Error Handling: refactor GetXlaTensor and related functions to use status types.

test/cpp/cpp_test_util.cpp

@@ -246,17 +246,17 @@ void WithAllDevices(
 }
 
 std::string GetTensorTextGraph(at::Tensor tensor) {
-  XLATensorPtr xtensor = bridge::GetXlaTensor(tensor);
+  XLATensorPtr xtensor = GetValueOrThrow(bridge::GetXlaTensor(tensor));
   return DumpUtil::ToText({xtensor->GetIrValue().node.get()});
 }
 
 std::string GetTensorDotGraph(at::Tensor tensor) {
-  XLATensorPtr xtensor = bridge::GetXlaTensor(tensor);
+  XLATensorPtr xtensor = GetValueOrThrow(bridge::GetXlaTensor(tensor));
   return DumpUtil::ToDot({xtensor->GetIrValue().node.get()});
 }
 
 std::string GetTensorHloGraph(at::Tensor tensor) {
-  XLATensorPtr xtensor = bridge::GetXlaTensor(tensor);
+  XLATensorPtr xtensor = GetValueOrThrow(bridge::GetXlaTensor(tensor));
   return DumpUtil::ToHlo({xtensor->GetIrValue()}, xtensor->GetDevice());
 }
 

test/cpp/test_aten_xla_tensor_1.cpp

@@ -27,7 +27,7 @@ TEST_F(AtenXlaTensorTest, TestStorage) {
   torch::Tensor a = torch::tensor({0.0});
   ForEachDevice([&](const torch::Device& device) {
     torch::Tensor xla_a = CopyToDevice(a, device);
-    XLATensorPtr xla_tensor_a = bridge::GetXlaTensor(xla_a);
+    XLATensorPtr xla_tensor_a = GetValueOrThrow(bridge::GetXlaTensor(xla_a));
     EXPECT_EQ(xla_a.device(), xla_tensor_a->Storage().device());
     AllClose(a, xla_a);
   });

torch_xla/csrc/aten_autograd_ops.cpp

@@ -8,6 +8,7 @@
 #include "torch_xla/csrc/aten_fallback.h"
 #include "torch_xla/csrc/aten_xla_bridge.h"
 #include "torch_xla/csrc/helpers.h"
+#include "torch_xla/csrc/status.h"
 #include "torch_xla/csrc/tensor_methods.h"
 #include "torch_xla/csrc/torch_util.h"
 
@@ -33,7 +34,8 @@ torch::Tensor EinsumAutogradFunction::forward(
   }
   ctx->save_for_backward(vars);
 
-  std::vector<XLATensorPtr> xla_tensors = bridge::GetXlaTensors(tensors);
+  std::vector<XLATensorPtr> xla_tensors =
+      GetValueOrThrow(bridge::GetXlaTensors(tensors));
   XLATensorPtr output = tensor_methods::einsum(eq_str, xla_tensors);
   return bridge::AtenFromXlaTensor(output);
 }
@@ -43,11 +45,13 @@ torch::autograd::variable_list EinsumAutogradFunction::backward(
     torch::autograd::variable_list grad_output) {
   std::string equation = ctx->saved_data["equation"].toString()->string();
   torch::autograd::variable_list tensors = ctx->get_saved_variables();
-  std::vector<XLATensorPtr> xla_tensors = bridge::GetXlaTensors(tensors);
+  std::vector<XLATensorPtr> xla_tensors =
+      GetValueOrThrow(bridge::GetXlaTensors(tensors));
 
   std::tuple<XLATensorPtr, XLATensorPtr> outputs =
-      tensor_methods::einsum_backward(bridge::GetXlaTensor(grad_output[0]),
-                                      xla_tensors, equation);
+      tensor_methods::einsum_backward(
+          GetValueOrThrow(bridge::GetXlaTensor(grad_output[0])), xla_tensors,
+          equation);
 
   // For both einsum and max pool, we use "undef" as a placeholder for the
   // non-tensor grad inputs, in this case the equation string.
@@ -190,7 +194,7 @@ torch::Tensor MaxPool3dAutogradFunction::forward(
   }
   ctx->save_for_backward({self});
   auto outputs = tensor_methods::max_pool_nd(
-      bridge::GetXlaTensor(self), /*spatial_dim_count=*/3,
+      GetValueOrThrow(bridge::GetXlaTensor(self)), /*spatial_dim_count=*/3,
       XlaHelpers::I64List(kernel_size), XlaHelpers::I64List(stride),
       XlaHelpers::I64List(padding), ceil_mode);
   return bridge::AtenFromXlaTensor(std::get<0>(outputs));
@@ -218,7 +222,8 @@ torch::autograd::variable_list MaxPool3dAutogradFunction::backward(
                                                          ceil_mode, indices);
   }
   grad = bridge::AtenFromXlaTensor(tensor_methods::max_pool_nd_backward(
-      bridge::GetXlaTensor(grad_output[0]), bridge::GetXlaTensor(self),
+      GetValueOrThrow(bridge::GetXlaTensor(grad_output[0])),
+      GetValueOrThrow(bridge::GetXlaTensor(self)),
       /*spatial_dim_count=*/3, XlaHelpers::I64List(kernel_size),
       XlaHelpers::I64List(stride), XlaHelpers::I64List(padding), ceil_mode));
 
