Await always waits

runtime/vm/flow_graph_builder.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/class_finalizer.h"
@@ skipping 240 matching lines @@
         exit_collector_(exit_collector),
         guarded_fields_(new(I) ZoneGrowableArray<const Field*>()),
         last_used_block_id_(0),  // 0 is used for the graph entry.
         try_index_(CatchClauseNode::kInvalidTryIndex),
         catch_try_index_(CatchClauseNode::kInvalidTryIndex),
         loop_depth_(0),
         graph_entry_(NULL),
         temp_count_(0),
         args_pushed_(0),
         nesting_stack_(NULL),
-        osr_id_(osr_id),
-        jump_cnt_(0),
-        await_joins_(new(I) ZoneGrowableArray<JoinEntryInstr*>()),
-        await_levels_(new(I) ZoneGrowableArray<intptr_t>()) { }
+        osr_id_(osr_id) { }
 
 
 void FlowGraphBuilder::AddCatchEntry(CatchBlockEntryInstr* entry) {
   graph_entry_->AddCatchEntry(entry);
 }
 
 
 void InlineExitCollector::PrepareGraphs(FlowGraph* callee_graph) {
   ASSERT(callee_graph->graph_entry()->SuccessorCount() == 1);
   ASSERT(callee_graph->max_block_id() > caller_graph_->max_block_id());
@@ skipping 813 matching lines @@
   ASSERT(current_context_level >= 0);
   if (owner()->parsed_function()->saved_entry_context_var() != NULL) {
     // CTX on entry was saved, but not linked as context parent.
     BuildRestoreContext(*owner()->parsed_function()->saved_entry_context_var());
   } else {
     UnchainContexts(current_context_level);
   }
 
 
   AddReturnExit(node->token_pos(), return_value);
+
+  if (function.is_async_closure() &&
+      (node->return_type() == ReturnNode::kContinuationTarget)) {
+    JoinEntryInstr* const join = new(I) JoinEntryInstr(
+        owner()->AllocateBlockId(), owner()->try_index());
+    owner()->await_joins().Add(join);
+    exit_ = join;
+  }
 }
 
 
 // <Expression> ::= Literal { literal: Instance }
 void EffectGraphVisitor::VisitLiteralNode(LiteralNode* node) {
   ReturnDefinition(new(I) ConstantInstr(node->literal()));
 }
 
 
 // Type nodes are used when a type is referenced as a literal. Type nodes
@@ skipping 1114 matching lines @@
     LocalVariable* jump_var = node->scope()->LookupVariable(
         Symbols::AwaitJumpVar(), false);
     LocalVariable* ctx_var = node->scope()->LookupVariable(
         Symbols::AwaitContextVar(), false);
     ASSERT((jump_var != NULL) && jump_var->is_captured());
     ASSERT((ctx_var != NULL) && ctx_var->is_captured());
     const intptr_t jump_cnt = owner()->next_await_counter();
     ASSERT(jump_cnt >= 0);
     // Sanity check that we always add a JoinEntryInstr before adding a new
     // state.
-    ASSERT(jump_cnt == owner()->await_joins()->length());
+    ASSERT(jump_cnt == owner()->await_joins().length());
     // Store the counter in :await_jump_var.
     Value* jump_val = Bind(new (I) ConstantInstr(
         Smi::ZoneHandle(I, Smi::New(jump_cnt))));
     Do(BuildStoreLocal(*jump_var, jump_val));
     // Save the current context for resuming.
     BuildSaveContext(*ctx_var);
-    owner()->await_levels()->Add(owner()->context_level());
+    owner()->await_levels().Add(owner()->context_level());
     return;
   }
   if (node->marker_type() == AwaitMarkerNode::kTargetForContinuation) {
-    // We need to create a new await target which involves:
-    // * Append a join that is also added to the list that will later result in
-    //   a preamble.
-    JoinEntryInstr* const join = new(I) JoinEntryInstr(
-        owner()->AllocateBlockId(), owner()->try_index());
-    owner()->await_joins()->Add(join);
-    Goto(join);
-    exit_ = join;
-    return;
+    UNREACHABLE();  //XXX
   }
   UNREACHABLE();
 }
 
 
 intptr_t EffectGraphVisitor::GetCurrentTempLocalIndex() const {
   return kFirstLocalSlotFromFp
       - owner()->num_stack_locals()
       - owner()->num_copied_params()
       - owner()->args_pushed()
@@ skipping 1612 matching lines @@
     ASSERT(jump_var != NULL && jump_var->is_captured());
 
     Instruction* saved_entry = entry_;
     Instruction* saved_exit = exit_;
     entry_ = NULL;
     exit_ = NULL;
 
     LoadLocalNode* load_jump_cnt = new(I) LoadLocalNode(
         Scanner::kNoSourcePos, jump_var);
     ComparisonNode* check_jump_cnt;
-    const intptr_t num_await_states = owner()->await_joins()->length();
+    const intptr_t num_await_states = owner()->await_joins().length();
     for (intptr_t i = 0; i < num_await_states; i++) {
       check_jump_cnt = new(I) ComparisonNode(
           Scanner::kNoSourcePos,
           Token::kEQ,
           load_jump_cnt,
           new(I) LiteralNode(
               Scanner::kNoSourcePos, Smi::ZoneHandle(I, Smi::New(i))));
       TestGraphVisitor for_test(owner(), Scanner::kNoSourcePos);
       check_jump_cnt->Visit(&for_test);
       EffectGraphVisitor for_true(owner());
       EffectGraphVisitor for_false(owner());
 
       for_true.BuildAwaitJump(top_scope,
-                              (*owner()->await_levels())[i],
-                              (*owner()->await_joins())[i]);
+                              owner()->await_levels()[i],
+                              owner()->await_joins()[i]);
       Join(for_test, for_true, for_false);
 
       if (i == 0) {
         // Manually link up the preamble start.
         preamble_start->previous()->set_next(for_test.entry());
         for_test.entry()->set_previous(preamble_start->previous());
       }
       if (i == (num_await_states - 1)) {
         // Link up preamble end.
         if (exit_ == NULL) {
@@ skipping 375 matching lines @@
   Report::MessageF(Report::kBailout,
                    Script::Handle(function.script()),
                    function.token_pos(),
                    "FlowGraphBuilder Bailout: %s %s",
                    String::Handle(function.name()).ToCString(),
                    reason);
   UNREACHABLE();
 }
 
 }  // namespace dart