deps: update V8 to 6.8.275.24

PR-URL: https://github.com/nodejs/node/pull/21079
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yang Guo <yangguo@chromium.org>

12 files changed, 71 insertions, 18 deletions

diff --git a/deps/v8/src/base/adapters.h b/deps/v8/src/base/adapters.h
index f04391e2b2..6eeaed140b 100644
--- a/deps/v8/src/base/adapters.h
+++ b/deps/v8/src/base/adapters.h
@@ -8,6 +8,8 @@
 #ifndef V8_BASE_ADAPTERS_H_
 #define V8_BASE_ADAPTERS_H_
 
+#include <iterator>
+
 #include "src/base/macros.h"
 
 namespace v8 {
@@ -17,13 +19,15 @@ namespace base {
 template <typename T>
 class ReversedAdapter {
  public:
-  typedef decltype(static_cast<T*>(nullptr)->rbegin()) Iterator;
+  using Iterator =
+      std::reverse_iterator<decltype(std::begin(std::declval<T>()))>;
 
   explicit ReversedAdapter(T& t) : t_(t) {}
-  ReversedAdapter(const ReversedAdapter& ra) : t_(ra.t_) {}
+  ReversedAdapter(const ReversedAdapter& ra) = default;
 
-  Iterator begin() const { return t_.rbegin(); }
-  Iterator end() const { return t_.rend(); }
+  // TODO(clemensh): Use std::rbegin/std::rend once we have C++14 support.
+  Iterator begin() const { return Iterator(std::end(t_)); }
+  Iterator end() const { return Iterator(std::begin(t_)); }
 
  private:
   T& t_;
diff --git a/deps/v8/src/base/atomic-utils.h b/deps/v8/src/base/atomic-utils.h
index 5ba1ad4246..7787e4ff52 100644
--- a/deps/v8/src/base/atomic-utils.h
+++ b/deps/v8/src/base/atomic-utils.h
@@ -14,6 +14,7 @@
 namespace v8 {
 namespace base {
 
+// Deprecated. Use std::atomic<T> for new code.
 template <class T>
 class AtomicNumber {
  public:
diff --git a/deps/v8/src/base/ieee754.cc b/deps/v8/src/base/ieee754.cc
index 95b84cf328..7a1cc175cb 100644
--- a/deps/v8/src/base/ieee754.cc
+++ b/deps/v8/src/base/ieee754.cc
@@ -51,6 +51,7 @@ namespace {
 /*
  * A union which permits us to convert between a double and two 32 bit
  * ints.
+ * TODO(jkummerow): This is undefined behavior. Use bit_cast instead.
  */
 
 #if V8_TARGET_LITTLE_ENDIAN
diff --git a/deps/v8/src/base/logging.cc b/deps/v8/src/base/logging.cc
index e58fdba09f..64f7fed413 100644
--- a/deps/v8/src/base/logging.cc
+++ b/deps/v8/src/base/logging.cc
@@ -135,7 +135,7 @@ class FailureMessage {
 
   static const uintptr_t kStartMarker = 0xdecade10;
   static const uintptr_t kEndMarker = 0xdecade11;
-  static const int kMessageBufferSize = 1024;
+  static const int kMessageBufferSize = 512;
 
   uintptr_t start_marker_ = kStartMarker;
   char message_[kMessageBufferSize];
@@ -154,6 +154,7 @@ void V8_Fatal(const char* file, int line, const char* format, ...) {
 
   fflush(stdout);
   fflush(stderr);
+  // Print the formatted message to stdout without cropping the output.
   v8::base::OS::PrintError("\n\n#\n# Fatal error in %s, line %d\n# ", file,
                            line);
 
diff --git a/deps/v8/src/base/macros.h b/deps/v8/src/base/macros.h
index db2f194591..3437309bc7 100644
--- a/deps/v8/src/base/macros.h
+++ b/deps/v8/src/base/macros.h
@@ -43,7 +43,6 @@ template <typename T, size_t N>
 char (&ArraySizeHelper(const T (&array)[N]))[N];
 #endif
 
-
 // bit_cast<Dest,Source> is a template function that implements the
 // equivalent of "*reinterpret_cast<Dest*>(&source)".  We need this in
 // very low-level functions like the protobuf library and fast math
@@ -150,20 +149,27 @@ V8_INLINE Dest bit_cast(Source const& source) {
 #define INLINE(declarator)    V8_INLINE declarator
 #define NO_INLINE(declarator) V8_NOINLINE declarator
 
