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Random Number Generator Refactoring (removing from Module)

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This patch removes the RNG from Module. Passes should instead create a new RNG for their use as needed.

Patch by Stephen Crane @rinon.

Differential revision: http://reviews.llvm.org/D4377

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224444 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
JF Bastien
2014-12-17 18:12:10 +00:00
parent 9830b459be
commit 544f63e84a
4 changed files with 61 additions and 52 deletions
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30
lib/Support/RandomNumberGenerator.cpp
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@@ -7,16 +7,16 @@
//
//===----------------------------------------------------------------------===//
//
// This file implements random number generation (RNG).
// This file implements deterministic 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"
#include "llvm/Support/RandomNumberGenerator.h"
using namespace llvm;
@@ -31,31 +31,25 @@ Seed("rng-seed", cl::value_desc("seed"),
RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) {
DEBUG(
if (Seed == 0)
errs() << "Warning! Using unseeded random number generator.\n"
dbgs() << "Warning! Using unseeded random number generator.\n"
);
// Combine seed and salt using std::seed_seq.
// Entropy: Seed-low, Seed-high, Salt...
// Combine seed and salts using std::seed_seq.
// Data: Seed-low, Seed-high, Salt
// Note: std::seed_seq can only store 32-bit values, even though we
// are using a 64-bit RNG. This isn't a problem since the Mersenne
// twister constructor copies these correctly into its initial state.
std::vector<uint32_t> Data;
Data.reserve(2 + Salt.size()/4 + 1);
Data.reserve(2 + Salt.size());
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::copy(Salt.begin(), Salt.end(), Data.end());
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);
uint_fast64_t RandomNumberGenerator::operator()() {
return Generator();
}