[compiler] Generalize JSContextSpecialization.

src/compiler/opcodes.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_OPCODES_H_
 #define V8_COMPILER_OPCODES_H_
 
 #include <iosfwd>
 
 #include "src/globals.h"
@@ skipping 777 matching lines @@
   static bool IsInlineeOpcode(Value value) {
     return value == kJSCallConstruct || value == kJSCallFunction;
   }
 
   // Returns true if opcode for comparison operator.
   static bool IsComparisonOpcode(Value value) {
     return (kJSEqual <= value && value <= kJSGreaterThanOrEqual) ||
            (kNumberEqual <= value && value <= kStringLessThanOrEqual) ||
            (kWord32Equal <= value && value <= kFloat64LessThanOrEqual);
   }
+
+  static bool IsContextExtendingOpcode(Value value) {

[Michael Starzinger, 2017/01/13 13:36:26]

nit: Can we either rename this predicate to "IsContextChainExtendingOpcode" or
at least add a comment that explains this is about extending the context
_chain_. Otherwise this risks being confused with the context extension we
perform for e.h. with-contexts. A comment might be useful either way.

[neis, 2017/01/13 14:08:02]

Done. Totally agree.

+    return kJSCreateFunctionContext <= value && value <= kJSCreateScriptContext;
+  }
 };
 
 V8_EXPORT_PRIVATE std::ostream& operator<<(std::ostream&, IrOpcode::Value);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_OPCODES_H_