Relay.analysis.alpha_equal: Questions and Potential Issues

zhiics · February 17, 2020, 9:09pm

Yes, I briefly talked about the reason above, it is caused by how we store info to the map here:

apache/incubator-tvm/blob/master/src/relay/ir/alpha_equal.cc#L157


  */
 bool ExprEqual(const Expr& lhs, const Expr& rhs) {
   auto compute = [&]() {
     if (lhs.same_as(rhs)) return true;
     if (!lhs.defined() || !rhs.defined()) return false;
     auto it = equal_map_.find(lhs);
     if (it != equal_map_.end()) {
       return it->second.same_as(rhs);
     }
     if (this->VisitExpr(lhs, rhs)) {
       equal_map_[lhs] = rhs;
       return true;
     } else {
       return false;
     }
   };
   return Compare(compute(), lhs, rhs);
 }


protected:
 /*!

For example, if lhs and rhs are: %1 = add(x, y) %2 = add(x, y)

and %1’ = add(x, y)

We can mapping %1 and %2 on lhs to %1` and the rhs, but this will fail if we flip rhs and lhs because we cannot map %1’ to both %1 and %2.