Merging upstream version 126.0.

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

23 files changed, 1338 insertions, 407 deletions

diff --git a/js/src/builtin/Array.cpp b/js/src/builtin/Array.cpp
index 76493eee7f..2ced07b6b9 100644
--- a/js/src/builtin/Array.cpp
+++ b/js/src/builtin/Array.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/DebugOnly.h"
 #include "mozilla/MathAlgorithms.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/ScopeExit.h"
 #include "mozilla/SIMD.h"
 #include "mozilla/TextUtils.h"
 
@@ -23,6 +24,7 @@
 
 #include "ds/Sort.h"
 #include "jit/InlinableNatives.h"
+#include "jit/TrampolineNatives.h"
 #include "js/Class.h"
 #include "js/Conversions.h"
 #include "js/experimental/JitInfo.h"  // JSJitGetterOp, JSJitInfo
@@ -2026,57 +2028,10 @@ static bool FillWithUndefined(JSContext* cx, HandleObject obj, uint32_t start,
   return true;
 }
 
-static bool ArrayNativeSortImpl(JSContext* cx, Handle<JSObject*> obj,
-                                Handle<Value> fval, ComparatorMatchResult comp);
-
-bool js::intrinsic_ArrayNativeSort(JSContext* cx, unsigned argc, Value* vp) {
-  // This function is called from the self-hosted Array.prototype.sort
-  // implementation. It returns |true| if the array was sorted, otherwise it
-  // returns |false| to notify the self-hosted code to perform the sorting.
-  CallArgs args = CallArgsFromVp(argc, vp);
-  MOZ_ASSERT(args.length() == 1);
-
-  HandleValue fval = args[0];
-  MOZ_ASSERT(fval.isUndefined() || IsCallable(fval));
-
-  ComparatorMatchResult comp;
-  if (fval.isObject()) {
-    comp = MatchNumericComparator(cx, &fval.toObject());
-    if (comp == Match_Failure) {
-      return false;
-    }
-
-    if (comp == Match_None) {
-      // Non-optimized user supplied comparators perform much better when
-      // called from within a self-hosted sorting function.
-      args.rval().setBoolean(false);
-      return true;
-    }
-  } else {
-    comp = Match_None;
-  }
-
-  Rooted<JSObject*> obj(cx, &args.thisv().toObject());
-
-  if (!ArrayNativeSortImpl(cx, obj, fval, comp)) {
-    return false;
-  }
-
-  args.rval().setBoolean(true);
-  return true;
-}
-
-static bool ArrayNativeSortImpl(JSContext* cx, Handle<JSObject*> obj,
-                                Handle<Value> fval,
-                                ComparatorMatchResult comp) {
-  uint64_t length;
-  if (!GetLengthPropertyInlined(cx, obj, &length)) {
-    return false;
-  }
-  if (length < 2) {
-    /* [] and [a] remain unchanged when sorted. */
-    return true;
-  }
+static bool ArraySortWithoutComparator(JSContext* cx, Handle<JSObject*> obj,
+                                       uint64_t length,
+                                       ComparatorMatchResult comp) {
+  MOZ_ASSERT(length > 1);
 
   if (length > UINT32_MAX) {
     ReportAllocationOverflow(cx);
@@ -2225,6 +2180,519 @@ static bool ArrayNativeSortImpl(JSContext* cx, Handle<JSObject*> obj,
   return true;
 }
 
