Optimized code when array is c contiguous and added test to warn user.

theano/tensor/blas_c.py

@@ -405,20 +405,7 @@ def gemv_c_code(aa, xx, yy, zz, alpha, beta, destructive, fail, force_init_beta=
         {
             if (PyArray_CHKFLAGS(%(zz)s, NPY_ARRAY_C_CONTIGUOUS))
             {
-                if (PyArray_DESCR(%(zz)s)->type_num == NPY_FLOAT)
-                {
-                    memset((void *)PyArray_DATA(%(zz)s), 0, PyArray_ITEMSIZE(%(zz)s));
-                }
-                else if (PyArray_DESCR(%(zz)s)->type_num == NPY_DOUBLE)
-                {
-                    memset((void *)PyArray_DATA(%(zz)s), 0, PyArray_ITEMSIZE(%(zz)s));
-                }
-                else
-                {
-                    PyErr_SetString(PyExc_AssertionError,
-                                    "neither float nor double dtype");
-                    %(fail)s
-                }
+                memset((void *)PyArray_DATA(%(zz)s), 0, PyArray_SIZE(%(zz)s)*PyArray_ITEMSIZE(%(zz)s));
             }
             else
             {

theano/tensor/tests/test_blas_c.py

@@ -15,6 +15,8 @@ from theano.tensor.blas_c import CGemv
 from theano.tensor.blas_scipy import ScipyGer
 from theano.tensor.blas import Gemv
 
+from theano.tensor.blas_c import check_force_gemv_init
+
 from theano.tests import unittest_tools
 from theano.tests.unittest_tools import TestOptimizationMixin
 
@@ -170,6 +172,14 @@ class TestCGemv(TestCase, TestOptimizationMixin):
         assert numpy.allclose(f(self.Aval[::-1, ::-1], self.yval),
                 numpy.dot(self.Aval[::-1, ::-1], self.yval))
 
+    def test_force_gemv_init(self):
+        if check_force_gemv_init():
+            sys.stderr.write(
+                "WARNING: The current BLAS requires Theano to initialize"
+                + " memory for some GEMV calls which will result in a minor"
+                + " degradation in performance for such calls."
+            )
+
     def t_gemv1(self, m_shp):
         ''' test vector2 + dot(matrix, vector1) '''
         rng = numpy.random.RandomState(unittest_tools.fetch_seed())