@@ -234,7 +239,7 @@ torch::Tensor max_pool2d_forward(torch::Tensor self,
                                  torch::IntArrayRef padding,
                                  torch::IntArrayRef dilation, bool ceil_mode) {
   auto outputs = tensor_methods::max_pool_nd(
-      bridge::GetXlaTensor(self), /*spatial_dim_count=*/2,
+      GetValueOrThrow(bridge::GetXlaTensor(self)), /*spatial_dim_count=*/2,
       XlaHelpers::I64List(kernel_size), XlaHelpers::I64List(stride),
       XlaHelpers::I64List(padding), ceil_mode);
   return bridge::AtenFromXlaTensor(std::get<0>(outputs));
@@ -245,7 +250,8 @@ torch::Tensor max_pool2d_backward(torch::Tensor grad_output, torch::Tensor self,
                                   torch::IntArrayRef stride,
                                   torch::IntArrayRef padding, bool ceil_mode) {
   auto grad = bridge::AtenFromXlaTensor(tensor_methods::max_pool_nd_backward(
-      bridge::GetXlaTensor(grad_output), bridge::GetXlaTensor(self),
+      GetValueOrThrow(bridge::GetXlaTensor(grad_output)),
+      GetValueOrThrow(bridge::GetXlaTensor(self)),
       /*spatial_dim_count=*/2, XlaHelpers::I64List(kernel_size),
       XlaHelpers::I64List(stride), XlaHelpers::I64List(padding), ceil_mode));
   return grad;

torch_xla/csrc/aten_fallback.cpp

@@ -137,7 +137,7 @@ static bool validate_tensor_list(const c10::List<at::Tensor>& tensorlist) {
 
 // Retrieve the inner XLATensorPtr, and check it lives inside CUDA.
 static XLATensorPtr get_xla_cuda_tensor(const at::Tensor& tensor) {
-  XLATensorPtr xla_tensor = bridge::GetXlaTensor(tensor);
+  XLATensorPtr xla_tensor = GetValueOrThrow(bridge::GetXlaTensor(tensor));
   const torch::lazy::BackendDevice& device = xla_tensor->GetDevice();
   TORCH_CHECK(device.type() == static_cast<int8_t>(XlaDeviceType::CUDA),
               "OpenXLA CUDA fallback only supports XLA:CUDA tensors. Found a "

torch_xla/csrc/aten_xla_bridge.cpp

@@ -7,10 +7,12 @@
 #include <string>
 #include <vector>
 
+#include "absl/status/status.h"
 #include "absl/strings/str_cat.h"
 #include "torch_xla/csrc/device.h"
 #include "torch_xla/csrc/runtime/debug_macros.h"
 #include "torch_xla/csrc/runtime/runtime.h"
+#include "torch_xla/csrc/status.h"
 #include "torch_xla/csrc/tensor_impl.h"
 #include "torch_xla/csrc/torch_util.h"
 #include "torch_xla/csrc/xla_graph_executor.h"
@@ -72,72 +74,68 @@ AtenXlaDeviceMapper* AtenXlaDeviceMapper::Get() {
   return device_mapper;
 }
 
-XLATensorImpl* GetXlaTensorImpl(const at::Tensor& tensor) {
+static absl::StatusOr<XLATensorImpl * absl_nonnull> GetXlaTensorImpl(
+    const at::Tensor& tensor) {
   auto inner_tensor = torch::lazy::maybe_unwrap_functional(tensor);
-  return dynamic_cast<XLATensorImpl*>(inner_tensor.unsafeGetTensorImpl());
+  XLATensorImpl* impl =
+      dynamic_cast<XLATensorImpl*>(inner_tensor.unsafeGetTensorImpl());
+  if (impl == nullptr) {
+    return XLA_ERROR_WITH_LOCATION(absl::InvalidArgumentError(absl::StrCat(
+        "Input tensor is not an XLA tensor: ", tensor.toString())));
+  }
+  return impl;
 }
 
