Do not insert Usmm when there is no blas

theano/sparse/opt.py

@@ -675,7 +675,8 @@ local_usmm = gof.opt.PatternSub(
     (theano.tensor.sub, 'z',
      (theano.tensor.mul,
       {'pattern': 'alpha',
-       'constraint': lambda expr: numpy.all(expr.type.broadcastable)},
+       'constraint': lambda expr: (numpy.all(expr.type.broadcastable) and
+                                   theano.config.blas.ldflags)},
     (sparse._dot, 'x', 'y'))),
     (usmm, (theano.tensor.neg, 'alpha'), 'x', 'y', 'z'))
 register_specialize(local_usmm, name="local_usmm")

theano/sparse/tests/test_basic.py

@@ -1204,7 +1204,16 @@ class UsmmTests(unittest.TestCase):
 
             fast_compile = theano.config.mode == "FAST_COMPILE"
 
-            if (y.type.dtype == up and format1 == 'csc' and format2 == 'dense'
+            if not theano.config.blas.ldflags:
+                # Usmm should not be inserted, because it relies on BLAS
+                assert len(topo) == 4, topo
+                assert isinstance(topo[0].op, theano.sparse.Dot)
+                assert isinstance(topo[1].op, theano.tensor.DimShuffle)
+                assert (isinstance(topo[2].op, theano.tensor.Elemwise) and
+                        isinstance(topo[2].op.scalar_op, theano.scalar.Mul))
+                assert (isinstance(topo[3].op, theano.tensor.Elemwise) and
+                        isinstance(topo[3].op.scalar_op, theano.scalar.Sub))
+            elif (y.type.dtype == up and format1 == 'csc' and format2 == 'dense'
                 and not fast_compile and theano.config.cxx and
                 up in ('float32', 'float64')):
                 # The op UsmmCscDense should be inserted