Added tests for optimization of inequalities comparing a variable with itself.

theano/tensor/opt.py

@@ -4295,7 +4295,7 @@ def local_useless_elemwise_comparison(node):
     # Elemwise[{LT,GT}](X, X) -> Elemwise[zeros](X)
     if (isinstance(node.op.scalar_op, (scalar.LT, scalar.GT)) and
         node.inputs[0] is node.inputs[1]):
-        return [T.zeros_like(node.outputs[0])]
+        return [T.zeros_like(node.outputs[0], dtype=node.outputs[0].type.dtype)]
     # Elemwise[{LE,GE}](X, X) -> Elemwise[ones](X)
     if (isinstance(node.op.scalar_op, (scalar.LE, scalar.GE)) and
         node.inputs[0] is node.inputs[1]):

theano/tensor/tests/test_opt.py

@@ -3136,7 +3136,17 @@ def test_local_fill_useless():
     f(m_, x_)
 
 
-def test_local_useless_elemwise_comparison():
+def assert_eqs_const(topo, val):
+    elem = topo[0]
+    assert len(topo) == 1
+    assert elem.op == deep_copy_op
+    assert len(elem.inputs) == 1
+    assert isinstance(elem.inputs[0], T.TensorConstant)
+    assert T.extract_constant(elem.inputs[0]) == val
+
+
+class Test_local_useless_elemwise_comparison(unittest.TestCase):
+    def test_local_useless_elemwise_comparison(self):
         # TODO: test each case individually.
         # The following case is what made me discover those cases.
         X = T.matrix('X')
@@ -3151,6 +3161,21 @@ def test_local_useless_elemwise_comparison():
         f = theano.function([X, Y], Z, mode=mode)
         theano.printing.debugprint(f, print_type=True)
 
+    def test_inequality_with_self(self):
+        x = T.scalar('x', dtype=config.floatX)
+
+        f = theano.function([x], T.lt(x, x))
+        assert_eqs_const(f.maker.fgraph.toposort(), 0)
+
+        f = theano.function([x], T.le(x, x))
+        assert_eqs_const(f.maker.fgraph.toposort(), 1)
+
+        f = theano.function([x], T.gt(x, x))
+        assert_eqs_const(f.maker.fgraph.toposort(), 0)
+
+        f = theano.function([x], T.ge(x, x))
+        assert_eqs_const(f.maker.fgraph.toposort(), 1)
+
 
 class Test_local_useless_alloc(unittest.TestCase):
     def setUp(self):
@@ -3924,28 +3949,30 @@ class T_useless_elemwise(unittest.TestCase):
         assert len(topo) == 1
         assert topo[0].op == deep_copy_op
 
-    def assert_eqs_const(self, topo, val):
-        elem = topo[0]
-        assert len(topo) == 1
-        assert elem.op == deep_copy_op
-        assert len(elem.inputs) == 1
-        assert isinstance(elem.inputs[0], T.TensorConstant)
-        assert T.extract_constant(elem.inputs[0]) == val
-
     def assert_identity(self, f):
         topo = f.maker.fgraph.toposort()
         assert topo[0].op == deep_copy_op
-        x_val = numpy.random.randint(256)
+        x_val = -128
+        assert f(x_val) == x_val
+        x_val = -1
+        assert f(x_val) == x_val
+        x_val = 0
+        assert f(x_val) == x_val
+        x_val = 1
+        assert f(x_val) == x_val
+        x_val = 127
+        assert f(x_val) == x_val
+        x_val = numpy.random.randint(255)-128
         assert f(x_val) == x_val
 
     def test_and(self):
-        x = T.scalar('x', dtype='int64')
+        x = T.scalar('x', dtype='int8')
 
         f = theano.function([x], T.and_(x, 0), mode=self.mode)
-        self.assert_eqs_const(f.maker.fgraph.toposort(), 0)
+        assert_eqs_const(f.maker.fgraph.toposort(), 0)
 
         f = theano.function([x], T.and_(0, x), mode=self.mode)
-        self.assert_eqs_const(f.maker.fgraph.toposort(), 0)
+        assert_eqs_const(f.maker.fgraph.toposort(), 0)
 
         f = theano.function([x], T.and_(x, 1), mode=self.mode)
         self.assert_identity(f)
@@ -3954,13 +3981,13 @@ class T_useless_elemwise(unittest.TestCase):
         self.assert_identity(f)
 
     def test_or(self):
-        x = T.scalar('x', dtype='int64')
+        x = T.scalar('x', dtype='int8')
 
         f = theano.function([x], T.or_(x, 1), mode=self.mode)
-        self.assert_eqs_const(f.maker.fgraph.toposort(), 1)
+        assert_eqs_const(f.maker.fgraph.toposort(), 1)
 
         f = theano.function([x], T.or_(1, x), mode=self.mode)
-        self.assert_eqs_const(f.maker.fgraph.toposort(), 1)
+        assert_eqs_const(f.maker.fgraph.toposort(), 1)
 
         f = theano.function([x], T.or_(x, 0), mode=self.mode)
         self.assert_identity(f)
@@ -3969,10 +3996,10 @@ class T_useless_elemwise(unittest.TestCase):
         self.assert_identity(f)
 
     def test_xor(self):
-        x = T.scalar('x', dtype='int64')
+        x = T.scalar('x', dtype='int8')
 
         f = theano.function([x], T.xor(x, x), mode=self.mode)
-        self.assert_eqs_const(f.maker.fgraph.toposort(), 0)
+        assert_eqs_const(f.maker.fgraph.toposort(), 0)
 
 
 class T_cast_cast(unittest.TestCase):