polish migrate_all_to_cpu

Author: cjld

python/jittor/__init__.py

@@ -9,7 +9,7 @@
 # file 'LICENSE.txt', which is part of this source code package.
 # ***************************************************************
 
-__version__ = '1.3.4.0'
+__version__ = '1.3.4.1'
 from jittor_utils import lock
 with lock.lock_scope():
     ori_int = int

python/jittor/src/var_holder.cc

@@ -240,9 +240,9 @@ void migrate_all_to_cpu() {
 #ifdef HAS_CUDA
     for (auto vh : hold_vars) {
         auto v = vh->var;
-        if (v->_outputs.size()) continue;
-        if (v->allocator && !v->allocator->is_cuda())
-            migrate_to_gpu(v, cpu_allocator);
+        // if (v->_outputs.size()) continue;
+        if (v->allocator && v->mem_ptr && !v->allocator->is_cuda())
+            migrate_to_cpu(v, cpu_allocator);
     }
 #endif
 }