Merge "Revert "Use arc4random when available to select delta for image relocation.""

3 files changed, 4 insertions, 26 deletions

diff --git a/runtime/gc/space/image_space.cc b/runtime/gc/space/image_space.cc
index e2b2431054..1fe9a03159 100644
--- a/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@ -58,7 +58,10 @@ static int32_t ChooseRelocationOffsetDelta(int32_t min_delta, int32_t max_delta)
   CHECK_ALIGNED(max_delta, kPageSize);
   CHECK_LT(min_delta, max_delta);
 
-  int32_t r = GetRandomNumber<int32_t>(min_delta, max_delta);
+  std::default_random_engine generator;
+  generator.seed(NanoTime() * getpid());
+  std::uniform_int_distribution<int32_t> distribution(min_delta, max_delta);
+  int32_t r = distribution(generator);
   if (r % 2 == 0) {
     r = RoundUp(r, kPageSize);
   } else {
diff --git a/runtime/utils.cc b/runtime/utils.cc
index 7da56403e5..68db7e3a73 100644
--- a/runtime/utils.cc
+++ b/runtime/utils.cc
@@ -18,14 +18,12 @@
 
 #include <inttypes.h>
 #include <pthread.h>
-#include <stdlib.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
 #include <memory>
-#include <random>
 
 #include "art_field-inl.h"
 #include "art_method-inl.h"
@@ -62,26 +60,6 @@ namespace art {
 static constexpr bool kUseAddr2line = !kIsTargetBuild;
 #endif
 
-#if defined(__BIONIC__)
-struct Arc4RandomGenerator {
-  typedef uint32_t result_type;
-  uint32_t min() { return std::numeric_limits<uint32_t>::min(); }
-  uint32_t max() { return std::numeric_limits<uint32_t>::max(); }
-  uint32_t operator() { return arc4random(); }
-};
-using RNG = Arc4RandomGenerator;
-#else
-using RNG = std::random_device;
-#endif
-
-template <typename T>
-T GetRandomNumber(T min, T max) {
-  CHECK_LT(min, max);
-  std::uniform_int_distribution<T> dist(min, max);
-  RNG rng;
-  return dist(rng);
-}
-
 pid_t GetTid() {
 #if defined(__APPLE__)
   uint64_t owner;
diff --git a/runtime/utils.h b/runtime/utils.h
index c3684e0bbb..3690f86a80 100644
--- a/runtime/utils.h
+++ b/runtime/utils.h
@@ -350,9 +350,6 @@ void ParseDouble(const std::string& option,
                  double* parsed_value,
                  UsageFn Usage);
 
-template <typename T>
-T GetRandomNumber(T min, T max);
-
 }  // namespace art
 
 #endif  // ART_RUNTIME_UTILS_H_