+void ArraySortData::init(JSObject* obj, JSObject* comparator, ValueVector&& vec,
+                         uint32_t length, uint32_t denseLen) {
+  MOZ_ASSERT(!vec.empty(), "must have items to sort");
+  MOZ_ASSERT(denseLen <= length);
+
+  obj_ = obj;
+  comparator_ = comparator;
+
+  this->length = length;
+  this->denseLen = denseLen;
+  this->vec = std::move(vec);
+
+  auto getComparatorKind = [](JSContext* cx, JSObject* comparator) {
+    if (!comparator->is<JSFunction>()) {
+      return ComparatorKind::Unoptimized;
+    }
+    JSFunction* fun = &comparator->as<JSFunction>();
+    if (!fun->hasJitEntry() || fun->isClassConstructor()) {
+      return ComparatorKind::Unoptimized;
+    }
+    if (fun->realm() == cx->realm() && fun->nargs() <= ComparatorActualArgs) {
+      return ComparatorKind::JSSameRealmNoRectifier;
+    }
+    return ComparatorKind::JS;
+  };
+  comparatorKind_ = getComparatorKind(cx(), comparator);
+}
+
+// This function handles sorting without a comparator function (or with a
+// trivial comparator function that we can pattern match) by calling
+// ArraySortWithoutComparator.
+//
+// If there's a non-trivial comparator function, it initializes the
+// ArraySortData struct for ArraySortData::sortWithComparator. This function
+// must be called next to perform the sorting.
+//
+// This is separate from ArraySortData::sortWithComparator because it lets the
+// compiler generate better code for ArraySortData::sortWithComparator.
+//
+// https://tc39.es/ecma262/#sec-array.prototype.sort
+// 23.1.3.30 Array.prototype.sort ( comparefn )
+static MOZ_ALWAYS_INLINE bool ArraySortPrologue(JSContext* cx,
+                                                Handle<Value> thisv,
+                                                Handle<Value> comparefn,
+                                                ArraySortData* d, bool* done) {
+  // Step 1.
+  if (MOZ_UNLIKELY(!comparefn.isUndefined() && !IsCallable(comparefn))) {
+    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_SORT_ARG);
+    return false;
+  }
+
+  // Step 2.
+  Rooted<JSObject*> obj(cx, ToObject(cx, thisv));
+  if (!obj) {
+    return false;
+  }
+
+  // Step 3.
+  uint64_t length;
+  if (MOZ_UNLIKELY(!GetLengthPropertyInlined(cx, obj, &length))) {
+    return false;
+  }
+
+  // Arrays with less than two elements remain unchanged when sorted.
+  if (length <= 1) {
+    d->setReturnValue(obj);
+    *done = true;
+    return true;
+  }
+
+  // Use a fast path if there's no comparator or if the comparator is a function
+  // that we can pattern match.
+  do {
+    ComparatorMatchResult comp = Match_None;
+    if (comparefn.isObject()) {
+      comp = MatchNumericComparator(cx, &comparefn.toObject());
+      if (comp == Match_Failure) {
+        return false;
+      }
+      if (comp == Match_None) {
+        // Pattern matching failed.
+        break;
+      }
+    }
+    if (!ArraySortWithoutComparator(cx, obj, length, comp)) {
+      return false;
+    }
+    d->setReturnValue(obj);
+    *done = true;
+    return true;
+  } while (false);
+
+  // Ensure length * 2 (used below) doesn't overflow UINT32_MAX.
+  if (MOZ_UNLIKELY(length > UINT32_MAX / 2)) {
+    ReportAllocationOverflow(cx);
+    return false;
+  }
+  uint32_t len = uint32_t(length);
+
+  // Merge sort requires extra scratch space.
+  bool needsScratchSpace = len >= ArraySortData::InsertionSortLimit;
+
+  Rooted<ArraySortData::ValueVector> vec(cx);
+  if (MOZ_UNLIKELY(!vec.reserve(needsScratchSpace ? (2 * len) : len))) {
+    ReportOutOfMemory(cx);
+    return false;
+  }
+
+  // Append elements to the vector. Skip holes.
+  if (IsPackedArray(obj)) {
+    Handle<ArrayObject*> array = obj.as<ArrayObject>();
+    const Value* elements = array->getDenseElements();
+    vec.infallibleAppend(elements, len);
+  } else {
+    RootedValue v(cx);
+    for (uint32_t i = 0; i < len; i++) {
+      if (!CheckForInterrupt(cx)) {
+        return false;
+      }
+
+      bool hole;
+      if (!HasAndGetElement(cx, obj, i, &hole, &v)) {
+        return false;
+      }
+      if (hole) {
+        continue;
+      }
+      vec.infallibleAppend(v);
+    }
