[turbofan] Introduce PretenureFlagOf helper function.

src/compiler/simplified-operator.h

 // Copyright 2014 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_SIMPLIFIED_OPERATOR_H_
 #define V8_COMPILER_SIMPLIFIED_OPERATOR_H_
 
 #include <iosfwd>
 
 #include "src/compiler/operator.h"
@@ skipping 165 matching lines @@
   kNumberOrOddball,  // Inputs were Number or Oddball, output was Number.
 };
 
 size_t hash_value(NumberOperationHint);
 
 std::ostream& operator<<(std::ostream&, NumberOperationHint);
 
 NumberOperationHint NumberOperationHintOf(const Operator* op)
     WARN_UNUSED_RESULT;
 
+PretenureFlag PretenureFlagOf(const Operator* op) WARN_UNUSED_RESULT;
+
 // Interface for building simplified operators, which represent the
 // medium-level operations of V8, including adding numbers, allocating objects,
 // indexing into objects and arrays, etc.
 // All operators are typed but many are representation independent.
 
 // Number values from JS can be in one of these representations:
 //   - Tagged: word-sized integer that is either
 //     - a signed small integer (31 or 32 bits plus a tag)
 //     - a tagged pointer to a HeapNumber object that has a float64 field
 //   - Int32: an untagged signed 32-bit integer
@@ skipping 185 matching lines @@
   Zone* const zone_;
 
   DISALLOW_COPY_AND_ASSIGN(SimplifiedOperatorBuilder);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SIMPLIFIED_OPERATOR_H_