avoid calling front() on empty working set (#21396)

suo · facebook-github-bot · commit ddac8da813a3 · 2019-06-10T12:41:58.000-07:00
Summary: Pull Request resolved: #21396 ghimport-source-id: 7e57282099d2fd57c58c990b51ae933e427aecb2 Reviewed By: jamesr66a Differential Revision: D15642663 Pulled By: suo fbshipit-source-id: f9b467ba53f03438879bf3929da522aabaff2343
diff --git a/torch/csrc/jit/passes/alias_analysis.cpp b/torch/csrc/jit/passes/alias_analysis.cpp
@@ -865,6 +865,9 @@ class AliasDb::WorkingSet {
 
  private:
   bool hasDataDependency(Node* n) const {
+    if (!mover_ && nodes_.empty()) {
+      return false;
+    }
     const Node* pivot = mover_ ? mover_ : nodes_.front();
     if (n->isAfter(pivot)) {
       return producesFor(n);