 }  // namespace
 
 XLATensorPtr TryGetXlaTensor(const at::Tensor& tensor) {
+  return GetXlaTensor(tensor).value_or(XLATensorPtr{});
+}
+
+absl::StatusOr<absl_nonnull XLATensorPtr> GetXlaTensor(
+    const at::Tensor& tensor) {
   if (tensor.defined() &&
       at::functionalization::impl::isFunctionalTensor(tensor)) {
     // To make sure we have the most updated version of tensor.
     at::functionalization::impl::sync(tensor);
   }
-  XLATensorImpl* impl = GetXlaTensorImpl(tensor);
-  if (impl == nullptr) {
-    return XLATensorPtr();
-  }
+  XLA_ASSIGN_OR_RETURN(XLATensorImpl * impl, GetXlaTensorImpl(tensor));
   return impl->tensor();
 }
 
-std::vector<XLATensorPtr> TryGetXlaTensors(const at::ITensorListRef& tensors) {
-  std::vector<XLATensorPtr> xla_tensors;
+absl::StatusOr<std::vector<absl_nonnull XLATensorPtr>> GetXlaTensors(
+    const at::ITensorListRef& tensors) {
+  std::vector<absl_nonnull XLATensorPtr> xla_tensors;
   xla_tensors.reserve(tensors.size());
   for (const auto& tensor : tensors) {
-    xla_tensors.push_back(bridge::TryGetXlaTensor(tensor));
+    XLA_ASSIGN_OR_RETURN(XLATensorPtr ptr, bridge::GetXlaTensor(tensor));
+    xla_tensors.push_back(std::move(ptr));
   }
   return xla_tensors;
 }
 
 bool IsXlaTensor(const at::Tensor& tensor) {
-  return GetXlaTensorImpl(tensor) != nullptr;
-}
-
-XLATensorPtr GetXlaTensor(const at::Tensor& tensor) {
-  auto xtensor = TryGetXlaTensor(tensor);
-  XLA_CHECK(xtensor) << "Input tensor is not an XLA tensor: "
-                     << tensor.toString();
-  return xtensor;
+  return GetXlaTensorImpl(tensor).ok();
 }
 
-void ReplaceXlaTensor(const at::Tensor& tensor, XLATensorPtr new_xla_tensor) {
-  auto inner_tensor = torch::lazy::maybe_unwrap_functional(tensor);
-  XLATensorImpl* impl =
-      dynamic_cast<XLATensorImpl*>(inner_tensor.unsafeGetTensorImpl());
-  XLA_CHECK(impl != nullptr)
-      << "Input tensor is not an XLA tensor: " << inner_tensor.toString();
+absl::Status ReplaceXlaTensor(const at::Tensor& tensor,
+                              XLATensorPtr new_xla_tensor) {
+  XLA_ASSIGN_OR_RETURN(XLATensorImpl * impl, GetXlaTensorImpl(tensor));
   impl->set_tensor(std::move(new_xla_tensor));
+  return absl::OkStatus();
 }
 
-void ReplaceXlaTensor(const std::vector<at::Tensor>& tensors,
-                      const std::vector<XLATensorPtr> new_xla_tensors) {
-  XLA_CHECK(tensors.size() == new_xla_tensors.size())
-      << "The size of tensors and new_xla_tensors are not equal: "
-      << tensors.size() << " vs. " << new_xla_tensors.size();
-  for (size_t i = 0; i < tensors.size(); ++i) {
-    ReplaceXlaTensor(tensors[i], new_xla_tensors[i]);
+absl::Status ReplaceXlaTensor(const std::vector<at::Tensor>& tensors,
+                              const std::vector<XLATensorPtr> new_xla_tensors) {
+  if (tensors.size() != new_xla_tensors.size()) {
+    return XLA_ERROR_WITH_LOCATION(absl::InvalidArgumentError(
+        absl::StrCat("The size of tensors and new_xla_tensors are not equal: ",
+                     tensors.size(), " vs. ", new_xla_tensors.size())));
   }
-}
-
-std::vector<XLATensorPtr> GetXlaTensors(const at::ITensorListRef& tensors) {
-  std::vector<XLATensorPtr> xla_tensors;
-  xla_tensors.reserve(tensors.size());
-  for (const auto& tensor : tensors) {
-    xla_tensors.push_back(bridge::GetXlaTensor(tensor));
+  for (size_t i = 0; i < tensors.size(); ++i) {
+    XLA_RETURN_IF_ERROR(ReplaceXlaTensor(tensors[i], new_xla_tensors[i]));
   }
-  return xla_tensors;
+  return absl::OkStatus();
 }
 
 torch_xla::XLATensorPtr GetXlaTensorOrCreateForWrappedNumber(
@@ -146,7 +144,7 @@ torch_xla::XLATensorPtr GetXlaTensorOrCreateForWrappedNumber(
       (tensor.dim() == 0 && tensor.numel() == 1)) {
     return torch_xla::bridge::GetOrCreateXlaTensor(tensor, device);
   } else {
-    return torch_xla::bridge::GetXlaTensor(tensor);
+    return GetValueOrThrow(torch_xla::bridge::GetXlaTensor(tensor));
   }
 }
 
