Added forked versions of stateless If and While ops. They should only be used,

when the if then/else body of If or the While body funcs do not have stateful
ops.

The are lowered to the same XLA ops.

One use case is in the S4TF compiler: https://github.com/apple/swift/pull/18509

PiperOrigin-RevId: 207977126

3 files changed, 84 insertions, 0 deletions

diff --git a/tensorflow/c/c_api_function_test.cc b/tensorflow/c/c_api_function_test.cc
index bb9433ce25..73fe73769b 100644
--- a/tensorflow/c/c_api_function_test.cc
+++ b/tensorflow/c/c_api_function_test.cc
@@ -1619,5 +1619,66 @@ TEST_F(CApiFunctionTest, GetFunctionsFromGraph) {
   TF_DeleteFunction(func1);
 }
 
+// This test only works when the TF build includes XLA compiler. One way to set
+// this up is via bazel build option "--define with_xla_support=true".
+//
+// FIXME: generalize the macro name TENSORFLOW_EAGER_USE_XLA to
+// something like TENSORFLOW_CAPI_USE_XLA.
+#ifdef TENSORFLOW_EAGER_USE_XLA
+TEST_F(CApiFunctionTest, StatelessIf_XLA) {
+  TF_Function* func;
+  const std::string funcName = "BranchFunc";
+  DefineFunction(funcName.c_str(), &func);
+  TF_GraphCopyFunction(host_graph_, func, nullptr, s_);
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+
+  TF_Operation* feed = Placeholder(host_graph_, s_);
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+
+  TF_Operation* true_cond = ScalarConst(true, host_graph_, s_);
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+
+  TF_OperationDescription* desc =
+      TF_NewOperation(host_graph_, "StatelessIf", "IfNode");
+  TF_AddInput(desc, {true_cond, 0});
+  TF_Output inputs[] = {{feed, 0}};
+  TF_AddInputList(desc, inputs, TF_ARRAYSIZE(inputs));
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+  TF_SetAttrType(desc, "Tcond", TF_BOOL);
+  TF_DataType inputType = TF_INT32;
+  TF_SetAttrTypeList(desc, "Tin", &inputType, 1);
+  TF_SetAttrTypeList(desc, "Tout", &inputType, 1);
+  TF_SetAttrFuncName(desc, "then_branch", funcName.data(), funcName.size());
+  TF_SetAttrFuncName(desc, "else_branch", funcName.data(), funcName.size());
+  TF_SetDevice(desc, "/device:XLA_CPU:0");
+  auto op = TF_FinishOperation(desc, s_);
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+  ASSERT_NE(op, nullptr);
+
+  // Create a session for this graph.
+  CSession csession(host_graph_, s_, /*use_XLA*/ true);
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+
+  // Run the graph.
+  csession.SetInputs({{feed, Int32Tensor(17)}});
+  csession.SetOutputs({op});
+  csession.Run(s_);
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+  TF_Tensor* out = csession.output_tensor(0);
+  ASSERT_TRUE(out != nullptr);
+  EXPECT_EQ(TF_INT32, TF_TensorType(out));
+  EXPECT_EQ(0, TF_NumDims(out));  // scalar
+  ASSERT_EQ(sizeof(int32), TF_TensorByteSize(out));
+  int32* output_contents = static_cast<int32*>(TF_TensorData(out));
+  EXPECT_EQ(-17, *output_contents);
+
+  // Clean up
+  csession.CloseAndDelete(s_);
+  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
+
+  TF_DeleteFunction(func);
+}
+#endif  // TENSORFLOW_EAGER_USE_XLA
+
 }  // namespace
 }  // namespace tensorflow
diff --git a/tensorflow/c/c_test_util.cc b/tensorflow/c/c_test_util.cc
index 24eb6c069b..f15d9ee20a 100644
--- a/tensorflow/c/c_test_util.cc
+++ b/tensorflow/c/c_test_util.cc
@@ -26,6 +26,10 @@ limitations under the License.
 using tensorflow::GraphDef;
 using tensorflow::NodeDef;
 
+static void BoolDeallocator(void* data, size_t, void* arg) {
+  delete[] static_cast<bool*>(data);
+}
+
 static void Int32Deallocator(void* data, size_t, void* arg) {
   delete[] static_cast<int32_t*>(data);
 }
@@ -38,6 +42,14 @@ static void FloatDeallocator(void* data, size_t, void* arg) {
   delete[] static_cast<float*>(data);
 }
 
+TF_Tensor* BoolTensor(bool v) {
+  const int num_bytes = sizeof(bool);
+  bool* values = new bool[1];
+  values[0] = v;
+  return TF_NewTensor(TF_BOOL, nullptr, 0, values, num_bytes, &BoolDeallocator,
+                      nullptr);
+}
+
 TF_Tensor* Int8Tensor(const int64_t* dims, int num_dims, const char* values) {
   int64_t num_values = 1;
   for (int i = 0; i < num_dims; ++i) {
@@ -131,6 +143,12 @@ TF_Operation* Const(TF_Tensor* t, TF_Graph* graph, TF_Status* s,
   return op;
 }
 
+TF_Operation* ScalarConst(bool v, TF_Graph* graph, TF_Status* s,
+                          const char* name) {
+  unique_tensor_ptr tensor(BoolTensor(v), TF_DeleteTensor);
+  return Const(tensor.get(), graph, s, name);
+}
+
 TF_Operation* ScalarConst(int32_t v, TF_Graph* graph, TF_Status* s,
                           const char* name) {
   unique_tensor_ptr tensor(Int32Tensor(v), TF_DeleteTensor);
diff --git a/tensorflow/c/c_test_util.h b/tensorflow/c/c_test_util.h
index 38313d647c..7eeb1ee5e1 100644
--- a/tensorflow/c/c_test_util.h
+++ b/tensorflow/c/c_test_util.h
@@ -31,6 +31,8 @@ using ::tensorflow::string;
 typedef std::unique_ptr<TF_Tensor, decltype(&TF_DeleteTensor)>
     unique_tensor_ptr;
 
+TF_Tensor* BoolTensor(int32_t v);
+
 // Create a tensor with values of type TF_INT8 provided by `values`.
 TF_Tensor* Int8Tensor(const int64_t* dims, int num_dims, const char* values);
 
@@ -55,6 +57,9 @@ TF_Operation* Placeholder(TF_Graph* graph, TF_Status* s,
 TF_Operation* Const(TF_Tensor* t, TF_Graph* graph, TF_Status* s,
                     const char* name = "const");
 
+TF_Operation* ScalarConst(bool v, TF_Graph* graph, TF_Status* s,
+                          const char* name = "scalar");
+
 TF_Operation* ScalarConst(int32_t v, TF_Graph* graph, TF_Status* s,
                           const char* name = "scalar");