From 38bfc611fbb6d9fb89d25e79305f4245caff0cc3 Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Tue, 4 Aug 2026 15:53:53 +0100
Subject: [PATCH 01/11] Make statement abstract with the new abstract methods

---
 .../common/psylayer/global_reduction.py       | 19 ++++++
 src/psyclone/psyGen.py                        | 36 +++++++++++
 src/psyclone/psyir/nodes/call.py              | 31 ++++++++--
 src/psyclone/psyir/nodes/codeblock.py         | 20 ++++++
 src/psyclone/psyir/nodes/directive.py         | 21 +++++++
 src/psyclone/psyir/nodes/if_block.py          | 21 +++++++
 src/psyclone/psyir/nodes/loop.py              | 21 +++++++
 src/psyclone/psyir/nodes/psy_data_node.py     | 20 ++++++
 src/psyclone/psyir/nodes/return_stmt.py       | 21 +++++++
 src/psyclone/psyir/nodes/routine.py           | 20 ++++++
 src/psyclone/psyir/nodes/statement.py         | 24 +++++++-
 src/psyclone/psyir/nodes/while_loop.py        | 21 +++++++
 .../tests/psyir/backend/debug_writer_test.py  |  6 ++
 .../tests/psyir/backend/visitor_test.py       |  6 ++
 src/psyclone/tests/psyir/nodes/node_test.py   | 61 ++++++++++---------
 .../tests/psyir/nodes/psy_data_node_test.py   | 10 +--
 .../tests/psyir/nodes/schedule_test.py        |  6 +-
 .../transformations/inline_trans_test.py      |  7 ++-
 .../transformations/transformations_test.py   |  9 +--
 .../tests/test_files/dummy_statement.py       | 51 ++++++++++++++++
 20 files changed, 383 insertions(+), 48 deletions(-)
 create mode 100644 src/psyclone/tests/test_files/dummy_statement.py

diff --git a/src/psyclone/domain/common/psylayer/global_reduction.py b/src/psyclone/domain/common/psylayer/global_reduction.py
index c8bde83d35..43adf9182a 100644
--- a/src/psyclone/domain/common/psylayer/global_reduction.py
+++ b/src/psyclone/domain/common/psylayer/global_reduction.py
@@ -40,6 +40,7 @@
 ''' This module provides the GlobalReduction base class. '''
 
 import copy
+from typing import List
 
 from psyclone.configuration import Config
 from psyclone.core import AccessType
@@ -114,3 +115,21 @@ def args(self) -> list[KernelArgument]:
         ''':returns: the list of arguments associated with this node. Override
                      the base method and simply return our argument.'''
         return [self._scalar]
+
+    def next_accesses(self) -> List[Node]:
+        '''
+        next_accesses on base GlobalReduction class just uses the base
+        Statement implementation, returning an empty list.
+
+        :returns: an empty list.
+        '''
+        return super().next_accesses()
+
+    def previous_accesses(self) -> List[Node]:
+        '''
+        previous_accesses on base GlobalReduction class just uses the base
+        Statement implementation, returning an empty list.
+
+        :returns: an empty list.
+        '''
+        return super().previous_accesses()
diff --git a/src/psyclone/psyGen.py b/src/psyclone/psyGen.py
index 0da689f2a6..c92bd938bb 100644
--- a/src/psyclone/psyGen.py
+++ b/src/psyclone/psyGen.py
@@ -771,6 +771,24 @@ def node_str(self, colour=True):
                 f"type='{self._halo_type}', depth={self._halo_depth}, "
                 f"check_dirty={self._check_dirty}]")
 
+    def next_accesses(self) -> list[Node]:
+        '''
+        next_accesses on base HaloExchange class just uses the base Statement
+        implementation, returning an empty list.
+
+        :returns: an empty list.
+        '''
+        return super().next_accesses()
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        previous_accesses on base HaloExchange class just uses the base
+        Statement implementation, returning an empty list.
+
+        :returns: an empty list.
+        '''
+        return super().previous_accesses()
+
 
 class Kern(Statement):
     '''Base class representing a call to a sub-program unit from within the
@@ -1163,6 +1181,24 @@ def lower_to_language_level(self):
 
         return super().lower_to_language_level()
 
+    def next_accesses(self) -> list[Node]:
+        '''
+        next_accesses on base Kern class just uses the base Statement
+        implementation, returning an empty list.
+
+        :returns: an empty list.
+        '''
+        return super().next_accesses()
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        previous_accesses on base Kern class just uses the base Statement
+        implementation, returning an empty list.
+
+        :returns: an empty list.
+        '''
+        return super().previous_accesses()
+
 
 class CodedKern(Kern):
     '''
diff --git a/src/psyclone/psyir/nodes/call.py b/src/psyclone/psyir/nodes/call.py
index 23f2013f36..c2727b9842 100644
--- a/src/psyclone/psyir/nodes/call.py
+++ b/src/psyclone/psyir/nodes/call.py
@@ -40,7 +40,7 @@
 from __future__ import annotations
 
 from collections.abc import Iterable
-from typing import List, Tuple, Union, Optional
+from typing import Tuple, Union, Optional
 
 from psyclone.configuration import Config
 from psyclone.core import AccessType, VariablesAccessMap
@@ -49,6 +49,7 @@
 from psyclone.psyir.nodes.container import Container
 from psyclone.psyir.nodes.statement import Statement
 from psyclone.psyir.nodes.datanode import DataNode
+from psyclone.psyir.nodes.node import Node
 from psyclone.psyir.nodes.reference import Reference
 from psyclone.psyir.nodes.routine import Routine
 from psyclone.psyir.symbols import (
@@ -531,7 +532,7 @@ def copy(self):
 
         return new_copy
 
-    def get_callees(self) -> List[Routine]:
+    def get_callees(self) -> list[Routine]:
         '''
         Searches for the implementation(s) of all potential target routines
         for this Call. It does *not* attempt to resolve static polymorphism
@@ -787,7 +788,7 @@ def type_symbols_match(type1: Union[DataTypeSymbol, DataType],
                     f"'{routine_arg_str}' ({dummy_type})"
                 )
 
-    def get_argument_map(self, routine: Routine) -> List[int]:
+    def get_argument_map(self, routine: Routine) -> list[int]:
         '''Return a list of indices mapping from each argument of this
         call to the corresponding entry in the argument list of the
         supplied routine.
@@ -803,7 +804,7 @@ def get_argument_map(self, routine: Routine) -> List[int]:
         '''
         # Create a copy of the list of actual arguments to the routine.
         # Once an argument has been successfully matched, set it to 'None'
-        routine_argument_list: List[DataSymbol] = (
+        routine_argument_list: list[DataSymbol] = (
             routine.symbol_table.argument_list[:]
         )
 
@@ -888,7 +889,7 @@ def get_argument_map(self, routine: Routine) -> List[int]:
     def get_callee(
             self,
             use_first_callee_and_no_arg_check: bool = False
-    ) -> Tuple[Routine, List[int]]:
+    ) -> Tuple[Routine, list[int]]:
         '''
         Searches for the implementation(s) of the target routine for this Call
         including argument checks.
@@ -940,3 +941,23 @@ def get_callee(
             f"No matching routine found for '{call_str}':"
             "\n" + error_msg
         )
+
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
diff --git a/src/psyclone/psyir/nodes/codeblock.py b/src/psyclone/psyir/nodes/codeblock.py
index 5474b4d008..950997b5b6 100644
--- a/src/psyclone/psyir/nodes/codeblock.py
+++ b/src/psyclone/psyir/nodes/codeblock.py
@@ -258,6 +258,26 @@ def get_fortran_lines(self) -> list[str]:
             return []
         raise NotImplementedError("Use appropriate CodeBlock subclass")
 
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
+
 
 class Fparser2CodeBlock(CodeBlock):
     ''' The fparser2 implementation of CodeBlock. '''
diff --git a/src/psyclone/psyir/nodes/directive.py b/src/psyclone/psyir/nodes/directive.py
index d1368eed55..0d393080ff 100644
--- a/src/psyclone/psyir/nodes/directive.py
+++ b/src/psyclone/psyir/nodes/directive.py
@@ -50,6 +50,7 @@
 from psyclone.psyir.nodes.array_of_structures_reference import (
     ArrayOfStructuresReference)
 from psyclone.psyir.nodes.clause import Clause
+from psyclone.psyir.nodes.node import Node
 from psyclone.psyir.nodes.reference import Reference
 from psyclone.psyir.nodes.schedule import Schedule
 from psyclone.psyir.nodes.statement import Statement
@@ -180,6 +181,26 @@ def create_data_movement_deep_copy_refs(self):
                         *base_args, members)
         return read_only, write_only, readwrites
 
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
+
 
 class RegionDirective(Directive):
     '''
diff --git a/src/psyclone/psyir/nodes/if_block.py b/src/psyclone/psyir/nodes/if_block.py
index 2bc158b514..bb4bef37be 100644
--- a/src/psyclone/psyir/nodes/if_block.py
+++ b/src/psyclone/psyir/nodes/if_block.py
@@ -41,6 +41,7 @@
 from psyclone.core import VariablesAccessMap
 from psyclone.errors import InternalError, GenerationError
 from psyclone.psyir.nodes.datanode import DataNode
+from psyclone.psyir.nodes.node import Node
 from psyclone.psyir.nodes.schedule import Schedule
 from psyclone.psyir.nodes.statement import Statement
 
@@ -195,3 +196,23 @@ def reference_accesses(self) -> VariablesAccessMap:
         if self.else_body:
             var_accesses.update(self.else_body.reference_accesses())
         return var_accesses
+
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
diff --git a/src/psyclone/psyir/nodes/loop.py b/src/psyclone/psyir/nodes/loop.py
index 0ec4eb1f4d..1980c5e3aa 100644
--- a/src/psyclone/psyir/nodes/loop.py
+++ b/src/psyclone/psyir/nodes/loop.py
@@ -43,6 +43,7 @@
 
 from psyclone.core import VariablesAccessMap
 from psyclone.psyir.nodes.datanode import DataNode
+from psyclone.psyir.nodes.node import Node
 from psyclone.psyir.nodes.statement import Statement
 from psyclone.psyir.nodes.routine import Routine
 from psyclone.psyir.nodes.reference import Reference
@@ -545,3 +546,23 @@ def enters_scope(self, scope, visited_nodes=None) -> bool:
         '''
         # pylint: disable=unused-argument
         return False
+
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
diff --git a/src/psyclone/psyir/nodes/psy_data_node.py b/src/psyclone/psyir/nodes/psy_data_node.py
index 872b64986b..e3df5da451 100644
--- a/src/psyclone/psyir/nodes/psy_data_node.py
+++ b/src/psyclone/psyir/nodes/psy_data_node.py
@@ -732,6 +732,26 @@ def gen_type_bound_call(typename, methodname, argument_list=None,
         self.detach()
         return self.parent
 
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
+
 
 # For AutoAPI documentation generation
 __all__ = ['PSyDataNode']
diff --git a/src/psyclone/psyir/nodes/return_stmt.py b/src/psyclone/psyir/nodes/return_stmt.py
index 5698d6fc26..68d828182f 100644
--- a/src/psyclone/psyir/nodes/return_stmt.py
+++ b/src/psyclone/psyir/nodes/return_stmt.py
@@ -38,6 +38,7 @@
 
 ''' This module contains the Return node implementation.'''
 
+from psyclone.psyir.nodes.node import Node
 from psyclone.psyir.nodes.statement import Statement
 
 
@@ -51,3 +52,23 @@ class Return(Statement):
     _children_valid_format = "<LeafNode>"
     _text_name = "Return"
     _colour = "yellow"
+
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
diff --git a/src/psyclone/psyir/nodes/routine.py b/src/psyclone/psyir/nodes/routine.py
index a5f44c8b58..7bcbbbaab1 100644
--- a/src/psyclone/psyir/nodes/routine.py
+++ b/src/psyclone/psyir/nodes/routine.py
@@ -567,6 +567,26 @@ def replace_with(self, node, keep_name_in_context=True):
                 "replaced.")
         super().replace_with(node, keep_name_in_context=keep_name_in_context)
 
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
+
 
 # For automatic documentation generation
 __all__ = ["Routine"]
diff --git a/src/psyclone/psyir/nodes/statement.py b/src/psyclone/psyir/nodes/statement.py
index 05953eb240..79b27bbe60 100644
--- a/src/psyclone/psyir/nodes/statement.py
+++ b/src/psyclone/psyir/nodes/statement.py
@@ -36,15 +36,37 @@
 
 ''' This module contains the Statement abstract node implementation.'''
 