+    // If there are only holes, the object is already sorted.
+    if (vec.empty()) {
+      d->setReturnValue(obj);
+      *done = true;
+      return true;
+    }
+  }
+
+  uint32_t denseLen = vec.length();
+  if (needsScratchSpace) {
+    MOZ_ALWAYS_TRUE(vec.resize(denseLen * 2));
+  }
+  d->init(obj, &comparefn.toObject(), std::move(vec.get()), len, denseLen);
+
+  // Continue in ArraySortData::sortWithComparator.
+  MOZ_ASSERT(!*done);
+  return true;
+}
+
+static ArraySortResult CallComparatorSlow(ArraySortData* d, const Value& x,
+                                          const Value& y) {
+  JSContext* cx = d->cx();
+  FixedInvokeArgs<2> callArgs(cx);
+  callArgs[0].set(x);
+  callArgs[1].set(y);
+  Rooted<Value> comparefn(cx, ObjectValue(*d->comparator()));
+  Rooted<Value> rval(cx);
+  if (!js::Call(cx, comparefn, UndefinedHandleValue, callArgs, &rval)) {
+    return ArraySortResult::Failure;
+  }
+  d->setComparatorReturnValue(rval);
+  return ArraySortResult::Done;
+}
+
+static MOZ_ALWAYS_INLINE ArraySortResult
+MaybeYieldToComparator(ArraySortData* d, const Value& x, const Value& y) {
+  // https://tc39.es/ecma262/#sec-comparearrayelements
+  // 23.1.3.30.2 CompareArrayElements ( x, y, comparefn )
+
+  // Steps 1-2.
+  if (x.isUndefined()) {
+    d->setComparatorReturnValue(Int32Value(y.isUndefined() ? 0 : 1));
+    return ArraySortResult::Done;
+  }
+
+  // Step 3.
+  if (y.isUndefined()) {
+    d->setComparatorReturnValue(Int32Value(-1));
+    return ArraySortResult::Done;
+  }
+
+  // Step 4. Yield to the JIT trampoline (or js::array_sort) if the comparator
+  // is a JS function we can call more efficiently from JIT code.
+  auto kind = d->comparatorKind();
+  if (MOZ_LIKELY(kind != ArraySortData::ComparatorKind::Unoptimized)) {
+    d->setComparatorArgs(x, y);
+    return (kind == ArraySortData::ComparatorKind::JSSameRealmNoRectifier)
+               ? ArraySortResult::CallJSSameRealmNoRectifier
+               : ArraySortResult::CallJS;
+  }
+  return CallComparatorSlow(d, x, y);
+}
+
+static MOZ_ALWAYS_INLINE bool RvalIsLessOrEqual(ArraySortData* data,
+                                                bool* lessOrEqual) {
+  // https://tc39.es/ecma262/#sec-comparearrayelements
+  // 23.1.3.30.2 CompareArrayElements ( x, y, comparefn )
+
+  // Fast path for int32 return values.
+  Value rval = data->comparatorReturnValue();
+  if (MOZ_LIKELY(rval.isInt32())) {
+    *lessOrEqual = rval.toInt32() <= 0;
+    return true;
+  }
+
+  // Step 4.a.
+  Rooted<Value> rvalRoot(data->cx(), rval);
+  double d;
+  if (MOZ_UNLIKELY(!ToNumber(data->cx(), rvalRoot, &d))) {
+    return false;
+  }
+
+  // Step 4.b-c.
+  *lessOrEqual = std::isnan(d) ? true : (d <= 0);
+  return true;
+}
+
+static void CopyValues(Value* out, const Value* list, uint32_t start,
+                       uint32_t end) {
+  for (uint32_t i = start; i <= end; i++) {
+    out[i] = list[i];
+  }
+}
+
+// static
+ArraySortResult ArraySortData::sortWithComparator(ArraySortData* d) {
+  JSContext* cx = d->cx();
+  auto& vec = d->vec;
+
+  // This function is like a generator that is called repeatedly from the JIT
+  // trampoline or js::array_sort. Resume the sorting algorithm where we left
+  // off before calling the comparator.
+  switch (d->state) {
+    case State::Initial:
+      break;
+    case State::InsertionSortCall1:
+      goto insertion_sort_call1;
+    case State::InsertionSortCall2:
+      goto insertion_sort_call2;
+    case State::MergeSortCall1:
+      goto merge_sort_call1;
+    case State::MergeSortCall2:
+      goto merge_sort_call2;
+  }
+
+  d->list = vec.begin();
+
+  // Use insertion sort for small arrays.
+  if (d->denseLen < InsertionSortLimit) {
+    for (d->i = 1; d->i < d->denseLen; d->i++) {
+      d->item = vec[d->i];
+      d->j = d->i - 1;
+      do {
+        {
+          ArraySortResult res = MaybeYieldToComparator(d, vec[d->j], d->item);
+          if (res != ArraySortResult::Done) {
+            d->state = State::InsertionSortCall1;
+            return res;
+          }
+        }
+      insertion_sort_call1:
+        bool lessOrEqual;
+        if (!RvalIsLessOrEqual(d, &lessOrEqual)) {
