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

src/compiler/common-operator.h

 // Copyright 2013 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_COMMON_OPERATOR_H_
 #define V8_COMPILER_COMMON_OPERATOR_H_
 
 #include "src/compiler/machine-type.h"
 #include "src/unique.h"
 
@@ skipping 15 matching lines @@
 // Prediction hint for branches.
 enum class BranchHint : uint8_t { kNone, kTrue, kFalse };
 
 inline size_t hash_value(BranchHint hint) { return static_cast<size_t>(hint); }
 
 std::ostream& operator<<(std::ostream&, BranchHint);
 
 BranchHint BranchHintOf(const Operator* const);
 
 
-size_t CaseIndexOf(const Operator* const);
-
-
 class SelectParameters FINAL {
  public:
   explicit SelectParameters(MachineType type,
                             BranchHint hint = BranchHint::kNone)
       : type_(type), hint_(hint) {}
 
   MachineType type() const { return type_; }
   BranchHint hint() const { return hint_; }
 
  private:
@@ skipping 120 matching lines @@
   // still unfoldable. This is required to properly connect non terminating
   // loops to end (in both the sea of nodes and the CFG).
   const Operator* Always();
 
   const Operator* Dead();
   const Operator* End();
   const Operator* Branch(BranchHint = BranchHint::kNone);
   const Operator* IfTrue();
   const Operator* IfFalse();
   const Operator* Switch(size_t control_output_count);
-  const Operator* Case(size_t index);
+  const Operator* IfValue(int32_t value);
+  const Operator* IfDefault();
   const Operator* Throw();
   const Operator* Return();
 
   const Operator* Start(int num_formal_parameters);
   const Operator* Loop(int control_input_count);
   const Operator* Merge(int control_input_count);
   const Operator* Parameter(int index);
 
   const Operator* OsrNormalEntry();
   const Operator* OsrLoopEntry();
@@ skipping 32 matching lines @@
   Zone* const zone_;
 
   DISALLOW_COPY_AND_ASSIGN(CommonOperatorBuilder);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_COMMON_OPERATOR_H_