Save/restore only live registers in the generator suspend/resume.

src/compiler/js-operator.h

 // Copyright 2013 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_JS_OPERATOR_H_
 #define V8_COMPILER_JS_OPERATOR_H_
 
 #include "src/base/compiler-specific.h"
 #include "src/globals.h"
 #include "src/handles.h"
@@ skipping 752 matching lines @@
   const Operator* ForInNext();
   const Operator* ForInPrepare();
 
   const Operator* LoadMessage();
   const Operator* StoreMessage();
 
   // Used to implement Ignition's SuspendGenerator bytecode.
   const Operator* GeneratorStore(int register_count,
                                  SuspendFlags suspend_flags);
 
-  // Used to implement Ignition's ResumeGenerator bytecode.
+  // Used to implement Ignition's RestoreGeneratorState bytecode.
   const Operator* GeneratorRestoreContinuation();
+  // Used to implement Ignition's RestoreGeneratorRegisters bytecode.
   const Operator* GeneratorRestoreRegister(int index);
 
   const Operator* StackCheck();
   const Operator* Debugger();
 
   const Operator* CreateFunctionContext(int slot_count, ScopeType scope_type);
   const Operator* CreateCatchContext(const Handle<String>& name,
                                      const Handle<ScopeInfo>& scope_info);
   const Operator* CreateWithContext(const Handle<ScopeInfo>& scope_info);
   const Operator* CreateBlockContext(const Handle<ScopeInfo>& scpope_info);
   const Operator* CreateModuleContext();
   const Operator* CreateScriptContext(const Handle<ScopeInfo>& scpope_info);
 
  private:
   Zone* zone() const { return zone_; }
 
   const JSOperatorGlobalCache& cache_;
   Zone* const zone_;
 
   DISALLOW_COPY_AND_ASSIGN(JSOperatorBuilder);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_OPERATOR_H_