------------ |
| // parallel_stable_sort |
| //------------------------------------------------------------------------ |
| |
| //------------------------------------------------------------------------ |
| // stable_sort utilities |
| // |
| // These are used by parallel implementations but do not depend on them. |
| //------------------------------------------------------------------------ |
| |
| template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _RandomAccessIterator3, |
| typename _Compare, typename _Cleanup, typename _LeafMerge> |
| class __merge_task : public tbb::task |
| { |
| /*override*/ tbb::task* |
| execute(); |
| _RandomAccessIterator1 _M_xs, _M_xe; |
| _RandomAccessIterator2 _M_ys, _M_ye; |
| _RandomAccessIterator3 _M_zs; |
| _Compare _M_comp; |
| _Cleanup _M_cleanup; |
| _LeafMerge _M_leaf_merge; |
| |
| public: |
| __merge_task(_RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, _RandomAccessIterator2 __ys, |
| _RandomAccessIterator2 __ye, _RandomAccessIterator3 __zs, _Compare __comp, _Cleanup __cleanup, |
| _LeafMerge __leaf_merge) |
| : _M_xs(__xs), _M_xe(__xe), _M_ys(__ys), _M_ye(__ye), _M_zs(__zs), _M_comp(__comp), _M_cleanup(__cleanup), |
| _M_leaf_merge(__leaf_merge) |
| { |
| } |
| }; |
| |
| #define _PSTL_MERGE_CUT_OFF 2000 |
| |
| template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _RandomAccessIterator3, |
| typename __M_Compare, typename _Cleanup, typename _LeafMerge> |
| tbb::task* |
| __merge_task<_RandomAccessIterator1, _RandomAccessIterator2, _RandomAccessIterator3, __M_Compare, _Cleanup, |
| _LeafMerge>::execute() |
| { |
| typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType1; |
| typedef typename std::iterator_traits<_RandomAccessIterator2>::difference_type _DifferenceType2; |
| typedef typename std::common_type<_DifferenceType1, _DifferenceType2>::type _SizeType; |
| const _SizeType __n = (_M_xe - _M_xs) + (_M_ye - _M_ys); |
| const _SizeType __merge_cut_off = _PSTL_MERGE_CUT_OFF; |
| if (__n <= __merge_cut_off) |
| { |
| _M_leaf_merge(_M_xs, _M_xe, _M_ys, _M_ye, _M_zs, _M_comp); |
| |
| //we clean the buffer one time on last step of the sort |
| _M_cleanup(_M_xs, _M_xe); |
| _M_cleanup(_M_ys, _M_ye); |
| return nullptr; |
| } |
| else |
| { |
| _RandomAccessIterator1 __xm; |
| _RandomAccessIterator2 __ym; |
| if (_M_xe - _M_xs < _M_ye - _M_ys) |
| { |
| __ym = _M_ys + (_M_ye - _M_ys) / 2; |
| __xm = std::upper_bound(_M_xs, _M_xe, *__ym, _M_comp); |
| } |
| else |
| { |
| __xm = _M_xs + (_M_xe - _M_xs) / 2; |
| __ym = std::lower_bound(_M_ys, _M_ye, *__xm, _M_comp); |
| } |
| const _RandomAccessIterator3 __zm = _M_zs + ((__xm - _M_xs) + (__ym - _M_ys)); |
| tbb::task* __right = new (tbb::task::allocate_additional_child_of(*parent())) |
| __merge_task(__xm, _M_xe, __ym, _M_ye, __zm, _M_comp, _M_cleanup, _M_leaf_merge); |
| tbb::task::spawn(*__right); |
| tbb::task::recycle_as_continuation(); |
| _M_xe = __xm; |
| _M_ye = __ym; |
| } |
| return this; |
| } |
| |
| template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Compare, typename _LeafSort> |
| class __stable_sort_task : public tbb::task |
| { |
| public: |
| typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType1; |
| typedef typename std::iterator_traits<_RandomAccessIterator2>::difference_type _DifferenceType2; |
| typedef typename std::common_type<_DifferenceType1, _DifferenceType2>::type _SizeType; |
| |
| private: |
| /*override*/ tbb::task* |
| execute(); |
| _RandomAccessIterator1 _M_xs, _M_xe; |
| _RandomAccessIterator2 _M_zs; |
| _Compare _M_comp; |
| _LeafSort _M_leaf_sort; |
| int32_t _M_inplace; |