+import abc
+
 from psyclone.psyir.nodes.node import Node
 from psyclone.psyir.commentable_mixin import CommentableMixin
 
 
-class Statement(Node, CommentableMixin):
+class Statement(Node, CommentableMixin, metaclass=abc.ABCMeta):
     '''
     Abstract node representing a general PSyIR Statement.
     '''
 
+    @abc.abstractmethod
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        return []
+
+    @abc.abstractmethod
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        return []
+
 
 # For automatic API documentation generation
 __all__ = ["Statement"]
diff --git a/src/psyclone/psyir/nodes/while_loop.py b/src/psyclone/psyir/nodes/while_loop.py
index f6e4d75553..3a1d60db62 100644
--- a/src/psyclone/psyir/nodes/while_loop.py
+++ b/src/psyclone/psyir/nodes/while_loop.py
@@ -39,6 +39,7 @@
 from psyclone.core import VariablesAccessMap
 from psyclone.errors import InternalError, GenerationError
 from psyclone.psyir.nodes.datanode import DataNode
+from psyclone.psyir.nodes.node import Node
 from psyclone.psyir.nodes.schedule import Schedule
 from psyclone.psyir.nodes.statement import Statement
 
@@ -154,3 +155,23 @@ def reference_accesses(self) -> VariablesAccessMap:
         var_accesses = self.condition.reference_accesses()
         var_accesses.update(self.loop_body.reference_accesses())
         return var_accesses
+
+    def next_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the next_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return future accesses to any References contained in the statement.
+
+        :returns: an empty list.
+        '''
+        # FIXME Implement
+        return []
+
+    def previous_accesses(self) -> list[Node]:
+        '''
+        Abstract method for finding the previous_accesses of a statement.
+        Subclasses should override this according to their own structure to
+        return previous accesses to any References contained in the statement.
+        '''
+        # FIXME Implement
+        return []
diff --git a/src/psyclone/tests/psyir/backend/debug_writer_test.py b/src/psyclone/tests/psyir/backend/debug_writer_test.py
index aca9bde203..5ba6521c84 100644
--- a/src/psyclone/tests/psyir/backend/debug_writer_test.py
+++ b/src/psyclone/tests/psyir/backend/debug_writer_test.py
@@ -85,6 +85,12 @@ def lower_to_language_level(self):
         def validate_global_constraints(self):
             raise NotImplementedError("This should not be called")
 
+        def next_accesses(self):
+            '''Needed on all Statement subclasses.'''
+
+        def previous_accesses(self):
+            '''Needed on all Statement subclasses.'''
+
     class MyDSLDataNode(DataNode):
         ''' A dummy DSL DataNode that doesn't like being lowered '''
         def lower_to_language_level(self):
diff --git a/src/psyclone/tests/psyir/backend/visitor_test.py b/src/psyclone/tests/psyir/backend/visitor_test.py
index 9e109ca4aa..506cf77458 100644
--- a/src/psyclone/tests/psyir/backend/visitor_test.py
+++ b/src/psyclone/tests/psyir/backend/visitor_test.py
@@ -214,6 +214,12 @@ def lower_to_language_level(self):
             self.replace_with(new_node)
             return new_node
 
+        def next_accesses(self):
+            '''Needed on all Statement subclasses.'''
+
+        def previous_accesses(self):
+            '''Needed on all Statement subclasses.'''
+
     class MyVisitor(PSyIRVisitor):
         ''' Simple Visitor for Schedules and Return statements '''
 
diff --git a/src/psyclone/tests/psyir/nodes/node_test.py b/src/psyclone/tests/psyir/nodes/node_test.py
index 73de0fc13b..7dc5a3423b 100644
--- a/src/psyclone/tests/psyir/nodes/node_test.py
+++ b/src/psyclone/tests/psyir/nodes/node_test.py
@@ -51,14 +51,19 @@
 from psyclone.parse.algorithm import parse
 from psyclone.psyGen import PSyFactory, Kern
 from psyclone.psyir.backend.debug_writer import DebugWriter
-from psyclone.psyir.nodes import Schedule, Reference, Container, Routine, \
-    Assignment, Return, Loop, Literal, Statement, node, KernelSchedule, \
+from psyclone.psyir.nodes import (
+    Schedule, Reference, Container, Routine, node,
+    Assignment, Return, Loop, Literal, KernelSchedule, Statement,
     BinaryOperation, ArrayReference, Call, Range
+)
 from psyclone.psyir.nodes.node import ChildrenList, Node
-from psyclone.psyir.symbols import DataSymbol, SymbolError, \
-    ScalarType, SymbolTable, ArrayType, RoutineSymbol, NoType
+from psyclone.psyir.symbols import (
+    DataSymbol, SymbolError, ScalarType, SymbolTable, ArrayType,
+    RoutineSymbol, NoType
+)
 from psyclone.tests.utilities import get_invoke
 from psyclone.psyir.nodes.node import colored
+from psyclone.tests.test_files.dummy_statement import DummyStatement
 
 BASE_PATH = os.path.join(os.path.dirname(os.path.dirname(os.path.dirname(
     os.path.abspath(__file__)))), "test_files", "lfric")
@@ -334,7 +339,7 @@ def test_compute_cached_abs_positions_error():
     just happens with inconsistent parent-child connections). '''
 
     parent = Schedule()
-    node1 = Statement()
+    node1 = DummyStatement()
     # Manually connect the _parent attribute which won't make a consistent
     # two-way relationship
     node1._parent = parent
@@ -397,7 +402,7 @@ def test_node_abs_position_error():
     happens with inconsistent parent-child connections). '''
 
     parent = Schedule()
-    node1 = Statement()
+    node1 = DummyStatement()
     # Manually connect the _parent attribute which won't make a consistent
     # two-way relationship
     node1._parent = parent
@@ -1153,8 +1158,8 @@ def test_children_setter():
     assert isinstance(testnode.children, ChildrenList)
 
     # When is set up with a list, this becomes a ChildrenList
-    statement1 = Statement()
-    statement2 = Statement()
+    statement1 = DummyStatement()
+    statement2 = DummyStatement()
     testnode.children = [statement1, statement2]
     assert isinstance(testnode.children, ChildrenList)
     assert statement1.parent is testnode
@@ -1176,8 +1181,8 @@ def test_children_setter():
 def test_children_clear():
     '''Test that the clear() method works correctly for a ChildrenList.'''
     testnode = Schedule()
-    stmt1 = Statement()
-    stmt2 = Statement()
+    stmt1 = DummyStatement()
+    stmt2 = DummyStatement()
     testnode.addchild(stmt1)
     testnode.addchild(stmt2)
     assert len(testnode.children) == 2
@@ -1273,11 +1278,11 @@ def test_lower_to_language_level(monkeypatch):
     # Monkeypatch the lower_to_language_level to just mark a flag
     def visited(self):
         self._visited_flag = True
-    monkeypatch.setattr(Statement, "lower_to_language_level", visited)
+    monkeypatch.setattr(DummyStatement, "lower_to_language_level", visited)
 
     testnode = Schedule()
-    node1 = Statement()
-    node2 = Statement()
+    node1 = DummyStatement()
+    node2 = DummyStatement()
     testnode.children = [node1, node2]
 
     # Execute method
@@ -1296,9 +1301,9 @@ def test_replace_with():
     '''Check that the replace_with method behaves as expected.'''
 
     parent_node = Schedule()
-    node1 = Statement()
-    node2 = Statement()
-    node3 = Statement()
+    node1 = DummyStatement()
+    node2 = DummyStatement()
+    node3 = DummyStatement()
     parent_node.children = [node1, node2, node3]
     new_node = Assignment()
 
@@ -1374,8 +1379,8 @@ def test_replace_with_error2():
 
     '''
     parent = Schedule()
-    node1 = Statement()
-    node2 = Statement()
+    node1 = DummyStatement()
+    node2 = DummyStatement()
 
     with pytest.raises(TypeError) as info:
         node1.replace_with("hello")
@@ -1418,9 +1423,9 @@ def test_pop_all_children():
 
     # Create a PSyIR tree
     parent = Schedule()
-    node1 = Statement()
+    node1 = DummyStatement()
     parent.addchild(node1)
-    node2 = Statement()
+    node2 = DummyStatement()
     parent.addchild(node2)
 
     # Execute pop_all_children method
@@ -1471,19 +1476,19 @@ def test_parent_references_coherency():
     parent = Schedule()
 
     # Children addition methods
-    node1 = Statement()
+    node1 = DummyStatement()
     parent.addchild(node1)
     assert node1.parent is parent
 
-    node2 = Statement()
+    node2 = DummyStatement()
     parent.children.append(node2)
     assert node2.parent is parent
 
-    node3 = Statement()
+    node3 = DummyStatement()
     parent.children.extend([node3])
     assert node3.parent is parent
 
-    node4 = Statement()
+    node4 = DummyStatement()
     parent.children.insert(0, node4)
     assert node4.parent is parent
 
@@ -1518,7 +1523,7 @@ def test_node_constructor_with_parent():
     wrong_parent = Schedule()
 
     # By default no parent reference is given
-    node = Statement()
+    node = DummyStatement()
     assert node.parent is None
     assert node.has_constructor_parent is False
 
@@ -1630,8 +1635,8 @@ def test_equality():
     parent1._symbol_table = symboltable
     parent2 = Schedule()
     parent2._symbol_table = symboltable
-    zero = Statement()
-    one = Statement()
+    zero = DummyStatement()
+    one = DummyStatement()
 
     assert parent1 != zero
     assert parent1 == parent2
@@ -1644,7 +1649,7 @@ def test_equality():
     assert parent1 == parent2
 
     # Add a second child to parent1
-    two = Statement()
+    two = DummyStatement()
     parent1.addchild(two)
     assert parent1 != parent2
 
diff --git a/src/psyclone/tests/psyir/nodes/psy_data_node_test.py b/src/psyclone/tests/psyir/nodes/psy_data_node_test.py
index f0d6581366..c00f693b84 100644
--- a/src/psyclone/tests/psyir/nodes/psy_data_node_test.py
+++ b/src/psyclone/tests/psyir/nodes/psy_data_node_test.py
@@ -45,13 +45,13 @@
 from psyclone.psyir.nodes import (
     CodeBlock, PSyDataNode, Schedule, Return, Routine)
 from psyclone.parse import ModuleManager
-from psyclone.psyir.nodes.statement import Statement
 from psyclone.psyir.transformations import PSyDataTrans, TransformationError
 from psyclone.psyir.symbols import (
     ContainerSymbol, ImportInterface, SymbolTable, DataTypeSymbol,
     UnresolvedType, DataSymbol, UnsupportedFortranType)
 from psyclone.psyGen import Kern
 from psyclone.tests.utilities import get_base_path, get_invoke
+from psyclone.tests.test_files.dummy_statement import DummyStatement
 
 
 # -----------------------------------------------------------------------------
@@ -174,7 +174,7 @@ def test_psy_data_node_tree_correct():
 
     # 3. No parent, but children:
     # ===========================
-    children = [Statement(), Statement()]
+    children = [DummyStatement(), DummyStatement()]
     psy_node = PSyDataNode.create(children, SymbolTable())
 
     # The children must be connected to the schedule, which is
@@ -193,10 +193,10 @@ def test_psy_data_node_tree_correct():
     # =======================
     parent = Schedule()
     # The children must be added to the parent before creating the ExtractNode
-    parent.addchild(Statement())
-    parent.addchild(Statement())
+    parent.addchild(DummyStatement())
+    parent.addchild(DummyStatement())
     # Add another child that must stay with the parent node
-    third_child = Statement()
+    third_child = DummyStatement()
     parent.addchild(third_child)
     assert parent.children[2] is third_child
     # Only move the first two children, leave the third where it is
diff --git a/src/psyclone/tests/psyir/nodes/schedule_test.py b/src/psyclone/tests/psyir/nodes/schedule_test.py
index 4ab008da79..9ca8a12630 100644
--- a/src/psyclone/tests/psyir/nodes/schedule_test.py
+++ b/src/psyclone/tests/psyir/nodes/schedule_test.py
@@ -40,12 +40,13 @@
 
 import os
 import pytest
-from psyclone.psyir.nodes import Schedule, Assignment, Range, Statement
+from psyclone.psyir.nodes import Schedule, Assignment, Range
 from psyclone.psyir.nodes.node import colored
 from psyclone.psyir.symbols import SymbolTable
 from psyclone.psyGen import PSyFactory
 from psyclone.parse.algorithm import parse
 from psyclone.errors import GenerationError
+from psyclone.tests.test_files.dummy_statement import DummyStatement
 
