Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 673 insertions, 0 deletions

diff --git a/js/public/Utility.h b/js/public/Utility.h
new file mode 100644
index 0000000000..7176320e64
--- /dev/null
+++ b/js/public/Utility.h
@@ -0,0 +1,673 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef js_Utility_h
+#define js_Utility_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Compiler.h"
+#include "mozilla/TemplateLib.h"
+#include "mozilla/UniquePtr.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <type_traits>
+#include <utility>
+
+#include "jstypes.h"
+#include "mozmemory.h"
+#include "js/TypeDecls.h"
+
+/* The public JS engine namespace. */
+namespace JS {}
+
+/* The mozilla-shared reusable template/utility namespace. */
+namespace mozilla {}
+
+/* The private JS engine namespace. */
+namespace js {}
+
+extern MOZ_NORETURN MOZ_COLD JS_PUBLIC_API void JS_Assert(const char* s,
+                                                          const char* file,
+                                                          int ln);
+
+/*
+ * Custom allocator support for SpiderMonkey
+ */
+#if defined JS_USE_CUSTOM_ALLOCATOR
+#  include "jscustomallocator.h"
+#else
+
+namespace js {
+
+/*
+ * Thread types are used to tag threads for certain kinds of testing (see
+ * below), and also used to characterize threads in the thread scheduler (see
+ * js/src/vm/HelperThreads.cpp).
+ *
+ * Please update oom::FirstThreadTypeToTest and oom::LastThreadTypeToTest when
+ * adding new thread types.
+ */
+enum ThreadType {
+  THREAD_TYPE_NONE = 0,              // 0
+  THREAD_TYPE_MAIN,                  // 1
+  THREAD_TYPE_WASM_COMPILE_TIER1,    // 2
+  THREAD_TYPE_WASM_COMPILE_TIER2,    // 3
+  THREAD_TYPE_ION,                   // 4
+  THREAD_TYPE_PARSE,                 // 5
+  THREAD_TYPE_COMPRESS,              // 6
+  THREAD_TYPE_GCPARALLEL,            // 7
+  THREAD_TYPE_PROMISE_TASK,          // 8
+  THREAD_TYPE_ION_FREE,              // 9
+  THREAD_TYPE_WASM_GENERATOR_TIER2,  // 10
+  THREAD_TYPE_WORKER,                // 11
+  THREAD_TYPE_DELAZIFY,              // 12
+  THREAD_TYPE_DELAZIFY_FREE,         // 13
+  THREAD_TYPE_MAX                    // Used to check shell function arguments
+};
+
+namespace oom {
+
+/*
+ * Theads are tagged only in certain debug contexts.  Notably, to make testing
+ * OOM in certain helper threads more effective, we allow restricting the OOM
+ * testing to a certain helper thread type. This allows us to fail e.g. in
+ * off-thread script parsing without causing an OOM in the active thread first.
+ *
+ * Getter/Setter functions to encapsulate mozilla::ThreadLocal, implementation
+ * is in util/Utility.cpp.
+ */
+#  if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
+
+// Define the range of threads tested by simulated OOM testing and the
+// like. Testing worker threads is not supported.
