fix dim equality test && fix fetch var sync bug (#1805)

mobile/src/framework/ddim.cpp

@@ -133,6 +133,10 @@ bool DDim::operator==(DDim d) const {
   std::vector<int64_t> v1 = vectorize(*this);
   std::vector<int64_t> v2 = vectorize(d);
 
+  if (v1.size() != v2.size()) {
+    return false;
+  }
+
   for (unsigned int i = 0; i < v1.size(); i++) {
     if (v1[i] != v2[i]) {
       return false;

mobile/src/framework/tensor.h

@@ -89,7 +89,7 @@ class Tensor : public TensorBase {
   /*! The internal of two tensors share the same memory block. */
   inline Tensor &ShareDataWith(const Tensor &src) {
     src.check_memory_size();
-    if (holder_.get() != src.holder_.get()) {
+    if (holder_.get() != src.holder_.get() || dims_ != src.dims()) {
       *this = src;
     }
     return *this;