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# Author: R. W. Ford, STFC Daresbury Lab
# Modified: S. Siso, STFC Daresbury Lab
'''Module providing a transformation from a PSyIR SUM intrinsic to an
equivalent PSyIR loop structure. This could be useful if the SUM
intrinsic is not supported by the back-end, the required
parallelisation approach, or if the performance in the inline code is
better than the intrinsic.
'''
from psyclone.psyir.nodes import BinaryOperation, Literal, IntrinsicCall
from psyclone.psyir.symbols import ScalarType
from psyclone.psyir.transformations.intrinsics.array_reduction_base_trans \
import ArrayReductionBaseTrans
[docs]class Sum2LoopTrans(ArrayReductionBaseTrans):
'''Provides a transformation from a PSyIR SUM IntrinsicCall node to an
equivalent PSyIR loop structure that is suitable for running in
parallel on CPUs and GPUs. Validity checks are also performed.
If SUM contains a single positional argument which is an array,
all elements of that array are summed and the result returned in
the scalar R.
.. code-block:: fortran
R = SUM(ARRAY)
For example, if the array is two dimensional, the equivalent code
for real data is:
.. code-block:: fortran
R = 0.0
DO J=LBOUND(ARRAY,2),UBOUND(ARRAY,2)
DO I=LBOUND(ARRAY,1),UBOUND(ARRAY,1)
R = R + ARRAY(I,J)
If the mask argument is provided then the mask is used to
determine whether the sum is applied:
.. code-block:: fortran
R = SUM(ARRAY, mask=MOD(ARRAY, 2.0)==1)
If the array is two dimensional, the equivalent code
for real data is:
.. code-block:: fortran
R = 0.0
DO J=LBOUND(ARRAY,2),UBOUND(ARRAY,2)
DO I=LBOUND(ARRAY,1),UBOUND(ARRAY,1)
IF (MOD(ARRAY(I,J), 2.0)==1) THEN
R = R + ARRAY(I,J)
The dimension argument is currently not supported and will result
in a TransformationError exception being raised.
.. code-block:: fortran
R = SUM(ARRAY, dimension=2)
The array passed to MAXVAL may use any combination of array
syntax, array notation, array sections and scalar bounds:
.. code-block:: fortran
R = SUM(ARRAY) ! array syntax
R = SUM(ARRAY(:,:)) ! array notation
R = SUM(ARRAY(1:10,lo:hi)) ! array sections
R = SUM(ARRAY(1:10,:)) ! mix of array section and array notation
R = SUM(ARRAY(1:10,2)) ! mix of array section and scalar bound
For example:
>>> from psyclone.psyir.backend.fortran import FortranWriter
>>> from psyclone.psyir.frontend.fortran import FortranReader
>>> from psyclone.psyir.transformations import Sum2LoopTrans
>>> code = ("subroutine sum_test(array,n,m)\\n"
... " integer :: n, m\\n"
... " real :: array(10,10)\\n"
... " real :: result\\n"
... " result = sum(array)\\n"
... "end subroutine\\n")
>>> psyir = FortranReader().psyir_from_source(code)
>>> sum_node = psyir.children[0].children[0].children[1]
>>> Sum2LoopTrans().apply(sum_node)
>>> print(FortranWriter()(psyir))
subroutine sum_test(array, n, m)
integer :: n
integer :: m
real, dimension(10,10) :: array
real :: result
integer :: idx
integer :: idx_1
<BLANKLINE>
result = 0.0
do idx = 1, 10, 1
do idx_1 = 1, 10, 1
result = result + array(idx_1,idx)
enddo
enddo
<BLANKLINE>
end subroutine sum_test
<BLANKLINE>
'''
_INTRINSIC_NAME = "SUM"
_INTRINSIC_TYPE = IntrinsicCall.Intrinsic.SUM
def _loop_body(self, lhs, rhs):
'''Provide the body of the nested loop that computes the sum
of the lhs and rhs.
:param lhs: the lhs value for the sum operation.
:type lhs: :py:class:`psyclone.psyir.nodes.Node`
:param rhs: the rhs value for the sum operation.
:type rhs: :py:class:`psyclone.psyir.nodes.Node`
:returns: the sum of the lhs and rhs.
:rtype: :py:class:`psyclone.psyir.nodes.BinaryOperation`
'''
# return lhs + rhs
return BinaryOperation.create(BinaryOperation.Operator.ADD, lhs, rhs)
def _init_var(self, reference):
'''The initial value for the variable that computes the sum
of an array.
:param reference: the reference used to store the final result.
:type reference: :py:class:`psyclone.psyir.node.Reference`
:returns: PSyIR for the value to initialise the variable that
computes the sum.
:rtype: :py:class:`psyclone.psyir.nodes.Literal`
'''
intrinsic = reference.datatype.intrinsic
precision = reference.datatype.precision
scalar_type = ScalarType(intrinsic, precision)
if intrinsic == ScalarType.Intrinsic.REAL:
value_str = "0.0"
elif intrinsic == ScalarType.Intrinsic.INTEGER:
value_str = "0"
# Note, the validate method guarantees that an else branch is
# not required.
return Literal(value_str, scalar_type)