+const ThreadType FirstThreadTypeToTest = THREAD_TYPE_MAIN;
+const ThreadType LastThreadTypeToTest = THREAD_TYPE_WASM_GENERATOR_TIER2;
+
+extern bool InitThreadType(void);
+extern void SetThreadType(ThreadType);
+extern JS_PUBLIC_API uint32_t GetThreadType(void);
+
+#  else
+
+inline bool InitThreadType(void) { return true; }
+inline void SetThreadType(ThreadType t){};
+inline uint32_t GetThreadType(void) { return 0; }
+inline uint32_t GetAllocationThreadType(void) { return 0; }
+inline uint32_t GetStackCheckThreadType(void) { return 0; }
+inline uint32_t GetInterruptCheckThreadType(void) { return 0; }
+
+#  endif
+
+} /* namespace oom */
+} /* namespace js */
+
+#  if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
+
+#    ifdef JS_OOM_BREAKPOINT
+#      if defined(_MSC_VER)
+static MOZ_NEVER_INLINE void js_failedAllocBreakpoint() {
+  __asm {}
+  ;
+}
+#      else
+static MOZ_NEVER_INLINE void js_failedAllocBreakpoint() { asm(""); }
+#      endif
+#      define JS_OOM_CALL_BP_FUNC() js_failedAllocBreakpoint()
+#    else
+#      define JS_OOM_CALL_BP_FUNC() \
+        do {                        \
+        } while (0)
+#    endif
+
+namespace js {
+namespace oom {
+
+/*
+ * Out of memory testing support.  We provide various testing functions to
+ * simulate OOM conditions and so we can test that they are handled correctly.
+ */
+class FailureSimulator {
+ public:
+  enum class Kind : uint8_t { Nothing, OOM, StackOOM, Interrupt };
+
+ private:
+  Kind kind_ = Kind::Nothing;
+  uint32_t targetThread_ = 0;
+  uint64_t maxChecks_ = UINT64_MAX;
+  uint64_t counter_ = 0;
+  bool failAlways_ = true;
+  bool inUnsafeRegion_ = false;
+
+ public:
+  uint64_t maxChecks() const { return maxChecks_; }
+  uint64_t counter() const { return counter_; }
+  void setInUnsafeRegion(bool b) {
+    MOZ_ASSERT(inUnsafeRegion_ != b);
+    inUnsafeRegion_ = b;
+  }
+  uint32_t targetThread() const { return targetThread_; }
+  bool isThreadSimulatingAny() const {
+    return targetThread_ && targetThread_ == js::oom::GetThreadType() &&
+           !inUnsafeRegion_;
+  }
+  bool isThreadSimulating(Kind kind) const {
+    return kind_ == kind && isThreadSimulatingAny();
+  }
+  bool isSimulatedFailure(Kind kind) const {
+    if (!isThreadSimulating(kind)) {
+      return false;
+    }
+    return counter_ == maxChecks_ || (counter_ > maxChecks_ && failAlways_);
+  }
+  bool hadFailure(Kind kind) const {
+    return kind_ == kind && counter_ >= maxChecks_;
+  }
+  bool shouldFail(Kind kind) {
+    if (!isThreadSimulating(kind)) {
+      return false;
+    }
+    counter_++;
+    if (isSimulatedFailure(kind)) {
+      JS_OOM_CALL_BP_FUNC();
+      return true;
+    }
+    return false;
+  }
+
+  void simulateFailureAfter(Kind kind, uint64_t checks, uint32_t thread,
+                            bool always);
+  void reset();
+};
+extern JS_PUBLIC_DATA FailureSimulator simulator;
+
+inline bool IsSimulatedOOMAllocation() {
+  return simulator.isSimulatedFailure(FailureSimulator::Kind::OOM);
+}
+
+inline bool ShouldFailWithOOM() {
+  return simulator.shouldFail(FailureSimulator::Kind::OOM);
+}
+
+inline bool HadSimulatedOOM() {
+  return simulator.hadFailure(FailureSimulator::Kind::OOM);
+}
+
+/*
+ * Out of stack space testing support, similar to OOM testing functions.
+ */
+
+inline bool IsSimulatedStackOOMCheck() {
+  return simulator.isSimulatedFailure(FailureSimulator::Kind::StackOOM);
+}
+
+inline bool ShouldFailWithStackOOM() {
+  return simulator.shouldFail(FailureSimulator::Kind::StackOOM);
+}
+
+inline bool HadSimulatedStackOOM() {
+  return simulator.hadFailure(FailureSimulator::Kind::StackOOM);
+}
+
+/*
+ * Interrupt testing support, similar to OOM testing functions.
