LLVM  3.7.0
RandomNumberGenerator.h
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1 //==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines an abstraction for deterministic random number
11 // generation (RNG). Note that the current implementation is not
12 // cryptographically secure as it uses the C++11 <random> facilities.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_
17 #define LLVM_SUPPORT_RANDOMNUMBERGENERATOR_H_
18 
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/Support/Compiler.h"
21 #include "llvm/Support/DataTypes.h" // Needed for uint64_t on Windows.
22 #include <random>
23 
24 namespace llvm {
25 
26 /// A random number generator.
27 ///
28 /// Instances of this class should not be shared across threads. The
29 /// seed should be set by passing the -rng-seed=<uint64> option. Use
30 /// Module::createRNG to create a new RNG instance for use with that
31 /// module.
33 public:
34  /// Returns a random number in the range [0, Max).
35  uint_fast64_t operator()();
36 
37 private:
38  /// Seeds and salts the underlying RNG engine.
39  ///
40  /// This constructor should not be used directly. Instead use
41  /// Module::createRNG to create a new RNG salted with the Module ID.
43 
44  // 64-bit Mersenne Twister by Matsumoto and Nishimura, 2000
45  // http://en.cppreference.com/w/cpp/numeric/random/mersenne_twister_engine
46  // This RNG is deterministically portable across C++11
47  // implementations.
48  std::mt19937_64 Generator;
49 
50  // Noncopyable.
51  RandomNumberGenerator(const RandomNumberGenerator &other) = delete;
52  RandomNumberGenerator &operator=(const RandomNumberGenerator &other) = delete;
53 
54  friend class Module;
55 };
56 }
57 
58 #endif
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:114
uint_fast64_t operator()()
Returns a random number in the range [0, Max).
A random number generator.
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40