Reland of [ignition/turbo] Perform liveness analysis on the bytecodes

src/interpreter/control-flow-builders.h

 // 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.
 
 #ifndef V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_
 #define V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_
 
 #include "src/interpreter/bytecode-array-builder.h"
 
 #include "src/interpreter/bytecode-label.h"
@@ skipping 67 matching lines @@
 // A class to help with co-ordinating break and continue statements with
 // their loop.
 class LoopBuilder final : public BreakableControlFlowBuilder {
  public:
   explicit LoopBuilder(BytecodeArrayBuilder* builder)
       : BreakableControlFlowBuilder(builder),
         continue_labels_(builder->zone()),
         header_labels_(builder->zone()) {}
   ~LoopBuilder();
 
-  void LoopHeader(ZoneVector<BytecodeLabel>* additional_labels);
+  void LoopHeader(ZoneVector<BytecodeLabel>* additional_labels = nullptr);
   void JumpToHeader(int loop_depth);
   void BindContinueTarget();
   void EndLoop();
 
   // This method is called when visiting continue statements in the AST.
   // Inserts a jump to an unbound label that is patched when BindContinueTarget
   // is called.
   void Continue() { EmitJump(&continue_labels_); }
   void ContinueIfTrue() { EmitJumpIfTrue(&continue_labels_); }
   void ContinueIfUndefined() { EmitJumpIfUndefined(&continue_labels_); }
@@ skipping 84 matching lines @@
 
   // Unbound labels that identify jumps to the finally block in the code.
   BytecodeLabels finalization_sites_;
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_