+ */
+
+inline bool IsSimulatedInterruptCheck() {
+  return simulator.isSimulatedFailure(FailureSimulator::Kind::Interrupt);
+}
+
+inline bool ShouldFailWithInterrupt() {
+  return simulator.shouldFail(FailureSimulator::Kind::Interrupt);
+}
+
+inline bool HadSimulatedInterrupt() {
+  return simulator.hadFailure(FailureSimulator::Kind::Interrupt);
+}
+
+} /* namespace oom */
+} /* namespace js */
+
+#    define JS_OOM_POSSIBLY_FAIL()                        \
+      do {                                                \
+        if (js::oom::ShouldFailWithOOM()) return nullptr; \
+      } while (0)
+
+#    define JS_OOM_POSSIBLY_FAIL_BOOL()                 \
+      do {                                              \
+        if (js::oom::ShouldFailWithOOM()) return false; \
+      } while (0)
+
+#    define JS_STACK_OOM_POSSIBLY_FAIL()                     \
+      do {                                                   \
+        if (js::oom::ShouldFailWithStackOOM()) return false; \
+      } while (0)
+
+#    define JS_INTERRUPT_POSSIBLY_FAIL()                             \
+      do {                                                           \
+        if (MOZ_UNLIKELY(js::oom::ShouldFailWithInterrupt())) {      \
+          cx->requestInterrupt(js::InterruptReason::CallbackUrgent); \
+          return cx->handleInterrupt();                              \
+        }                                                            \
+      } while (0)
+
+#  else
+
+#    define JS_OOM_POSSIBLY_FAIL() \
+      do {                         \
+      } while (0)
+#    define JS_OOM_POSSIBLY_FAIL_BOOL() \
+      do {                              \
+      } while (0)
+#    define JS_STACK_OOM_POSSIBLY_FAIL() \
+      do {                               \
+      } while (0)
+#    define JS_INTERRUPT_POSSIBLY_FAIL() \
+      do {                               \
+      } while (0)
+namespace js {
+namespace oom {
+static inline bool IsSimulatedOOMAllocation() { return false; }
+static inline bool ShouldFailWithOOM() { return false; }
+} /* namespace oom */
+} /* namespace js */
+
+#  endif /* DEBUG || JS_OOM_BREAKPOINT */
+
+#  ifdef FUZZING
+namespace js {
+namespace oom {
+extern JS_PUBLIC_DATA size_t largeAllocLimit;
+extern void InitLargeAllocLimit();
+} /* namespace oom */
+} /* namespace js */
+
+#    define JS_CHECK_LARGE_ALLOC(x)                                     \
+      do {                                                              \
+        if (js::oom::largeAllocLimit && x > js::oom::largeAllocLimit) { \
+          if (getenv("MOZ_FUZZ_CRASH_ON_LARGE_ALLOC")) {                \
+            MOZ_CRASH("Large allocation");                              \
+          } else {                                                      \
+            return nullptr;                                             \
+          }                                                             \
+        }                                                               \
+      } while (0)
+#  else
+#    define JS_CHECK_LARGE_ALLOC(x) \
+      do {                          \
+      } while (0)
+#  endif
+
+namespace js {
+
+/* Disable OOM testing in sections which are not OOM safe. */
+struct MOZ_RAII JS_PUBLIC_DATA AutoEnterOOMUnsafeRegion {
+  MOZ_NORETURN MOZ_COLD void crash(const char* reason);
+  MOZ_NORETURN MOZ_COLD void crash(size_t size, const char* reason);
+
+  using AnnotateOOMAllocationSizeCallback = void (*)(size_t);
+  static mozilla::Atomic<AnnotateOOMAllocationSizeCallback, mozilla::Relaxed>
+      annotateOOMSizeCallback;
+  static void setAnnotateOOMAllocationSizeCallback(
+      AnnotateOOMAllocationSizeCallback callback) {
+    annotateOOMSizeCallback = callback;
+  }
+
+#  if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
+  AutoEnterOOMUnsafeRegion()
+      : oomEnabled_(oom::simulator.isThreadSimulatingAny()) {
+    if (oomEnabled_) {
+      MOZ_ALWAYS_TRUE(owner_.compareExchange(nullptr, this));
+      oom::simulator.setInUnsafeRegion(true);
+    }
+  }
+
+  ~AutoEnterOOMUnsafeRegion() {
+    if (oomEnabled_) {
+      oom::simulator.setInUnsafeRegion(false);
+      MOZ_ALWAYS_TRUE(owner_.compareExchange(this, nullptr));
+    }
+  }
+
+ private:
+  // Used to catch concurrent use from other threads.
