SCCFuseVerticalLoops: introduce new arg 'apply_to' to possibly restri…

…ct routines this transformation is applied to

loki/transformations/single_column/tests/test_scc_vertical.py

@@ -83,6 +83,13 @@ def test_simple_scc_fuse_verticals_transformation(frontend, horizontal, vertical
     kernel_loops = FindNodes(Loop).visit(kernel.body)
     assert len(kernel_loops) == 5
 
+    # no-op as 'compute_column' is not within apply_to
+    SCCFuseVerticalLoops(vertical=vertical, apply_to=('another_kernel',)).apply(kernel, role='kernel')
+    # Ensure we have three loops in the kernel prior to transformation
+    kernel_loops = FindNodes(Loop).visit(kernel.body)
+    assert len(kernel_loops) == 5
+
+    # actual loop fusion and demotion ... (as apply_to is not provided and therefore all routines are dispatched)
     SCCFuseVerticalLoops(vertical=vertical).apply(kernel, role='kernel')
 
     # Ensure the two vertical loops are fused

loki/transformations/single_column/vertical.py

@@ -42,10 +42,14 @@ class SCCFuseVerticalLoops(Transformation):
     vertical : :any:`Dimension`
         :any:`Dimension` object describing the variable conventions used in code
         to define the vertical data dimension and iteration space.
+    apply_to : list of str, optional
+        list of routines to apply this transformation to, if not provided or None 
+        apply to all routines (default: None)
     """
 
-    def __init__(self, vertical=None):
+    def __init__(self, vertical=None, apply_to=None):
         self.vertical = vertical
+        self.apply_to = apply_to or ()
 
     def transform_subroutine(self, routine, **kwargs):
         """
@@ -63,6 +67,8 @@ def transform_subroutine(self, routine, **kwargs):
             return
         role = kwargs['role']
         if role == 'kernel':
+            if self.apply_to and routine.name.lower() not in self.apply_to:
+                return
             self.process_kernel(routine)
 
     def process_kernel(self, routine):