Merge pull request #3036 from devitocodes/dummy-bug

compiler: Fix CIRE placeholder leaking into Operator parameters

Author: EdCaunt

devito/passes/clusters/aliases.py

@@ -813,23 +813,13 @@ def make_variant(schedule, exprs, mapper):
     Create a Variant from a Schedule and the corresponding expressions.
     """
     # Some aliases may have been discarded along the way, and for
-    # them we reinstate the original sub-expressions
+    # them we reinstate the original sub-expressions. `mapper.extracted` binds
+    # each placeholder to exactly the (sub-)expression it replaced, including
+    # for compound extractions, where the placeholder stands for a subset of
+    # `expr.args` rather than for the whole `expr`
     retained = flatten(sa.aliaseds for sa in schedule)
 
-    subs = {}
-    for k, v in mapper.items():
-        if v in retained:
-            continue
-        elif isinstance(v, dict):
-            # E.g., `mapper = {u[t0, x+3, y+3] + u[t0, x+3, y+4]:
-            #                  {u[t0, x+3, y+4]: None, u[t0, x+3, y+3]: dummy0}}`
-            try:
-                v1, = [i for i in v.values() if i not in retained]
-            except ValueError:
-                continue
-            subs[v1] = k
-        else:
-            subs[v] = k
+    subs = {v: k for k, v in mapper.extracted.items() if v not in retained}
 
     exprs = [uxreplace(e, subs) for e in exprs]
 

tests/test_dse.py

@@ -2748,6 +2748,31 @@ def test_split_cond(self):
         scalars = [i for i in FindSymbols().visit(op) if isinstance(i, Temp)]
         assert len(scalars) == 0
 
+    def test_split_cond_compound_alias(self):
+        """
+        MFE for the case in which a CIRE placeholder Symbol survives into
+        `op.parameters` because the compound extraction it stands for is
+        discarded by `lower_aliases` (scalar alias + guarded Cluster).
+        """
+        grid = Grid((11, 11))
+        time = grid.time_dim
+
+        u = TimeFunction(name='u', grid=grid, time_order=2, space_order=2)
+        u1 = TimeFunction(name='u1', grid=grid, time_order=2, space_order=2)
+
+        ct = ConditionalDimension(name='ct', parent=time, factor=2)
+
+        eqn = Eq(u.forward, u + sin(time)*cos(time), implicit_dims=ct)
+
+        op0 = Operator(eqn, opt='noop')
+        op1 = Operator(eqn, opt=('advanced', {'cire-mingain': 0}))
+
+        assert not any(i.name.startswith('dummy') for i in op1.parameters)
+
+        op0.apply(time_M=5)
+        op1.apply(time_M=5, u=u1)
+        assert np.allclose(u.data, u1.data, rtol=1e-5)
+
     def test_split_cond_multi_alias(self):
         grid = Grid((11, 11))
         time = grid.time_dim