[turbofan] Initial version of branch cloning.

test/unittests/compiler/control-flow-optimizer-unittest.cc

Index: test/unittests/compiler/control-flow-optimizer-unittest.cc
diff --git a/test/unittests/compiler/control-flow-optimizer-unittest.cc b/test/unittests/compiler/control-flow-optimizer-unittest.cc
index c083d4bab5c62afd6c2e23e7f2c659a3e69bf10e..f5c182934ba08ec5d481928c93d8dd0622125622 100644
--- a/test/unittests/compiler/control-flow-optimizer-unittest.cc
+++ b/test/unittests/compiler/control-flow-optimizer-unittest.cc
@@ -39,7 +39,7 @@ class ControlFlowOptimizerTest : public GraphTest {
 };
 
 
-TEST_F(ControlFlowOptimizerTest, Switch) {
+TEST_F(ControlFlowOptimizerTest, BuildSwitch) {
   Node* index = Parameter(0);
   Node* branch0 = graph()->NewNode(
       common()->Branch(),
@@ -65,6 +65,34 @@ TEST_F(ControlFlowOptimizerTest, Switch) {
                                               IsSwitch(index, start()))))));
 }
 
+
+TEST_F(ControlFlowOptimizerTest, CloneBranch) {
+  Node* cond0 = Parameter(0);
+  Node* cond1 = Parameter(1);
+  Node* cond2 = Parameter(2);
+  Node* branch0 = graph()->NewNode(common()->Branch(), cond0, start());
+  Node* control1 = graph()->NewNode(common()->IfTrue(), branch0);
+  Node* control2 = graph()->NewNode(common()->IfFalse(), branch0);
+  Node* merge0 = graph()->NewNode(common()->Merge(2), control1, control2);
+  Node* phi0 =
+      graph()->NewNode(common()->Phi(kRepBit, 2), cond1, cond2, merge0);
+  Node* branch = graph()->NewNode(common()->Branch(), phi0, merge0);
+  Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
+  Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
+  Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
+  graph()->SetEnd(graph()->NewNode(common()->End(), merge));
+  Optimize();
+  Capture<Node*> branch1_capture, branch2_capture;
+  EXPECT_THAT(
+      end(),
+      IsEnd(IsMerge(IsMerge(IsIfTrue(CaptureEq(&branch1_capture)),
+                            IsIfTrue(CaptureEq(&branch2_capture))),
+                    IsMerge(IsIfFalse(AllOf(CaptureEq(&branch1_capture),
+                                            IsBranch(cond1, control1))),
+                            IsIfFalse(AllOf(CaptureEq(&branch2_capture),
+                                            IsBranch(cond2, control2)))))));
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8