Extract: Improved region-outlining for complex procedures

loki/transformations/extract/outline.py

@@ -6,18 +6,155 @@
 # nor does it submit to any jurisdiction.
 
 from loki.analyse import dataflow_analysis_attached
-from loki.expression import Variable
+from loki.expression import symbols as sym, Variable
 from loki.ir import (
     CallStatement, Import, PragmaRegion, Section, FindNodes,
-    FindVariables, MaskedTransformer, Transformer, is_loki_pragma,
+    FindVariables, Transformer, is_loki_pragma,
     get_pragma_parameters, pragma_regions_attached
 )
 from loki.logging import info
 from loki.subroutine import Subroutine
-from loki.tools import as_tuple, CaseInsensitiveDict
+from loki.tools import as_tuple
+from loki.types import BasicType, DerivedType
 
 
-__all__ = ['outline_pragma_regions']
+
+__all__ = ['outline_region', 'outline_pragma_regions']
+
+
+def order_variables_by_type(variables, imports=None):
+    """
+    Apply a default ordering to variables based on their type, so that
+    their use in declaration lists is unified.
+    """
+    variables = sorted(variables, key=str)  # Lexicographical base order
+
+    derived = tuple(
+        v for v in variables
+        if isinstance(v.type.dtype, DerivedType) or v.type.dtype == BasicType.DEFERRED
+    )
+
+    if imports:
+        # Order derived types by the order of their type in imports
+        imported_symbols = tuple(s for i in imports for s in i.symbols if not i.c_import)
+        derived = tuple(sorted(derived, key=lambda x: imported_symbols.index(x.type.dtype.name)))
+
+    # Order declarations by type and put arrays before scalars
+    non_derived = tuple(v for v in variables if v not in derived)
+    arrays = tuple(v for v in non_derived if isinstance(v, sym.Array))
+    scalars = tuple(v for v in non_derived if isinstance(v, sym.Scalar))
+    assert len(derived) + len(arrays) + len(scalars) == len(variables)
+
+    return derived + arrays + scalars
+
+
+def outline_region(region, name, imports, intent_map=None):
+    """
+    Creates a new :any:`Subroutine` object from a given :any:`PragmaRegion`.
+
+    Parameters
+    ----------
+    region : :any:`PragmaRegion`
+        The region that holds the body for which to create a subroutine.
+    name : str
+        Name of the new subroutine
+    imports : tuple of :any:`Import`, optional
+        List of imports to replicate in the new subroutine
+    intent_map : dict, optional
+        Mapping of instent strings to list of variables to override intents
+
+    Returns
+    -------
+    tuple of :any:`CallStatement` and :any:`Subroutine`
+        The newly created call and respectice subroutine.
+    """
+    intent_map = intent_map or {}
+    imports = as_tuple(imports)
+    imported_symbols = {var for imp in imports for var in imp.symbols}
+    # Special-case for IFS-style C-imports
+    imported_symbols |= {
+        str(imp.module).split('.', maxsplit=1)[0] for imp in imports if imp.c_import
+    }
+
+    # Create the external subroutine containing the routine's imports and the region's body
+    spec = Section(body=imports)
+    body = Section(body=Transformer().visit(region.body))
+    region_routine = Subroutine(name, spec=spec, body=body)
+
+    # Filter derived-type component accesses and only use the root parent
+    region_uses_symbols = {s.parents[0] if s.parent else s for s in region.uses_symbols}
+    region_defines_symbols = {s.parents[0] if s.parent else s for s in region.defines_symbols}
+
