Implement compilation of conditional expressions.

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 "vm/ast_printer.h"
 #include "vm/flags.h"
 #include "vm/intermediate_language.h"
 #include "vm/longjump.h"
@@ skipping 520 matching lines @@
   arguments->Add(new TempVal(value_index));
   InstanceCallComp* store =
       new InstanceCallComp(node->store_id(), node->token_index(), store_name,
                            arguments, Array::ZoneHandle(), 1);
   AddInstruction(new DoInstr(store));
   ReturnValue(new TempVal(AllocateTempIndex()));
 }
 
 
 void EffectGraphVisitor::VisitConditionalExprNode(ConditionalExprNode* node) {
-  Bailout("EffectGraphVisitor::VisitConditionalExprNode");
+  TestGraphVisitor for_test(owner(), temp_index());
+  node->condition()->Visit(&for_test);
+  ASSERT(for_test.can_be_true() && for_test.can_be_false());
+
+  // Translate the subexpressions for their effects.
+  EffectGraphVisitor for_true(owner(), temp_index());
+  node->true_expr()->Visit(&for_true);
+  EffectGraphVisitor for_false(owner(), temp_index());
+  node->false_expr()->Visit(&for_false);
+
+  Join(for_test, for_true, for_false);
 }
 
 
+void ValueGraphVisitor::VisitConditionalExprNode(ConditionalExprNode* node) {
+  TestGraphVisitor for_test(owner(), temp_index());
+  node->condition()->Visit(&for_test);
+  ASSERT(for_test.can_be_true() && for_test.can_be_false());

[srdjan, 2012/03/08 17:43:53]

Again, what is the point of can_be_true and can_be_false? They are always true,
there is no way to test code that uses it (not here, but in other VisitXXX)

[Kevin Millikin (Google), 2012/03/09 09:53:01]

To support online constant folding of conditional expressions.

+
+  // Ensure that the value of the true/false subexpressions are named with
+  // the same temporary name.
+  ValueGraphVisitor for_true(owner(), temp_index());
+  node->true_expr()->Visit(&for_true);
+  ASSERT(for_true.is_open());
+  if (for_true.value()->IsTemp()) {
+    ASSERT(for_true.value()->AsTemp()->index() == temp_index());
+  } else {
+    for_true.AddInstruction(new BindInstr(temp_index(), for_true.value()));
+  }
+
+  ValueGraphVisitor for_false(owner(), temp_index());
+  node->false_expr()->Visit(&for_false);
+  ASSERT(for_false.is_open());
+  if (for_false.value()->IsTemp()) {
+    ASSERT(for_false.value()->AsTemp()->index() == temp_index());
+  } else {
+    for_false.AddInstruction(new BindInstr(temp_index(), for_false.value()));
+  }
+
+  Join(for_test, for_true, for_false);
+  ReturnValue(new TempVal(AllocateTempIndex()));
+}
+
+
 // <Statement> ::= If { condition: <Expression>
 //                      true_branch: <Sequence>
 //                      false_branch: <Sequence> }
 void EffectGraphVisitor::VisitIfNode(IfNode* node) {
   TestGraphVisitor for_test(owner(), temp_index());
   node->condition()->Visit(&for_test);
 
   EffectGraphVisitor for_true(owner(), temp_index());
   EffectGraphVisitor for_false(owner(), temp_index());
 
@@ skipping 621 matching lines @@
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len));
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart