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# Author: R. W. Ford, STFC Daresbury Lab
# Modified: S. Siso, STFC Daresbury Lab
'''Module providing a transformation from a reference to an Array (a = ...)
to an ArrayReference with one or more array ranges (a(:) = ...). This can
be useful to determine when we have array accesses (as it is not clear when
there is a reference to an Array) and can allow further optimisations such
as transforming to explicit loops.
'''
from psyclone.errors import LazyString
from psyclone.psyGen import Transformation
from psyclone.psyir.nodes import (Range, Reference, ArrayReference, Literal,
IntrinsicCall)
from psyclone.psyir.symbols import INTEGER_TYPE, ArrayType
from psyclone.psyir.transformations.transformation_error \
import TransformationError
[docs]class Reference2ArrayRangeTrans(Transformation):
'''Provides a transformation from PSyIR Array Notation (a reference to
an Array) to a PSyIR Range. For example:
>>> from psyclone.psyir.backend.fortran import FortranWriter
>>> from psyclone.psyir.frontend.fortran import FortranReader
>>> from psyclone.psyir.nodes import Reference
>>> from psyclone.psyir.transformations import TransformationError
>>> CODE = ("program example\\n"
... "real :: a(:)\\n"
... "a = 0.0\\n"
... "end program\\n")
>>> trans = Reference2ArrayRangeTrans()
>>> psyir = FortranReader().psyir_from_source(CODE)
>>> for reference in psyir.walk(Reference):
... try:
... trans.apply(reference)
... except TransformationError:
... pass
>>> print(FortranWriter()(psyir))
program example
real, dimension(:) :: a
<BLANKLINE>
a(:) = 0.0
<BLANKLINE>
end program example
<BLANKLINE>
This transformation does not currently support arrays within
structures, see issue #1858.
'''
@staticmethod
def _get_array_bound(symbol, index):
'''A utility function that returns the appropriate loop bounds (lower,
upper and step) for an array dimension. If the array
dimension is declared with known bounds (an integer or a
symbol) then these bound values are used. If the size is
unknown (a deferred or attribute type) then the LBOUND and
UBOUND PSyIR nodes are used.
:param symbol: the symbol that we are interested in.
:type symbol: :py:class:`psyir.symbols.DataSymbol`
:param int index: the (array) reference index that we are \
interested in.
:returns: the loop bounds for this array index.
:rtype: Tuple(:py:class:`psyclone.psyir.nodes.Literal`, \
:py:class:`psyclone.psyir.nodes.Literal`, \
:py:class:`psyclone.psyir.nodes.Literal`) or \
Tuple(:py:class:`psyclone.psyir.nodes.BinaryOperation`, \
:py:class:`psyclone.psyir.nodes.BinaryOperation`, \
:py:class:`psyclone.psyir.nodes.Literal`)
'''
# Look for explicit bounds in the array declaration.
my_dim = symbol.shape[index]
if isinstance(my_dim, ArrayType.ArrayBounds):
lower_bound = my_dim.lower.copy()
upper_bound = my_dim.upper.copy()
step = Literal("1", INTEGER_TYPE)
return (lower_bound, upper_bound, step)
# No explicit array bound information could be found so use the
# LBOUND and UBOUND intrinsics.
lower_bound = IntrinsicCall.create(
IntrinsicCall.Intrinsic.LBOUND,
[Reference(symbol), ("dim", Literal(str(index+1), INTEGER_TYPE))])
upper_bound = IntrinsicCall.create(
IntrinsicCall.Intrinsic.UBOUND,
[Reference(symbol), ("dim", Literal(str(index+1), INTEGER_TYPE))])
step = Literal("1", INTEGER_TYPE)
return (lower_bound, upper_bound, step)
def validate(self, node, options=None):
'''Check that the node is a Reference node and that the symbol it
references is an array.
:param node: a Reference node.
:type node: :py:class:`psyclone.psyir.nodes.Reference`
:param options: a dict with options for transformations.
:type options: Optional[Dict[str, Any]]
:raises TransformationError: if the node is not a Reference
node or the Reference node not does not reference an array
symbol.
:raises TransformationError: if the Reference node is within an
inquiry or DEALLOCATE intrinsic.
'''
# TODO issue #1858. Add support for structures containing arrays.
# pylint: disable=unidiomatic-typecheck
if not type(node) is Reference:
raise TransformationError(
f"The supplied node should be a Reference but found "
f"'{type(node).__name__}'.")
if not node.symbol.is_array:
raise TransformationError(
f"The supplied node should be a Reference to a symbol "
f"that is an array, but '{node.symbol.name}' is not.")
if isinstance(node.parent, IntrinsicCall) and node.parent.is_inquiry:
raise TransformationError(
f"References to arrays passed as arguments to intrinsic "
f"enquiry routine '{node.parent.routine.name}' should not be "
f"transformed.")
if (isinstance(node.parent, IntrinsicCall) and
node.parent.routine.name in ["DEALLOCATE"]):
raise TransformationError(LazyString(
lambda: f"References to arrays passed to "
f"'{node.parent.routine.name}' intrinsics should not be "
f"transformed, but found:\n {node.parent.debug_string()}"))
[docs] def apply(self, node, options=None):
'''Apply the Reference2ArrayRangeTrans transformation to the specified
node. The node must be a Reference to an array. The Reference
is replaced by an ArrayReference with appropriate explicit
range nodes (termed colon notation in Fortran).
:param node: a Reference node.
:type node: :py:class:`psyclone.psyir.nodes.Reference`
:param options: a dict with options for transformations.
:type options: Optional[Dict[str, Any]]
'''
self.validate(node, options=None)
symbol = node.symbol
indices = []
for idx, _ in enumerate(symbol.shape):
lbound, ubound, step = \
Reference2ArrayRangeTrans._get_array_bound(symbol, idx)
indices.append(Range.create(lbound, ubound, step))
array_ref = ArrayReference.create(symbol, indices)
node.replace_with(array_ref)