 
 BASE_PATH = os.path.join(os.path.dirname(os.path.dirname(os.path.dirname(
@@ -66,7 +67,8 @@ def test_sched_init():
     # A custom symbol table and parent and children nodes can be given as
     # arguments of Schedule.
     symtab = SymbolTable()
-    sched2 = Schedule(parent=sched, children=[Statement(), Statement()],
+    sched2 = Schedule(parent=sched, children=[DummyStatement(),
+                                              DummyStatement()],
                       symbol_table=symtab)
     assert isinstance(sched2, Schedule)
     assert sched2.parent is sched
diff --git a/src/psyclone/tests/psyir/transformations/inline_trans_test.py b/src/psyclone/tests/psyir/transformations/inline_trans_test.py
index 6f9366357e..c16b802c80 100644
--- a/src/psyclone/tests/psyir/transformations/inline_trans_test.py
+++ b/src/psyclone/tests/psyir/transformations/inline_trans_test.py
@@ -46,11 +46,12 @@
 from psyclone.psyir.backend.fortran import FortranWriter
 from psyclone.psyir.nodes import (
     Assignment, Call, IntrinsicCall, Loop, Node, Reference,
-    Routine, Statement)
+    Routine)
 from psyclone.psyir.symbols import (
     AutomaticInterface, DataSymbol, ImportInterface, UnresolvedType)
 from psyclone.psyir.transformations import (
     InlineTrans, TransformationError)
+from psyclone.tests.test_files.dummy_statement import DummyStatement
 from psyclone.tests.utilities import Compile, get_invoke
 
 MY_TYPE = ("  integer, parameter :: ngrids = 10\n"
@@ -2691,10 +2692,10 @@ def test_validate_automatic_array_sized_by_arg(fortran_reader, monkeypatch):
     inline_trans.validate(call)
     # Break Reference.previous_accesses() to exercise the InternalError.
     monkeypatch.setattr(call.arguments[1], "previous_accesses",
-                        lambda: [Statement()])
+                        lambda: [DummyStatement()])
     with pytest.raises(InternalError) as err:
         inline_trans.validate(call)
-    assert ("Unexpected node type (Statement) returned from Reference."
+    assert ("Unexpected node type (DummyStatement) returned from Reference."
             "previous_accesses()" in str(err.value))
 
 
diff --git a/src/psyclone/tests/psyir/transformations/transformations_test.py b/src/psyclone/tests/psyir/transformations/transformations_test.py
index edc31fcfae..16dfdf6301 100644
--- a/src/psyclone/tests/psyir/transformations/transformations_test.py
+++ b/src/psyclone/tests/psyir/transformations/transformations_test.py
@@ -46,7 +46,7 @@
 import pytest
 from fparser.common.readfortran import FortranStringReader
 from psyclone.psyir.nodes import (
-    CodeBlock, Literal, Loop, Node, Reference, Schedule, Statement,
+    CodeBlock, Literal, Loop, Node, Reference, Schedule,
     ACCLoopDirective, OMPMasterDirective, Fparser2CodeBlock,
     OMPDoDirective, OMPLoopDirective, Routine)
 from psyclone.psyir.symbols import (
@@ -60,6 +60,7 @@
     OMPSingleTrans, OMPMasterTrans)
 from psyclone.parse.algorithm import parse
 from psyclone.psyGen import PSyFactory
+from psyclone.tests.test_files.dummy_statement import DummyStatement
 
 GOCEAN_BASE_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)),
                                 os.pardir, os.pardir, "test_files",
@@ -95,7 +96,7 @@ def test_accloop():
     assert trans.name == "ACCLoopTrans"
     assert str(trans) == "Adds an 'OpenACC loop' directive to a loop"
 
-    cnode = Statement()
+    cnode = DummyStatement()
     tdir = trans._directive([cnode])
     assert isinstance(tdir, ACCLoopDirective)
 
@@ -265,7 +266,7 @@ class DummyVAM:  # pylint: disable=too-few-public-methods
         all_signatures = [DummySig()]
 
         def __getitem__(self, _):
-            return [DummyAccess(Statement())]
+            return [DummyAccess(DummyStatement())]
 
     monkeypatch.setattr(routine, "reference_accesses", lambda: DummyVAM())
     with pytest.raises(TransformationError) as err:
@@ -868,7 +869,7 @@ def test_profile_trans_invalid_name(value):
     # We need to have a schedule as parent, otherwise the node
     # (with no parent) will not be allowed.
     sched = Schedule()
-    node = Statement(parent=sched)
+    node = DummyStatement(parent=sched)
     sched.addchild(node)
     with pytest.raises(TransformationError) as excinfo:
         profile_trans.apply(node, options={"region_name": value})
diff --git a/src/psyclone/tests/test_files/dummy_statement.py b/src/psyclone/tests/test_files/dummy_statement.py
new file mode 100644
index 0000000000..0636741005
--- /dev/null
+++ b/src/psyclone/tests/test_files/dummy_statement.py
@@ -0,0 +1,51 @@
+# -----------------------------------------------------------------------------
+# BSD 3-Clause License
+#
+# Copyright (c) 2017-2026, Science and Technology Facilities Council.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# * Redistributions of source code must retain the above copyright notice, this
+#   list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+#
+# * Neither the name of the copyright holder nor the names of its
+#   contributors may be used to endorse or promote products derived from
+#   this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+# -----------------------------------------------------------------------------
+# Author A. B. G. Chalk, STFC Daresbury Lab
+
+'''This module contains a DummyStatement class used for tests where Statement
+nodes are initialised.'''
+
+from psyclone.psyir.nodes import Statement
+
+
+class DummyStatement(Statement):
+
+    def next_accesses(self) -> None:
+        '''Empty implementation of the required next_accesses
+        abstractmethod.'''
+
+    def previous_accesses(self) -> None:
+        '''Empty implementation of the required previous_accesses
+        abstractmethod.
+        '''

From 68c87c7bed372cebd179842ff14a0c93595f6780 Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Mon, 17 Aug 2026 15:53:58 +0100
Subject: [PATCH 02/11] Implements next and previous accesses for Statement
 subclasses

---
 src/psyclone/psyir/nodes/call.py          | 38 ++++++++++++++++-------
 src/psyclone/psyir/nodes/codeblock.py     | 34 +++++++++++++-------
 src/psyclone/psyir/nodes/directive.py     | 12 +++----
 src/psyclone/psyir/nodes/if_block.py      | 38 ++++++++++++++++-------
 src/psyclone/psyir/nodes/loop.py          | 27 +++++++++-------
 src/psyclone/psyir/nodes/psy_data_node.py | 13 ++------
 src/psyclone/psyir/nodes/return_stmt.py   | 15 +++------
 src/psyclone/psyir/nodes/routine.py       | 14 +++------
 src/psyclone/psyir/nodes/statement.py     | 26 ++++++++++++++++
 src/psyclone/psyir/nodes/while_loop.py    | 23 ++++++++------
 10 files changed, 144 insertions(+), 96 deletions(-)

diff --git a/src/psyclone/psyir/nodes/call.py b/src/psyclone/psyir/nodes/call.py
index 221b0775c0..7b81d60d91 100644
--- a/src/psyclone/psyir/nodes/call.py
+++ b/src/psyclone/psyir/nodes/call.py
@@ -915,20 +915,34 @@ def get_callee(
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: the next_accesses of children of this Call.
         '''
-        # FIXME Implement
-        return []
+        # Avoid circular import
+        # pylint: disable=import-outside-toplevel
+        from psyclone.psyir.tools import DefinitionUseChain
+        next_accesses = []
+        # Find all the children references
+        refs = [ref for ref in self.walk(Reference) if not
+                isinstance(ref.symbol, RoutineSymbol)]
+        chain = DefinitionUseChain(refs)
+        access_dict = chain.find_forward_accesses()
+        for accesses in access_dict:
+            self._merge_accesses(next_accesses, accesses)
+        return next_accesses
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        :returns: the previous_accesses of children of this Call.
         '''
-        # FIXME Implement
-        return []
+        # Avoid circular import
+        # pylint: disable=import-outside-toplevel
+        from psyclone.psyir.tools import DefinitionUseChain
+        prev_accesses = []
+        # Find all the children references
+        refs = [ref for ref in self.walk(Reference) if not
+                isinstance(ref.symbol, RoutineSymbol)]
+        chain = DefinitionUseChain(refs)
+        access_dict = chain.find_backward_accesses()
+        for accesses in access_dict:
+            self._merge_accesses(prev_accesses, accesses)
+        return prev_accesses
diff --git a/src/psyclone/psyir/nodes/codeblock.py b/src/psyclone/psyir/nodes/codeblock.py
index 1a07834ade..dfcbb96caa 100644
--- a/src/psyclone/psyir/nodes/codeblock.py
+++ b/src/psyclone/psyir/nodes/codeblock.py
@@ -229,23 +229,33 @@ def get_fortran_lines(self) -> list[str]:
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: the next_accesses for the child References of this
+            CodeBlock.
         '''
-        # FIXME Implement
-        return []
+        # Avoid circular import
+        # pylint: disable=import-outside-toplevel
+        from psyclone.psyir.tools import DefinitionUseChain
+        next_accesses = []
+        chain = DefinitionUseChain(self.children)
+        accesses = chain.find_forward_accesses()
+        for access in accesses:
+            self._merge_accesses(next_accesses, accesses)
+        return next_accesses
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        :returns: the previous_accesses for the child References of this
+            CodeBlock.
         '''
-        # FIXME Implement
-        return []
+        # Avoid circular import
+        # pylint: disable=import-outside-toplevel
+        from psyclone.psyir.tools import DefinitionUseChain
+        prev_accesses = []
+        chain = DefinitionUseChain(self.children)
+        accesses = chain.find_backward_accesses()
+        for access in accesses:
+            self._merge_accesses(prev_accesses, accesses)
+        return prev_accesses
 
 
 class Fparser2CodeBlock(CodeBlock):
diff --git a/src/psyclone/psyir/nodes/directive.py b/src/psyclone/psyir/nodes/directive.py
index ea4ddd3666..bae5593f90 100644
--- a/src/psyclone/psyir/nodes/directive.py
+++ b/src/psyclone/psyir/nodes/directive.py
@@ -150,22 +150,18 @@ def create_data_movement_deep_copy_refs(self):
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
+        Directive classes don't have next_accesses to compute.
 
