From 635e3f668d286152f8f3f2ca18915179254c1b9c Mon Sep 17 00:00:00 2001
From: Edward Caunt <ed@devitocodes.com>
Date: Wed, 4 Sep 2024 14:50:59 +0100
Subject: [PATCH] dsl: Purge UniqueDimension

---
 devito/ir/equations/algorithms.py |  2 +-
 devito/types/dimension.py         | 16 ----------------
 devito/types/grid.py              | 11 +++++------
 tests/test_caching.py             | 18 ------------------
 4 files changed, 6 insertions(+), 41 deletions(-)

diff --git a/devito/ir/equations/algorithms.py b/devito/ir/equations/algorithms.py
index cc72ccf6e5..818f307101 100644
--- a/devito/ir/equations/algorithms.py
+++ b/devito/ir/equations/algorithms.py
@@ -267,7 +267,7 @@ def _(d, mapper, rebuilt, sregistry):
         try:
             idim1 = rebuilt[idim0]
         except KeyError:
-            iname = sregistry.make_name(prefix=idim0.name)
+            iname = sregistry.make_name(prefix='n')
             rebuilt[idim0] = idim1 = idim0._rebuild(name=iname)
 
         kwargs['implicit_dimension'] = idim1
diff --git a/devito/types/dimension.py b/devito/types/dimension.py
index 3123db8312..1ccb847da8 100644
--- a/devito/types/dimension.py
+++ b/devito/types/dimension.py
@@ -395,22 +395,6 @@ def __eq__(self, other):
     __hash__ = Symbol.__hash__
 
 
-class UniqueDimension(BasicDimension):
-    """
-    Like BasicDimension, but with a tag for unique hashing.
-    """
-
-    __rargs__ = Dimension.__rargs__ + ('tag',)
-
-    def __init_finalize__(self, name, tag, **kwargs):
-        super().__init_finalize__(name, **kwargs)
-        self._tag = tag
-
-    @property
-    def tag(self):
-        return self._tag
-
-
 class DefaultDimension(Dimension, DataSymbol):
 
     """
diff --git a/devito/types/grid.py b/devito/types/grid.py
index 9bbd4a642a..9daae18ea6 100644
--- a/devito/types/grid.py
+++ b/devito/types/grid.py
@@ -16,8 +16,7 @@
 from devito.types.utils import DimensionTuple
 from devito.types.dimension import (Dimension, SpaceDimension, TimeDimension,
                                     Spacing, SteppingDimension, SubDimension,
-                                    MultiSubDimension, DefaultDimension,
-                                    UniqueDimension)
+                                    MultiSubDimension, DefaultDimension)
 
 __all__ = ['Grid', 'SubDomain', 'SubDomainSet']
 
@@ -738,10 +737,10 @@ def __subdomain_finalize__(self, grid, **kwargs):
         # Associate the `_local_bounds` to suitable symbolic objects that the
         # compiler can use to generate code
 
-        # Standard Dimensions hash the same, which means that they are all the same object
-        # if their names are the same. Hence tag them with the SubDomainSet location to
-        # make them unique.
-        i_dim = UniqueDimension('n', id(self))
+        # Dimensions with identical names hash the same, hence tag them with the
+        # SubDomainSet ID to make them unique so they can be used to key a dictionary
+        # of replacements without risking overwriting.
+        i_dim = Dimension('n_%s' % str(id(self)))
         d_dim = DefaultDimension(name='d', default_value=2*grid.dim)
         sd_func = Function(name=self.name, grid=self._grid,
                            shape=(self._n_domains, 2*grid.dim),
diff --git a/tests/test_caching.py b/tests/test_caching.py
index 02742a8728..8dca69fa60 100644
--- a/tests/test_caching.py
+++ b/tests/test_caching.py
@@ -12,7 +12,6 @@
 from devito.types import (DeviceID, NThreadsBase, NPThreads, Object, LocalObject,
                           Scalar, Symbol, ThreadID)
 from devito.types.basic import AbstractSymbol
-from devito.types.dimension import UniqueDimension
 
 
 @pytest.fixture
@@ -78,23 +77,6 @@ def test_dimension(self):
         assert hash(d3) != hash(d0)
         assert hash(d3) != hash(d1)
 
-    def test_unique_dimension(self):
-        """
-        Test that UniqueDimensions have different hash values, so long as
-        their tags differ.
-        """
-        d0 = UniqueDimension('d', 0)
-        d1 = UniqueDimension('d', 1)
-        assert hash(d0) != hash(d1)
-
-        s = Scalar(name='s')
-        d2 = UniqueDimension('d', 0, spacing=s)
-        d3 = UniqueDimension('d', 1, spacing=s)
-        assert hash(d2) != hash(d3)
-
-        d4 = UniqueDimension('d', 0)
-        assert hash(d0) == hash(d4)
-
     def test_sub_dimension(self):
         """Test that different SubDimensions have different hash value."""
         d0 = Dimension(name='d')