compiler: Add a check to pre-empt expensive symbolic comparisons before try-except

Author: EdCaunt

devito/ir/support/basic.py

@@ -365,14 +365,21 @@ def distance(self, other):
                 # Case 1: `sit` is an IterationInterval with statically known
                 # trip count. E.g. it ranges from 0 to 3; `other` performs a
                 # constant access at 4
-                for v in (self[n], other[n]):
-                    try:
-                        # NOTE: Split the boolean to make the conditional short circuit
-                        # more frequently for mild speedup
-                        if bool(v < sit.symbolic_min) or bool(v > sit.symbolic_max):
-                            return Vector(S.ImaginaryUnit)
-                    except TypeError:
-                        pass
+
+                # NOTE: To avoid evaluating expensive symbolic Lt or Gt operations,
+                # we pre-empt such operations by checking if the values to be compared
+                # to are symbolic, and skip this case if not.
+                if not any(isinstance(i, sympy.core.Basic)
+                           for i in (sit.symbolic_min, sit.symbolic_max)):
+
+                    for v in (self[n], other[n]):
+                        try:
+                            # NOTE: Split the boolean to make the conditional short circuit
+                            # more frequently for mild speedup
+                            if bool(v < sit.symbolic_min) or bool(v > sit.symbolic_max):
+                                return Vector(S.ImaginaryUnit)
+                        except TypeError:
+                            pass
 
                 # Case 2: `sit` is an IterationInterval over a local SubDimension
                 # and `other` performs a constant access