Add cheaper checks to Tensor::to

goldsborough · goldsborough · commit d49abaefb111 · 2018-06-25T15:18:53.000-07:00
diff --git a/aten/src/ATen/TensorOptions.h b/aten/src/ATen/TensorOptions.h
@@ -257,14 +257,23 @@ inline Tensor to(
 
 inline Tensor Tensor::to(Device device, ScalarType dtype, bool non_blocking)
     const {
+  if (this->device() == device && this->dtype() == dtype) {
+    return *this;
+  }
   return detail::to(*this, options().device(device).dtype(dtype), non_blocking);
 }
 
 inline Tensor Tensor::to(ScalarType dtype, bool non_blocking) const {
+  if (this->dtype() == dtype) {
+    return *this;
+  }
   return detail::to(*this, options().dtype(dtype), non_blocking);
 }
 
 inline Tensor Tensor::to(Device device, bool non_blocking) const {
+  if (this->device() == device) {
+    return *this;
+  }
   return detail::to(*this, options().device(device), non_blocking);
 }
 } // namespace at
