Enable await in while and do-while.

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 667 matching lines @@
   } else {
     JoinEntryInstr* join =
         new(I) JoinEntryInstr(owner()->AllocateBlockId(), owner()->try_index());
     true_exit->Goto(join);
     false_exit->Goto(join);
     exit_ = join;
   }
 }
 
 
-void EffectGraphVisitor::TieLoop(intptr_t token_pos,
-                                 const TestGraphVisitor& test_fragment,
-                                 const EffectGraphVisitor& body_fragment) {
+void EffectGraphVisitor::TieLoop(
+    intptr_t token_pos,
+    const TestGraphVisitor& test_fragment,
+    const EffectGraphVisitor& body_fragment,
+    const EffectGraphVisitor& test_preamble_fragment) {
   // We have: a test graph fragment with zero, one, or two available exits;
   // and an effect graph fragment with zero or one available exits.  We want
   // to append the 'while loop' consisting of the test graph fragment as
   // condition and the effect graph fragment as body.
   ASSERT(is_open());
 
   // 1. Connect the body to the test if it is reachable, and if so record
   // its exit (if any).
   BlockEntryInstr* body_entry = test_fragment.CreateTrueSuccessor();
   Instruction* body_exit = AppendFragment(body_entry, body_fragment);
 
   // 2. Connect the test to this graph, including the body if reachable and
   // using a fresh join node if the body is reachable and has an open exit.
   if (body_exit == NULL) {
+    Append(test_preamble_fragment);
     Append(test_fragment);
   } else {
     JoinEntryInstr* join =
         new(I) JoinEntryInstr(owner()->AllocateBlockId(), owner()->try_index());
     CheckStackOverflowInstr* check =
         new(I) CheckStackOverflowInstr(token_pos, owner()->loop_depth());
     join->LinkTo(check);
-    check->LinkTo(test_fragment.entry());
+    if (!test_preamble_fragment.is_empty()) {
+      check->LinkTo(test_preamble_fragment.entry());
+      test_preamble_fragment.exit()->LinkTo(test_fragment.entry());
+    } else {
+      check->LinkTo(test_fragment.entry());
+    }
     Goto(join);
     body_exit->Goto(join);
   }
 
   // 3. Set the exit to the graph to be the false successor of the test, a
   // fresh target node
   exit_ = test_fragment.CreateFalseSuccessor();
 }
 
 
@@ skipping 1237 matching lines @@
   ASSERT(!is_open());
   exit_ = exit_instruction;
 }
 
 
 // <Statement> ::= While { label:     SourceLabel
 //                         condition: <Expression>
 //                         body:      <Sequence> }
 // The fragment is composed as follows:
 // a) loop-join
-// b) [ test ] -> (body-entry-target, loop-exit-target)
-// c) body-entry-target
-// d) [ body ] -> (continue-join)
-// e) continue-join -> (loop-join)
-// f) loop-exit-target
-// g) break-join (optional)
+// b) [ test_preamble ]?
+// c) [ test ] -> (body-entry-target, loop-exit-target)
+// d) body-entry-target
+// e) [ body ] -> (continue-join)
+// f) continue-join -> (loop-join)
+// g) loop-exit-target
+// h) break-join (optional)
 void EffectGraphVisitor::VisitWhileNode(WhileNode* node) {
   NestedLoop nested_loop(owner(), node->label());
 
+  EffectGraphVisitor for_preamble(owner());
+  if (node->condition_preamble() != NULL) {
+    node->condition_preamble()->Visit(&for_preamble);
+  }
+
   TestGraphVisitor for_test(owner(), node->condition()->token_pos());
   node->condition()->Visit(&for_test);
   ASSERT(!for_test.is_empty());  // Language spec.
 
   EffectGraphVisitor for_body(owner());
   node->body()->Visit(&for_body);
 
   // Labels are set after body traversal.
   JoinEntryInstr* join = nested_loop.continue_target();
   if (join != NULL) {
     if (for_body.is_open()) for_body.Goto(join);
     for_body.exit_ = join;
   }
-  TieLoop(node->token_pos(), for_test, for_body);
+  TieLoop(node->token_pos(), for_test, for_body, for_preamble);
   join = nested_loop.break_target();
   if (join != NULL) {
     Goto(join);
     exit_ = join;
   }
 }
 
 
 // The fragment is composed as follows:
 // a) body-entry-join
@@ skipping 2184 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