+          return ArraySortResult::Failure;
+        }
+        if (lessOrEqual) {
+          break;
+        }
+        vec[d->j + 1] = vec[d->j];
+      } while (d->j-- > 0);
+      vec[d->j + 1] = d->item;
+    }
+  } else {
+    static constexpr size_t InitialWindowSize = 4;
+
+    // Use insertion sort for initial ranges.
+    for (d->start = 0; d->start < d->denseLen - 1;
+         d->start += InitialWindowSize) {
+      d->end =
+          std::min<uint32_t>(d->start + InitialWindowSize - 1, d->denseLen - 1);
+      for (d->i = d->start + 1; d->i <= d->end; d->i++) {
+        d->item = vec[d->i];
+        d->j = d->i - 1;
+        do {
+          {
+            ArraySortResult res = MaybeYieldToComparator(d, vec[d->j], d->item);
+            if (res != ArraySortResult::Done) {
+              d->state = State::InsertionSortCall2;
+              return res;
+            }
+          }
+        insertion_sort_call2:
+          bool lessOrEqual;
+          if (!RvalIsLessOrEqual(d, &lessOrEqual)) {
+            return ArraySortResult::Failure;
+          }
+          if (lessOrEqual) {
+            break;
+          }
+          vec[d->j + 1] = vec[d->j];
+        } while (d->j-- > d->start);
+        vec[d->j + 1] = d->item;
+      }
+    }
+
+    // Merge sort. Set d->out to scratch space initially.
+    d->out = vec.begin() + d->denseLen;
+    for (d->windowSize = InitialWindowSize; d->windowSize < d->denseLen;
+         d->windowSize *= 2) {
+      for (d->start = 0; d->start < d->denseLen;
+           d->start += 2 * d->windowSize) {
+        // The midpoint between the two subarrays.
+        d->mid = d->start + d->windowSize - 1;
+
+        // To keep from going over the edge.
+        d->end = std::min<uint32_t>(d->start + 2 * d->windowSize - 1,
+                                    d->denseLen - 1);
+
+        // Merge comparator-sorted slices list[start..<=mid] and
+        // list[mid+1..<=end], storing the merged sequence in out[start..<=end].
+
+        // Skip lopsided runs to avoid doing useless work.
+        if (d->mid >= d->end) {
+          CopyValues(d->out, d->list, d->start, d->end);
+          continue;
+        }
+
+        // Skip calling the comparator if the sub-list is already sorted.
+        {
+          ArraySortResult res =
+              MaybeYieldToComparator(d, d->list[d->mid], d->list[d->mid + 1]);
+          if (res != ArraySortResult::Done) {
+            d->state = State::MergeSortCall1;
+            return res;
+          }
+        }
+      merge_sort_call1:
+        bool lessOrEqual;
+        if (!RvalIsLessOrEqual(d, &lessOrEqual)) {
+          return ArraySortResult::Failure;
+        }
+        if (lessOrEqual) {
+          CopyValues(d->out, d->list, d->start, d->end);
+          continue;
+        }
+
+        d->i = d->start;
+        d->j = d->mid + 1;
+        d->k = d->start;
+
+        while (d->i <= d->mid && d->j <= d->end) {
+          {
+            ArraySortResult res =
+                MaybeYieldToComparator(d, d->list[d->i], d->list[d->j]);
+            if (res != ArraySortResult::Done) {
+              d->state = State::MergeSortCall2;
+              return res;
+            }
+          }
+        merge_sort_call2:
+          bool lessOrEqual;
+          if (!RvalIsLessOrEqual(d, &lessOrEqual)) {
+            return ArraySortResult::Failure;
+          }
+          d->out[d->k++] = lessOrEqual ? d->list[d->i++] : d->list[d->j++];
+        }
+
+        // Empty out any remaining elements. Use local variables to let the
+        // compiler generate more efficient code.
+        Value* out = d->out;
+        Value* list = d->list;
+        uint32_t k = d->k;
+        uint32_t mid = d->mid;
+        uint32_t end = d->end;
+        for (uint32_t i = d->i; i <= mid; i++) {
+          out[k++] = list[i];
+        }
+        for (uint32_t j = d->j; j <= end; j++) {
+          out[k++] = list[j];
+        }
+      }
+
+      // Swap both lists.
+      std::swap(d->list, d->out);
+    }
+  }
+
+  // Copy elements to the array.
+  Rooted<JSObject*> obj(cx, d->obj_);
+  if (!SetArrayElements(cx, obj, 0, d->denseLen, d->list)) {
