[interpreter] Minor clean-up of BytecodeSourceInfo.

src/interpreter/bytecode-register-optimizer.cc

 // Copyright 2016 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.
 
 #include "src/interpreter/bytecode-register-optimizer.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
@@ skipping 293 matching lines @@
 
   flush_required_ = false;
 }
 
 void BytecodeRegisterOptimizer::WriteToNextStage(BytecodeNode* node) const {
   next_stage_->Write(node);
 }
 
 void BytecodeRegisterOptimizer::WriteToNextStage(
     BytecodeNode* node, const BytecodeSourceInfo& source_info) const {
-  node->source_info().Update(source_info);
+  if (source_info.is_valid()) {
+    node->source_info().MakeInvalidEqualTo(source_info);
+  }
   next_stage_->Write(node);
 }
 
 void BytecodeRegisterOptimizer::OutputRegisterTransfer(
     RegisterInfo* input_info, RegisterInfo* output_info,
     const BytecodeSourceInfo& source_info) {
   Register input = input_info->register_value();
   Register output = output_info->register_value();
   DCHECK_NE(input.index(), output.index());
 
@@ skipping 81 matching lines @@
     RegisterInfo* materialized_info = input_info->GetMaterializedEquivalent();
     OutputRegisterTransfer(materialized_info, output_info, source_info);
   } else if (source_info.is_valid()) {
     // Emit a placeholder nop to maintain source position info.
     EmitNopForSourceInfo(source_info);
   }
 }
 
 void BytecodeRegisterOptimizer::EmitNopForSourceInfo(
     const BytecodeSourceInfo& source_info) const {
+  DCHECK(source_info.is_valid());
   BytecodeNode nop(Bytecode::kNop);
-  nop.source_info().Update(source_info);
+  nop.source_info().MakeInvalidEqualTo(source_info);
   WriteToNextStage(&nop);
 }
 
 void BytecodeRegisterOptimizer::DoLdar(const BytecodeNode* const node) {
   Register input = GetRegisterInputOperand(
       0, node->bytecode(), node->operands(), node->operand_count());
   RegisterInfo* input_info = GetRegisterInfo(input);
   RegisterTransfer(input_info, accumulator_info_, node->source_info());
 }
 
@@ skipping 189 matching lines @@
     if (info->materialized()) {
       CreateMaterializedEquivalent(info);
     }
     info->MoveToNewEquivalenceSet(kInvalidEquivalenceId, false);
   }
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8