Expose mehod name as part of backend init context

runtime/backend/backend_execution_context.h

@@ -21,8 +21,11 @@ class BackendExecutionContext final {
  public:
   BackendExecutionContext(
       EventTracer* event_tracer = nullptr,
-      MemoryAllocator* temp_allocator = nullptr)
-      : event_tracer_(event_tracer), temp_allocator_(temp_allocator) {}
+      MemoryAllocator* temp_allocator = nullptr,
+      const char* method_name = nullptr)
+      : event_tracer_(event_tracer),
+        temp_allocator_(temp_allocator),
+        method_name_(method_name) {}
 
   /**
    * Returns a pointer to an instance of EventTracer to do profiling/debugging
@@ -52,9 +55,17 @@ class BackendExecutionContext final {
     return temp_allocator_;
   }
 
+  /**
+   * Get the name of the executing method from the ExecuTorch runtime.
+   */
+  const char* get_method_name() const {
+    return method_name_;
+  }
+
  private:
   EventTracer* event_tracer_ = nullptr;
   MemoryAllocator* temp_allocator_ = nullptr;
+  const char* method_name_ = nullptr;
 };
 
 } // namespace runtime

runtime/backend/backend_init_context.h

@@ -18,8 +18,10 @@ namespace runtime {
  */
 class BackendInitContext final {
  public:
-  explicit BackendInitContext(MemoryAllocator* runtime_allocator)
-      : runtime_allocator_(runtime_allocator) {}
+  explicit BackendInitContext(
+      MemoryAllocator* runtime_allocator,
+      const char* method_name = nullptr)
+      : runtime_allocator_(runtime_allocator), method_name_(method_name) {}
 
   /** Get the runtime allocator passed from Method. It's the same runtime
    * executor used by the standard executor runtime and the life span is the
@@ -29,8 +31,20 @@ class BackendInitContext final {
     return runtime_allocator_;
   }
 
+  /** Get the loaded method name from ExecuTorch runtime. Usually it's
+   * "forward", however, if there are multiple methods in the .pte file, it can
+   * be different. One example is that we may have prefill and decode methods in
+   * the same .pte file. In this case, when client loads "prefill" method, the
+   * `get_method_name` function will return "prefill", when client loads
+   * "decode" method, the `get_method_name` function will return "decode".
+   */
+  const char* get_method_name() const {
+    return method_name_;
+  }
+
  private:
   MemoryAllocator* runtime_allocator_ = nullptr;
+  const char* method_name_ = nullptr;
 };
 
 } // namespace runtime

runtime/executor/method.cpp

@@ -626,7 +626,9 @@ Error Method::init(executorch_flatbuffer::ExecutionPlan* s_plan) {
 
     for (size_t i = 0; i < n_delegate; ++i) {
       const auto& delegate = *delegates->Get(i);
-      BackendInitContext backend_init_context(method_allocator);
+      BackendInitContext backend_init_context(
+          method_allocator,
+          /*method_name=*/serialization_plan_->name()->c_str());
       Error err = BackendDelegate::Init(
           delegate, program_, backend_init_context, &delegates_[i]);
       if (err != Error::Ok) {
@@ -1097,8 +1099,9 @@ Error Method::execute_instruction() {
           n_delegate_,
           step_state_.instr_idx);
       BackendExecutionContext backend_execution_context(
-          /*event_tracer*/ event_tracer_,
-          /*temp_allocator*/ temp_allocator_);
+          /*event_tracer=*/event_tracer_,
+          /*temp_allocator=*/temp_allocator_,
+          /*method_name=*/serialization_plan_->name()->c_str());
       err = delegates_[delegate_idx].Execute(
           backend_execution_context,
           chain.argument_lists_[step_state_.instr_idx].data());

runtime/executor/test/backend_integration_test.cpp

@@ -95,7 +95,7 @@ class StubBackend final : public BackendInterface {
   }
 
   Error execute(
-      ET_UNUSED BackendExecutionContext& context,
+      BackendExecutionContext& context,
       DelegateHandle* handle,
       EValue** args) const override {
     if (execute_fn_) {
@@ -530,6 +530,48 @@ TEST_P(BackendIntegrationTest, SegmentInfoIsPassedIntoDataLoader) {
   EXPECT_EQ(backend_load_was_called, using_segments());
 }
 
+TEST_P(BackendIntegrationTest, GetMethodNameDuringInitSuccess) {
+  Result<FileDataLoader> loader = FileDataLoader::from(program_path());
+  ASSERT_EQ(loader.error(), Error::Ok);
+  const void* processed_data = nullptr;
+  StubBackend::singleton().install_init(
+      [&](FreeableBuffer* processed,
+          ET_UNUSED ArrayRef<CompileSpec> compile_specs,
+          ET_UNUSED BackendInitContext& backend_init_context)
+          -> Result<DelegateHandle*> {
+        auto method_name = backend_init_context.get_method_name();
+        // Ensure that we can get the method name during init via context
+        EXPECT_STREQ(method_name, "forward");
+        processed_data = processed->data();
+        return nullptr;
+      });
+  Result<Program> program = Program::load(&loader.get());
+  ManagedMemoryManager mmm(kDefaultNonConstMemBytes, kDefaultRuntimeMemBytes);
+  Result<Method> method = program->load_method("forward", &mmm.get());
+  EXPECT_TRUE(method.ok());
+  ASSERT_EQ(program.error(), Error::Ok);
+}
+
+TEST_P(BackendIntegrationTest, GetMethodNameDuringExecuteSuccess) {
+  Result<FileDataLoader> loader = FileDataLoader::from(program_path());
+  ASSERT_EQ(loader.error(), Error::Ok);
+  StubBackend::singleton().install_execute(
+      [&](BackendExecutionContext& backend_execution_context,
+          ET_UNUSED DelegateHandle* handle,
+          ET_UNUSED EValue** args) -> Error {
+        // Ensure that we can get the method name during execution via context
+        auto method_name = backend_execution_context.get_method_name();
+        EXPECT_STREQ(method_name, "forward");
+        return Error::Ok;
+      });
+  Result<Program> program = Program::load(&loader.get());
+  ManagedMemoryManager mmm(kDefaultNonConstMemBytes, kDefaultRuntimeMemBytes);
+  Result<Method> method = program->load_method("forward", &mmm.get());
+  EXPECT_TRUE(method.ok());
+  Error err = method->execute();
+  ASSERT_EQ(err, Error::Ok);
+}
+
 // TODO: Add more tests for the runtime-to-backend interface. E.g.:
 // - Errors during init() or execute() result in runtime init/execution failures
 // - Correct values are passed to init()/execute()