         :returns: an empty list.
         '''
-        # FIXME Implement
         return []
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        Directive classes don't have previous_accesses to compute.
+
+        :returns: an empty list.
         '''
-        # FIXME Implement
         return []
 
 
diff --git a/src/psyclone/psyir/nodes/if_block.py b/src/psyclone/psyir/nodes/if_block.py
index b96be57518..3feae11a23 100644
--- a/src/psyclone/psyir/nodes/if_block.py
+++ b/src/psyclone/psyir/nodes/if_block.py
@@ -166,22 +166,36 @@ def reference_accesses(self) -> VariablesAccessMap:
             var_accesses.update(self.else_body.reference_accesses())
         return var_accesses
 
+
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: the combined next_accesses for the children of this IfBlock.
         '''
-        # FIXME Implement
-        return []
+        next_accesses = []
+        new_accesses = self.condition.next_accesses()
+        self._merge_accesses(next_accesses, new_accesses)
+        for child in self.if_body:
+            self._merge_accesses(next_accesses, child.next_accesses())
+        if self.else_body:
+            for child in self.else_body:
+                self._merge_accesses(next_accesses, child.next_accesses())
+
+        # FIXME Should we sort the output in some way?
+        return next_accesses
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        :returns: the combined previous_accesses for the children of this
+            IfBlock.
         '''
-        # FIXME Implement
-        return []
+        prev_accesses = []
+        new_accesses = self.condition.previous_accesses()
+        self._merge_accesses(prev_accesses, new_accesses)
+        for child in self.if_body:
+            self._merge_accesses(prev_accesses, child.previous_accesses())
+        if self.else_body:
+            for child in self.else_body:
+                self._merge_accesses(prev_accesses, child.previous_accesses())
+
+        # FIXME Should we sort the output in some way?
+        return previous_accesses
diff --git a/src/psyclone/psyir/nodes/loop.py b/src/psyclone/psyir/nodes/loop.py
index b6de55c1e5..0c115f2452 100644
--- a/src/psyclone/psyir/nodes/loop.py
+++ b/src/psyclone/psyir/nodes/loop.py
@@ -517,20 +517,23 @@ def enters_scope(self, scope, visited_nodes=None) -> bool:
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: the combined next_accesses for the children of this Loop.
         '''
-        # FIXME Implement
-        return []
+        next_accesses = []
+        var_acceses = self.variable_reference.next_accesses()
+        self._merge_accesses(next_accesses, var_accesses)
+        for child in self.loop_body:
+            self._merge_accesses(next_accesses, child.next_accesses())
+        return next_accesses
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        :returns: the combined previous_accesses for the children of this
+            Loop.
         '''
-        # FIXME Implement
-        return []
+        prev_accesses = []
+        var_acceses = self.variable_reference.previous_accesses()
+        self._merge_accesses(prev_accesses, var_accesses)
+        for child in self.loop_body:
+            self._merge_accesses(prev_accesses, child.previous_accesses())
+        return prev_accesses
diff --git a/src/psyclone/psyir/nodes/psy_data_node.py b/src/psyclone/psyir/nodes/psy_data_node.py
index 96a62c618e..33482919b7 100644
--- a/src/psyclone/psyir/nodes/psy_data_node.py
+++ b/src/psyclone/psyir/nodes/psy_data_node.py
@@ -704,22 +704,15 @@ def gen_type_bound_call(typename, methodname, argument_list=None,
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: an empty list as next_accesses isn't needed for PSyDataNode.
         '''
-        # FIXME Implement
         return []
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        :returns: an empty list as previous_accesses isn't needed for
+            PSyDataNode.
         '''
-        # FIXME Implement
         return []
 
 
diff --git a/src/psyclone/psyir/nodes/return_stmt.py b/src/psyclone/psyir/nodes/return_stmt.py
index 79f8bae06e..a9db95e3ea 100644
--- a/src/psyclone/psyir/nodes/return_stmt.py
+++ b/src/psyclone/psyir/nodes/return_stmt.py
@@ -24,20 +24,13 @@ class Return(Statement):
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: an empty list as there are no next_accesses after a Return.
         '''
-        # FIXME Implement
         return []
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        :returns: the previous_accesses of the return statement's child.
         '''
-        # FIXME Implement
-        return []
+        return self.children[0].previous_accesses()
+
diff --git a/src/psyclone/psyir/nodes/routine.py b/src/psyclone/psyir/nodes/routine.py
index 4706290acf..23e6c91dc3 100644
--- a/src/psyclone/psyir/nodes/routine.py
+++ b/src/psyclone/psyir/nodes/routine.py
@@ -569,22 +569,16 @@ def replace_with(self, node, keep_name_in_context=True):
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: an empty list as PSyclone doesn't know about dependencies
+            that go outside of Routine scope.
         '''
-        # FIXME Implement
         return []
 
     def previous_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the previous_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return previous accesses to any References contained in the statement.
+        :returns: an empty list as PSyclone doesn't know about dependencies
+            that go outside of Routine scope.
         '''
-        # FIXME Implement
         return []
 
 
diff --git a/src/psyclone/psyir/nodes/statement.py b/src/psyclone/psyir/nodes/statement.py
index dd49609638..d456e28755 100644
--- a/src/psyclone/psyir/nodes/statement.py
+++ b/src/psyclone/psyir/nodes/statement.py
@@ -35,9 +35,35 @@ def previous_accesses(self) -> list[Node]:
         Abstract method for finding the previous_accesses of a statement.
         Subclasses should override this according to their own structure to
         return previous accesses to any References contained in the statement.
+
+        :returns: an empty list.
         '''
         return []
 
+    def _merge_accesses(
+        self, current_accesses: list[Node], new_accesses: list[Node]
+    ) -> None:
+        '''
+        Helper function to merge access lists together for Statement
+        subclass next/previous_accesses functions.
+        Take all the accesses from new_accesses and adds them to the
+        current_accesses list if they're not already present and are
+        not contained in this nodes subtree.
+
+        :param current_accesses: The list of currently computed dependent
+            accesses for this node.
+        :param new_accesses: The list of accesses to merge into
+            current_accesses.
+        '''
+        for access in new_accesses:
+            in_subtree = access.is_descendant_of(self)
+            # If the access is not in the subtree of this node, and
+            # is not already present in the current_accesses array
+            # then add it to the array
+            if not in_subtree and all(
+                    [acc is not access for acc in current_accesses]):
+                current_accesses.append(access)
+
 
 # For automatic API documentation generation
 __all__ = ["Statement"]
diff --git a/src/psyclone/psyir/nodes/while_loop.py b/src/psyclone/psyir/nodes/while_loop.py
index da90f612b9..23e419433d 100644
--- a/src/psyclone/psyir/nodes/while_loop.py
+++ b/src/psyclone/psyir/nodes/while_loop.py
@@ -129,14 +129,15 @@ def reference_accesses(self) -> VariablesAccessMap:
 
     def next_accesses(self) -> list[Node]:
         '''
-        Abstract method for finding the next_accesses of a statement.
-        Subclasses should override this according to their own structure to
-        return future accesses to any References contained in the statement.
-
-        :returns: an empty list.
+        :returns: the combined next_accesses for the children of this
+            WhileLoop
         '''
-        # FIXME Implement
-        return []
+        next_accesses = []
+        var_acceses = self.condition.next_accesses()
+        self._merge_accesses(next_accesses, var_accesses)
+        for child in self.loop_body:
+            self._merge_accesses(next_accesses, child.next_accesses())
+        return next_accesses
 
     def previous_accesses(self) -> list[Node]:
         '''
@@ -144,5 +145,9 @@ def previous_accesses(self) -> list[Node]:
         Subclasses should override this according to their own structure to
         return previous accesses to any References contained in the statement.
         '''
-        # FIXME Implement
-        return []
+        prev_accesses = []
+        var_acceses = self.condition.previous_accesses()
+        self._merge_accesses(prev_accesses, var_accesses)
+        for child in self.loop_body:
+            self._merge_accesses(prev_accesses, child.previous_accesses())
+        return prev_accesses

From dbf7ec2549849413b724b23106f332ffc244bf5e Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Mon, 17 Aug 2026 15:59:59 +0100
Subject: [PATCH 03/11] linting

---
 src/psyclone/psyir/nodes/if_block.py    | 3 +--
 src/psyclone/psyir/nodes/loop.py        | 4 ++--
 src/psyclone/psyir/nodes/return_stmt.py | 1 -
 src/psyclone/psyir/nodes/while_loop.py  | 4 ++--
 4 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/psyclone/psyir/nodes/if_block.py b/src/psyclone/psyir/nodes/if_block.py
index 3feae11a23..0012e35197 100644
--- a/src/psyclone/psyir/nodes/if_block.py
+++ b/src/psyclone/psyir/nodes/if_block.py
@@ -166,7 +166,6 @@ def reference_accesses(self) -> VariablesAccessMap:
             var_accesses.update(self.else_body.reference_accesses())
         return var_accesses
 
-
     def next_accesses(self) -> list[Node]:
         '''
         :returns: the combined next_accesses for the children of this IfBlock.
@@ -198,4 +197,4 @@ def previous_accesses(self) -> list[Node]:
                 self._merge_accesses(prev_accesses, child.previous_accesses())
 
         # FIXME Should we sort the output in some way?
-        return previous_accesses
+        return prev_accesses
diff --git a/src/psyclone/psyir/nodes/loop.py b/src/psyclone/psyir/nodes/loop.py
index 0c115f2452..79df4a0e66 100644
--- a/src/psyclone/psyir/nodes/loop.py
+++ b/src/psyclone/psyir/nodes/loop.py
@@ -520,7 +520,7 @@ def next_accesses(self) -> list[Node]:
         :returns: the combined next_accesses for the children of this Loop.
         '''
         next_accesses = []
-        var_acceses = self.variable_reference.next_accesses()
+        var_accesses = self.variable_reference.next_accesses()
         self._merge_accesses(next_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(next_accesses, child.next_accesses())
@@ -532,7 +532,7 @@ def previous_accesses(self) -> list[Node]:
             Loop.
         '''
         prev_accesses = []
-        var_acceses = self.variable_reference.previous_accesses()
+        var_accesses = self.variable_reference.previous_accesses()
         self._merge_accesses(prev_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(prev_accesses, child.previous_accesses())
diff --git a/src/psyclone/psyir/nodes/return_stmt.py b/src/psyclone/psyir/nodes/return_stmt.py
index a9db95e3ea..c85ef0ba04 100644
--- a/src/psyclone/psyir/nodes/return_stmt.py
+++ b/src/psyclone/psyir/nodes/return_stmt.py
@@ -33,4 +33,3 @@ def previous_accesses(self) -> list[Node]:
         :returns: the previous_accesses of the return statement's child.
         '''
         return self.children[0].previous_accesses()
-
diff --git a/src/psyclone/psyir/nodes/while_loop.py b/src/psyclone/psyir/nodes/while_loop.py
index 23e419433d..9922c4579f 100644
--- a/src/psyclone/psyir/nodes/while_loop.py
+++ b/src/psyclone/psyir/nodes/while_loop.py
@@ -133,7 +133,7 @@ def next_accesses(self) -> list[Node]:
             WhileLoop
         '''
         next_accesses = []
-        var_acceses = self.condition.next_accesses()
+        var_accesses = self.condition.next_accesses()
         self._merge_accesses(next_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(next_accesses, child.next_accesses())
@@ -146,7 +146,7 @@ def previous_accesses(self) -> list[Node]:
         return previous accesses to any References contained in the statement.
         '''
         prev_accesses = []
-        var_acceses = self.condition.previous_accesses()
+        var_accesses = self.condition.previous_accesses()
         self._merge_accesses(prev_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(prev_accesses, child.previous_accesses())

From 2dc8ddce41df536235967123201a21692831443c Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Mon, 17 Aug 2026 16:03:12 +0100
Subject: [PATCH 04/11] Fixed linting from master merge

---
 src/psyclone/tests/psyir/transformations/inline_trans_test.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/psyclone/tests/psyir/transformations/inline_trans_test.py b/src/psyclone/tests/psyir/transformations/inline_trans_test.py
index e94063f0ea..fe1738be4b 100644
--- a/src/psyclone/tests/psyir/transformations/inline_trans_test.py
+++ b/src/psyclone/tests/psyir/transformations/inline_trans_test.py
@@ -17,7 +17,7 @@
 from psyclone.psyir.backend.fortran import FortranWriter
 from psyclone.psyir.nodes import (
     Assignment, Call, IntrinsicCall, Loop, Node, Reference,
-    Routine, Statement, Literal)
+    Routine, Literal)
 from psyclone.psyir.symbols import (
     AutomaticInterface, DataSymbol, ImportInterface, UnresolvedType,
     ScalarType)

From 9610ac8a7d5e14f09fb010bb47d144651307ea35 Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Wed, 19 Aug 2026 15:46:16 +0100
Subject: [PATCH 05/11] Fix condition for if_block

---
 src/psyclone/psyir/nodes/if_block.py | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/psyclone/psyir/nodes/if_block.py b/src/psyclone/psyir/nodes/if_block.py
index 0012e35197..4185d7341e 100644
--- a/src/psyclone/psyir/nodes/if_block.py
+++ b/src/psyclone/psyir/nodes/if_block.py
@@ -11,6 +11,7 @@
 from psyclone.errors import InternalError, GenerationError
 from psyclone.psyir.nodes.datanode import DataNode
 from psyclone.psyir.nodes.node import Node
+from psyclone.psyir.nodes.reference import Reference
 from psyclone.psyir.nodes.schedule import Schedule
 from psyclone.psyir.nodes.statement import Statement
 