+    return ArraySortResult::Failure;
+  }
+
+  // Re-create any holes that sorted to the end of the array.
+  for (uint32_t i = d->denseLen; i < d->length; i++) {
+    if (!CheckForInterrupt(cx) || !DeletePropertyOrThrow(cx, obj, i)) {
+      return ArraySortResult::Failure;
+    }
+  }
+
+  d->freeMallocData();
+  d->setReturnValue(obj);
+  return ArraySortResult::Done;
+}
+
+// https://tc39.es/ecma262/#sec-array.prototype.sort
+// 23.1.3.30 Array.prototype.sort ( comparefn )
+bool js::array_sort(JSContext* cx, unsigned argc, Value* vp) {
+  AutoJSMethodProfilerEntry pseudoFrame(cx, "Array.prototype", "sort");
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  // If we have a comparator argument, use the JIT trampoline implementation
+  // instead. This avoids a performance cliff (especially with large arrays)
+  // because C++ => JIT calls are much slower than Trampoline => JIT calls.
+  if (args.hasDefined(0) && jit::IsBaselineInterpreterEnabled()) {
+    return CallTrampolineNativeJitCode(cx, jit::TrampolineNative::ArraySort,
+                                       args);
+  }
+
+  Rooted<ArraySortData> data(cx, cx);
+
+  // On all return paths other than ArraySortWithComparatorLoop returning Done,
+  // we call freeMallocData to not fail debug assertions. This matches the JIT
+  // trampoline where we can't rely on C++ destructors.
+  auto freeData =
+      mozilla::MakeScopeExit([&]() { data.get().freeMallocData(); });
+
+  bool done = false;
+  if (!ArraySortPrologue(cx, args.thisv(), args.get(0), data.address(),
+                         &done)) {
+    return false;
+  }
+  if (done) {
+    args.rval().set(data.get().returnValue());
+    return true;
+  }
+
+  FixedInvokeArgs<2> callArgs(cx);
+  Rooted<Value> rval(cx);
+
+  while (true) {
+    ArraySortResult res = ArraySortData::sortWithComparator(data.address());
+    switch (res) {
+      case ArraySortResult::Failure:
+        return false;
+
+      case ArraySortResult::Done:
+        freeData.release();
+        args.rval().set(data.get().returnValue());
+        return true;
+
+      case ArraySortResult::CallJS:
+      case ArraySortResult::CallJSSameRealmNoRectifier:
+        MOZ_ASSERT(data.get().comparatorThisValue().isUndefined());
+        MOZ_ASSERT(&args[0].toObject() == data.get().comparator());
+        callArgs[0].set(data.get().comparatorArg(0));
+        callArgs[1].set(data.get().comparatorArg(1));
+        if (!js::Call(cx, args[0], UndefinedHandleValue, callArgs, &rval)) {
+          return false;
+        }
+        data.get().setComparatorReturnValue(rval);
+        break;
+    }
+  }
+}
+
+ArraySortResult js::ArraySortFromJit(JSContext* cx,
+                                     jit::TrampolineNativeFrameLayout* frame) {
+  // Initialize the ArraySortData class stored in the trampoline frame.
+  void* dataUninit = frame->getFrameData<ArraySortData>();
+  auto* data = new (dataUninit) ArraySortData(cx);
+
+  Rooted<Value> thisv(cx, frame->thisv());
+  Rooted<Value> comparefn(cx);
+  if (frame->numActualArgs() > 0) {
+    comparefn = frame->actualArgs()[0];
+  }
+
+  bool done = false;
+  if (!ArraySortPrologue(cx, thisv, comparefn, data, &done)) {
+    return ArraySortResult::Failure;
+  }
+  if (done) {
+    data->freeMallocData();
+    return ArraySortResult::Done;
+  }
+
+  return ArraySortData::sortWithComparator(data);
+}
+
+ArraySortData::ArraySortData(JSContext* cx) : cx_(cx) {
+#ifdef DEBUG
+  cx_->liveArraySortDataInstances++;
+#endif
+}
+
+void ArraySortData::freeMallocData() {
+  vec.clearAndFree();
+#ifdef DEBUG
+  MOZ_ASSERT(cx_->liveArraySortDataInstances > 0);
+  cx_->liveArraySortDataInstances--;
+#endif
+}
+
+void ArraySortData::trace(JSTracer* trc) {
+  TraceNullableRoot(trc, &comparator_, "comparator_");
+  TraceRoot(trc, &thisv, "thisv");
+  TraceRoot(trc, &callArgs[0], "callArgs0");
+  TraceRoot(trc, &callArgs[1], "callArgs1");
+  vec.trace(trc);
+  TraceRoot(trc, &item, "item");
+  TraceNullableRoot(trc, &obj_, "obj");
+}
+
 bool js::NewbornArrayPush(JSContext* cx, HandleObject obj, const Value& v) {
   Handle<ArrayObject*> arr = obj.as<ArrayObject>();
 
