[llvm] r211705 - Random Number Generator (llvm)
JF Bastien
jfb at google.com
Wed Jun 25 08:21:42 PDT 2014
Author: jfb
Date: Wed Jun 25 10:21:42 2014
New Revision: 211705
URL: http://llvm.org/viewvc/llvm-project?rev=211705&view=rev
Log:
Random Number Generator (llvm)
Provides an abstraction for a random number generator (RNG) that produces a stream of pseudo-random numbers.
The current implementation uses C++11 facilities and is therefore not cryptographically secure.
The RNG is salted with the text of the current command line invocation.
In addition, a user may specify a seed (reproducible builds).
In clang, the seed can be set via
-frandom-seed=X
In the back end, the seed can be set via
-rng-seed=X
This is the llvm part of the patch.
clang part: D3391
URL: http://reviews.llvm.org/D3390
Author: yln
I'm landing this for the second time, it broke Windows bots the first time around.
Added:
llvm/trunk/include/llvm/Support/RandomNumberGenerator.h (with props)
llvm/trunk/lib/Support/RandomNumberGenerator.cpp (with props)
Modified:
llvm/trunk/include/llvm/IR/Module.h
llvm/trunk/lib/IR/Module.cpp
llvm/trunk/lib/Support/CMakeLists.txt
Modified: llvm/trunk/include/llvm/IR/Module.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Module.h?rev=211705&r1=211704&r2=211705&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Module.h (original)
+++ llvm/trunk/include/llvm/IR/Module.h Wed Jun 25 10:21:42 2014
@@ -29,6 +29,7 @@ namespace llvm {
class FunctionType;
class GVMaterializer;
class LLVMContext;
+class RandomNumberGenerator;
class StructType;
template<typename T> struct DenseMapInfo;
template<typename KeyT, typename ValueT, typename KeyInfoT> class DenseMap;
@@ -201,6 +202,8 @@ private:
std::string ModuleID; ///< Human readable identifier for the module
std::string TargetTriple; ///< Platform target triple Module compiled on
void *NamedMDSymTab; ///< NamedMDNode names.
+ // Allow lazy initialization in const method.
+ mutable RandomNumberGenerator *RNG; ///< The random number generator for this module.
// We need to keep the string because the C API expects us to own the string
// representation.
@@ -249,6 +252,11 @@ public:
/// @returns a string containing the module-scope inline assembly blocks.
const std::string &getModuleInlineAsm() const { return GlobalScopeAsm; }
+ /// Get the RandomNumberGenerator for this module. The RNG can be
+ /// seeded via -rng-seed=<uint64> and is salted with the ModuleID.
+ /// The returned RNG should not be shared across threads.
+ RandomNumberGenerator &getRNG() const;
+
/// @}
/// @name Module Level Mutators
/// @{
Added: llvm/trunk/include/llvm/Support/RandomNumberGenerator.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/RandomNumberGenerator.h?rev=211705&view=auto
==============================================================================
--- llvm/trunk/include/llvm/Support/RandomNumberGenerator.h (added)
+++ llvm/trunk/include/llvm/Support/RandomNumberGenerator.h Wed Jun 25 10:21:42 2014
@@ -0,0 +1,54 @@
+//==- llvm/Support/RandomNumberGenerator.h - RNG for diversity ---*- C++ -*-==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines an abstraction for 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/ADT/StringRef.h"
+#include "llvm/Support/DataTypes.h" // Needed for uint64_t on Windows.
+#include <random>
+
+namespace llvm {
+
+/// A random number generator.
+/// Instances of this class should not be shared across threads.
+class RandomNumberGenerator {
+public:
+ /// Seeds and salts the underlying RNG engine. The salt of type StringRef
+ /// is passed into the constructor. The seed can be set on the command
+ /// line via -rng-seed=<uint64>.
+ /// The reason for the salt is to ensure different random streams even if
+ /// the same seed is used for multiple invocations of the compiler.
+ /// A good salt value should add additional entropy and be constant across
+ /// different machines (i.e., no paths) to allow for reproducible builds.
+ /// An instance of this class can be retrieved from the current Module.
+ /// \see Module::getRNG
+ RandomNumberGenerator(StringRef Salt);
+
+ /// Returns a random number in the range [0, Max).
+ uint64_t next(uint64_t Max);
+
+private:
+ // 64-bit Mersenne Twister by Matsumoto and Nishimura, 2000
+ // http://en.cppreference.com/w/cpp/numeric/random/mersenne_twister_engine
+ std::mt19937_64 Generator;
+
+ // Noncopyable.