+  static mozilla::Atomic<AutoEnterOOMUnsafeRegion*> owner_;
+
+  bool oomEnabled_;
+#  endif
+};
+
+} /* namespace js */
+
+// Malloc allocation.
+
+namespace js {
+
+extern JS_PUBLIC_DATA arena_id_t MallocArena;
+extern JS_PUBLIC_DATA arena_id_t ArrayBufferContentsArena;
+extern JS_PUBLIC_DATA arena_id_t StringBufferArena;
+
+extern void InitMallocAllocator();
+extern void ShutDownMallocAllocator();
+
+// This is a no-op if built without MOZ_MEMORY and MOZ_DEBUG.
+extern void AssertJSStringBufferInCorrectArena(const void* ptr);
+
+} /* namespace js */
+
+static inline void* js_arena_malloc(arena_id_t arena, size_t bytes) {
+  JS_OOM_POSSIBLY_FAIL();
+  JS_CHECK_LARGE_ALLOC(bytes);
+  return moz_arena_malloc(arena, bytes);
+}
+
+static inline void* js_malloc(size_t bytes) {
+  return js_arena_malloc(js::MallocArena, bytes);
+}
+
+static inline void* js_arena_calloc(arena_id_t arena, size_t bytes) {
+  JS_OOM_POSSIBLY_FAIL();
+  JS_CHECK_LARGE_ALLOC(bytes);
+  return moz_arena_calloc(arena, bytes, 1);
+}
+
+static inline void* js_arena_calloc(arena_id_t arena, size_t nmemb,
+                                    size_t size) {
+  JS_OOM_POSSIBLY_FAIL();
+  JS_CHECK_LARGE_ALLOC(nmemb * size);
+  return moz_arena_calloc(arena, nmemb, size);
+}
+
+static inline void* js_calloc(size_t bytes) {
+  return js_arena_calloc(js::MallocArena, bytes);
+}
+
+static inline void* js_calloc(size_t nmemb, size_t size) {
+  return js_arena_calloc(js::MallocArena, nmemb, size);
+}
+
+static inline void* js_arena_realloc(arena_id_t arena, void* p, size_t bytes) {
+  // realloc() with zero size is not portable, as some implementations may
+  // return nullptr on success and free |p| for this.  We assume nullptr
+  // indicates failure and that |p| is still valid.
+  MOZ_ASSERT(bytes != 0);
+
+  JS_OOM_POSSIBLY_FAIL();
+  JS_CHECK_LARGE_ALLOC(bytes);
+  return moz_arena_realloc(arena, p, bytes);
+}
+
+static inline void* js_realloc(void* p, size_t bytes) {
+  return js_arena_realloc(js::MallocArena, p, bytes);
+}
+
+static inline void js_free(void* p) {
+  // Bug 1784164: This should call |moz_arena_free(js::MallocArena, p)| but we
+  // currently can't enforce that all memory freed here was allocated by
+  // js_malloc(). All other memory should go through a different allocator and
+  // deallocator.
+  free(p);
+}
+#endif /* JS_USE_CUSTOM_ALLOCATOR */
+
+#include <new>
+
+/*
+ * [SMDOC] Low-level memory management in SpiderMonkey
+ *
+ *  ** Do not use the standard malloc/free/realloc: SpiderMonkey allows these
+ *     to be redefined (via JS_USE_CUSTOM_ALLOCATOR) and Gecko even #define's
+ *     these symbols.
