[turbofan] Factor out common switch-related code in instruction selectors.

src/compiler/instruction-selector-impl.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_INSTRUCTION_SELECTOR_IMPL_H_
 #define V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/schedule.h"
 #include "src/macro-assembler.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
+// Helper struct containing data about a table or lookup switch.
+struct SwitchInfo {
+  int32_t min_value;           // minimum value of {case_values}
+  int32_t max_value;           // maximum value of {case_values}
+  size_t value_range;          // |max_value - min_value| + 1
+  size_t case_count;           // number of cases
+  int32_t* case_values;        // actual case values, unsorted
+  BasicBlock** case_branches;  // basic blocks corresponding to case values
+  BasicBlock* default_branch;  // default branch target
+};
+
 // A helper class for the instruction selector that simplifies construction of
 // Operands. This class implements a base for architecture-specific helpers.
 class OperandGenerator {
  public:
   explicit OperandGenerator(InstructionSelector* selector)
       : selector_(selector) {}
 
   InstructionOperand NoOutput() {
     return InstructionOperand();  // Generates an invalid operand.
   }
@@ skipping 341 matching lines @@
                : (frame_state_descriptor->GetTotalSize() +
                   1);  // Include deopt id.
   }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_