1 files changed, 17 insertions, 6 deletions

diff --git a/deps/v8/src/utils/utils.h b/deps/v8/src/utils/utils.h
index 20d85aae10..27d3d5ef21 100644
--- a/deps/v8/src/utils/utils.h
+++ b/deps/v8/src/utils/utils.h
@@ -20,10 +20,13 @@
 #include "src/base/platform/platform.h"
 #include "src/base/v8-fallthrough.h"
 #include "src/common/globals.h"
-#include "src/third_party/siphash/halfsiphash.h"
 #include "src/utils/allocation.h"
 #include "src/utils/vector.h"
 
+#if defined(V8_USE_SIPHASH)
+#include "src/third_party/siphash/halfsiphash.h"
+#endif
+
 #if defined(V8_OS_AIX)
 #include <fenv.h>  // NOLINT(build/c++11)
 #endif
@@ -302,29 +305,36 @@ T SaturateSub(T a, T b) {
 // ----------------------------------------------------------------------------
 // BitField is a help template for encoding and decode bitfield with
 // unsigned content.
+// Instantiate them via 'using', which is cheaper than deriving a new class:
+// using MyBitField = BitField<int, 4, 2, MyEnum>;
+// The BitField class is final to enforce this style over derivation.
 
 template <class T, int shift, int size, class U = uint32_t>
-class BitField {
+class BitField final {
  public:
   STATIC_ASSERT(std::is_unsigned<U>::value);
   STATIC_ASSERT(shift < 8 * sizeof(U));  // Otherwise shifts by {shift} are UB.
   STATIC_ASSERT(size < 8 * sizeof(U));   // Otherwise shifts by {size} are UB.
   STATIC_ASSERT(shift + size <= 8 * sizeof(U));
+  STATIC_ASSERT(size > 0);
 
   using FieldType = T;
 
   // A type U mask of bit field.  To use all bits of a type U of x bits
   // in a bitfield without compiler warnings we have to compute 2^x
   // without using a shift count of x in the computation.
-  static constexpr U kShift = shift;
-  static constexpr U kSize = size;
+  static constexpr int kShift = shift;
+  static constexpr int kSize = size;
   static constexpr U kMask = ((U{1} << kShift) << kSize) - (U{1} << kShift);
-  static constexpr U kNext = kShift + kSize;
+  static constexpr int kLastUsedBit = kShift + kSize - 1;
   static constexpr U kNumValues = U{1} << kSize;
 
   // Value for the field with all bits set.
   static constexpr T kMax = static_cast<T>(kNumValues - 1);
 
+  template <class T2, int size2>
+  using Next = BitField<T2, kShift + kSize, size2, U>;
+
   // Tells whether the provided value fits into the bit field.
   static constexpr bool is_valid(T value) {
     return (static_cast<U>(value) & ~static_cast<U>(kMax)) == 0;
@@ -892,7 +902,8 @@ class BailoutId {
 
 // Our version of printf().
 V8_EXPORT_PRIVATE void PRINTF_FORMAT(1, 2) PrintF(const char* format, ...);
-void PRINTF_FORMAT(2, 3) PrintF(FILE* out, const char* format, ...);
+V8_EXPORT_PRIVATE void PRINTF_FORMAT(2, 3)
+    PrintF(FILE* out, const char* format, ...);
 
 // Prepends the current process ID to the output.
 void PRINTF_FORMAT(1, 2) PrintPID(const char* format, ...);