+ *
+ *  ** Do not use the builtin C++ operator new and delete: these throw on
+ *     error and we cannot override them not to.
+ *
+ * Allocation:
+ *
+ * - If the lifetime of the allocation is tied to the lifetime of a GC-thing
+ *   (that is, finalizing the GC-thing will free the allocation), call one of
+ *   the following functions:
+ *
+ *     JSContext::{pod_malloc,pod_calloc,pod_realloc}
+ *     Zone::{pod_malloc,pod_calloc,pod_realloc}
+ *
+ *   These functions accumulate the number of bytes allocated which is used as
+ *   part of the GC-triggering heuristics.
+ *
+ *   The difference between the JSContext and Zone versions is that the
+ *   cx version report an out-of-memory error on OOM. (This follows from the
+ *   general SpiderMonkey idiom that a JSContext-taking function reports its
+ *   own errors.)
+ *
+ *   If you don't want to report an error on failure, there are maybe_ versions
+ *   of these methods available too, e.g. maybe_pod_malloc.
+ *
+ *   The methods above use templates to allow allocating memory suitable for an
+ *   array of a given type and number of elements. There are _with_extra
+ *   versions to allow allocating an area of memory which is larger by a
+ *   specified number of bytes, e.g. pod_malloc_with_extra.
+ *
+ *   These methods are available on a JSRuntime, but calling them is
+ *   discouraged. Memory attributed to a runtime can only be reclaimed by full
+ *   GCs, and we try to avoid those where possible.
+ *
+ * - Otherwise, use js_malloc/js_realloc/js_calloc/js_new
+ *
+ * Deallocation:
+ *
+ * - Ordinarily, use js_free/js_delete.
+ *
+ * - For deallocations during GC finalization, use one of the following
+ *   operations on the JS::GCContext provided to the finalizer:
+ *
+ *     JS::GCContext::{free_,delete_}
+ */
+
+/*
+ * Given a class which should provide a 'new' method, add
+ * JS_DECLARE_NEW_METHODS (see js::MallocProvider for an example).
+ *
+ * Note: Do not add a ; at the end of a use of JS_DECLARE_NEW_METHODS,
+ * or the build will break.
+ */
+#define JS_DECLARE_NEW_METHODS(NEWNAME, ALLOCATOR, QUALIFIERS)              \
+  template <class T, typename... Args>                                      \
+  QUALIFIERS T* MOZ_HEAP_ALLOCATOR NEWNAME(Args&&... args) {                \
+    void* memory = ALLOCATOR(sizeof(T));                                    \
+    return MOZ_LIKELY(memory) ? new (memory) T(std::forward<Args>(args)...) \
+                              : nullptr;                                    \
+  }
+
+/*
+ * Given a class which should provide a 'new' method that takes an arena as
+ * its first argument, add JS_DECLARE_NEW_ARENA_METHODS
+ * (see js::MallocProvider for an example).
+ *
+ * Note: Do not add a ; at the end of a use of JS_DECLARE_NEW_ARENA_METHODS,
+ * or the build will break.
+ */
+#define JS_DECLARE_NEW_ARENA_METHODS(NEWNAME, ALLOCATOR, QUALIFIERS)           \
+  template <class T, typename... Args>                                         \
+  QUALIFIERS T* MOZ_HEAP_ALLOCATOR NEWNAME(arena_id_t arena, Args&&... args) { \
+    void* memory = ALLOCATOR(arena, sizeof(T));                                \
+    return MOZ_LIKELY(memory) ? new (memory) T(std::forward<Args>(args)...)    \
+                              : nullptr;                                       \
+  }
+
+/*
+ * Given a class which should provide 'make' methods, add
+ * JS_DECLARE_MAKE_METHODS (see js::MallocProvider for an example).  This
+ * method is functionally the same as JS_DECLARE_NEW_METHODS: it just declares
+ * methods that return mozilla::UniquePtr instances that will singly-manage
+ * ownership of the created object.
