[turbofan] Optimize certain chains of Branch into a Switch.

src/compiler/raw-machine-assembler.h

 // Copyright 2014 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.
 
 #ifndef V8_COMPILER_RAW_MACHINE_ASSEMBLER_H_
 #define V8_COMPILER_RAW_MACHINE_ASSEMBLER_H_
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph-builder.h"
 #include "src/compiler/linkage.h"
@@ skipping 382 matching lines @@
     return NewNode(machine()->Float64RoundTiesAway(), a);
   }
 
   // Parameters.
   Node* Parameter(size_t index);
 
   // Control flow.
   Label* Exit();
   void Goto(Label* label);
   void Branch(Node* condition, Label* true_val, Label* false_val);
-  void Switch(Node* index, Label** succ_labels, size_t succ_count);
+  void Switch(Node* index, Label* default_label, int32_t* case_values,
+              Label** case_labels, size_t case_count);
   // Call through CallFunctionStub with lazy deopt and frame-state.
   Node* CallFunctionStub0(Node* function, Node* receiver, Node* context,
                           Node* frame_state, CallFunctionFlags flags);
   // Call to a JS function with zero parameters.
   Node* CallJS0(Node* function, Node* receiver, Node* context,
                 Node* frame_state);
   // Call to a runtime function with zero parameters.
   Node* CallRuntime1(Runtime::FunctionId function, Node* arg0, Node* context,
                      Node* frame_state);
   void Return(Node* value);
@@ skipping 40 matching lines @@
   BasicBlock* current_block_;
 
   DISALLOW_COPY_AND_ASSIGN(RawMachineAssembler);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_RAW_MACHINE_ASSEMBLER_H_