| _SizeType _M_nsort; |
| |
| public: |
| __stable_sort_task(_RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, _RandomAccessIterator2 __zs, |
| int32_t __inplace, _Compare __comp, _LeafSort __leaf_sort, _SizeType __n) |
| : _M_xs(__xs), _M_xe(__xe), _M_zs(__zs), _M_comp(__comp), _M_leaf_sort(__leaf_sort), _M_inplace(__inplace), |
| _M_nsort(__n) |
| { |
| } |
| }; |
| |
| //! Binary operator that does nothing |
| struct __binary_no_op |
| { |
| template <typename _Tp> |
| void operator()(_Tp, _Tp) |
| { |
| } |
| }; |
| |
| #define _PSTL_STABLE_SORT_CUT_OFF 500 |
| |
| template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Compare, typename _LeafSort> |
| tbb::task* |
| __stable_sort_task<_RandomAccessIterator1, _RandomAccessIterator2, _Compare, _LeafSort>::execute() |
| { |
| const _SizeType __n = _M_xe - _M_xs; |
| const _SizeType __nmerge = _M_nsort > 0 ? _M_nsort : __n; |
| const _SizeType __sort_cut_off = _PSTL_STABLE_SORT_CUT_OFF; |
| if (__n <= __sort_cut_off) |
| { |
| _M_leaf_sort(_M_xs, _M_xe, _M_comp); |
| if (_M_inplace != 2) |
| __par_backend::__init_buf(_M_xs, _M_xe, _M_zs, _M_inplace == 0); |
| return NULL; |
| } |
| else |
| { |
| const _RandomAccessIterator1 __xm = _M_xs + __n / 2; |
| const _RandomAccessIterator2 __zm = _M_zs + (__xm - _M_xs); |
| const _RandomAccessIterator2 __ze = _M_zs + __n; |
| task* __m; |
| auto __move_values = [](_RandomAccessIterator2 __x, _RandomAccessIterator1 __z) { *__z = std::move(*__x); }; |
| auto __move_sequences = [](_RandomAccessIterator2 __first1, _RandomAccessIterator2 __last1, |
| _RandomAccessIterator1 __first2) { return std::move(__first1, __last1, __first2); }; |
| if (_M_inplace == 2) |
| __m = new (tbb::task::allocate_continuation()) |
| __merge_task<_RandomAccessIterator2, _RandomAccessIterator2, _RandomAccessIterator1, _Compare, |
| __serial_destroy, |
| __par_backend::__serial_move_merge<decltype(__move_values), decltype(__move_sequences)>>( |
| _M_zs, __zm, __zm, __ze, _M_xs, _M_comp, __serial_destroy(), |
| __par_backend::__serial_move_merge<decltype(__move_values), decltype(__move_sequences)>( |
| __nmerge, __move_values, __move_sequences)); |
| else if (_M_inplace) |
| __m = new (tbb::task::allocate_continuation()) |
| __merge_task<_RandomAccessIterator2, _RandomAccessIterator2, _RandomAccessIterator1, _Compare, |
| __par_backend::__binary_no_op, |
| __par_backend::__serial_move_merge<decltype(__move_values), decltype(__move_sequences)>>( |
| _M_zs, __zm, __zm, __ze, _M_xs, _M_comp, __par_backend::__binary_no_op(), |
| __par_backend::__serial_move_merge<decltype(__move_values), decltype(__move_sequences)>( |
| __nmerge, __move_values, __move_sequences)); |
| else |
| { |
| auto __move_values = [](_RandomAccessIterator1 __x, _RandomAccessIterator2 __z) { *__z = std::move(*__x); }; |
| auto __move_sequences = [](_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, |
| _RandomAccessIterator2 __first2) { |
| return std::move(__first1, __last1, __first2); |
| }; |
| __m = new (tbb::task::allocate_continuation()) |
| __merge_task<_RandomAccessIterator1, _RandomAccessIterator1, _RandomAccessIterator2, _Compare, |
| __par_backend::__binary_no_op, |
| __par_backend::__serial_move_merge<decltype(__move_values), decltype(__move_sequences)>>( |
| _M_xs, __xm, __xm, _M_xe, _M_zs, _M_comp, __par_backend::__binary_no_op(), |
| __par_backend::__serial_move_merge<decltype(__move_values), decltype(__move_sequences)>( |
| __nmerge, __move_values, __move_sequences)); |
| } |
| __m->set_ref_count(2); |
| task* __right = new (__m->allocate_child()) |
| __stable_sort_task(__xm, _M_xe, __zm, !_M_inplace, _M_comp, _M_leaf_sort, __nmerge); |