@@ -4846,7 +5314,7 @@ static const JSFunctionSpec array_methods[] = {
     /* Perl-ish methods. */
     JS_INLINABLE_FN("join", array_join, 1, 0, ArrayJoin),
     JS_FN("reverse", array_reverse, 0, 0),
-    JS_SELF_HOSTED_FN("sort", "ArraySort", 1, 0),
+    JS_TRAMPOLINE_FN("sort", array_sort, 1, 0, ArraySort),
     JS_INLINABLE_FN("push", array_push, 1, 0, ArrayPush),
     JS_INLINABLE_FN("pop", array_pop, 0, 0, ArrayPop),
     JS_INLINABLE_FN("shift", array_shift, 0, 0, ArrayShift),
diff --git a/js/src/builtin/Array.h b/js/src/builtin/Array.h
index f0de034998..f861505e7b 100644
--- a/js/src/builtin/Array.h
+++ b/js/src/builtin/Array.h
@@ -15,6 +15,10 @@
 
 namespace js {
 
+namespace jit {
+class TrampolineNativeFrameLayout;
+}
+
 class ArrayObject;
 
 MOZ_ALWAYS_INLINE bool IdIsIndex(jsid id, uint32_t* indexp) {
@@ -107,16 +111,12 @@ extern bool GetElements(JSContext* cx, HandleObject aobj, uint32_t length,
 
