Give the lowered fn computation a more meaningful name

Author: tengyifei

test/test_operations.py

@@ -2640,12 +2640,14 @@ def test_api(self):
 
     result = a + b
 
-    ctx = torch_xla._XLAC.lowering.LoweringContext()
+    ctx = torch_xla._XLAC.lowering.LoweringContext("MyCustomName")
     ctx.build([result])
     hlo = ctx.hlo()
     hlo_text = ctx.hlo_text()
-    self.assertTrue('opcode: "parameter"' in hlo_text)
-    self.assertTrue('opcode: "add"' in hlo_text)
+    self.assertIn('MyCustomName', hlo_text)
+    self.assertIn('opcode: "parameter"', hlo_text)
+    self.assertIn('opcode: "parameter"', hlo_text)
+    self.assertIn('opcode: "add"', hlo_text)
     mapping = ctx.parameter_id_tensor_mapping()
     self.assertEqual(len(mapping), 2)
 

torch_xla/csrc/init_python_bindings.cpp

@@ -978,10 +978,14 @@ void BuildProfilerSubmodule(py::module* m) {
 
 class PyLoweringContext {
  public:
-  PyLoweringContext() : PyLoweringContext(bridge::GetCurrentDevice()) {}
+  PyLoweringContext()
+      : PyLoweringContext("PyLoweringContext", bridge::GetCurrentDevice()) {}
 
-  PyLoweringContext(torch::lazy::BackendDevice device)
-      : lowering_ctx("PyLoweringContext", device) {}
+  PyLoweringContext(const std::string& name)
+      : PyLoweringContext(name, bridge::GetCurrentDevice()) {}
+
+  PyLoweringContext(const std::string& name, torch::lazy::BackendDevice device)
+      : lowering_ctx(name, device) {}
 
   // Builds a HLO graph given a set of output tensors.
   void Build(std::vector<at::Tensor> tensors) {
@@ -1188,7 +1192,8 @@ void BuildLoweringContextSubmodule(py::module* m) {
   py::class_<PyLoweringContext, std::unique_ptr<PyLoweringContext>>
       lowering_context_class(lowering, "LoweringContext", py::module_local());
 
-  lowering_context_class.def(py::init<>())
+  lowering_context_class.def(py::init())
+      .def(py::init<std::string>())
       .def("build", &PyLoweringContext::Build)
       .def("buildforiloop", &PyLoweringContext::BuildForiLoop)
       .def("hlo", &PyLoweringContext::GetHlo)

torch_xla/experimental/scan.py

@@ -477,7 +477,7 @@ def make_fake_tensor(v: torch.Tensor) -> torch.Tensor:
   y_len = len(fake_output_y)
   fn_outputs = fake_output_carry + fake_output_y
 
-  fn_ctx = torch_xla._XLAC.lowering.LoweringContext()
+  fn_ctx = torch_xla._XLAC.lowering.LoweringContext("FnComputation")
   fn_ctx.set_name_string("fn_ctx")
   fn_ctx.build(list(fn_outputs))
   fn_hlo = fn_ctx.hlo()