Reduce the number of virtual functions in hydrogen-instruction.h classes

src/x64/lithium-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 773 matching lines @@
 }
 
 
 LOperand* LChunkBuilder::FixedTemp(XMMRegister reg) {
   LUnallocated* operand = ToUnallocated(reg);
   allocator_->RecordTemporary(operand);
   return operand;
 }
 
 
+LInstruction* LChunkBuilder::DoPhi(HPhi* instr) {
+  UNREACHABLE();
+  return NULL;
+}
+
+
 LInstruction* LChunkBuilder::DoBlockEntry(HBlockEntry* instr) {
   return new LLabel(instr->block());
 }
 
 
 LInstruction* LChunkBuilder::DoDeoptimize(HDeoptimize* instr) {
   return AssignEnvironment(new LDeoptimize);
 }
 
 
@@ skipping 1324 matching lines @@
 
 LInstruction* LChunkBuilder::DoLeaveInlined(HLeaveInlined* instr) {
   HEnvironment* outer = current_block_->last_environment()->outer();
   current_block_->UpdateEnvironment(outer);
   return NULL;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64