[AOT][DeviceAPI] Wire up cpacked Device API context

Adding the same functionality for the Device API to the cpacked calling convention. The MakePackedAPI pass now implicitly uses any variable named `kDeviceContextVar` as the `resource_handle` and this is then used in the `cpacked` calling convention which always expects some form of resource_handle to be passed.

src/relay/backend/aot_executor_codegen.cc

@@ -347,18 +347,30 @@ class AOTExecutorCodegen : public MixedModeVisitor {
     }
 
     GlobalVar global_var = call_lowered_props.lowered_func;
+    tir::Var empty_var("no_device_context", DataType::Handle());
     bool has_c_device_api_context = device_contexts_.count(global_var) != 0;
+    bool use_cpacked_api = !use_unpacked_api_;
+
     if (has_c_device_api_context) {
+      // call_extern calling convention with context
       tir::Var context = device_contexts_.Get(global_var).value();
-      args.push_back(device_contexts_[global_var]);
+      args.push_back(context);
 
       tir::Evaluate func_call(tvm::tir::Call(DataType::Int(32), calling_pattern, args));
       create_func_call_stmts.push_back(tir::SeqStmt({
           GenerateDeviceHook(context, "Open"),
           func_call,
           GenerateDeviceHook(context, "Close"),
       }));
+    } else if (use_cpacked_api) {
+      // call_cpacked calling convention needs a blank context
+      args.push_back(empty_var);
+
+      tir::Evaluate func_call(tvm::tir::Call(DataType::Int(32), calling_pattern, args));
+      tir::LetStmt set_zero(empty_var, tir::make_zero(DataType::Handle()), func_call);
+      create_func_call_stmts.push_back(set_zero);
     } else {
+      // call_extern calling convention without context
       tir::Evaluate func_call(tvm::tir::Call(DataType::Int(32), calling_pattern, args));
       create_func_call_stmts.push_back(func_call);
     }

src/target/source/codegen_c_host.cc

@@ -250,7 +250,8 @@ void CodeGenCHost::PrintFuncCall(const std::string& packed_func_name, int num_ar
   this->stream << "}\n";
 }
 
-void CodeGenCHost::PrintFuncCallC(const std::string& packed_func_name, int num_args) {
+void CodeGenCHost::PrintFuncCallC(const std::string& packed_func_name, int num_args,
+                                  const std::string& resource_handle_name) {
   this->PrintIndent();
   std::string ret_val = GetUniqueName("ret_val");
   std::string ret_type_code = GetUniqueName("ret_type_code");
@@ -265,7 +266,7 @@ void CodeGenCHost::PrintFuncCallC(const std::string& packed_func_name, int num_a
                << "(int*) stack_tcode"
                << ", " << num_args << ", "
                << "&" << ret_val << ", "
-               << "&" << ret_type_code << ", NULL) != 0){\n";
+               << "&" << ret_type_code << ", " << resource_handle_name << ") != 0){\n";
 
   int func_call_scope = this->BeginScope();
   this->PrintIndent();
@@ -275,7 +276,8 @@ void CodeGenCHost::PrintFuncCallC(const std::string& packed_func_name, int num_a
   this->stream << "}\n";
 }
 
-CodeGenCHost::FunctionInfo CodeGenCHost::GetFunctionInfo(const CallNode* op) {
+CodeGenCHost::FunctionInfo CodeGenCHost::GetFunctionInfo(const CallNode* op,
+                                                         bool has_resource_handle) {
   const StringImmNode* s = op->args[0].as<StringImmNode>();
   ICHECK(s != nullptr) << "tvm_call_packed_lowered expects first argument as function name";
   int64_t begin = op->args[3].as<IntImmNode>()->value;
@@ -295,6 +297,10 @@ CodeGenCHost::FunctionInfo CodeGenCHost::GetFunctionInfo(const CallNode* op) {
     declared_globals_[packed_func_name] = unique_name;
     decl_stream << "static void* " << unique_name << " = NULL;\n";
   }
+  if (has_resource_handle) {
+    std::string resource_handle_name = op->args[5].as<StringImmNode>()->value;
+    return {func_name, unique_name, num_args - 1, resource_handle_name};
+  }
   return {func_name, unique_name, num_args};
 }
 
