[x86] Fix register constraints for multiply-high.

src/compiler/instruction.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_H_
 #define V8_COMPILER_INSTRUCTION_H_
 
 #include <deque>
 #include <iosfwd>
 #include <map>
@@ skipping 239 matching lines @@
     return FixedRegisterField::decode(value_);
   }
 
   // [virtual_register]: The virtual register ID for this operand.
   int virtual_register() const { return VirtualRegisterField::decode(value_); }
   void set_virtual_register(unsigned id) {
     value_ = VirtualRegisterField::update(value_, id);
   }
 
   // [lifetime]: Only for non-FIXED_SLOT.
-  bool IsUsedAtStart() {
+  bool IsUsedAtStart() const {
     DCHECK(basic_policy() == EXTENDED_POLICY);
     return LifetimeField::decode(value_) == USED_AT_START;
   }
 };
 
 
 class MoveOperands FINAL {
  public:
   MoveOperands(InstructionOperand* source, InstructionOperand* destination)
       : source_(source), destination_(destination) {}
@@ skipping 709 matching lines @@
   DeoptimizationVector deoptimization_entries_;
 };
 
 std::ostream& operator<<(std::ostream& os, const InstructionSequence& code);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_H_