@@ -171,8 +172,10 @@ def next_accesses(self) -> list[Node]:
         :returns: the combined next_accesses for the children of this IfBlock.
         '''
         next_accesses = []
-        new_accesses = self.condition.next_accesses()
-        self._merge_accesses(next_accesses, new_accesses)
+        # Find all the next_accesses for the References in the condition.
+        for ref in self.condition.walk(Reference):
+            new_accesses = ref.next_accesses()
+            self._merge_accesses(next_accesses, new_accesses)
         for child in self.if_body:
             self._merge_accesses(next_accesses, child.next_accesses())
         if self.else_body:
@@ -188,8 +191,10 @@ def previous_accesses(self) -> list[Node]:
             IfBlock.
         '''
         prev_accesses = []
-        new_accesses = self.condition.previous_accesses()
-        self._merge_accesses(prev_accesses, new_accesses)
+        # Find all the next_accesses for the References in the condition.
+        for ref in self.condition.walk(Reference):
+            new_accesses = ref.previous_accesses()
+            self._merge_accesses(prev_accesses, new_accesses)
         for child in self.if_body:
             self._merge_accesses(prev_accesses, child.previous_accesses())
         if self.else_body:

From 974b8cd60792b6fea883d09e6f6b35c15615250b Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Wed, 19 Aug 2026 15:46:31 +0100
Subject: [PATCH 06/11] Changes towards initial if_block tests

---
 .../tests/psyir/nodes/if_block_test.py        | 31 +++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/psyclone/tests/psyir/nodes/if_block_test.py b/src/psyclone/tests/psyir/nodes/if_block_test.py
index d4affa9135..29b46a9a3d 100644
--- a/src/psyclone/tests/psyir/nodes/if_block_test.py
+++ b/src/psyclone/tests/psyir/nodes/if_block_test.py
@@ -8,8 +8,9 @@
 ''' Performs py.test tests on the IfBlock PSyIR node. '''
 
 import pytest
-from psyclone.psyir.nodes import IfBlock, Literal, Reference, Schedule, \
-    Return, Assignment
+from psyclone.psyir.nodes import (
+        IfBlock, Literal, Reference, Schedule, Return, Assignment
+)
 from psyclone.psyir.symbols import DataSymbol, ScalarType
 from psyclone.errors import InternalError, GenerationError
 from psyclone.psyir.backend.fortran import FortranWriter
@@ -256,3 +257,29 @@ def test_ifblock_children_validation():
         ifblock.addchild(else_body)
     assert ("Item 'Schedule' can't be child 3 of 'If'. The valid format is: "
             "'DataNode, Schedule [, Schedule]'." in str(excinfo.value))
+
+
+def test_ifblock_next_accesses_condition(fortran_reader):
+    '''Test the next_accesses finds the next_accesses for references
+    in the ifblock's condition correctly.'''
+
+    code = """subroutine test
+    integer :: i, j, k, l
+
+    if(i > 3) then
+        j = 1
+    else
+        k = 1
+    end if
+    l = i
+    i = 1
+    end subroutine test"""
+
+    psyir = fortran_reader.psyir_from_source(code)
+    ifblock = psyir.walk(IfBlock)[0]
+    accesses = ifblock.next_accesses()
+    # The next_accesses are the two accesses to i after the ifblock.
+    assert len(accesses) == 2
+    assigns = psyir.walk(Assignment)
+    assert accesses[0] is assignment[2].rhs
+    assert accesses[1] is assignment[3].lhs

From 3a2d2eb39ae0394a81dae5be17b4482c984d3008 Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Fri, 21 Aug 2026 10:43:31 +0100
Subject: [PATCH 07/11] Some coverage

---
 .../tests/psyir/nodes/assignment_test.py      |  34 ++--
 src/psyclone/tests/psyir/nodes/call_test.py   |  40 +++-
 .../tests/psyir/nodes/codeblock_test.py       |  45 ++++-
 .../tests/psyir/nodes/if_block_test.py        | 116 ++++++++++-
 src/psyclone/tests/psyir/nodes/loop_test.py   | 191 ++++++++++++++++++
 .../tests/psyir/nodes/while_loop_test.py      |  84 +++++++-
 6 files changed, 482 insertions(+), 28 deletions(-)

diff --git a/src/psyclone/tests/psyir/nodes/assignment_test.py b/src/psyclone/tests/psyir/nodes/assignment_test.py
index cfe2a13641..31431e076c 100644
--- a/src/psyclone/tests/psyir/nodes/assignment_test.py
+++ b/src/psyclone/tests/psyir/nodes/assignment_test.py
@@ -370,10 +370,9 @@ def test_next_accesses(fortran_reader):
 
     reaches = assigns[0].next_accesses()
     sig = assigns[0].lhs.get_signature_and_indices()[0]
-    assert len(reaches) == 1
-    assert len(reaches[sig]) == 2
-    assert reaches[sig][0] is assigns[1].rhs.children[0]
-    assert reaches[sig][1] is assigns[1].lhs
+    assert len(reaches) == 2
+    assert reaches[0] is assigns[1].rhs.children[0]
+    assert reaches[1] is assigns[1].lhs
 
     # Next test multiple References to different symbols in the
     # Assignment
@@ -390,12 +389,10 @@ def test_next_accesses(fortran_reader):
     reaches = assigns[0].next_accesses()
     a_sig = assigns[0].lhs.get_signature_and_indices()[0]
     b_sig = assigns[0].rhs.get_signature_and_indices()[0]
-    assert len(reaches) == 2
-    assert len(reaches[a_sig]) == 2
-    assert reaches[a_sig][0] is assigns[1].rhs.children[0]
-    assert reaches[a_sig][1] is assigns[1].lhs
-    assert len(reaches[b_sig]) == 1
-    assert reaches[b_sig][0] is assigns[2].lhs
+    assert len(reaches) == 3
+    assert reaches[0] is assigns[1].rhs.children[0]
+    assert reaches[1] is assigns[1].lhs
+    assert reaches[2] is assigns[2].lhs
 
     # Test References inside an inquiry function are ignored
     psyir = fortran_reader.psyir_from_source(
@@ -411,9 +408,7 @@ def test_next_accesses(fortran_reader):
     reaches = assigns[0].next_accesses()
     a_sig = assigns[0].lhs.get_signature_and_indices()[0]
     b_sig = assigns[0].rhs.children[0].get_signature_and_indices()[0]
-    assert len(reaches) == 2
-    assert len(reaches[a_sig]) == 0
-    assert len(reaches[b_sig]) == 0
+    assert len(reaches) == 0
 
 
 def test_previous_accesses(fortran_reader):
@@ -432,8 +427,7 @@ def test_previous_accesses(fortran_reader):
     reaches = assigns[1].previous_accesses()
     sig = assigns[0].lhs.get_signature_and_indices()[0]
     assert len(reaches) == 1
-    assert len(reaches[sig]) == 1
-    assert reaches[sig][0] is assigns[0].lhs
+    assert reaches[0] is assigns[0].lhs
 
     # Next test multiple References to different symbols in the
     # Assignment
@@ -451,10 +445,8 @@ def test_previous_accesses(fortran_reader):
     a_sig = assigns[2].lhs.get_signature_and_indices()[0]
     b_sig = assigns[2].rhs.get_signature_and_indices()[0]
     assert len(reaches) == 2
-    assert len(reaches[a_sig]) == 1
-    assert reaches[a_sig][0] is assigns[1].lhs
-    assert len(reaches[b_sig]) == 1
-    assert reaches[b_sig][0] is assigns[0].lhs
+    assert reaches[0] is assigns[1].lhs
+    assert reaches[1] is assigns[0].lhs
 
