message: Turn relatively expensive CHECK on Shape::rank() into a DCHECK.
  Eliminates 2.6% of compilation time in profiling one compile-intensive workload.
diff: @@ -49,7 +49,7 @@ class Shape {
  // Returns the rank (number of dimensions) of the given shape. Shape must be
  // an array.
  int64 rank() const {
  - CHECK(IsArray()) << "Non-arrays do not have a rank, shape: " << ToString();
  + DCHECK(IsArray()) << "Non-arrays do not have a rank, shape: " << ToString();
  return dimensions_.size();
  }
  