[stubs]: Support 1->2 byte copies in CopyStringCharacters

src/compiler/code-assembler.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_COMPILER_CODE_ASSEMBLER_H_
 #define V8_COMPILER_CODE_ASSEMBLER_H_
 
 #include <map>
 #include <memory>
 
@@ skipping 194 matching lines @@
     MachineRepresentation rep() const;
     bool IsBound() const;
 
    private:
     friend class CodeAssembler;
     class Impl;
     Impl* impl_;
     CodeAssembler* assembler_;
   };
 
+  typedef ZoneList<Variable*> VariableList;
+
   // ===========================================================================
   // Base Assembler
   // ===========================================================================
 
   // Constants.
   Node* Int32Constant(int32_t value);
   Node* Int64Constant(int64_t value);
   Node* IntPtrConstant(intptr_t value);
   Node* NumberConstant(double value);
   Node* SmiConstant(Smi* value);
@@ skipping 260 matching lines @@
 };
 
 class CodeAssembler::Label {
  public:
   enum Type { kDeferred, kNonDeferred };
 
   explicit Label(
       CodeAssembler* assembler,
       CodeAssembler::Label::Type type = CodeAssembler::Label::kNonDeferred)
       : CodeAssembler::Label(assembler, 0, nullptr, type) {}
+  Label(CodeAssembler* assembler, const VariableList& merged_variables,
+        CodeAssembler::Label::Type type = CodeAssembler::Label::kNonDeferred)
+      : CodeAssembler::Label(assembler, merged_variables.length(),
+                             &(merged_variables[0]), type) {}
+  Label(CodeAssembler* assembler, size_t count, Variable** vars,
+        CodeAssembler::Label::Type type = CodeAssembler::Label::kNonDeferred);
   Label(CodeAssembler* assembler, CodeAssembler::Variable* merged_variable,
         CodeAssembler::Label::Type type = CodeAssembler::Label::kNonDeferred)
-      : CodeAssembler::Label(assembler, 1, &merged_variable, type) {}
-  Label(CodeAssembler* assembler, int merged_variable_count,
-        CodeAssembler::Variable** merged_variables,
-        CodeAssembler::Label::Type type = CodeAssembler::Label::kNonDeferred);
+      : Label(assembler, 1, &merged_variable, type) {}
   ~Label() {}
 
  private:
   friend class CodeAssembler;
 
   void Bind();
   void MergeVariables();
 
   bool bound_;
   size_t merge_count_;
   CodeAssembler* assembler_;
   RawMachineLabel* label_;
   // Map of variables that need to be merged to their phi nodes (or placeholders
   // for those phis).
   std::map<Variable::Impl*, Node*> variable_phis_;
   // Map of variables to the list of value nodes that have been added from each
   // merge path in their order of merging.
   std::map<Variable::Impl*, std::vector<Node*>> variable_merges_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_CODE_ASSEMBLER_H_