     # Test References inside an inquiry function are ignored
     psyir = fortran_reader.psyir_from_source(
@@ -470,6 +462,4 @@ def test_previous_accesses(fortran_reader):
     reaches = assigns[1].previous_accesses()
     a_sig = assigns[1].lhs.get_signature_and_indices()[0]
     b_sig = assigns[1].rhs.children[0].get_signature_and_indices()[0]
-    assert len(reaches) == 2
-    assert len(reaches[a_sig]) == 0
-    assert len(reaches[b_sig]) == 0
+    assert len(reaches) == 0
diff --git a/src/psyclone/tests/psyir/nodes/call_test.py b/src/psyclone/tests/psyir/nodes/call_test.py
index 13c7ae813d..fd2f5d2246 100644
--- a/src/psyclone/tests/psyir/nodes/call_test.py
+++ b/src/psyclone/tests/psyir/nodes/call_test.py
@@ -13,7 +13,7 @@
 from psyclone.core import Signature
 from psyclone.errors import GenerationError
 from psyclone.psyir.nodes import (
-    ArrayReference, BinaryOperation, Call, Literal,
+    ArrayReference, Assignment, BinaryOperation, Call, Literal,
     Node, Reference, Routine, Schedule, CallMatchingArgumentsNotFound)
 from psyclone.psyir.nodes.node import colored
 from psyclone.psyir.symbols import (
@@ -2051,3 +2051,41 @@ def test_call_datatype(fortran_reader):
     # TODO #1799: Improve datatype inference, the following one
     # has a definition that says is an ArrayType
     assert isinstance(calls[3].datatype, UnresolvedType)
+
+
+def test_call_next_accesses(fortran_reader):
+    ''' Test the next_accesses method of Call gives the correct results.'''
+    psyir = fortran_reader.psyir_from_source("""
+    subroutine test
+        use some_mod
+        integer :: i, j, k
+        call my_fun(i)
+        j = i
+        i = k
+   end subroutine test""")
+    call = psyir.walk(Call)[0]
+    access = call.next_accesses()
+    assigns = psyir.walk(Assignment)
+    # The result is the 2 following accesses to i.
+    assert len(access) == 2
+    assert access[0] is assigns[0].rhs
+    assert access[1] is assigns[1].lhs
+
+
+def test_call_previous_accesses(fortran_reader):
+    ''' Test the previous_accesses method of Call gives the correct results.'''
+    psyir = fortran_reader.psyir_from_source("""
+    subroutine test
+        use some_mod
+        integer :: i, j, k
+        i = k
+        j = i
+        call my_fun(i)
+   end subroutine test""")
+    call = psyir.walk(Call)[0]
+    access = call.previous_accesses()
+    assigns = psyir.walk(Assignment)
+    # The result is the 2 following accesses to i.
+    assert len(access) == 2
+    assert access[0] is assigns[1].rhs
+    assert access[1] is assigns[0].lhs
diff --git a/src/psyclone/tests/psyir/nodes/codeblock_test.py b/src/psyclone/tests/psyir/nodes/codeblock_test.py
index 689d373070..7083a3ffa8 100644
--- a/src/psyclone/tests/psyir/nodes/codeblock_test.py
+++ b/src/psyclone/tests/psyir/nodes/codeblock_test.py
@@ -12,7 +12,7 @@
 from fparser.common.readfortran import FortranStringReader
 from psyclone.configuration import Config
 from psyclone.psyir.frontend.fortran import FortranReader
-from psyclone.psyir.nodes import Reference, Schedule
+from psyclone.psyir.nodes import Assignment, Reference, Schedule
 from psyclone.psyir.frontend.fparser2 import Fparser2Reader
 from psyclone.psyir.frontend.fortran_treesitter_reader import \
     FortranTreeSitterReader
@@ -346,3 +346,46 @@ def test_codeblock_has_potential_control_flow_jump(fortran_reader):
     assert codeblocks[2].has_potential_control_flow_jump()
     # labelled statement
     assert codeblocks[3].has_potential_control_flow_jump()
+
+
+def test_codeblock_next_accesses(fortran_reader):
+    """Test that the next_accesses method works correctly for CodeBlocks."""
+    code = """subroutine test()
+    integer :: i, j, k
+    print *, i
+    k = 0 ! Extra assignment to separate the CodeBlocks.
+    print *, j, i
+    j = 3
+    i = 1
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    codeblocks = psyir.walk(CodeBlock)
+    assigns = psyir.walk(Assignment)
+    accesses = codeblocks[0].next_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is codeblocks[1].children[1]
+    accesses = codeblocks[1].next_accesses()
+    assert len(accesses) == 2
+    assert accesses[0] is assigns[1].lhs
+    assert accesses[1] is assigns[2].lhs
+
+
+def test_codeblock_previous_accesses(fortran_reader):
+    """Test that the previous_accesses method works correctly for CodeBlocks."""
+    code = """subroutine test()
+    integer :: i, j, k
+    i = 1
+    j = 3
+    print *, j, i
+    k = 0 ! Extra assignment to separate the CodeBlocks.
+    print *, i
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    codeblocks = psyir.walk(CodeBlock)
+    assigns = psyir.walk(Assignment)
+    accesses = codeblocks[1].previous_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is codeblocks[0].children[1]
+    accesses = codeblocks[0].previous_accesses()
+    assert accesses[0] is assigns[1].lhs
+    assert accesses[1] is assigns[0].lhs
diff --git a/src/psyclone/tests/psyir/nodes/if_block_test.py b/src/psyclone/tests/psyir/nodes/if_block_test.py
index 29b46a9a3d..319ed1dcd5 100644
--- a/src/psyclone/tests/psyir/nodes/if_block_test.py
+++ b/src/psyclone/tests/psyir/nodes/if_block_test.py
@@ -281,5 +281,117 @@ def test_ifblock_next_accesses_condition(fortran_reader):
     # The next_accesses are the two accesses to i after the ifblock.
     assert len(accesses) == 2
     assigns = psyir.walk(Assignment)
-    assert accesses[0] is assignment[2].rhs
-    assert accesses[1] is assignment[3].lhs
+    assert accesses[0] is assigns[2].rhs
+    assert accesses[1] is assigns[3].lhs
+
+    # Check that accesses within the ifblock aren't found.
+    code = """subroutine test
+    integer :: i, j, k
+    if (i > 3) then
+        i = 2
+    else
+        i = 4
+    end if
+    k = 1
+    end subroutine test"""
+
+    psyir = fortran_reader.psyir_from_source(code)
+    ifblock = psyir.walk(IfBlock)[0]
+    accesses = ifblock.next_accesses()
+    assert len(accesses) == 0
+
+
+def test_ifblock_next_accesses_bodies(fortran_reader):
+    '''Test the next_accesses method finds the next_accesses for
+    references in the ifblock's bodies.'''
+    code = """subroutine test
+    integer :: i, j, k, l
+    if(i > 3) then
+        j = 1
+    else
+        k = 1
+    end if
+    l = j
+    l = l + k
+    j = 3
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    ifblock = psyir.walk(IfBlock)[0]
+    accesses = ifblock.next_accesses()
+    assigns = psyir.walk(Assignment)
+    assert len(accesses) == 3
+    # First access after the ifblock to j.
+    assert accesses[0] is assigns[2].rhs
+    # First access after the ifblock to k.
+    assert accesses[2] is assigns[3].rhs.children[1]
+    # Write access after the ifblock to j.
+    assert accesses[1] is assigns[4].lhs
+
+
+def test_ifblock_previous_accesses_condition(fortran_reader):
+    '''Test the previous_accesses finds the previous_accesses for references
+    in the ifblock's condition correctly.'''
+
+    code = """subroutine test
+    integer :: i, j, k, l
+
+    i = 1
+    l = i
+    if(i > 3) then
+        j = 1
+    else
+        k = 1
+    end if
+    end subroutine test"""
+
+    psyir = fortran_reader.psyir_from_source(code)
+    ifblock = psyir.walk(IfBlock)[0]
+    accesses = ifblock.previous_accesses()
+    # The previous_accesses are the two accesses to i after the ifblock.
+    assert len(accesses) == 2
+    assigns = psyir.walk(Assignment)
+    assert accesses[0] is assigns[1].rhs
+    assert accesses[1] is assigns[0].lhs
+
+    # Check that accesses within the ifblock aren't found.
+    code = """subroutine test
+    integer :: i, j, k
+    k = 1
+    if (i > 3) then
+        i = 2
+    else
+        i = 4
+    end if
+    end subroutine test"""
+
+    psyir = fortran_reader.psyir_from_source(code)
+    ifblock = psyir.walk(IfBlock)[0]
+    accesses = ifblock.previous_accesses()
+    assert len(accesses) == 0
+
+
+def test_ifblock_previous_accesses_bodies(fortran_reader):
+    '''Test the previous_accesses method finds the previous_accesses for
+    references in the ifblock's bodies.'''
+    code = """subroutine test
+    integer :: i, j, k, l
+    j = 3
+    l = l + k
+    l = j
+    if(i > 3) then
+        j = 1
+    else
+        k = 1
+    end if
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    ifblock = psyir.walk(IfBlock)[0]
+    accesses = ifblock.previous_accesses()
+    assigns = psyir.walk(Assignment)
+    assert len(accesses) == 3
+    # First access after the ifblock to j.
+    assert accesses[0] is assigns[2].rhs
+    # First access after the ifblock to k.
+    assert accesses[2] is assigns[1].rhs.children[1]
+    # Write access after the ifblock to j.
+    assert accesses[1] is assigns[0].lhs
diff --git a/src/psyclone/tests/psyir/nodes/loop_test.py b/src/psyclone/tests/psyir/nodes/loop_test.py
index 84e5645f4e..d41e1b8821 100644
--- a/src/psyclone/tests/psyir/nodes/loop_test.py
+++ b/src/psyclone/tests/psyir/nodes/loop_test.py
@@ -551,3 +551,194 @@ def test_loops_enters_scope():
     # Always returns false, regardless of the scope, as the loop variable
     # by definition gets the first value assigned here from the loop bounds.
     assert not loop.enters_scope(None)
+
+
+def test_loop_variable_next_accesses(fortran_reader):
+    """Test that the next_accesses function works correctly for the loop
+    variable."""
+    code = """subroutine test
+    integer :: i, j, k
+    do i = 1, 100
+       j = 2
+    end do
+    i = k
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.next_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[1].lhs
+
+
+def test_loop_variable_previous_accesses(fortran_reader):
+    """Test that the previous_accesses function works correctly for the loop
+    variable."""
+    code = """subroutine test
+    integer :: i, j, k
+    i = k
+    do i = 1, 100
+       j = 2
+    end do
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.previous_accesses()
+    assert len(accesses) == 0
+    pytest.xfail(reason="#3486 Definition Use Chains don't yet account"
+                        "for loop variables.") 
+    # Correct implementation should result in:
+    # assert len(accesses) == 1
+    # assert accesses[0] is assigns[0].lhs
+
+
+def test_loop_start_value_next_accesses(fortran_reader):
+    """Test that the next_accesses function works correctly for the start
+    condition."""
+    code = """subroutine test
+    integer :: i, j, k
+    do i = j, 100
+        k = 1
+    end do
+    j = 2
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.next_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[1].lhs
+
+
+def test_loop_start_value_previous_accesses(fortran_reader):
+    """Test that the previous_accesses function works correctly for the start
+    condition."""
+    code = """subroutine test
+    integer :: i, j, k
+    j = 2
+    do i = j, 100
+        k = 1
+    end do
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.previous_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[0].lhs
+
+
+def test_loop_stop_value_next_accesses(fortran_reader):
+    """Test that the next_accesses function works correctly for the stop
+    condition."""
+    code = """subroutine test
+    integer :: i, j, k
+    do i = 1, j
+        k = 1
+    end do
+    j = 2
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.next_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[1].lhs
+
+
+def test_loop_stop_value_previous_accesses(fortran_reader):
+    """Test that the previous_accesses function works correctly for the stop
+    condition."""
+    code = """subroutine test
+    integer :: i, j, k
+    j = 2
+    do i = 1, j
+        k = 1
+    end do
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.previous_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[0].lhs
+
+def test_loop_step_value_next_accesses(fortran_reader):
+    """Test that the next_accesses function works correctly for the step
+    condition."""
+    code = """subroutine test
+    integer :: i, j, k
+    do i = 1, 100, j
+        k = 1
+    end do
+    j = 2
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.next_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[1].lhs
+
+
+def test_loop_step_value_previous_accesses(fortran_reader):
+    """Test that the previous_accesses function works correctly for the step
+    condition."""
+    code = """subroutine test
+    integer :: i, j, k
+    j = 2
+    do i = 1, 100, j
+        k = 1
+    end do
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.previous_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[0].lhs
+
+
+def test_loop_body_next_accesses(fortran_reader):
+    """Test that the next_accesses function works correctly for the
+    loop_body."""
+    code = """subroutine test
+    integer :: i, j, k
+    do i = 1, 100
+        j = 4 * i
+        k = 3 + i
+    end do
+    j = j * 2
+    k = k + 3
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.next_accesses()
+    assert len(accesses) == 4
+    assert accesses[0] is assigns[2].rhs.children[0]
+    assert accesses[1] is assigns[2].lhs
+    assert accesses[2] is assigns[3].rhs.children[0]
+    assert accesses[3] is assigns[3].lhs
+
+
+def test_loop_body_previous_accesses(fortran_reader):
+    """Test that the previous_accesses function works correctly for the
+    loop_body."""
+    code = """subroutine test
+    integer :: i, j, k
+    k = k + 3
+    j = j * 2
+    do i = 1, 100
+        j = 4 * i
+        k = 3 + i
+    end do
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    loop = psyir.walk(Loop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.previous_accesses()
+    assert len(accesses) == 2
+    assert accesses[0] is assigns[1].lhs
+    assert accesses[1] is assigns[0].lhs
diff --git a/src/psyclone/tests/psyir/nodes/while_loop_test.py b/src/psyclone/tests/psyir/nodes/while_loop_test.py
index 61d85c4151..5e972b8c1e 100644
--- a/src/psyclone/tests/psyir/nodes/while_loop_test.py
+++ b/src/psyclone/tests/psyir/nodes/while_loop_test.py
@@ -10,8 +10,8 @@
 import pytest
 from psyclone.errors import InternalError, GenerationError
 from psyclone.psyir.backend.fortran import FortranWriter
-from psyclone.psyir.nodes import Assignment, BinaryOperation, Literal, \
-                                 Reference, Return, Schedule, WhileLoop
+from psyclone.psyir.nodes import (Assignment, BinaryOperation, Literal,
+                                  Reference, Return, Schedule, WhileLoop)
 from psyclone.psyir.nodes.node import colored
 from psyclone.psyir.symbols import DataSymbol, ScalarType
 from psyclone.tests.utilities import check_links
@@ -139,3 +139,83 @@ def test_whileloop_can_be_printed():
     assert "WhileLoop[]\n" in str(loop)
     assert "condition1" in str(loop)  # Test condition is printed
     assert "Return[]" in str(loop)  # Test loop body is printed
+
+
+def test_whileloop_condition_next_accesses(fortran_reader):
+    '''Test that the next_accesses method works correctly on References
+    in the WhileLoop condition.'''
+    code = """subroutine test
+        integer :: i, j, k
+        
+        do while(i < 2)
+            j = 2
+        end do
+        i = k + 1
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+
+    loop = psyir.walk(WhileLoop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.next_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[1].lhs
+
+
+def test_whileloop_condition_previous_accesses(fortran_reader):
+    '''Test that the previous_accesses method works correctly on References
+    in the WhileLoop condition.'''
+    code = """subroutine test
+        integer :: i, j, k
+        
+        i = k + 1
+        do while(i < 2)
+            j = 2
+        end do
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+
+    loop = psyir.walk(WhileLoop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.previous_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[0].lhs
+
+
+def test_whileloop_body_next_accesses(fortran_reader):
+    '''Test that the next_accesses method works correctly on the
+    WhileLoop body.'''
+    code = """subroutine test
+        integer :: i, j, k
+        
+        do while(i < 2)
+            j = 2
+        end do
+        j = k + 1
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+
+    loop = psyir.walk(WhileLoop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.next_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[1].lhs
+
+
+def test_whileloop_body_previous_accesses(fortran_reader):
+    '''Test that the previous_accesses method works correctly on the
+    WhileLoop body.'''
+    code = """subroutine test
+        integer :: i, j, k
+        
+        j = k + 1
+        do while(i < 2)
+            j = 2
+        end do
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+
+    loop = psyir.walk(WhileLoop)[0]
+    assigns = psyir.walk(Assignment)
+    accesses = loop.previous_accesses()
+    assert len(accesses) == 1
+    assert accesses[0] is assigns[0].lhs

From 0b02f50cb7f726de523a1489b7f8434072fdfe3e Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Fri, 21 Aug 2026 10:51:33 +0100
Subject: [PATCH 08/11] linting

---
 src/psyclone/psyir/nodes/assignment.py        | 24 ++++++++++++++-----
 src/psyclone/psyir/nodes/call.py              |  8 +++----
 src/psyclone/psyir/nodes/codeblock.py         |  4 ++--
 src/psyclone/psyir/nodes/loop.py              | 14 +++++++----
 src/psyclone/psyir/nodes/while_loop.py        | 11 +++++----
 .../tests/psyir/nodes/assignment_test.py      | 10 --------
 .../tests/psyir/nodes/codeblock_test.py       |  3 ++-
 src/psyclone/tests/psyir/nodes/loop_test.py   |  5 ++--
 .../tests/psyir/nodes/while_loop_test.py      |  8 +++----
 9 files changed, 50 insertions(+), 37 deletions(-)

diff --git a/src/psyclone/psyir/nodes/assignment.py b/src/psyclone/psyir/nodes/assignment.py
index 4a64a23aaf..dad0028ea6 100644
--- a/src/psyclone/psyir/nodes/assignment.py
+++ b/src/psyclone/psyir/nodes/assignment.py
@@ -7,7 +7,7 @@
 
 ''' This module contains the Assignment node implementation.'''
 
