make GpuSoftmax don't crash when input shape contains 0.

theano/sandbox/cuda/nnet.py

@@ -351,7 +351,7 @@ class GpuSoftmax (GpuOp):
 
     def c_code_cache_version(self):
         #return ()
-        return (6,) + inline_softmax.code_version
+        return (7,) + inline_softmax.code_version
 
     def c_code(self, node, nodename, inp, out, sub):
         x, = inp
@@ -384,6 +384,8 @@ class GpuSoftmax (GpuOp):
             int n_threads = std::min(CudaNdarray_HOST_DIMS(%(x)s)[1], 512);
             int n_shared_bytes = CudaNdarray_HOST_DIMS(%(x)s)[1] * 2 * sizeof(float);
 
+            if (CudaNdarray_HOST_DIMS(%(x)s)[0] > 0)
+            {
                 kSoftmax_%(nodename)s
                     <<<
                         n_blocks,
@@ -413,6 +415,7 @@ class GpuSoftmax (GpuOp):
                     %(fail)s;
                 }
             }
+        }
         assert(%(z)s);
         """ % locals()
 

theano/sandbox/cuda/tests/test_nnet.py

@@ -228,7 +228,10 @@ def test_softmax():
 
     def cmp(n, m, catch=False):
         """Some old card won't accept the configuration arguments of
-        this implementation. For those cases set catch=True to skip those errors."""
+        this implementation. For those cases set catch=True to skip
+        those errors.
+
+        """
         try:
             #print "test_softmax",n,m
             data = numpy.arange(n * m, dtype='float32').reshape(n, m)
@@ -238,6 +241,7 @@ def test_softmax():
         except RuntimeError, e:
             if not catch:
                 raise
+            # Different CUDA driver have different error message
             assert (e.args[0].startswith(
               'Cuda error: kSoftmax_node_0: invalid configuration argument.\n') or
             e.args[0].startswith('Cuda error: kSoftmax_node_0: invalid argument.\n'))
@@ -246,6 +250,7 @@ def test_softmax():
     cmp(2, 5)
     cmp(2 << 15, 5)
     cmp(4074, 400)
+    cmp(0, 10)
     cmp(784, 784)
     cmp(4, 1000)
     cmp(4, 1024)