@@ -326,8 +332,9 @@ void CodeGenCHost::VisitExpr_(const CallNode* op, std::ostream& os) {  // NOLINT
     this->PrintGetFuncFromBackend(function_info.func_name, function_info.func_name_packed);
     this->PrintFuncCall(function_info.func_name_packed, function_info.num_args);
   } else if (op->op.same_as(builtin::tvm_call_cpacked_lowered())) {
-    auto function_info = GetFunctionInfo(op);
-    this->PrintFuncCallC(function_info.func_name, function_info.num_args);
+    auto function_info = GetFunctionInfo(op, true);
+    this->PrintFuncCallC(function_info.func_name, function_info.num_args,
+                         function_info.resource_handle_name);
   } else if (op->op.same_as(builtin::tvm_throw_last_error())) {
     this->PrintIndent();
     this->stream << "return -1;\n";

src/target/source/codegen_c_host.h

@@ -73,6 +73,8 @@ class CodeGenCHost : public CodeGenC {
     std::string func_name_packed;
     /* number of arguments required by the function */
     int64_t num_args;
+    /* \brief name of resource_handle to pass */
+    std::string resource_handle_name;
   };
   std::string module_name_;
   /* \brief mapping global packed func to the unique name */
@@ -82,10 +84,11 @@ class CodeGenCHost : public CodeGenC {
   /*! \brief whether to emit asserts in the resulting C code */
   bool emit_asserts_;
 
-  FunctionInfo GetFunctionInfo(const CallNode* op);
+  FunctionInfo GetFunctionInfo(const CallNode* op, bool has_resource_handle = false);
   void PrintGetFuncFromBackend(const std::string& func_name, const std::string& packed_func_name);
   void PrintFuncCall(const std::string& packed_func_name, int num_args);
-  void PrintFuncCallC(const std::string& packed_func_name, int num_args);
+  void PrintFuncCallC(const std::string& packed_func_name, int num_args,
+                      const std::string& resource_handle_name);
 
   /*!
    * \brief Print ternary conditional operator implementing binary `op`

src/tir/transforms/lower_tvm_builtin.cc

@@ -280,11 +280,18 @@ class BuiltinLower : public StmtExprMutator {
     size_t restore_array_stack = scope.run_array_stack;
     size_t arg_stack_begin = scope.run_arg_stack;
 
-    scope.run_arg_stack += op->args.size();
+    size_t arg_count = op->args.size();
+
+    // cpacked expects a resource_handle parameter
+    if (!use_string_lookup) {
+      arg_count--;
+    }
+
+    scope.run_arg_stack += arg_count;
     // Specially handle the buffer packed intrinsic
     PrimExpr expr = StmtExprMutator::VisitExpr_(op);
     op = expr.as<CallNode>();
-    for (size_t i = 1; i < op->args.size(); ++i) {
+    for (size_t i = 1; i < arg_count; ++i) {
       PrimExpr stack_index = ConstInt32(arg_stack_begin + i - 1);
       PrimExpr arg = op->args[i];
       DataType t = arg.dtype();
@@ -314,6 +321,12 @@ class BuiltinLower : public StmtExprMutator {
                                    ConstInt32(arg_stack_begin),
                                    ConstInt32(arg_stack_begin + op->args.size() - 1)};
 