+    # Use dataflow analysis to find in, out and inout variables to that region
+    # (ignoring any symbols that are external imports)
+    region_in_args = region_uses_symbols - region_defines_symbols - imported_symbols
+    region_inout_args = region_uses_symbols & region_defines_symbols - imported_symbols
+    region_out_args = region_defines_symbols - region_uses_symbols - imported_symbols
+
+    # Remove any parameters from in args
+    region_in_args = {arg for arg in region_in_args if not arg.type.parameter}
+
+    # Extract arguments given in pragma annotations
+    pragma_in_args = {v.clone(scope=region_routine) for v in intent_map['in']}
+    pragma_inout_args = {v.clone(scope=region_routine) for v in intent_map['inout']}
+    pragma_out_args = {v.clone(scope=region_routine) for v in intent_map['out']}
+
+    # Override arguments according to pragma annotations
+    region_in_args = (region_in_args - (pragma_inout_args | pragma_out_args)) | pragma_in_args
+    region_inout_args = (region_inout_args - (pragma_in_args | pragma_out_args)) | pragma_inout_args
+    region_out_args = (region_out_args - (pragma_in_args | pragma_inout_args)) | pragma_out_args
+
+    # Now fix the order
+    region_inout_args = as_tuple(region_inout_args)
+    region_in_args = as_tuple(region_in_args)
+    region_out_args = as_tuple(region_out_args)
+
+    # Set the list of variables used in region routine (to create declarations)
+    # and put all in the new scope
+    region_routine_variables = tuple(
+        v.clone(dimensions=v.type.shape or None, scope=region_routine)
+        for v in FindVariables().visit(region.body)
+        if v.clone(dimensions=None) not in imported_symbols
+    )
+    # Filter out derived-type component variables from declarations
+    region_routine_variables = tuple(
+        v.parents[0] if v.parent else v for v in region_routine_variables
+    )
+
+    # Build the call signature
+    region_routine_var_map = {v.name: v for v in region_routine_variables}
+    region_routine_arguments = []
+    for intent, args in zip(('in', 'inout', 'out'), (region_in_args, region_inout_args, region_out_args)):
+        for arg in args:
+            local_var = region_routine_var_map.get(arg.name, arg)
+            # Sanitise argument types
+            local_var = local_var.clone(
+                type=local_var.type.clone(intent=intent, allocatable=None, target=None),
+                scope=region_routine
+            )
+
+            region_routine_var_map[arg.name] = local_var
+            region_routine_arguments += [local_var]
+
+    # Order the arguments and local declaration lists and put arguments first
+    region_routine_locals = tuple(
+        v for v in region_routine_variables if not v in region_routine_arguments
+    )
+    region_routine_arguments = order_variables_by_type(region_routine_arguments, imports=imports)
+    region_routine_locals = order_variables_by_type(region_routine_locals, imports=imports)
+
+    region_routine.variables = region_routine_arguments + region_routine_locals
+    region_routine.arguments = region_routine_arguments
+
+    # Ensure everything has been rescoped
+    region_routine.rescope_symbols()
+
+    # Create the call according to the wrapped code region
+    call_arg_map = {v.name: v for v in region_in_args + region_inout_args + region_out_args}
+    call_arguments = tuple(call_arg_map[a.name] for a in region_routine_arguments)
+    call = CallStatement(name=Variable(name=name), arguments=call_arguments, kwarguments=())
+
+    return call, region_routine
 