+ *
+ * Note: Do not add a ; at the end of a use of JS_DECLARE_MAKE_METHODS,
+ * or the build will break.
+ */
+#define JS_DECLARE_MAKE_METHODS(MAKENAME, NEWNAME, QUALIFIERS)             \
+  template <class T, typename... Args>                                     \
+  QUALIFIERS mozilla::UniquePtr<T, JS::DeletePolicy<T>> MOZ_HEAP_ALLOCATOR \
+  MAKENAME(Args&&... args) {                                               \
+    T* ptr = NEWNAME<T>(std::forward<Args>(args)...);                      \
+    return mozilla::UniquePtr<T, JS::DeletePolicy<T>>(ptr);                \
+  }
+
+JS_DECLARE_NEW_METHODS(js_new, js_malloc, static MOZ_ALWAYS_INLINE)
+JS_DECLARE_NEW_ARENA_METHODS(js_arena_new, js_arena_malloc,
+                             static MOZ_ALWAYS_INLINE)
+
+namespace js {
+
+/*
+ * Calculate the number of bytes needed to allocate |numElems| contiguous
+ * instances of type |T|.  Return false if the calculation overflowed.
+ */
+template <typename T>
+[[nodiscard]] inline bool CalculateAllocSize(size_t numElems,
+                                             size_t* bytesOut) {
+  *bytesOut = numElems * sizeof(T);
+  return (numElems & mozilla::tl::MulOverflowMask<sizeof(T)>::value) == 0;
+}
+
+/*
+ * Calculate the number of bytes needed to allocate a single instance of type
+ * |T| followed by |numExtra| contiguous instances of type |Extra|.  Return
+ * false if the calculation overflowed.
+ */
+template <typename T, typename Extra>
+[[nodiscard]] inline bool CalculateAllocSizeWithExtra(size_t numExtra,
+                                                      size_t* bytesOut) {
+  *bytesOut = sizeof(T) + numExtra * sizeof(Extra);
+  return (numExtra & mozilla::tl::MulOverflowMask<sizeof(Extra)>::value) == 0 &&
+         *bytesOut >= sizeof(T);
+}
+
+} /* namespace js */
+
+template <class T>
+static MOZ_ALWAYS_INLINE void js_delete(const T* p) {
+  if (p) {
+    p->~T();
+    js_free(const_cast<T*>(p));
+  }
+}
+
+template <class T>
+static MOZ_ALWAYS_INLINE void js_delete_poison(const T* p) {
+  if (p) {
+    p->~T();
+    memset(static_cast<void*>(const_cast<T*>(p)), 0x3B, sizeof(T));
+    js_free(const_cast<T*>(p));
+  }
+}
+
+template <class T>
+static MOZ_ALWAYS_INLINE T* js_pod_arena_malloc(arena_id_t arena,
+                                                size_t numElems) {
+  size_t bytes;
+  if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(numElems, &bytes))) {
+    return nullptr;
+  }
+  return static_cast<T*>(js_arena_malloc(arena, bytes));
+}
+
+template <class T>
+static MOZ_ALWAYS_INLINE T* js_pod_malloc(size_t numElems) {
+  return js_pod_arena_malloc<T>(js::MallocArena, numElems);
+}
+
+template <class T>
+static MOZ_ALWAYS_INLINE T* js_pod_arena_calloc(arena_id_t arena,
+                                                size_t numElems) {
+  size_t bytes;
+  if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(numElems, &bytes))) {
+    return nullptr;
+  }
+  return static_cast<T*>(js_arena_calloc(arena, bytes, 1));
+}
+
+template <class T>
+static MOZ_ALWAYS_INLINE T* js_pod_calloc(size_t numElems) {
+  return js_pod_arena_calloc<T>(js::MallocArena, numElems);
