[turbofan] Initial version of branch cloning.

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

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/control-flow-optimizer.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/machine-operator.h"
 #include "test/unittests/compiler/graph-unittest.h"
 #include "test/unittests/compiler/node-test-utils.h"
@@ skipping 21 matching lines @@
     optimizer.Optimize();
   }
 
   MachineOperatorBuilder* machine() { return &machine_; }
 
  private:
   MachineOperatorBuilder machine_;
 };
 
 
-TEST_F(ControlFlowOptimizerTest, Switch) {
+TEST_F(ControlFlowOptimizerTest, BuildSwitch) {
   Node* index = Parameter(0);
   Node* branch0 = graph()->NewNode(
       common()->Branch(),
       graph()->NewNode(machine()->Word32Equal(), index, Int32Constant(0)),
       start());
   Node* if_true0 = graph()->NewNode(common()->IfTrue(), branch0);
   Node* if_false0 = graph()->NewNode(common()->IfFalse(), branch0);
   Node* branch1 = graph()->NewNode(
       common()->Branch(),
       graph()->NewNode(machine()->Word32Equal(), index, Int32Constant(1)),
       if_false0);
   Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
   Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
   Node* merge =
       graph()->NewNode(common()->Merge(3), if_true0, if_true1, if_false1);
   graph()->SetEnd(graph()->NewNode(common()->End(), merge));
   Optimize();
   Capture<Node*> switch_capture;
   EXPECT_THAT(end(),
               IsEnd(IsMerge(IsIfValue(0, CaptureEq(&switch_capture)),
                             IsIfValue(1, CaptureEq(&switch_capture)),
                             IsIfDefault(AllOf(CaptureEq(&switch_capture),
                                               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