+    // cpacked call resource_handle
+    if (!use_string_lookup) {
+      tir::Var resource_handle = Downcast<Var>(op->args[arg_count]);
+      packed_args.push_back(StringImm(resource_handle->name_hint));
+    }
+
     auto builtin_call = use_string_lookup ? builtin::tvm_call_packed_lowered()
                                           : builtin::tvm_call_cpacked_lowered();
     return Call(op->dtype, builtin_call, packed_args);

src/tir/transforms/make_packed_api.cc

@@ -40,6 +40,8 @@
 namespace tvm {
 namespace tir {
 
+static constexpr const char* kDeviceContextVar = "device_api_context";
+
 class ReturnRewriter : public StmtMutator {
  public:
   explicit ReturnRewriter(Var ret_var, Var ret_tcode) : ret_var_(ret_var), ret_tcode_(ret_tcode) {}
@@ -161,15 +163,11 @@ PrimFunc MakePackedAPI(PrimFunc&& func, int num_unpacked_args) {
   };
   // ---------------------------
   // start of logics
-  // add signiture for packed arguments.
+  // add signature for packed arguments.
   if (pack_args) {
     args.push_back(v_packed_args);
     args.push_back(v_packed_arg_type_ids);
     args.push_back(v_num_packed_args);
-    std::ostringstream os;
-
-    os << name_hint << ": num_args should be " << num_packed_args;
-    seq_init.emplace_back(MakeAssertEQ(v_num_packed_args, num_packed_args, os.str()));
   }
 
   // Need to re-declare vars, in case some arguments also appears in the buffer.
@@ -180,6 +178,13 @@ PrimFunc MakePackedAPI(PrimFunc&& func, int num_unpacked_args) {
     Var param = func_ptr->params[i];
     Var v_arg = Var("arg" + std::to_string(i), param->dtype);
 
+    // Pluck the device API context out based on name
+    if (param->name_hint == kDeviceContextVar) {
+      num_packed_args--;
+      v_resource_handle = param;
+      continue;
+    }
+
     auto it = func_ptr->buffer_map.find(param);
     if (it != func_ptr->buffer_map.end()) {
       buffer_def.emplace_back(v_arg, (*it).second);
@@ -262,7 +267,17 @@ PrimFunc MakePackedAPI(PrimFunc&& func, int num_unpacked_args) {
       body = SeqStmt({set_device, body});
     }
   }
-  func_ptr->body = MergeNest({seq_init, binder.init_nest(), seq_check, binder.asserts()}, body);
+
+  if (pack_args) {
+    std::ostringstream num_args_error;
+    num_args_error << name_hint << ": num_args should be " << num_packed_args;
+    std::vector<Stmt> arg_assert = {
+        MakeAssertEQ(v_num_packed_args, num_packed_args, num_args_error.str())};
+    func_ptr->body =
+        MergeNest({arg_assert, seq_init, binder.init_nest(), seq_check, binder.asserts()}, body);
+  } else {
+    func_ptr->body = MergeNest({seq_init, binder.init_nest(), seq_check, binder.asserts()}, body);
+  }
   func_ptr->params = args;
 
   Array<Var> undefined = UndefinedVars(func_ptr->body, func_ptr->params);

tests/python/contrib/test_ethosu/infra.py

@@ -189,7 +189,7 @@ def deserialize_command_stream(blob):
     return cmms
 
 
-def _create_test_runner(accel):
+def create_test_runner(accel="ethos-u55-256"):
     file_dir = os.path.dirname(os.path.abspath(__file__))
     test_root = os.path.join(file_dir, "reference_system")
     ethosu_macs = accel[accel.rfind("-") + 1 :]
@@ -215,7 +215,7 @@ def _create_test_runner(accel):
 
 
 def build_source(module, inputs, outputs, accel="ethos-u55-256", output_tolerance=0):
-    test_runner = _create_test_runner(accel)
+    test_runner = create_test_runner(accel)
     return compile_models(
         models=AOTTestModel(
             module=module,
@@ -239,7 +239,7 @@ def verify_source(
     This method verifies the generated source from an NPU module by building it and running on an FVP.
     """
     interface_api = "c"
-    test_runner = _create_test_runner(accel)
+    test_runner = create_test_runner(accel)
     run_and_check(
         models,
         test_runner,