-// Define V8_USE_ADDRESS_SANITIZER macros.
+// Define V8_USE_ADDRESS_SANITIZER macro.
 #if defined(__has_feature)
 #if __has_feature(address_sanitizer)
 #define V8_USE_ADDRESS_SANITIZER 1
 #endif
 #endif
 
-// Define DISABLE_ASAN macros.
+// Define DISABLE_ASAN macro.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #define DISABLE_ASAN __attribute__((no_sanitize_address))
 #else
 #define DISABLE_ASAN
 #endif
 
+// Define V8_USE_MEMORY_SANITIZER macro.
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer)
+#define V8_USE_MEMORY_SANITIZER 1
+#endif
+#endif
+
 // Helper macro to define no_sanitize attributes only with clang.
 #if defined(__clang__) && defined(__has_attribute)
 #if __has_attribute(no_sanitize)
@@ -271,6 +277,14 @@ struct Use {
 }  // namespace base
 }  // namespace v8
 
+// implicit_cast<A>(x) triggers an implicit cast from {x} to type {A}. This is
+// useful in situations where static_cast<A>(x) would do too much.
+// Only use this for cheap-to-copy types, or use move semantics explicitly.
+template <class A>
+V8_INLINE A implicit_cast(A x) {
+  return x;
+}
+
 // Define our own macros for writing 64-bit constants.  This is less fragile
 // than defining __STDC_CONSTANT_MACROS before including <stdint.h>, and it
 // works on compilers that don't have it (like MSVC).
@@ -296,6 +310,14 @@ struct Use {
 #define V8PRIdPTR V8_PTR_PREFIX "d"
 #define V8PRIuPTR V8_PTR_PREFIX "u"
 
+#ifdef V8_TARGET_ARCH_64_BIT
+#define V8_PTR_HEX_DIGITS 12
+#define V8PRIxPTR_FMT "0x%012" V8PRIxPTR
+#else
+#define V8_PTR_HEX_DIGITS 8
+#define V8PRIxPTR_FMT "0x%08" V8PRIxPTR
+#endif
+
 // ptrdiff_t is 't' according to the standard, but MSVC uses 'I'.
 #if V8_CC_MSVC
 #define V8PRIxPTRDIFF "Ix"
diff --git a/deps/v8/src/base/platform/mutex.h b/deps/v8/src/base/platform/mutex.h
index 59b653d6cd..6b4158f079 100644
--- a/deps/v8/src/base/platform/mutex.h
+++ b/deps/v8/src/base/platform/mutex.h
@@ -203,11 +203,21 @@ typedef LazyStaticInstance<RecursiveMutex,
 // object was created, the LockGuard is destructed and the mutex is released.
 // The LockGuard class is non-copyable.
 
-template <typename Mutex>
+// Controls whether a LockGuard always requires a valid Mutex or will just
+// ignore it if it's nullptr.
+enum class NullBehavior { kRequireNotNull, kIgnoreIfNull };
+
+template <typename Mutex, NullBehavior Behavior = NullBehavior::kRequireNotNull>
 class LockGuard final {
  public:
-  explicit LockGuard(Mutex* mutex) : mutex_(mutex) { mutex_->Lock(); }
-  ~LockGuard() { mutex_->Unlock(); }
+  explicit LockGuard(Mutex* mutex) : mutex_(mutex) {
+    if (Behavior == NullBehavior::kRequireNotNull || mutex_ != nullptr) {
+      mutex_->Lock();
+    }
+  }
+  ~LockGuard() {
+    if (mutex_ != nullptr) mutex_->Unlock();
+  }
 
  private:
   Mutex* mutex_;
diff --git a/deps/v8/src/base/platform/platform-cygwin.cc b/deps/v8/src/base/platform/platform-cygwin.cc
index ddcdc1a2d3..c5d94fc6ba 100644
--- a/deps/v8/src/base/platform/platform-cygwin.cc
+++ b/deps/v8/src/base/platform/platform-cygwin.cc
@@ -34,6 +34,8 @@ DWORD GetProtectionFromMemoryPermission(OS::MemoryPermission access) {
   switch (access) {
     case OS::MemoryPermission::kNoAccess:
       return PAGE_NOACCESS;
+    case OS::MemoryPermission::kRead:
+      return PAGE_READONLY;
     case OS::MemoryPermission::kReadWrite:
       return PAGE_READWRITE;
     case OS::MemoryPermission::kReadWriteExecute:
diff --git a/deps/v8/src/base/platform/platform-fuchsia.cc b/deps/v8/src/base/platform/platform-fuchsia.cc
index bba3f1baba..3a9d65a12d 100644
--- a/deps/v8/src/base/platform/platform-fuchsia.cc
+++ b/deps/v8/src/base/platform/platform-fuchsia.cc
@@ -19,6 +19,8 @@ uint32_t GetProtectionFromMemoryPermission(OS::MemoryPermission access) {
   switch (access) {
     case OS::MemoryPermission::kNoAccess:
       return 0;  // no permissions
+    case OS::MemoryPermission::kRead:
+      return ZX_VM_FLAG_PERM_READ;
     case OS::MemoryPermission::kReadWrite:
       return ZX_VM_FLAG_PERM_READ | ZX_VM_FLAG_PERM_WRITE;
     case OS::MemoryPermission::kReadWriteExecute:
diff --git a/deps/v8/src/base/platform/platform-posix.cc b/deps/v8/src/base/platform/platform-posix.cc
index fee67589b6..d21107d6f7 100644
--- a/deps/v8/src/base/platform/platform-posix.cc
+++ b/deps/v8/src/base/platform/platform-posix.cc
@@ -112,6 +112,8 @@ int GetProtectionFromMemoryPermission(OS::MemoryPermission access) {
   switch (access) {
     case OS::MemoryPermission::kNoAccess:
       return PROT_NONE;
+    case OS::MemoryPermission::kRead:
+      return PROT_READ;
     case OS::MemoryPermission::kReadWrite:
       return PROT_READ | PROT_WRITE;
     case OS::MemoryPermission::kReadWriteExecute:
@@ -352,6 +354,18 @@ bool OS::SetPermissions(void* address, size_t size, MemoryPermission access) {
   if (ret == 0 && access == OS::MemoryPermission::kNoAccess) {
     ret = ReclaimInaccessibleMemory(address, size);
   }
+
+// For accounting purposes, we want to call MADV_FREE_REUSE on macOS after
+// changing permissions away from OS::MemoryPermission::kNoAccess. Since this
+// state is not kept at this layer, we always call this if access != kNoAccess.
+// The cost is a syscall that effectively no-ops.
+// TODO(erikchen): Fix this to only call MADV_FREE_REUSE when necessary.
+// https://crbug.com/823915
+#if defined(OS_MACOSX)
+  if (access != OS::MemoryPermission::kNoAccess)
+    madvise(address, size, MADV_FREE_REUSE);
+#endif
+
   return ret == 0;
 }
 
diff --git a/deps/v8/src/base/platform/platform-win32.cc b/deps/v8/src/base/platform/platform-win32.cc
index d4aa44f8a7..f618c65fb6 100644
--- a/deps/v8/src/base/platform/platform-win32.cc
+++ b/deps/v8/src/base/platform/platform-win32.cc
@@ -758,6 +758,8 @@ DWORD GetProtectionFromMemoryPermission(OS::MemoryPermission access) {
   switch (access) {
     case OS::MemoryPermission::kNoAccess:
       return PAGE_NOACCESS;
+    case OS::MemoryPermission::kRead:
+      return PAGE_READONLY;
     case OS::MemoryPermission::kReadWrite:
       return PAGE_READWRITE;
     case OS::MemoryPermission::kReadWriteExecute:
diff --git a/deps/v8/src/base/platform/platform.h b/deps/v8/src/base/platform/platform.h
index 4fbc87c4aa..5d015eeeac 100644
--- a/deps/v8/src/base/platform/platform.h
+++ b/deps/v8/src/base/platform/platform.h
@@ -159,6 +159,7 @@ class V8_BASE_EXPORT OS {
   // v8::PageAllocator.
   enum class MemoryPermission {
     kNoAccess,
+    kRead,
     kReadWrite,
     // TODO(hpayer): Remove this flag. Memory should never be rwx.
     kReadWriteExecute,
diff --git a/deps/v8/src/base/template-utils.h b/deps/v8/src/base/template-utils.h
index 07356346ec..cbbe7e3cbf 100644
--- a/deps/v8/src/base/template-utils.h
+++ b/deps/v8/src/base/template-utils.h
@@ -56,13 +56,6 @@ std::unique_ptr<T> make_unique(Args&&... args) {
   return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
 }
 
-// implicit_cast<A>(x) triggers an implicit cast from {x} to type {A}. This is
-// useful in situations where static_cast<A>(x) would do too much.
-template <class A>
-A implicit_cast(A x) {
-  return x;
-}
-
 // Helper to determine how to pass values: Pass scalars and arrays by value,
 // others by const reference (even if it was a non-const ref before; this is
 // disallowed by the style guide anyway).