-from psyclone.core import VariablesAccessMap, AccessType, Signature
+from psyclone.core import VariablesAccessMap, AccessType
 from psyclone.errors import InternalError
 from psyclone.psyir.nodes.literal import Literal
 from psyclone.psyir.nodes.array_reference import ArrayReference
@@ -213,7 +213,7 @@ def is_literal_assignment(self):
         '''
         return isinstance(self.rhs, Literal)
 
-    def previous_accesses(self) -> dict[Signature, list[Node]]:
+    def previous_accesses(self) -> list[Node]:
         '''
         :returns: the nodes containing the previous accesses of the symbols
                   accessed within this node. It can be multiple nodes for
@@ -229,9 +229,15 @@ def previous_accesses(self) -> dict[Signature, list[Node]]:
         # pylint: disable=import-outside-toplevel
         from psyclone.psyir.tools import DefinitionUseChain
         chain = DefinitionUseChain(refs)
-        return chain.find_backward_accesses()
-
-    def next_accesses(self) -> dict[Signature, list[Node]]:
+        accesses = chain.find_backward_accesses()
+        results = []
+        for sig in accesses:
+            for access in accesses[sig]:
+                if all(x is not access for x in results):
+                    results.append(access)
+        return results
+
+    def next_accesses(self) -> list[Node]:
         '''
         :returns: the nodes containing the next accesses of the symbols
                   accessed within this node. It can be multiple nodes for
@@ -247,4 +253,10 @@ def next_accesses(self) -> dict[Signature, list[Node]]:
         # pylint: disable=import-outside-toplevel
         from psyclone.psyir.tools import DefinitionUseChain
         chain = DefinitionUseChain(refs)
-        return chain.find_forward_accesses()
+        accesses = chain.find_forward_accesses()
+        results = []
+        for sig in accesses:
+            for access in accesses[sig]:
+                if all(x is not access for x in results):
+                    results.append(access)
+        return results
diff --git a/src/psyclone/psyir/nodes/call.py b/src/psyclone/psyir/nodes/call.py
index 7b81d60d91..d67b7a3a74 100644
--- a/src/psyclone/psyir/nodes/call.py
+++ b/src/psyclone/psyir/nodes/call.py
@@ -926,8 +926,8 @@ def next_accesses(self) -> list[Node]:
                 isinstance(ref.symbol, RoutineSymbol)]
         chain = DefinitionUseChain(refs)
         access_dict = chain.find_forward_accesses()
-        for accesses in access_dict:
-            self._merge_accesses(next_accesses, accesses)
+        for access in access_dict:
+            self._merge_accesses(next_accesses, access_dict[access])
         return next_accesses
 
     def previous_accesses(self) -> list[Node]:
@@ -943,6 +943,6 @@ def previous_accesses(self) -> list[Node]:
                 isinstance(ref.symbol, RoutineSymbol)]
         chain = DefinitionUseChain(refs)
         access_dict = chain.find_backward_accesses()
-        for accesses in access_dict:
-            self._merge_accesses(prev_accesses, accesses)
+        for access in access_dict:
+            self._merge_accesses(prev_accesses, access_dict[access])
         return prev_accesses
diff --git a/src/psyclone/psyir/nodes/codeblock.py b/src/psyclone/psyir/nodes/codeblock.py
index dfcbb96caa..3fba4d3166 100644
--- a/src/psyclone/psyir/nodes/codeblock.py
+++ b/src/psyclone/psyir/nodes/codeblock.py
@@ -239,7 +239,7 @@ def next_accesses(self) -> list[Node]:
         chain = DefinitionUseChain(self.children)
         accesses = chain.find_forward_accesses()
         for access in accesses:
-            self._merge_accesses(next_accesses, accesses)
+            self._merge_accesses(next_accesses, accesses[access])
         return next_accesses
 
     def previous_accesses(self) -> list[Node]:
@@ -254,7 +254,7 @@ def previous_accesses(self) -> list[Node]:
         chain = DefinitionUseChain(self.children)
         accesses = chain.find_backward_accesses()
         for access in accesses:
-            self._merge_accesses(prev_accesses, accesses)
+            self._merge_accesses(prev_accesses, accesses[access])
         return prev_accesses
 
 
diff --git a/src/psyclone/psyir/nodes/loop.py b/src/psyclone/psyir/nodes/loop.py
index 79df4a0e66..f519c8d792 100644
--- a/src/psyclone/psyir/nodes/loop.py
+++ b/src/psyclone/psyir/nodes/loop.py
@@ -520,8 +520,11 @@ def next_accesses(self) -> list[Node]:
         :returns: the combined next_accesses for the children of this Loop.
         '''
         next_accesses = []
-        var_accesses = self.variable_reference.next_accesses()
-        self._merge_accesses(next_accesses, var_accesses)
+        # Loop through the non loop_body children and compute accesses.
+        for child in self.children[0:4]:
+            for ref in child.walk(Reference):
+                var_accesses = ref.next_accesses()
+                self._merge_accesses(next_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(next_accesses, child.next_accesses())
         return next_accesses
@@ -532,8 +535,11 @@ def previous_accesses(self) -> list[Node]:
             Loop.
         '''
         prev_accesses = []
-        var_accesses = self.variable_reference.previous_accesses()
-        self._merge_accesses(prev_accesses, var_accesses)
+        # Loop through the non loop_body children and compute accesses.
+        for child in self.children[0:4]:
+            for ref in child.walk(Reference):
+                var_accesses = ref.previous_accesses()
+                self._merge_accesses(prev_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(prev_accesses, child.previous_accesses())
         return prev_accesses
diff --git a/src/psyclone/psyir/nodes/while_loop.py b/src/psyclone/psyir/nodes/while_loop.py
index 9922c4579f..3240bdf636 100644
--- a/src/psyclone/psyir/nodes/while_loop.py
+++ b/src/psyclone/psyir/nodes/while_loop.py
@@ -11,6 +11,7 @@
 from psyclone.errors import InternalError, GenerationError
 from psyclone.psyir.nodes.datanode import DataNode
 from psyclone.psyir.nodes.node import Node
+from psyclone.psyir.nodes.reference import Reference
 from psyclone.psyir.nodes.schedule import Schedule
 from psyclone.psyir.nodes.statement import Statement
 
@@ -133,8 +134,9 @@ def next_accesses(self) -> list[Node]:
             WhileLoop
         '''
         next_accesses = []
-        var_accesses = self.condition.next_accesses()
-        self._merge_accesses(next_accesses, var_accesses)
+        for ref in self.condition.walk(Reference):
+            var_accesses = ref.next_accesses()
+            self._merge_accesses(next_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(next_accesses, child.next_accesses())
         return next_accesses
@@ -146,8 +148,9 @@ def previous_accesses(self) -> list[Node]:
         return previous accesses to any References contained in the statement.
         '''
         prev_accesses = []
-        var_accesses = self.condition.previous_accesses()
-        self._merge_accesses(prev_accesses, var_accesses)
+        for ref in self.condition.walk(Reference):
+            var_accesses = ref.previous_accesses()
+            self._merge_accesses(prev_accesses, var_accesses)
         for child in self.loop_body:
             self._merge_accesses(prev_accesses, child.previous_accesses())
         return prev_accesses
diff --git a/src/psyclone/tests/psyir/nodes/assignment_test.py b/src/psyclone/tests/psyir/nodes/assignment_test.py
index 31431e076c..1d8709a00c 100644
--- a/src/psyclone/tests/psyir/nodes/assignment_test.py
+++ b/src/psyclone/tests/psyir/nodes/assignment_test.py
@@ -369,7 +369,6 @@ def test_next_accesses(fortran_reader):
     assigns = psyir.walk(Assignment)
 
     reaches = assigns[0].next_accesses()
-    sig = assigns[0].lhs.get_signature_and_indices()[0]
     assert len(reaches) == 2
     assert reaches[0] is assigns[1].rhs.children[0]
     assert reaches[1] is assigns[1].lhs
@@ -387,8 +386,6 @@ def test_next_accesses(fortran_reader):
     )
     assigns = psyir.walk(Assignment)
     reaches = assigns[0].next_accesses()
-    a_sig = assigns[0].lhs.get_signature_and_indices()[0]
-    b_sig = assigns[0].rhs.get_signature_and_indices()[0]
     assert len(reaches) == 3
     assert reaches[0] is assigns[1].rhs.children[0]
     assert reaches[1] is assigns[1].lhs
@@ -406,8 +403,6 @@ def test_next_accesses(fortran_reader):
     )
     assigns = psyir.walk(Assignment)
     reaches = assigns[0].next_accesses()
-    a_sig = assigns[0].lhs.get_signature_and_indices()[0]
-    b_sig = assigns[0].rhs.children[0].get_signature_and_indices()[0]
     assert len(reaches) == 0
 
 
@@ -425,7 +420,6 @@ def test_previous_accesses(fortran_reader):
     assigns = psyir.walk(Assignment)
 
     reaches = assigns[1].previous_accesses()
-    sig = assigns[0].lhs.get_signature_and_indices()[0]
     assert len(reaches) == 1
     assert reaches[0] is assigns[0].lhs
 
@@ -442,8 +436,6 @@ def test_previous_accesses(fortran_reader):
     )
     assigns = psyir.walk(Assignment)
     reaches = assigns[2].previous_accesses()
-    a_sig = assigns[2].lhs.get_signature_and_indices()[0]
-    b_sig = assigns[2].rhs.get_signature_and_indices()[0]
     assert len(reaches) == 2
     assert reaches[0] is assigns[1].lhs
     assert reaches[1] is assigns[0].lhs
@@ -460,6 +452,4 @@ def test_previous_accesses(fortran_reader):
     )
     assigns = psyir.walk(Assignment)
     reaches = assigns[1].previous_accesses()
-    a_sig = assigns[1].lhs.get_signature_and_indices()[0]
-    b_sig = assigns[1].rhs.children[0].get_signature_and_indices()[0]
     assert len(reaches) == 0
diff --git a/src/psyclone/tests/psyir/nodes/codeblock_test.py b/src/psyclone/tests/psyir/nodes/codeblock_test.py
index 7083a3ffa8..08158fde24 100644
--- a/src/psyclone/tests/psyir/nodes/codeblock_test.py
+++ b/src/psyclone/tests/psyir/nodes/codeblock_test.py
@@ -371,7 +371,8 @@ def test_codeblock_next_accesses(fortran_reader):
 
 
 def test_codeblock_previous_accesses(fortran_reader):
-    """Test that the previous_accesses method works correctly for CodeBlocks."""
+    """Test that the previous_accesses method works correctly for
+    CodeBlocks."""
     code = """subroutine test()
     integer :: i, j, k
     i = 1
diff --git a/src/psyclone/tests/psyir/nodes/loop_test.py b/src/psyclone/tests/psyir/nodes/loop_test.py
index d41e1b8821..49936c09df 100644
--- a/src/psyclone/tests/psyir/nodes/loop_test.py
+++ b/src/psyclone/tests/psyir/nodes/loop_test.py
@@ -583,12 +583,12 @@ def test_loop_variable_previous_accesses(fortran_reader):
     end subroutine test"""
     psyir = fortran_reader.psyir_from_source(code)
     loop = psyir.walk(Loop)[0]
-    assigns = psyir.walk(Assignment)
     accesses = loop.previous_accesses()
     assert len(accesses) == 0
     pytest.xfail(reason="#3486 Definition Use Chains don't yet account"
-                        "for loop variables.") 
+                        "for loop variables.")
     # Correct implementation should result in:
+    # assigns = psyir.walk(Assignment)
     # assert len(accesses) == 1
     # assert accesses[0] is assigns[0].lhs
 
