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<execution>: parallel scans should avoid passing output values to the binary (reduce) operation #4701

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Merged
Stephan T. Lavavej (StephanTLavavej) merged 18 commits into from
Aug 15, 2024
Merged

<execution>: parallel scans should avoid passing output values to the binary (reduce) operation #4701

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d9f860f
Fix #3783
Andor233 May 30, 2024
851efc1
Add _STD to defend ADL
Andor233 May 30, 2024
a5ac91c
1. Add _STD to defend ADL, towards #140,
Andor233 May 31, 2024
f253732
Format code
Andor233 May 31, 2024
ad5b303
Remove _STD before the typename
Andor233 Jun 1, 2024
3fa174c
Merge branch 'main' into gh_3783
StephanTLavavej Aug 12, 2024
d4fe3c2
Use emplace_back's returned reference.
StephanTLavavej Aug 12, 2024
4c69b75
`_FwdIt2 _First2` => `_Ty* _First2`; it's always `_Intermediate_resul…
StephanTLavavej Aug 12, 2024
640c67e
Drop unnecessary comment in `_Transform_inclusive_scan_per_chunk`.
StephanTLavavej Aug 12, 2024
7c6aa01
Reduce code duplication.
StephanTLavavej Aug 12, 2024
0b751e8
Remove mysterious runtime branch. Nobody will notice, right?
StephanTLavavej Aug 12, 2024
e35ff3a
Improve comment grammar.
StephanTLavavej Aug 12, 2024
8830be2
Pre-allocate storage for intermediates
CaseyCarter Aug 12, 2024
f65e3bc
Don't allocate space we won't use
CaseyCarter Aug 12, 2024
c2fd190
Update comment.
StephanTLavavej Aug 13, 2024
d8703ee
All shall love `_NODISCARD` and despair.
StephanTLavavej Aug 13, 2024
28174fe
All shall love `explicit` and despair.
StephanTLavavej Aug 13, 2024
7d07226
Rename to avoid ODR violations: `(_Static_partitioned_(transform_)?(e…
StephanTLavavej Aug 13, 2024
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210 changes: 154 additions & 56 deletions stl/inc/execution
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18 changes: 9 additions & 9 deletions stl/inc/vector
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Original file line number Diff line number Diff line change
Expand Up @@ -788,7 +788,7 @@ private:
if constexpr (conjunction_v<is_nothrow_constructible<_Ty, _Valty...>,
_Uses_default_construct<_Alloc, _Ty*, _Valty...>>) {
_ASAN_VECTOR_MODIFY(1);
_Construct_in_place(*_Mylast, _STD forward<_Valty>(_Val)...);
_STD _Construct_in_place(*_Mylast, _STD forward<_Valty>(_Val)...);
} else {
_ASAN_VECTOR_EXTEND_GUARD(static_cast<size_type>(_Mylast - _My_data._Myfirst) + 1);
_Alty_traits::construct(_Getal(), _Unfancy(_Mylast), _STD forward<_Valty>(_Val)...);
Expand Down Expand Up @@ -822,27 +822,27 @@ private:
const size_type _Newsize = _Oldsize + 1;
size_type _Newcapacity = _Calculate_growth(_Newsize);

const pointer _Newvec = _Allocate_at_least_helper(_Al, _Newcapacity);
const pointer _Newvec = _STD _Allocate_at_least_helper(_Al, _Newcapacity);
const pointer _Constructed_last = _Newvec + _Whereoff + 1;
pointer _Constructed_first = _Constructed_last;

_TRY_BEGIN
_Alty_traits::construct(_Al, _Unfancy(_Newvec + _Whereoff), _STD forward<_Valty>(_Val)...);
_Alty_traits::construct(_Al, _STD _Unfancy(_Newvec + _Whereoff), _STD forward<_Valty>(_Val)...);
_Constructed_first = _Newvec + _Whereoff;

