Debugger support for step-into async and async* functions.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index 23ca9317e3d68753a6981d935d120a7f088af64b..30105dcad83dfd6e00632682a265fdfad63108f7 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -7261,6 +7261,18 @@ SequenceNode* Parser::CloseAsyncGeneratorFunction(const Function& closure_func,
 
   TokenPosition token_pos = TokenPosition::kNoSource;
 
+
+  // Add to AST:
+  //   :async_op = <closure>;  (containing the original body)
+  LocalVariable* async_op_var =
+      current_block_->scope->LookupVariable(Symbols::AsyncOperation(), false);
+  ClosureNode* closure_obj = new (Z) ClosureNode(
+      TokenPosition::kNoSource, closure_func, NULL, closure_body->scope());
+  StoreLocalNode* store_async_op = new (Z)
+      StoreLocalNode(TokenPosition::kNoSource, async_op_var, closure_obj);
+
+  current_block_->statements->Add(store_async_op);
+
   if (FLAG_causal_async_stacks) {
     // Add to AST:
     //   :async_stack_trace = _asyncStackTraceHelper();
@@ -7270,6 +7282,8 @@ SequenceNode* Parser::CloseAsyncGeneratorFunction(const Function& closure_func,
     ASSERT(!async_stack_trace_helper.IsNull());
     ArgumentListNode* async_stack_trace_helper_args =
         new (Z) ArgumentListNode(TokenPosition::kNoSource);
+    async_stack_trace_helper_args->Add(
+        new (Z) LoadLocalNode(TokenPosition::kNoSource, async_op_var));
     StaticCallNode* async_stack_trace_helper_call = new (Z) StaticCallNode(
         token_pos, async_stack_trace_helper, async_stack_trace_helper_args);
     LocalVariable* async_stack_trace_var =
@@ -7280,18 +7294,6 @@ SequenceNode* Parser::CloseAsyncGeneratorFunction(const Function& closure_func,
     current_block_->statements->Add(store_async_stack_trace);
   }
 
-
-  // Add to AST:
-  //   :async_op = <closure>;  (containing the original body)
-  LocalVariable* async_op_var =
-      current_block_->scope->LookupVariable(Symbols::AsyncOperation(), false);
-  ClosureNode* closure_obj = new (Z) ClosureNode(
-      TokenPosition::kNoSource, closure_func, NULL, closure_body->scope());
-  StoreLocalNode* store_async_op = new (Z)
-      StoreLocalNode(TokenPosition::kNoSource, async_op_var, closure_obj);
-
-  current_block_->statements->Add(store_async_op);
-
   // :async_then_callback = _asyncThenWrapperHelper(:async_op)
   const Function& async_then_wrapper_helper = Function::ZoneHandle(
       Z,
@@ -7504,6 +7506,8 @@ SequenceNode* Parser::CloseAsyncFunction(const Function& closure,
     ASSERT(!async_stack_trace_helper.IsNull());
     ArgumentListNode* async_stack_trace_helper_args =
         new (Z) ArgumentListNode(token_pos);
+    async_stack_trace_helper_args->Add(
+        new (Z) LoadLocalNode(token_pos, async_op_var));
     StaticCallNode* async_stack_trace_helper_call = new (Z) StaticCallNode(
         token_pos, async_stack_trace_helper, async_stack_trace_helper_args);
     LocalVariable* async_stack_trace_var =
@@ -9234,6 +9238,19 @@ AstNode* Parser::ParseAwaitForStatement(String* label_name) {
       stream_expr_pos, new (Z) LoadLocalNode(stream_expr_pos, iterator_var),
       Symbols::MoveNext(), no_args);
   OpenBlock();
+  // Call '_asyncStarMoveNextHelper' so that the debugger can intercept and

[rmacnak, 2017/03/23 20:20:18]

if (FLAG_support_debugger) {

[Cutch, 2017/03/23 21:24:51]

Done.

+  // handle single stepping into a async* generator.
+  const Function& async_star_move_next_helper = Function::ZoneHandle(
+      Z, isolate()->object_store()->async_star_move_next_helper());
+  ASSERT(!async_star_move_next_helper.IsNull());
+  ArgumentListNode* async_star_move_next_helper_args =
+      new (Z) ArgumentListNode(stream_expr_pos);
+  async_star_move_next_helper_args->Add(
+      new (Z) LoadLocalNode(stream_expr_pos, stream_var));
+  StaticCallNode* async_star_move_next_helper_call =
+      new (Z) StaticCallNode(stream_expr_pos, async_star_move_next_helper,
+                             async_star_move_next_helper_args);
+  current_block_->statements->Add(async_star_move_next_helper_call);
   AstNode* await_moveNext = new (Z) AwaitNode(
       stream_expr_pos, iterator_moveNext, saved_try_ctx, async_saved_try_ctx,
       outer_saved_try_ctx, outer_async_saved_try_ctx, current_block_->scope);