Prevent moving "gpu_from_host" outside of scan

Detect if the inner replacement would have a different type, so that a new gpu_from_host is not inserted in the inner graph in replacement of the one that was just pushed out.

Prevent moving "gpu_from_host" outside of scan
35381fc1 · Pascal Lamblin · b321e079 · 35381fc1
--- a/theano/scan_module/scan_opt.py
+++ b/theano/scan_module/scan_opt.py
@@ -250,7 +250,11 @@ class PushOutNonSeqScan(gof.Optimizer):
        for nd in existent_nodes:
            to_keep += nd.inputs
        for idx, out in enumerate(to_replace):
-            if out in to_keep and out.owner not in existent_nodes:
+            if (out in to_keep
+                    and out.owner not in existent_nodes
+                    # If types are different, conversion Op will be inserted,
+                    # and it may trigger an infinite loop.
+                    and replace_with_in[idx].type == out.type):
                clean_to_replace += [out]
                clean_replace_with_in += [replace_with_in[idx]]
                clean_replace_with_out += [replace_with_out[idx]]