Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file defines an abstraction for deterministic random number

// generation (RNG).  Note that the current implementation is not

// cryptographically secure as it uses the C++11 <random> facilities.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_

#define LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_

#include "llvm/Support/Compiler.h"

#include "llvm/Support/DataTypes.h" // Needed for uint64_t on Windows.

#include <random>

#include <system_error>

namespace llvm {

class StringRef;

/// A random number generator.

///

/// Instances of this class should not be shared across threads. The

/// seed should be set by passing the -rng-seed=<uint64> option. Use

/// Module::createRNG to create a new RNG instance for use with that

/// module.

class RandomNumberGenerator {

  // 64-bit Mersenne Twister by Matsumoto and Nishimura, 2000

  // http://en.cppreference.com/w/cpp/numeric/random/mersenne_twister_engine

  // This RNG is deterministically portable across C++11

  // implementations.

  using generator_type = std::mt19937_64;

public:

  using result_type = generator_type::result_type;

  /// Returns a random number in the range [0, Max).

  result_type operator()();

  static constexpr result_type min() { return generator_type::min(); }

  static constexpr result_type max() { return generator_type::max(); }

private:

  /// Seeds and salts the underlying RNG engine.

  ///

  /// This constructor should not be used directly. Instead use

  /// Module::createRNG to create a new RNG salted with the Module ID.

  RandomNumberGenerator(StringRef Salt);

  generator_type Generator;

  // Noncopyable.

  RandomNumberGenerator(const RandomNumberGenerator &other) = delete;

  RandomNumberGenerator &operator=(const RandomNumberGenerator &other) = delete;

  friend class Module;

};

// Get random vector of specified size

std::error_code getRandomBytes(void *Buffer, size_t Size);

}

#endif