@@ -155,22 +153,23 @@ XLATensorPtr GetOrCreateXlaTensor(const at::Tensor& tensor,
   if (!tensor.defined()) {
     return XLATensorPtr();
   }
+
   auto inner_tensor = torch::lazy::maybe_unwrap_functional(tensor);
   if (!inner_tensor.defined()) {
     return XLATensorPtr();
   }
-  auto xtensor = TryGetXlaTensor(tensor);
-  return xtensor ? xtensor : XLATensor::Create(inner_tensor, device);
+
+  auto xtensor = GetXlaTensor(tensor);
+  return xtensor.ok() ? xtensor.value()
+                      : XLATensor::Create(inner_tensor, device);
 }
 
 XLATensorPtr GetOrCreateXlaTensor(const std::optional<at::Tensor>& tensor,
                                   const torch::lazy::BackendDevice& device) {
-  if (!IsDefined(tensor)) {
+  if (!tensor.has_value()) {
     return XLATensorPtr();
   }
-  auto xtensor = TryGetXlaTensor(*tensor);
-  auto inner_tensor = torch::lazy::maybe_unwrap_functional(*tensor);
-  return xtensor ? xtensor : XLATensor::Create(inner_tensor, device);
+  return GetOrCreateXlaTensor(*tensor, device);
 }
 
 std::vector<XLATensorPtr> GetOrCreateXlaTensors(
@@ -199,10 +198,10 @@ std::vector<at::Tensor> XlaCreateTensorList(const at::ITensorListRef& tensors) {
       continue;
     }
 
-    auto xtensor = TryGetXlaTensor(tensor);
-    if (xtensor) {
+    auto xtensor_status = GetXlaTensor(tensor);
+    if (xtensor_status.ok()) {
       to_translate[ix] = true;
-      xla_tensors.push_back(xtensor);
+      xla_tensors.push_back(xtensor_status.value());
     } else {
       aten_xla_tensors[ix] = tensor;
     }
@@ -253,13 +252,14 @@ void XlaUpdateTensors(absl::Span<const at::Tensor> dest_xla_tensors,
   for (auto index : indices) {
     at::Tensor dest = dest_xla_tensors.at(index);
     at::Tensor source = source_cpu_tensors.at(index);
-    XLATensorImpl* dest_impl = GetXlaTensorImpl(dest);
-    if (dest_impl != nullptr) {
-      auto xla_source = TryGetXlaTensor(source);
-      if (!xla_source) {
-        dest_impl->tensor()->UpdateFromTensorOut(source);
+    auto dest_impl_status = GetXlaTensorImpl(dest);
+    if (dest_impl_status.ok()) {
+      auto dest_impl = std::move(dest_impl_status).value();
+      auto xla_source_status = GetXlaTensor(source);
+      if (xla_source_status.ok()) {
+        dest_impl->tensor()->UpdateFromTensorOut(xla_source_status.value());
       } else {
-        dest_impl->tensor()->UpdateFromTensorOut(xla_source);
+        dest_impl->tensor()->UpdateFromTensorOut(source);
       }
       dest_impl->force_refresh_sizes();
     } else {
@@ -270,11 +270,11 @@ void XlaUpdateTensors(absl::Span<const at::Tensor> dest_xla_tensors,
 
 std::optional<torch::lazy::BackendDevice> GetXlaDevice(
     const at::Tensor& tensor) {
-  auto xtensor = TryGetXlaTensor(tensor);
-  if (!xtensor) {
+  auto xtensor_status = GetXlaTensor(tensor);
+  if (!xtensor_status.ok()) {
     return std::nullopt;
   }
-  return xtensor->GetDevice();
+  return xtensor_status.value()->GetDevice();
 }
 
 std::optional<torch::lazy::BackendDevice> GetXlaDevice(
@@ -469,12 +469,15 @@ std::vector<at::Tensor> CreateXlaTensors(
 }
 
 const at::Tensor& GetRootBase(const at::Tensor& tensor) {
-  auto xla_tensor = TryGetXlaTensor(tensor);
-  if (xla_tensor && xla_tensor->Base().defined()) {
-    return GetRootBase(xla_tensor->Base());
-  } else {
+  auto xla_tensor_status = GetXlaTensor(tensor);
+  if (!xla_tensor_status.ok()) {
+    return tensor;
+  }
+  auto xla_tensor = std::move(xla_tensor_status).value();
+  if (!xla_tensor->Base().defined()) {
     return tensor;
   }
+  return GetRootBase(xla_tensor->Base());
 }
 
 XLATensorPtr SetBaseTensor(XLATensorPtr tensor, const at::Tensor& base) {