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# Author: R. W. Ford, STFC Daresbury Lab
# Modified: A. R. Porter, S. Siso and N. Nobre, STFC Daresbury Lab
'''Module providing a transformation from a PSyIR ABS operator to
PSyIR code. This could be useful if the ABS operator is not supported
by the back-end or if the performance in the inline code is better
than the intrinsic.
'''
from psyclone.psyir.transformations.intrinsics.intrinsic2code_trans import (
Intrinsic2CodeTrans)
from psyclone.psyir.nodes import (
BinaryOperation, Assignment, Reference, Literal, IfBlock, IntrinsicCall)
from psyclone.psyir.symbols import DataSymbol, REAL_TYPE
[docs]class Abs2CodeTrans(Intrinsic2CodeTrans):
'''Provides a transformation from a PSyIR ABS Operator node to
equivalent code in a PSyIR tree. Validity checks are also
performed.
The transformation replaces
.. code-block:: python
R = ABS(X)
with the following logic:
.. code-block:: python
IF X < 0.0:
R = X*-1.0
ELSE:
R = X
'''
def __init__(self):
super().__init__()
self._intrinsic = IntrinsicCall.Intrinsic.ABS
[docs] def apply(self, node, options=None):
'''Apply the ABS intrinsic conversion transformation to the specified
node. This node must be an ABS UnaryOperation. The ABS
UnaryOperation is converted to equivalent inline code. This is
implemented as a PSyIR transform from:
.. code-block:: python
R = ... ABS(X) ...
to:
.. code-block:: python
tmp_abs = X
if tmp_abs < 0.0:
res_abs = tmp_abs*-1.0
else:
res_abs = tmp_abs
R = ... res_abs ...
where ``X`` could be an arbitrarily complex PSyIR expression
and ``...`` could be arbitrary PSyIR code.
This transformation requires the operation node to be a
descendent of an assignment and will raise an exception if
this is not the case.
:param node: an ABS UnaryOperation node.
:type node: :py:class:`psyclone.psyir.nodes.UnaryOperation`
:param options: a dictionary with options for transformations.
:type options: Optional[Dict[str, Any]]
'''
# pylint: disable=too-many-locals
self.validate(node, options)
symbol_table = node.scope.symbol_table
assignment = node.ancestor(Assignment)
# Create two temporary variables. There is an assumption here
# that the ABS Operator returns a PSyIR real type. This might
# not be what is wanted (e.g. the args might PSyIR integers),
# or there may be errors (arguments are of different types)
# but this can't be checked as we don't have the appropriate
# methods to query nodes (see #658).
symbol_res_var = symbol_table.new_symbol(
"res_abs", symbol_type=DataSymbol, datatype=REAL_TYPE)
symbol_tmp_var = symbol_table.new_symbol(
"tmp_abs", symbol_type=DataSymbol, datatype=REAL_TYPE)
# Replace operation with a temporary (res_X).
node.replace_with(Reference(symbol_res_var))
# tmp_var=X
lhs = Reference(symbol_tmp_var)
rhs = node.arguments[0].detach()
new_assignment = Assignment.create(lhs, rhs)
assignment.parent.children.insert(assignment.position, new_assignment)
# if condition: tmp_var>0.0
lhs = Reference(symbol_tmp_var)
rhs = Literal("0.0", REAL_TYPE)
if_condition = BinaryOperation.create(BinaryOperation.Operator.GT,
lhs, rhs)
# then_body: res_var=tmp_var
lhs = Reference(symbol_res_var)
rhs = Reference(symbol_tmp_var)
then_body = [Assignment.create(lhs, rhs)]
# else_body: res_var=-1.0*tmp_var
lhs = Reference(symbol_res_var)
lhs_child = Reference(symbol_tmp_var)
rhs_child = Literal("-1.0", REAL_TYPE)
rhs = BinaryOperation.create(BinaryOperation.Operator.MUL, lhs_child,
rhs_child)
else_body = [Assignment.create(lhs, rhs)]
# if [if_condition] then [then_body] else [else_body]
if_stmt = IfBlock.create(if_condition, then_body, else_body)
assignment.parent.children.insert(assignment.position, if_stmt)