 
 def outline_pragma_regions(routine):
@@ -46,12 +183,12 @@ def outline_pragma_regions(routine):
     -------
     list of :any:`Subroutine`
         the list of newly created subroutines.
-
     """
     counter = 0
-    routines, starts, stops = [], [], []
-    imports = {var for imprt in FindNodes(Import).visit(routine.spec) for var in imprt.symbols}
-    mask_map = {}
+    routines = []
+    imports = FindNodes(Import).visit(routine.spec)
+    parent_vmap = routine.variable_map
+    mapper = {}
     with pragma_regions_attached(routine):
         with dataflow_analysis_attached(routine):
             for region in FindNodes(PragmaRegion).visit(routine.body):
@@ -63,74 +200,21 @@ def outline_pragma_regions(routine):
                 name = parameters.get('name', f'{routine.name}_outlined_{counter}')
                 counter += 1
 
-                # Create the external subroutine containing the routine's imports and the region's body
-                spec = Section(body=Transformer().visit(FindNodes(Import).visit(routine.spec)))
-                body = Section(body=Transformer().visit(region.body))
-                region_routine = Subroutine(name, spec=spec, body=body)
-
-                # Use dataflow analysis to find in, out and inout variables to that region
-                # (ignoring any symbols that are external imports)
-                region_in_args = region.uses_symbols - region.defines_symbols - imports
-                region_inout_args = region.uses_symbols & region.defines_symbols - imports
-                region_out_args = region.defines_symbols - region.uses_symbols - imports
-
-                # Remove any parameters from in args
-                region_in_args = {arg for arg in region_in_args if not arg.type.parameter}
-
-                # Extract arguments given in pragma annotations
-                region_var_map = CaseInsensitiveDict(
-                    (v.name, v.clone(dimensions=None))
-                    for v in FindVariables().visit(region.body) if v.clone(dimensions=None) not in imports
-                )
-                pragma_in_args = {region_var_map[v.lower()] for v in parameters.get('in', '').split(',') if v}
-                pragma_inout_args = {region_var_map[v.lower()] for v in parameters.get('inout', '').split(',') if v}
-                pragma_out_args = {region_var_map[v.lower()] for v in parameters.get('out', '').split(',') if v}
-
-                # Override arguments according to pragma annotations
-                region_in_args = (region_in_args - (pragma_inout_args | pragma_out_args)) | pragma_in_args
-                region_inout_args = (region_inout_args - (pragma_in_args | pragma_out_args)) | pragma_inout_args
-                region_out_args = (region_out_args - (pragma_in_args | pragma_inout_args)) | pragma_out_args
-
-                # Now fix the order
-                region_inout_args = as_tuple(region_inout_args)
-                region_in_args = as_tuple(region_in_args)
-                region_out_args = as_tuple(region_out_args)
-
-                # Set the list of variables used in region routine (to create declarations)
-                # and put all in the new scope
-                region_routine_variables = {v.clone(dimensions=v.type.shape or None)
-                                            for v in FindVariables().visit(region_routine.body)
-                                            if v.name in region_var_map}
-                region_routine.variables = as_tuple(region_routine_variables)
-                region_routine.rescope_symbols()
-
-                # Build the call signature
-                region_routine_var_map = region_routine.variable_map
-                region_routine_arguments = []
-                for intent, args in zip(('in', 'inout', 'out'), (region_in_args, region_inout_args, region_out_args)):
-                    for arg in args:
-                        local_var = region_routine_var_map[arg.name]
-                        local_var = local_var.clone(type=local_var.type.clone(intent=intent))
-                        region_routine_var_map[arg.name] = local_var
-                        region_routine_arguments += [local_var]
-
-                # We need to update the list of variables again to avoid duplicate declarations
-                region_routine.variables = as_tuple(region_routine_var_map.values())
-                region_routine.arguments = as_tuple(region_routine_arguments)
+                # Extract explicitly requested symbols from context
+                intent_map = {}
+                intent_map['in'] = tuple(parent_vmap[v.lower()] for v in parameters.get('in', '').split(',') if v)
+                intent_map['inout'] = tuple(parent_vmap[v.lower()] for v in parameters.get('inout', '').split(',') if v)
+                intent_map['out'] = tuple(parent_vmap[v.lower()] for v in parameters.get('out', '').split(',') if v)
+
+                call, region_routine = outline_region(region, name, imports, intent_map=intent_map)
 
                 # insert into list of new routines
                 routines.append(region_routine)
 
-                # Register start and end nodes in transformer mask for original routine
-                starts += [region.pragma_post]
-                stops += [region.pragma]
-
-                # Replace end pragma by call in original routine
-                call_arguments = region_in_args + region_inout_args + region_out_args
-                call = CallStatement(name=Variable(name=name), arguments=call_arguments)
-                mask_map[region.pragma_post] = call
+                # Replace region by call in original routine
+                mapper[region] = call
 
-    routine.body = MaskedTransformer(active=True, start=starts, stop=stops, mapper=mask_map).visit(routine.body)
+            routine.body = Transformer(mapper=mapper).visit(routine.body)
     info('%s: converted %d region(s) to calls', routine.name, counter)
 
     return routines