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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211715 91177308-0d34-0410-b5e6-96231b3b80d8
58 lines
2.1 KiB
C++
58 lines
2.1 KiB
C++
//==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines an abstraction for random number generation (RNG).
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// Note that the current implementation is not cryptographically secure
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// as it uses the C++11 <random> facilities.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_
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#define LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/DataTypes.h" // Needed for uint64_t on Windows.
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#include <random>
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namespace llvm {
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/// A random number generator.
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/// Instances of this class should not be shared across threads.
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class RandomNumberGenerator {
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public:
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/// Seeds and salts the underlying RNG engine. The salt of type StringRef
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/// is passed into the constructor. The seed can be set on the command
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/// line via -rng-seed=<uint64>.
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/// The reason for the salt is to ensure different random streams even if
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/// the same seed is used for multiple invocations of the compiler.
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/// A good salt value should add additional entropy and be constant across
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/// different machines (i.e., no paths) to allow for reproducible builds.
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/// An instance of this class can be retrieved from the current Module.
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/// \see Module::getRNG
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RandomNumberGenerator(StringRef Salt);
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/// Returns a random number in the range [0, Max).
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uint64_t next(uint64_t Max);
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private:
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// 64-bit Mersenne Twister by Matsumoto and Nishimura, 2000
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// http://en.cppreference.com/w/cpp/numeric/random/mersenne_twister_engine
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std::mt19937_64 Generator;
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// Noncopyable.
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RandomNumberGenerator(const RandomNumberGenerator &other)
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LLVM_DELETED_FUNCTION;
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RandomNumberGenerator &
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operator=(const RandomNumberGenerator &other) LLVM_DELETED_FUNCTION;
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};
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}
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#endif
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