compiler: Further misc improvements (minor)

Author: EdCaunt

devito/ir/support/basic.py

@@ -317,6 +317,8 @@ def lex_le(self, other):
     def lex_lt(self, other):
         return self.timestamp < other.timestamp
 
+    # NOTE: This is called a lot with the same arguments - memoize yields mild speedup
+    @memoized_meth
     def distance(self, other):
         """
         Compute the distance from ``self`` to ``other``.
@@ -365,7 +367,9 @@ def distance(self, other):
                 # constant access at 4
                 for v in (self[n], other[n]):
                     try:
-                        if bool(v < sit.symbolic_min or v > sit.symbolic_max):
+                        # 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

devito/passes/clusters/misc.py

@@ -352,8 +352,7 @@ def is_cross(source, sink):
                 v = len(cg0.exprs)
                 return t0 < v <= t1 or t1 < v <= t0
 
-            for cg1 in cgroups[n+1:]:
-                n1 = cgroups.index(cg1)
+            for n1, cg1 in enumerate(cgroups[n+1:], start=n+1):
 
                 # A Scope to compute all cross-ClusterGroup anti-dependences
                 scope = Scope(exprs=cg0.exprs + cg1.exprs, rules=is_cross)

devito/passes/iet/mpi.py

@@ -24,6 +24,7 @@ def optimize_halospots(iet, **kwargs):
     merged and moved around in order to improve the halo exchange performance.
     """
     iet = _drop_reduction_halospots(iet)
+    # TODO: _hoist_invariant and _merge_halospots are both slow
     iet = _hoist_invariant(iet)
     iet = _merge_halospots(iet)
     iet = _drop_if_unwritten(iet, **kwargs)
@@ -81,6 +82,8 @@ def _hoist_invariant(iet):
     cond_mapper = _make_cond_mapper(iet)
     iter_mapper = _filter_iter_mapper(iet)
 
+    # from IPython import embed; embed()
+
     for it, halo_spots in iter_mapper.items():
         for hs0, hs1 in combinations(halo_spots, r=2):
             if _check_control_flow(hs0, hs1, cond_mapper):
@@ -157,6 +160,7 @@ def _merge_halospots(iet):
 
             for f, v in hs1.fmapper.items():
                 for dep in scope.d_flow.project(f):
+                    # NOTE: The else clause gets skipped if this is ever true
                     if not any(rule(dep, hs1, v.loc_indices) for rule in rules):
                         break
                 else: