Implement compilation of conditional expressions.

runtime/vm/flow_graph_builder.cc

Index: runtime/vm/flow_graph_builder.cc
diff --git a/runtime/vm/flow_graph_builder.cc b/runtime/vm/flow_graph_builder.cc
index 4f387f971414ebb17531c0859d5693006b903521..20c01ef4e5e5c54f2cf5568e216b39d1150b94f5 100644
--- a/runtime/vm/flow_graph_builder.cc
+++ b/runtime/vm/flow_graph_builder.cc
@@ -538,7 +538,47 @@ void ValueGraphVisitor::VisitIncrOpIndexedNode(IncrOpIndexedNode* node) {
 
 
 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()));
 }