Initial implementation of a record-level bitcode fuzzer.

lib/Bitcode/NaCl/TestUtils/NaClRandNumGen.cpp

+//===- NaClRandNumGen.cpp - Random number generator -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides a default implementation of a random number generator.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/NaCl/NaClRandNumGen.h"
+
+#include <vector>
+#include <algorithm>
+
+namespace naclfuzz {
+
+// Put destructor in .cpp file guarantee vtable construction.
+RandomNumberGenerator::~RandomNumberGenerator() {}
+
+DefaultRandomNumberGenerator::DefaultRandomNumberGenerator(llvm::StringRef Seed)
+    : Seed(Seed) {
+  saltSeed(0);
+}
+
+uint64_t DefaultRandomNumberGenerator::operator()() {
+  return Generator();
+}
+
+void DefaultRandomNumberGenerator::saltSeed(uint64_t Salt) {
+  // Combine seed and salt and pass to generator.
+  std::vector<uint32_t> Data;
+  Data.reserve(Seed.size() + 2);
+  Data.push_back(static_cast<uint32_t>(Salt));
+  Data.push_back(static_cast<uint32_t>(Salt >> 32));
+  std::copy(Seed.begin(), Seed.end(), Data.end());
+  std::seed_seq SeedSeq(Data.begin(), Data.end());
+  Generator.seed(SeedSeq);
+}
+
+} // end of namespace naclfuzz