if (_Whereptr == _Mylast) { // at back, provide strong guarantee
if constexpr (is_nothrow_move_constructible_v<_Ty> || !is_copy_constructible_v<_Ty>) {
_Uninitialized_move(_Myfirst, _Mylast, _Newvec, _Al);
_STD _Uninitialized_move(_Myfirst, _Mylast, _Newvec, _Al);
} else {
_Uninitialized_copy(_Myfirst, _Mylast, _Newvec, _Al);
_STD _Uninitialized_copy(_Myfirst, _Mylast, _Newvec, _Al);
}
} else { // provide basic guarantee
_Uninitialized_move(_Myfirst, _Whereptr, _Newvec, _Al);
_STD _Uninitialized_move(_Myfirst, _Whereptr, _Newvec, _Al);
_Constructed_first = _Newvec;
_Uninitialized_move(_Whereptr, _Mylast, _Newvec + _Whereoff + 1, _Al);
_STD _Uninitialized_move(_Whereptr, _Mylast, _Newvec + _Whereoff + 1, _Al);
}
_CATCH_ALL
_Destroy_range(_Constructed_first, _Constructed_last, _Al);
_STD _Destroy_range(_Constructed_first, _Constructed_last, _Al);
_Al.deallocate(_Newvec, _Newcapacity);
_RERAISE;
_CATCH_END
Expand Down Expand Up @@ -2024,7 +2024,7 @@ private:
_My_data._Orphan_all();

if (_Myfirst) { // destroy and deallocate old array
_Destroy_range(_Myfirst, _Mylast, _Al);
_STD _Destroy_range(_Myfirst, _Mylast, _Al);
_ASAN_VECTOR_REMOVE;
_Al.deallocate(_Myfirst, static_cast<size_type>(_Myend - _Myfirst));
}
Expand Down
6 changes: 3 additions & 3 deletions stl/inc/xmemory
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Expand Up @@ -1905,15 +1905,15 @@ _CONSTEXPR20 _Alloc_ptr_t<_Alloc> _Uninitialized_move(
// move [_First, _Last) to raw _Dest, using _Al
// note: only called internally from elsewhere in the STL
using _Ptrval = typename _Alloc::value_type*;
auto _UFirst = _Get_unwrapped(_First);
const auto _ULast = _Get_unwrapped(_Last);
auto _UFirst = _STD _Get_unwrapped(_First);
const auto _ULast = _STD _Get_unwrapped(_Last);
if constexpr (conjunction_v<bool_constant<_Iter_move_cat<decltype(_UFirst), _Ptrval>::_Bitcopy_constructible>,
_Uses_default_construct<_Alloc, _Ptrval, decltype(_STD move(*_UFirst))>>) {
#if _HAS_CXX20
if (!_STD is_constant_evaluated())
#endif // _HAS_CXX20
{
_Copy_memmove(_UFirst, _ULast, _Unfancy(_Dest));
_STD _Copy_memmove(_UFirst, _ULast, _STD _Unfancy(_Dest));
return _Dest + (_ULast - _UFirst);
}
}
Expand Down
5 changes: 0 additions & 5 deletions tests/std/tests/P0024R2_parallel_algorithms_exclusive_scan/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -184,11 +184,6 @@ struct typesBop {
bopResult operator()(intermediateType&&, intermediateType&&) {
return 0;
}

// *result = binary_op(tmp, move(*result))
bopResult operator()(intermediateType&, outputType&&) {
return 0;
}
};

void test_case_exclusive_scan_init_writes_intermediate_type() {
Expand Down
5 changes: 0 additions & 5 deletions tests/std/tests/P0024R2_parallel_algorithms_inclusive_scan/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -193,11 +193,6 @@ struct typesBop {
bopResult operator()(intermediateType&&, intermediateType&&) {
return 0;
}

// *result = binary_op(tmp, move(*result))
bopResult operator()(intermediateType&, outputType&&) {
return 0;
}
};

void test_case_inclusive_scan_init_writes_intermediate_type() {
Expand Down
5 changes: 0 additions & 5 deletions tests/std/tests/P0024R2_parallel_algorithms_transform_exclusive_scan/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -179,11 +179,6 @@ struct typesBop {
bopResult operator()(intermediateType&&, intermediateType&&) {
return 0;
}

// *result = binary_op(tmp, move(*result))
bopResult operator()(intermediateType&, outputType&&) {
return 0;
}
};

void test_case_transform_exclusive_scan_init_writes_intermediate_type() {
Expand Down
5 changes: 0 additions & 5 deletions tests/std/tests/P0024R2_parallel_algorithms_transform_inclusive_scan/test.cpp
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Expand Up @@ -203,11 +203,6 @@ struct typesBop {
bopResult operator()(intermediateType&&, intermediateType&&) {
return 0;
}

// *result = binary_op(tmp, move(*result))
bopResult operator()(intermediateType&, outputType&&) {
return 0;
}
};

void test_case_transform_inclusive_scan_init_writes_intermediate_type() {
Expand Down