PatternOptimizer can now take ResultBase instances marked as constant in its patterns

gof/_test_opt.py

@@ -114,6 +114,18 @@ class _test_PatternOptimizer(unittest.TestCase):
                          '1').optimize(g)
         assert str(g) == "[Op1(x)]"
 
+    def test_6(self):
+        x, y, z = inputs()
+        x.constant = True
+        x.value = 2
+        z.constant = True
+        z.value = 2
+        e = op1(op1(x, y), y)
+        g = env([y], [e])
+        PatternOptimizer((Op1, z, '1'),
+                         (Op2, '1', z)).optimize(g)
+        assert str(g) == "[Op1(Op2(y, z), y)]"
+
 
 class _test_OpSubOptimizer(unittest.TestCase):
     

gof/opt.py

 
 from op import Op
+from result import ResultBase
 from env import InconsistencyError
 import utils
 import unify
@@ -140,10 +141,14 @@ class PatternOptimizer(OpSpecificOptimizer):
                     return False
                 else:
                     u = u.merge(expr, v)
-            else:
-                if pattern != expr:
-                    return False
+            elif isinstance(pattern, ResultBase) \
+                    and getattr(pattern, 'constant', False) \
+                    and isinstance(expr, ResultBase) \
+                    and getattr(expr, 'constant', False) \
+                    and pattern.hash() == expr.hash():
                 return u
+            else:
+                return False
             return u
 
         def build(pattern, u):
@@ -204,8 +209,12 @@ class MergeOptimizer(Optimizer):
         for i, r in enumerate(env.orphans().union(env.inputs)):
             if getattr(r, 'constant', False) and hasattr(r, 'hash'):
                 ref = ('const', r.hash())
-                cid[r] = ref
-                inv_cid[ref] = r
+                other_r = inv_cid.get(ref, None)
+                if other_r is not None:
+                    env.replace(r, other_r)
+                else:
+                    cid[r] = ref
+                    inv_cid[ref] = r
             else:
                 cid[r] = i
                 inv_cid[i] = r