tests: add staggered origin in Abs MFE

tests/test_symbolics.py

@@ -9,7 +9,7 @@
                     Operator, SubDimension, norm, Le, Ge, Gt, Lt, Abs, sin, cos, Min, Max)
 from devito.ir import Expression, FindNodes
 from devito.symbolics import (retrieve_functions, retrieve_indexed, evalrel,  # noqa
-                              CallFromPointer, Cast, FieldFromPointer,
+                              CallFromPointer, Cast, FieldFromPointer, INT,
                               FieldFromComposite, IntDiv, ccode, uxreplace)
 from devito.types import Array, Bundle, LocalObject, Object, Symbol as dSymbol
 
@@ -31,6 +31,18 @@ def test_float_indices():
     assert indices == 1
 
 
+def test_func_of_indices():
+    """
+    Test that origin is correctly processed with functions
+    """
+    grid = Grid((10,))
+    x = grid.dimensions[0]
+    u = Function(name="u", grid=grid, space_order=2, staggered=x)
+    us = u.subs({u.indices[0]: INT(Abs(u.indices[0]))})
+    assert us.indices[0] == INT(Abs(x + x.spacing/2))
+    assert us.indexify().indices[0] == INT(Abs(x))
+
+
 @pytest.mark.parametrize('dtype,expected', [
     (np.float32, "float r0 = 1.0F/h_x;"),
     (np.float64, "double r0 = 1.0/h_x;")