+ RandomNumberGenerator(const RandomNumberGenerator &other) = delete;
+ RandomNumberGenerator &operator=(const RandomNumberGenerator &other) = delete;
+};
+}
+
+#endif
Propchange: llvm/trunk/include/llvm/Support/RandomNumberGenerator.h
------------------------------------------------------------------------------
svn:eol-style = LF
Modified: llvm/trunk/lib/IR/Module.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Module.cpp?rev=211705&r1=211704&r2=211705&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Module.cpp (original)
+++ llvm/trunk/lib/IR/Module.cpp Wed Jun 25 10:21:42 2014
@@ -24,6 +24,8 @@
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LeakDetector.h"
#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/RandomNumberGenerator.h"
#include <algorithm>
#include <cstdarg>
#include <cstdlib>
@@ -44,7 +46,7 @@ template class llvm::SymbolTableListTrai
//
Module::Module(StringRef MID, LLVMContext &C)
- : Context(C), Materializer(), ModuleID(MID), DL("") {
+ : Context(C), Materializer(), ModuleID(MID), RNG(nullptr), DL("") {
ValSymTab = new ValueSymbolTable();
NamedMDSymTab = new StringMap<NamedMDNode *>();
Context.addModule(this);
@@ -59,6 +61,7 @@ Module::~Module() {
NamedMDList.clear();
delete ValSymTab;
delete static_cast<StringMap<NamedMDNode *> *>(NamedMDSymTab);
+ delete RNG;
}
/// getNamedValue - Return the first global value in the module with
@@ -355,6 +358,16 @@ const DataLayout *Module::getDataLayout(
return &DL;
}
+// We want reproducible builds, but ModuleID may be a full path so we just use
+// the filename to salt the RNG (although it is not guaranteed to be unique).
+RandomNumberGenerator &Module::getRNG() const {
+ if (RNG == nullptr) {
+ StringRef Salt = sys::path::filename(ModuleID);
+ RNG = new RandomNumberGenerator(Salt);
+ }
+ return *RNG;
+}
+
//===----------------------------------------------------------------------===//
// Methods to control the materialization of GlobalValues in the Module.
//
Modified: llvm/trunk/lib/Support/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/CMakeLists.txt?rev=211705&r1=211704&r2=211705&view=diff
==============================================================================
--- llvm/trunk/lib/Support/CMakeLists.txt (original)
+++ llvm/trunk/lib/Support/CMakeLists.txt Wed Jun 25 10:21:42 2014
@@ -41,6 +41,7 @@ add_llvm_library(LLVMSupport
MD5.cpp
PluginLoader.cpp
PrettyStackTrace.cpp
+ RandomNumberGenerator.cpp
Regex.cpp
ScaledNumber.cpp
SmallPtrSet.cpp
Added: llvm/trunk/lib/Support/RandomNumberGenerator.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/RandomNumberGenerator.cpp?rev=211705&view=auto
==============================================================================
--- llvm/trunk/lib/Support/RandomNumberGenerator.cpp (added)
+++ llvm/trunk/lib/Support/RandomNumberGenerator.cpp Wed Jun 25 10:21:42 2014
@@ -0,0 +1,61 @@
+//===-- RandomNumberGenerator.cpp - Implement RNG class -------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements random number generation (RNG).
+// The current implementation is NOT cryptographically secure as it uses
+// the C++11 <random> facilities.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "rng"
+#include "llvm/Support/RandomNumberGenerator.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+
+using namespace llvm;
+
+// Tracking BUG: 19665
+// http://llvm.org/bugs/show_bug.cgi?id=19665
+//
+// Do not change to cl::opt<uint64_t> since this silently breaks argument parsing.
+static cl::opt<unsigned long long>
+Seed("rng-seed", cl::value_desc("seed"),
+ cl::desc("Seed for the random number generator"), cl::init(0));
+
+RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) {
+ DEBUG(
+ if (Seed == 0)
+ errs() << "Warning! Using unseeded random number generator.\n"
+ );
+
+ // Combine seed and salt using std::seed_seq.
+ // Entropy: Seed-low, Seed-high, Salt...
+ std::vector<uint32_t> Data;
+ Data.reserve(2 + Salt.size()/4 + 1);
+ Data.push_back(Seed);
+ Data.push_back(Seed >> 32);
+
+ uint32_t Pack = 0;
+ for (size_t I = 0; I < Salt.size(); ++I) {
+ Pack <<= 8;
+ Pack += Salt[I];
+
+ if (I%4 == 3)
+ Data.push_back(Pack);
+ }
+ Data.push_back(Pack);
+
+ std::seed_seq SeedSeq(Data.begin(), Data.end());
+ Generator.seed(SeedSeq);
+}
+
+uint64_t RandomNumberGenerator::next(uint64_t Max) {
+ std::uniform_int_distribution<uint64_t> distribution(0, Max - 1);
+ return distribution(Generator);
+}
Propchange: llvm/trunk/lib/Support/RandomNumberGenerator.cpp
------------------------------------------------------------------------------
svn:eol-style = LF
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