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# Author: R. W. Ford, STFC Daresbury Laboratory

'''File containing a PSyclone transformation script for the Dynamo0.3
API to apply redundant computation to halo depth 1 for all instances
of loops that iterate over dofs and contain the setval_c builtin.

'''
from __future__ import absolute_import
from psyclone.transformations import Dynamo0p3RedundantComputationTrans

ITERATION_SPACES = ["dofs"]
KERNEL_NAMES = ["setval_c"]
DEPTH = 1


def trans(psy):
    '''PSyclone transformation script for the dynamo0.3 API to apply
    redundant computation into the level 1 halo generically to all
    loops that iterate over dofs and exclusively contain the setval_c
    builtin. The reason for choosing this particular builtin is that
    this builtin only writes to data so will not cause any additional
    halo exchanges, or increases in halo exchange depth, through
    redundant computation.

    '''
    rc_trans = Dynamo0p3RedundantComputationTrans()

    transformed = 0

    for invoke in psy.invokes.invoke_list:
        schedule = invoke.schedule
        for loop in schedule.loops():
            if loop.iteration_space in ITERATION_SPACES:
                # we may have more than one kernel in the loop so
                # check that all of them are in the list of accepted
                # kernel names
                setcalls = True
                for call in loop.kernels():
                    if call.name not in KERNEL_NAMES:
                        setcalls = False
                        break
                if setcalls:
                    transformed += 1
                    rc_trans.apply(loop, {"depth": DEPTH})

    print("Transformed {0} loops".format(transformed))
    return psy
