Only use the variable when they exist and are needed.

theano/gpuarray/c_code/topk_dense.cu

@@ -21,7 +21,7 @@ extern "C" __global__ void k_topk_dense(
         // ssize_t dsti_strides_0, ssize_t dsti_strides_1, ... , dsti_strides_$${NDIM}
         ssize_t k,
         INPUT_TYPE* src,
-	size_t src_offset
+	size_t src_offset,
         $src_strides
         // ssize_t src_strides_0, ssize_t src_strides_1, ... , src_strides_$${NDIM}
         size_t size) {
@@ -33,10 +33,6 @@ extern "C" __global__ void k_topk_dense(
     size_t out_idx;
 
     const unsigned char warp_id = idx / GA_WARP_SIZE;
-    dstv = ptr_add(dstv, dstv_offset);
-    dsti = ptr_add(dsti, dsti_offset);
-    src = ptr_add(src, src_offset);
-
     // 0. get the slice for thread block to work on
 
     size_t gid = blockIdx.x, gidx;

theano/gpuarray/c_code/topk_dense_large.cu

@@ -211,7 +211,7 @@ extern "C" __global__ void KERNEL_NAME(
         // ssize_t dsti_strides_0, ssize_t dsti_strides_1, ... , dsti_strides_$${NDIM}
         ssize_t k,
         INPUT_TYPE* src,
-	size_t src_offset
+	size_t src_offset,
         $src_strides
         // ssize_t src_strides_0, ssize_t src_strides_1, ... , src_strides_$${NDIM}
         size_t size) {
@@ -222,9 +222,6 @@ extern "C" __global__ void KERNEL_NAME(
     k = (order ? k : -k);
     const int idx = threadIdx.x;
     const int warp_id = idx / GA_WARP_SIZE;
-    dstv = ptr_add(dstv, dstv_offset);
-    dsti = ptr_add(dsti, dsti_offset);
-    src = ptr_add(src, src_offset);
 
     // get the slice for thread block to work on
     // size <- the axis to work on

theano/gpuarray/sort.py

@@ -77,6 +77,17 @@ class GpuTopKOp(GpuKernelBase, TopKOp):
                 dsti='dsti = ptr_add(dsti, gidx*dsti_strides_%(i)d)' if self.return_indices else '')
             set_slice_code = ''.join(
                 set_slice_code % dict(i=j) for j in range(1, ndim))
+            if self.return_values:
+                set_slice_code += """
+                dstv = ptr_add(dstv, dstv_offset);
+                """
+            if self.return_indices:
+                set_slice_code += """
+                dsti = ptr_add(dsti, dsti_offset);
+                """
+            set_slice_code += """
+                src = ptr_add(src, src_offset);
+            """
             flags = Kernel.get_flags(node.inputs[0].dtype)
             subs = dict(
                 inp_t=ga.dtype_to_ctype(node.inputs[0].dtype),