[Interpreter] Add a simple dead-code elimination bytecode optimizer.

src/interpreter/bytecode-array-builder.cc

 // Copyright 2015 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-array-builder.h"
 
 #include "src/compiler.h"
 #include "src/interpreter/bytecode-array-writer.h"
+#include "src/interpreter/bytecode-dead-code-optimizer.h"
 #include "src/interpreter/bytecode-label.h"
 #include "src/interpreter/bytecode-peephole-optimizer.h"
 #include "src/interpreter/bytecode-register-optimizer.h"
 #include "src/interpreter/interpreter-intrinsics.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
 BytecodeArrayBuilder::BytecodeArrayBuilder(Isolate* isolate, Zone* zone,
                                            int parameter_count,
                                            int context_count, int locals_count,
                                            FunctionLiteral* literal)
     : isolate_(isolate),
       zone_(zone),
       bytecode_generated_(false),
       constant_array_builder_(isolate, zone),
       handler_table_builder_(isolate, zone),
       return_seen_in_block_(false),
       parameter_count_(parameter_count),
       local_register_count_(locals_count),
       context_register_count_(context_count),
       temporary_allocator_(zone, fixed_register_count()),
       bytecode_array_writer_(isolate, zone, &constant_array_builder_),
       pipeline_(&bytecode_array_writer_) {
   DCHECK_GE(parameter_count_, 0);
   DCHECK_GE(context_register_count_, 0);
   DCHECK_GE(local_register_count_, 0);
 
+  if (FLAG_ignition_deadcode) {
+    pipeline_ = new (zone) BytecodeDeadCodeOptimizer(pipeline_);
+  }
+
   if (FLAG_ignition_peephole) {
     pipeline_ = new (zone)
         BytecodePeepholeOptimizer(&constant_array_builder_, pipeline_);
   }
 
   if (FLAG_ignition_reo) {
     pipeline_ = new (zone) BytecodeRegisterOptimizer(
         zone, &temporary_allocator_, parameter_count, pipeline_);
   }
 
@@ skipping 869 matching lines @@
       return Bytecode::kTailCall;
     default:
       UNREACHABLE();
   }
   return Bytecode::kIllegal;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8