psyclone.domain.nemo.transformations.nemo_arrayaccess2loop_trans

Module providing a transformation that transforms a constant index access to an array (i.e. one that does not contain a loop iterator) to a single trip loop. The node representing the constant index access is provided to the apply method of the transformation to indicate which array index should be transformed.

Classes

• NemoArrayAccess2LoopTrans: Provides a transformation to transform a constant index access to

class psyclone.domain.nemo.transformations.nemo_arrayaccess2loop_trans.NemoArrayAccess2LoopTrans

Provides a transformation to transform a constant index access to an array (i.e. one that does not contain a loop iterator) to a single trip loop. For example:

>>> from psyclone.domain.nemo.transformations import \
...     NemoArrayAccess2LoopTrans
>>> 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)\n"
...         "  a(1) = 0.0\n"
...         "end program example\n")
>>> psyir = FortranReader().psyir_from_source(code)
>>> assignment = psyir.walk(Assignment)[0]
>>> NemoArrayAccess2LoopTrans().apply(assignment.lhs.children[0])
>>> print(FortranWriter()(psyir))
program example
  real, dimension(10) :: a
  integer :: ji

  do ji = 1, 1, 1
    a(ji) = 0.0
  enddo

end program example

Inheritance

apply(node, options=None)

Apply the NemoArrayAccess2Loop transformation if the supplied node is an access to an array index within an Array Reference that is on the left-hand-side of an Assignment node. The access must be a scalar (i.e. not a range) and must not include a loop variable (as we are transforming a single access to a loop).

These constraints are required for correctness and an exception will be raised if they are not satisfied. If the constraints are satisfied then the array access is replaced with a loop iterator and a single trip loop.

The new loop will be placed immediately around the assignment i.e. it will not take into account any expected nesting (ji, jj, jk etc) constraints. Loop re-ordering should be performed by a separate transformation.

The name of the loop index is taken from the PSyclone configuration file if a name exists for the particular array index, otherwise a new name is generated.

Parameters:

• node (psyclone.psyir.nodes.Node) – an array index.

• options (Optional[Dict[str, Any]]) – a dictionary with options for transformations. No options are used in this transformation. This is an optional argument that defaults to None.

validate(node, options=None)

Perform various checks to ensure that it is valid to apply the NemoArrayAccess2LoopTrans transformation to the supplied PSyIR Node.

Parameters:

• node (psyclone.psyir.nodes.Node) – the node that is being checked.

• options (Optional[Dict[str, Any]]) – a dictionary with options for transformations. No options are used in this transformation. This is an optional argument that defaults to None.