+}
+
+template <class T>
+static MOZ_ALWAYS_INLINE T* js_pod_arena_realloc(arena_id_t arena, T* prior,
+                                                 size_t oldSize,
+                                                 size_t newSize) {
+  MOZ_ASSERT(!(oldSize & mozilla::tl::MulOverflowMask<sizeof(T)>::value));
+  size_t bytes;
+  if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(newSize, &bytes))) {
+    return nullptr;
+  }
+  return static_cast<T*>(js_arena_realloc(arena, prior, bytes));
+}
+
+template <class T>
+static MOZ_ALWAYS_INLINE T* js_pod_realloc(T* prior, size_t oldSize,
+                                           size_t newSize) {
+  return js_pod_arena_realloc<T>(js::MallocArena, prior, oldSize, newSize);
+}
+
+namespace JS {
+
+template <typename T>
+struct DeletePolicy {
+  constexpr DeletePolicy() = default;
+
+  template <typename U>
+  MOZ_IMPLICIT DeletePolicy(
+      DeletePolicy<U> other,
+      std::enable_if_t<std::is_convertible_v<U*, T*>, int> dummy = 0) {}
+
+  void operator()(const T* ptr) { js_delete(const_cast<T*>(ptr)); }
+};
+
+struct FreePolicy {
+  void operator()(const void* ptr) { js_free(const_cast<void*>(ptr)); }
+};
+
+typedef mozilla::UniquePtr<char[], JS::FreePolicy> UniqueChars;
+typedef mozilla::UniquePtr<char16_t[], JS::FreePolicy> UniqueTwoByteChars;
+typedef mozilla::UniquePtr<JS::Latin1Char[], JS::FreePolicy> UniqueLatin1Chars;
+
+}  // namespace JS
+
+/* sixgill annotation defines */
+#ifndef HAVE_STATIC_ANNOTATIONS
+#  define HAVE_STATIC_ANNOTATIONS
+#  ifdef XGILL_PLUGIN
+#    define STATIC_PRECONDITION(COND) __attribute__((precondition(#    COND)))
+#    define STATIC_PRECONDITION_ASSUME(COND) \
+      __attribute__((precondition_assume(#COND)))
+#    define STATIC_POSTCONDITION(COND) __attribute__((postcondition(#    COND)))
+#    define STATIC_POSTCONDITION_ASSUME(COND) \
+      __attribute__((postcondition_assume(#COND)))
+#    define STATIC_INVARIANT(COND) __attribute__((invariant(#    COND)))
+#    define STATIC_INVARIANT_ASSUME(COND) \
+      __attribute__((invariant_assume(#COND)))
+#    define STATIC_ASSUME(COND)                                          \
+      JS_BEGIN_MACRO                                                     \
+        __attribute__((assume_static(#COND), unused)) int STATIC_PASTE1( \
+            assume_static_, __COUNTER__);                                \
+      JS_END_MACRO
+#  else                                       /* XGILL_PLUGIN */
+#    define STATIC_PRECONDITION(COND)         /* nothing */
+#    define STATIC_PRECONDITION_ASSUME(COND)  /* nothing */
+#    define STATIC_POSTCONDITION(COND)        /* nothing */
+#    define STATIC_POSTCONDITION_ASSUME(COND) /* nothing */
+#    define STATIC_INVARIANT(COND)            /* nothing */
+#    define STATIC_INVARIANT_ASSUME(COND)     /* nothing */
+#    define STATIC_ASSUME(COND)    \
+      JS_BEGIN_MACRO /* nothing */ \
+      JS_END_MACRO
+#  endif /* XGILL_PLUGIN */
+#  define STATIC_SKIP_INFERENCE STATIC_INVARIANT(skip_inference())
+#endif /* HAVE_STATIC_ANNOTATIONS */
+
+#endif /* js_Utility_h */