1 files changed, 55 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Support/RandomNumberGenerator.cpp b/contrib/llvm/lib/Support/RandomNumberGenerator.cpp
new file mode 100644
index 0000000..2943137
--- /dev/null
+++ b/contrib/llvm/lib/Support/RandomNumberGenerator.cpp
@@ -0,0 +1,55 @@
+//===-- 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 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/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/RandomNumberGenerator.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)
+      dbgs() << "Warning! Using unseeded random number generator.\n"
+  );
+
+  // 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());
+  Data.push_back(Seed);
+  Data.push_back(Seed >> 32);
+
+  std::copy(Salt.begin(), Salt.end(), Data.end());
+
+  std::seed_seq SeedSeq(Data.begin(), Data.end());
+  Generator.seed(SeedSeq);
+}
+
+uint_fast64_t RandomNumberGenerator::operator()() {
+  return Generator();
+}