@@ -664,6 +664,7 @@ def test_loop_stop_value_previous_accesses(fortran_reader):
     assert len(accesses) == 1
     assert accesses[0] is assigns[0].lhs
 
+
 def test_loop_step_value_next_accesses(fortran_reader):
     """Test that the next_accesses function works correctly for the step
     condition."""
diff --git a/src/psyclone/tests/psyir/nodes/while_loop_test.py b/src/psyclone/tests/psyir/nodes/while_loop_test.py
index 5e972b8c1e..eb7cbf7d10 100644
--- a/src/psyclone/tests/psyir/nodes/while_loop_test.py
+++ b/src/psyclone/tests/psyir/nodes/while_loop_test.py
@@ -146,7 +146,7 @@ def test_whileloop_condition_next_accesses(fortran_reader):
     in the WhileLoop condition.'''
     code = """subroutine test
         integer :: i, j, k
-        
+
         do while(i < 2)
             j = 2
         end do
@@ -166,7 +166,7 @@ def test_whileloop_condition_previous_accesses(fortran_reader):
     in the WhileLoop condition.'''
     code = """subroutine test
         integer :: i, j, k
-        
+
         i = k + 1
         do while(i < 2)
             j = 2
@@ -186,7 +186,7 @@ def test_whileloop_body_next_accesses(fortran_reader):
     WhileLoop body.'''
     code = """subroutine test
         integer :: i, j, k
-        
+
         do while(i < 2)
             j = 2
         end do
@@ -206,7 +206,7 @@ def test_whileloop_body_previous_accesses(fortran_reader):
     WhileLoop body.'''
     code = """subroutine test
         integer :: i, j, k
-        
+
         j = k + 1
         do while(i < 2)
             j = 2

From cc4e97567cee052a24968ac57d513e7d7a682300 Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Fri, 21 Aug 2026 13:24:34 +0100
Subject: [PATCH 09/11] Fixes and coverage improvements

---
 src/psyclone/psyir/nodes/return_stmt.py          |  2 +-
 src/psyclone/tests/dependency_test.py            |  8 ++++++++
 src/psyclone/tests/psyGen_test.py                |  8 ++++++++
 src/psyclone/tests/psyir/nodes/directive_test.py |  8 ++++++++
 src/psyclone/tests/psyir/nodes/node_test.py      |  7 +++++++
 .../tests/psyir/nodes/psy_data_node_test.py      |  8 ++++++++
 .../tests/psyir/nodes/return_stmt_test.py        | 16 ++++++++++++++++
 src/psyclone/tests/psyir/nodes/routine_test.py   | 14 ++++++++++++++
 src/psyclone/tests/test_files/dummy_statement.py |  6 ++++--
 9 files changed, 74 insertions(+), 3 deletions(-)

diff --git a/src/psyclone/psyir/nodes/return_stmt.py b/src/psyclone/psyir/nodes/return_stmt.py
index c85ef0ba04..f5ab075a88 100644
--- a/src/psyclone/psyir/nodes/return_stmt.py
+++ b/src/psyclone/psyir/nodes/return_stmt.py
@@ -32,4 +32,4 @@ def previous_accesses(self) -> list[Node]:
         '''
         :returns: the previous_accesses of the return statement's child.
         '''
-        return self.children[0].previous_accesses()
+        return []
diff --git a/src/psyclone/tests/dependency_test.py b/src/psyclone/tests/dependency_test.py
index e8a34b99de..828e9eff86 100644
--- a/src/psyclone/tests/dependency_test.py
+++ b/src/psyclone/tests/dependency_test.py
@@ -588,3 +588,11 @@ def test_lfric_stub_boundary_dofmap():
     create_arg_list = KernStubArgList(kernel)
     create_arg_list.generate(var_accesses=var_accesses)
     assert "boundary_dofs_op_1: READ" in str(var_accesses)
+
+
+def test_lfrickern_accesses():
+    '''Check that next/previous_accesses methods on Kern classes
+    return an empty list.'''
+    kernel = LFRicKern()
+    assert kernel.next_accesses() == []
+    assert kernel.previous_accesses() == []
diff --git a/src/psyclone/tests/psyGen_test.py b/src/psyclone/tests/psyGen_test.py
index 1b93ce34f2..b9633961ea 100644
--- a/src/psyclone/tests/psyGen_test.py
+++ b/src/psyclone/tests/psyGen_test.py
@@ -975,6 +975,14 @@ def test_haloexchange_unknown_halo_depth():
     assert halo_exchange._halo_depth is None
 
 
+def test_haloexchange_accesses():
+    '''Test that the next/previous_accesses on HaloExchange class returns
+    an empty list.'''
+    halo_exchange = HaloExchange(None)
+    assert halo_exchange.next_accesses() == []
+    assert halo_exchange.previous_acccesses() == []
+
+
 def test_args_filter():
     '''the args_filter() method is in both Loop() and Arguments() classes
     with the former method calling the latter. This example tests the
diff --git a/src/psyclone/tests/psyir/nodes/directive_test.py b/src/psyclone/tests/psyir/nodes/directive_test.py
index 2f6fc275e8..7a3cd00e7a 100644
--- a/src/psyclone/tests/psyir/nodes/directive_test.py
+++ b/src/psyclone/tests/psyir/nodes/directive_test.py
@@ -170,3 +170,11 @@ def test_standalonedirective_children_validation():
         cdir.addchild(schedule)
     assert ("Item 'Schedule' can't be child 0 of 'StandaloneDirective'. The "
             "valid format is: 'Clause*'." in str(excinfo.value))
+
+
+def test_directive_accesses():
+    '''Test that the next_accesses and previous_accesses methods
+    of Directive return an empty list.'''
+    x = nodes.StandaloneDirective()
+    assert x.next_accesses() == []
+    assert x.previous_accesses() == []
diff --git a/src/psyclone/tests/psyir/nodes/node_test.py b/src/psyclone/tests/psyir/nodes/node_test.py
index adedf9f68d..aafe1619e2 100644
--- a/src/psyclone/tests/psyir/nodes/node_test.py
+++ b/src/psyclone/tests/psyir/nodes/node_test.py
@@ -2104,3 +2104,10 @@ def test_get_last_descendant_node(fortran_reader):
     ifblock = psyir.children[0].children[0]
     assigns = psyir.walk(Assignment)
     assert ifblock.get_last_descendant_node() is assigns[2].rhs.children[1]
+
+
+def test_statement_accesses():
+    '''Test the Statement class accesses methods.'''
+    node = DummyStatement()
+    assert node.next_accesses() == []
+    assert node.previous_accesses() == []
diff --git a/src/psyclone/tests/psyir/nodes/psy_data_node_test.py b/src/psyclone/tests/psyir/nodes/psy_data_node_test.py
index 74c188a602..3d5b21d10b 100644
--- a/src/psyclone/tests/psyir/nodes/psy_data_node_test.py
+++ b/src/psyclone/tests/psyir/nodes/psy_data_node_test.py
@@ -559,3 +559,11 @@ def test_psy_data_node_gocean_inside_of_loop(fortran_writer):
                   r"call psy_data_1 % PostEnd.*")
 
     assert re.search(correct_re, code, re.I) is not None
+
+
+def test_psy_data_node_accesses():
+    '''Test that the next/previous_accesses methods of PSyDataNode
+    return empty lists.'''
+    psy_node = PSyDataNode()
+    assert psy_node.next_accesses() == []
+    assert psy_node.previous_accesses() == []
diff --git a/src/psyclone/tests/psyir/nodes/return_stmt_test.py b/src/psyclone/tests/psyir/nodes/return_stmt_test.py
index ec72176c9c..45e3d02eda 100644
--- a/src/psyclone/tests/psyir/nodes/return_stmt_test.py
+++ b/src/psyclone/tests/psyir/nodes/return_stmt_test.py
@@ -38,3 +38,19 @@ def test_return_children_validation():
         return_stmt.addchild(return_stmt1)
     assert ("Item 'Return' can't be child 0 of 'Return'. Return is a"
             " LeafNode and doesn't accept children.") in str(excinfo.value)
+
+
+def test_return_stmt_accesses(fortran_reader):
+    '''Test that the return statement next/previous_accesses return an empty
+    list.'''
+    code = """subroutine test
+    integer :: i
+    i = 1
+    return
+    i = 2
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    print(psyir.view())
+    stmt = psyir.walk(Return)[0]
+    assert stmt.next_accesses() == []
+    assert stmt.previous_accesses() == []
diff --git a/src/psyclone/tests/psyir/nodes/routine_test.py b/src/psyclone/tests/psyir/nodes/routine_test.py
index 986a7e3d1b..a8510ac9ce 100644
--- a/src/psyclone/tests/psyir/nodes/routine_test.py
+++ b/src/psyclone/tests/psyir/nodes/routine_test.py
@@ -691,3 +691,17 @@ def test_outer_scope_accesses_module_data(fortran_reader):
         rt1.check_outer_scope_accesses(call, "call")
     assert ("'second' contains accesses to 'vaar' which is declared in the "
             "callee module scope" in str(err.value))
+
+
+def test_routine_accesses(fortran_reader):
+    ''' Test that the next/previous_accesses methods on Routine return
+    an empty list.'''
+    code = """subroutine test
+        integer :: i
+        i = 3
+        i = 4
+    end subroutine test"""
+    psyir = fortran_reader.psyir_from_source(code)
+    routine = psyir.children[0]
+    assert routine.next_accesses() == []
+    assert routine.previous_accesses() == []
diff --git a/src/psyclone/tests/test_files/dummy_statement.py b/src/psyclone/tests/test_files/dummy_statement.py
index 0636741005..c5008b3f40 100644
--- a/src/psyclone/tests/test_files/dummy_statement.py
+++ b/src/psyclone/tests/test_files/dummy_statement.py
@@ -41,11 +41,13 @@
 
 class DummyStatement(Statement):
 
-    def next_accesses(self) -> None:
+    def next_accesses(self) -> list:
         '''Empty implementation of the required next_accesses
         abstractmethod.'''
+        return super().next_accesses()
 
-    def previous_accesses(self) -> None:
+    def previous_accesses(self) -> list:
         '''Empty implementation of the required previous_accesses
         abstractmethod.
         '''
+        return super().previous_accesses()

From af187d6cab4a7013e1ea9bdb5a42528b07760d0e Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Fri, 21 Aug 2026 14:35:41 +0100
Subject: [PATCH 10/11] typo

---
 src/psyclone/tests/psyGen_test.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/psyclone/tests/psyGen_test.py b/src/psyclone/tests/psyGen_test.py
index b9633961ea..b244dc1dbc 100644
--- a/src/psyclone/tests/psyGen_test.py
+++ b/src/psyclone/tests/psyGen_test.py
@@ -980,7 +980,7 @@ def test_haloexchange_accesses():
     an empty list.'''
     halo_exchange = HaloExchange(None)
     assert halo_exchange.next_accesses() == []
-    assert halo_exchange.previous_acccesses() == []
+    assert halo_exchange.previous_accesses() == []
 
 
 def test_args_filter():

From bf51be667f97d4065ca46bf62544c9cd900cd054 Mon Sep 17 00:00:00 2001
From: LonelyCat124 <3043914+LonelyCat124@users.noreply.github.com.>
Date: Fri, 21 Aug 2026 15:00:19 +0100
Subject: [PATCH 11/11] Final coverage

---
 .../domain/common/psylayer/global_reduction_test.py   | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/psyclone/tests/domain/common/psylayer/global_reduction_test.py b/src/psyclone/tests/domain/common/psylayer/global_reduction_test.py
index 8a85e669eb..d3e6225ee6 100644
--- a/src/psyclone/tests/domain/common/psylayer/global_reduction_test.py
+++ b/src/psyclone/tests/domain/common/psylayer/global_reduction_test.py
@@ -129,3 +129,14 @@ def test_globalreduction_reference_accesses():
                      "GlobalReduction is held in a bespoke '_scalar' "
                      "property.")
     assert list(vam) == ["FIXME"]
+
+
+def test_globalreduction_accesses():
+    '''Test the next/previous_accesses methods return an empty list
+    for a GlobalReduction.'''
+    _, invoke = get_invoke("15.14.3_sum_setval_field_builtin.f90",
+                           api="lfric", dist_mem=True, idx=0)
+    schedule = invoke.schedule
+    global_sum = schedule.children[2]
+    assert global_sum.next_accesses() == []
+    assert global_sum.previous_accesses() == []