Fix updates in CVM

theano/gof/lazylinker_c.c.txt

@@ -103,7 +103,7 @@ typedef struct {
     Py_ssize_t * node_n_prereqs;
     Py_ssize_t ** node_prereqs;
 
-    Py_ssize_t * update_storage; // dst0, src0, dst1, src1, ... cells to switch after a call
+    Py_ssize_t * update_storage; // input cells to update with the last outputs in output_vars
     Py_ssize_t n_updates;
 
     void ** thunk_cptr_fn;
@@ -467,8 +467,6 @@ CLazyLinker_init(CLazyLinker *self, PyObject *args, PyObject *kwds)
     if (unpack_list_of_ssize_t(update_storage, &self->update_storage, &self->n_updates,
                                "updates_storage"))
       return -1;
-    assert((self->n_updates % 2) == 0);
-    self->n_updates /= 2;
     return 0;
 }
 static void set_position_of_error(CLazyLinker * self, int owner_idx)
@@ -841,8 +839,6 @@ CLazyLinker_call(PyObject *_self, PyObject *args, PyObject *kwds)
       if (!err)
         {
           // save references to outputs prior to updating storage containers
-          if ((call_i + 1) == n_calls)
-            {
           assert (self->n_output_vars >= self->n_updates);
           Py_DECREF(rval);
           rval = PyList_New(self->n_output_vars);
@@ -853,14 +849,13 @@ CLazyLinker_call(PyObject *_self, PyObject *args, PyObject *kwds)
               Py_INCREF(item);
               PyList_SetItem(rval, i, item);
             }
-            }
 
+          // Update the inputs that have an update rule
           for (int i = 0; i < self->n_updates; ++i)
             {
-              Py_ssize_t dst = self->update_storage[2*i];
-              Py_ssize_t src = self->update_storage[2*i+1];
-              PyObject* tmp = PyList_GetItem(self->var_value_cells[src], 0);
+              PyObject* tmp = PyList_GetItem(rval, self->n_output_vars - self->n_updates + i);
               Py_INCREF(tmp);
+              Py_ssize_t dst = self->update_storage[i];
               PyList_SetItem(self->var_value_cells[dst], 0, tmp);
             }
         }
@@ -973,7 +968,7 @@ static PyTypeObject lazylinker_ext_CLazyLinkerType = {
 
 static PyObject * get_version(PyObject *dummy, PyObject *args)
 {
-  PyObject *result = PyFloat_FromDouble(0.18);
+  PyObject *result = PyFloat_FromDouble(0.19);
   return result;
 }
 

theano/gof/lazylinker_c.py

@@ -13,7 +13,7 @@ if config.compiledir not in sys.path:
     sys.path.append(config.compiledir)
 
 force_compile = False
-version = 0.18 # must match constant returned in function get_version()
+version = 0.19  # must match constant returned in function get_version()
 
 
 try:

theano/gof/vm.py

@@ -707,11 +707,19 @@ class VM_Linker(link.LocalLinker):
                 prereq_var_idxs.sort()  # TODO: why sort?
                 node_prereqs.append(prereq_var_idxs)
 
+            # Builds the list of input storage to update (according to update
+            # rules) when the outputs are computed.
+            # They are in the same order as the second part of output_vars
+            # (output_vars contains first the returned outputs, then the
+            # values of the update expressions).
             update_storage = []
+            update_in_from_out = {}
             for (ivar, ovar) in updated_vars.items():
                 if ivar != ovar:
-                    update_storage.append(vars_idx[ivar])  # dst
-                    update_storage.append(vars_idx[ovar])  # src
+                    update_in_from_out[vars_idx[ovar]] = vars_idx[ivar]
+            for oidx in output_vars:
+                if oidx in update_in_from_out:
+                    update_storage.append(update_in_from_out[oidx])
 
             c0 = sys.getrefcount(node_n_inputs)
             vm = CVM(