| tbb::task::spawn(*__right); |
| tbb::task::recycle_as_child_of(*__m); |
| _M_xe = __xm; |
| _M_inplace = !_M_inplace; |
| } |
| return this; |
| } |
| |
| template <class _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare, typename _LeafSort> |
| void |
| __parallel_stable_sort(_ExecutionPolicy&&, _RandomAccessIterator __xs, _RandomAccessIterator __xe, _Compare __comp, |
| _LeafSort __leaf_sort, std::size_t __nsort = 0) |
| { |
| tbb::this_task_arena::isolate([=, &__nsort]() { |
| //sorting based on task tree and parallel merge |
| typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _ValueType; |
| typedef typename std::iterator_traits<_RandomAccessIterator>::difference_type _DifferenceType; |
| const _DifferenceType __n = __xe - __xs; |
| if (__nsort == 0) |
| __nsort = __n; |
| |
| const _DifferenceType __sort_cut_off = _PSTL_STABLE_SORT_CUT_OFF; |
| if (__n > __sort_cut_off) |
| { |
| _PSTL_ASSERT(__nsort > 0 && __nsort <= __n); |
| __buffer<_ValueType> __buf(__n); |
| using tbb::task; |
| task::spawn_root_and_wait(*new (task::allocate_root()) |
| __stable_sort_task<_RandomAccessIterator, _ValueType*, _Compare, _LeafSort>( |
| __xs, __xe, (_ValueType*)__buf.get(), 2, __comp, __leaf_sort, __nsort)); |
| return; |
| } |
| //serial sort |
| __leaf_sort(__xs, __xe, __comp); |
| }); |
| } |
| |
| //------------------------------------------------------------------------ |
| // parallel_merge |
| //------------------------------------------------------------------------ |
| |
| template <class _ExecutionPolicy, typename _RandomAccessIterator1, typename _RandomAccessIterator2, |
| typename _RandomAccessIterator3, typename _Compare, typename _LeafMerge> |
| void |
| __parallel_merge(_ExecutionPolicy&&, _RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, |
| _RandomAccessIterator2 __ys, _RandomAccessIterator2 __ye, _RandomAccessIterator3 __zs, _Compare __comp, |
| _LeafMerge __leaf_merge) |
| { |
| typedef typename std::iterator_traits<_RandomAccessIterator1>::difference_type _DifferenceType1; |
| typedef typename std::iterator_traits<_RandomAccessIterator2>::difference_type _DifferenceType2; |
| typedef typename std::common_type<_DifferenceType1, _DifferenceType2>::type _SizeType; |
| const _SizeType __n = (__xe - __xs) + (__ye - __ys); |
| const _SizeType __merge_cut_off = _PSTL_MERGE_CUT_OFF; |
| if (__n <= __merge_cut_off) |
| { |
| // Fall back on serial merge |
| __leaf_merge(__xs, __xe, __ys, __ye, __zs, __comp); |
| } |
| else |
| { |
| tbb::this_task_arena::isolate([=]() { |
| typedef __merge_task<_RandomAccessIterator1, _RandomAccessIterator2, _RandomAccessIterator3, _Compare, |
| __par_backend::__binary_no_op, _LeafMerge> |
| _TaskType; |
| tbb::task::spawn_root_and_wait(*new (tbb::task::allocate_root()) _TaskType( |
| __xs, __xe, __ys, __ye, __zs, __comp, __par_backend::__binary_no_op(), __leaf_merge)); |
| }); |
| } |
| } |
| |
| //------------------------------------------------------------------------ |
| // parallel_invoke |
| //------------------------------------------------------------------------ |
| template <class _ExecutionPolicy, typename _F1, typename _F2> |
| void |
| __parallel_invoke(_ExecutionPolicy&&, _F1&& __f1, _F2&& __f2) |
| { |
| //TODO: a version of tbb::this_task_arena::isolate with variadic arguments pack should be added in the future |
| tbb::this_task_arena::isolate([&]() { tbb::parallel_invoke(std::forward<_F1>(__f1), std::forward<_F2>(__f2)); }); |
| } |
| |
| } // namespace __par_backend |
| } // namespace __pstl |
| |
| #endif /* _PSTL_PARALLEL_BACKEND_TBB_H */ |
