allarrayaccess2loop_trans.py

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# Authors: R. W. Ford, N. Nobre and S. Siso, STFC Daresbury Lab
 
'''Module providing a transformation that transforms all constant
index accesses to an array (i.e. ones that do not contain loop
iterators) to single-trip loops.
 
'''
 
from psyclone.psyir.transformations.arrayaccess2loop_trans import \
    ArrayAccess2LoopTrans
from psyclone.psyGen import Transformation
from psyclone.psyir.nodes import Assignment
from psyclone.psyir.transformations.transformation_error \
    import TransformationError
 
 
class AllArrayAccess2LoopTrans(Transformation):
    '''Provides a transformation from a PSyIR Assignment containing
    constant index accesses to an array into single-trip loops. For
    example:
 
    >>> from psyclone.psyir.transformations import AllArrayAccess2LoopTrans
    >>> from psyclone.psyir.backend.fortran import FortranWriter
    >>> from psyclone.psyir.frontend.fortran import FortranReader
    >>> from psyclone.psyir.nodes import Assignment
    >>> code = ("program example\\n"
    ...         "  real a(10,10), b(10,10)\\n"
    ...         "  integer :: n\\n"
    ...         "  a(1,n-1) = b(1,n-1)\\n"
    ...         "end program example\\n")
    >>> psyir = FortranReader().psyir_from_source(code)
    >>> assignment = psyir.walk(Assignment)[0]
    >>> AllArrayAccess2LoopTrans().apply(assignment)
    >>> print(FortranWriter()(psyir))
    program example
      real, dimension(10,10) :: a
      real, dimension(10,10) :: b
      integer :: n
      integer :: idx
      integer :: idx_1
    <BLANKLINE>
      do idx = 1, 1, 1
        do idx_1 = n - 1, n - 1, 1
          a(idx,idx_1) = b(idx,idx_1)
        enddo
      enddo
    <BLANKLINE>
    end program example
    <BLANKLINE>
 
    '''
    def apply(self, node, options=None):
        '''Apply the AllArrayAccess2Loop transformation if the supplied
        node is an Assignment with an Array Reference on its
        left-hand-side. Each constant array index access (i.e. one not
        containing a loop iterator or a range) is then transformed into
        an iterator and the assignment placed within a single-trip loop,
        subject to any constraints in the ArrayAccess2Loop transformation.
 
        If any of the AllArrayAccess2Loop constraints are not
        satisfied for a loop index then this transformation does
        nothing for that index and silently moves to the next.
 
        :param node: an assignment.
        :type node: :py:class:`psyclone.psyir.nodes.Assignment`
        :param options: a dictionary with options for transformations.
            This is an optional argument that defaults to None.
        :type options: Optional[Dict[str, Any]]
 
        '''
        self.validatevalidatevalidate(node, options)
 
        trans = ArrayAccess2LoopTrans()
 
        for index in node.lhs.children:
            try:
                trans.apply(index)
            except TransformationError:
                pass
 
    def validate(self, node, options=None):
        '''Perform any checks to ensure that it is valid to apply the
        AllArrayAccess2LoopTrans transformation to the supplied
        PSyIR Node.
 
        :param node: the node that is being checked.
        :type node: :py:class:`psyclone.psyir.nodes.Node`
        :param options: a dictionary with options for transformations.
            This is an optional argument that defaults to None.
        :type options: Optional[Dict[str, Any]]
 
        '''
        # Not a PSyIR Assignment node
        if not isinstance(node, Assignment):
            raise TransformationError(
                f"Error in AllArrayAccess2LoopTrans transformation. The "
                f"supplied node argument should be a PSyIR Assignment, "
                f"but found '{type(node).__name__}'.")
 
    def __str__(self):
        return (
            "Convert the constant indices of a PSyIR array-element assignment "
            "into single-trip Loops.")
 
    @property
    def name(self):
        '''
        :returns: the name of the transformation as a string.
        :rtype: str
 
        '''
        return type(self).__name__
 
 
# For automatic document generation
__all__ = ['AllArrayAccess2LoopTrans']