 /* Natives exposed for optimization by the interpreter and JITs. */
 
-extern bool intrinsic_ArrayNativeSort(JSContext* cx, unsigned argc,
-                                      js::Value* vp);
-
 extern bool array_includes(JSContext* cx, unsigned argc, js::Value* vp);
 extern bool array_indexOf(JSContext* cx, unsigned argc, js::Value* vp);
 extern bool array_lastIndexOf(JSContext* cx, unsigned argc, js::Value* vp);
-
 extern bool array_pop(JSContext* cx, unsigned argc, js::Value* vp);
-
 extern bool array_join(JSContext* cx, unsigned argc, js::Value* vp);
+extern bool array_sort(JSContext* cx, unsigned argc, js::Value* vp);
 
 extern void ArrayShiftMoveElements(ArrayObject* arr);
 
@@ -172,6 +172,147 @@ extern bool ArrayLengthGetter(JSContext* cx, HandleObject obj, HandleId id,
 extern bool ArrayLengthSetter(JSContext* cx, HandleObject obj, HandleId id,
                               HandleValue v, ObjectOpResult& result);
 
+// Note: we use uint32_t because the JIT code uses branch32.
+enum class ArraySortResult : uint32_t {
+  Failure,
+  Done,
+  CallJS,
+  CallJSSameRealmNoRectifier
+};
+
+// We use a JIT trampoline to optimize sorting with a comparator function. The
+// trampoline frame has an ArraySortData instance that contains all state used
+// by the sorting algorithm. The sorting algorithm is implemented as a C++
+// "generator" that can yield to the trampoline to perform a fast JIT => JIT
+// call to the comparator function. When the comparator function returns, the
+// trampoline calls back into C++ to resume the sorting algorithm.
+//
+// ArraySortData stores the JS Values in a js::Vector. To ensure we don't leak
+// its memory, we have debug assertions to check that for each C++ constructor
+// call we call |freeMallocData| exactly once. C++ code calls |freeMallocData|
+// when it's done sorting and the JIT exception handler calls it when unwinding
+// the trampoline frame.
+class ArraySortData {
+ public:
+  enum class ComparatorKind : uint8_t {
+    Unoptimized,
+    JS,
+    JSSameRealmNoRectifier,
+  };
+
+  static constexpr size_t ComparatorActualArgs = 2;
+
+  // Insertion sort is used if the length is < InsertionSortLimit.
+  static constexpr size_t InsertionSortLimit = 24;
+
+  using ValueVector = GCVector<Value, 8, SystemAllocPolicy>;
+
+ protected:  // Silence Clang warning about unused private fields.
+  // Data for the comparator call. These fields must match the JitFrameLayout
+  // to let us perform efficient calls to the comparator from JIT code.
+  // This is asserted in the JIT trampoline code.
+  // callArgs[0] is also used to store the return value of the sort function and
+  // the comparator.
+  uintptr_t descriptor_;
+  JSObject* comparator_ = nullptr;
+  Value thisv;
+  Value callArgs[ComparatorActualArgs];
+
+ private:
+  ValueVector vec;
+  Value item;
+  JSContext* cx_;
+  JSObject* obj_ = nullptr;
+
+  Value* list;
+  Value* out;
+
+  // The value of the .length property.
+  uint32_t length;
+
+  // The number of items to sort. Can be less than |length| if the object has
+  // holes.
+  uint32_t denseLen;
+
+  uint32_t windowSize;
+  uint32_t start;
+  uint32_t mid;
+  uint32_t end;
+  uint32_t i, j, k;
+
+  // The state value determines where we resume in sortWithComparator.
+  enum class State : uint8_t {
+    Initial,
+    InsertionSortCall1,
+    InsertionSortCall2,
+    MergeSortCall1,
+    MergeSortCall2
+  };
+  State state = State::Initial;
+  ComparatorKind comparatorKind_;
+
+  // Optional padding to ensure proper alignment of the comparator JIT frame.
+#if !defined(JS_64BIT) && !defined(DEBUG)
+ protected:  // Silence Clang warning about unused private field.
+  size_t padding;
+#endif
+
+ public:
+  explicit ArraySortData(JSContext* cx);
+
+  void MOZ_ALWAYS_INLINE init(JSObject* obj, JSObject* comparator,
+                              ValueVector&& vec, uint32_t length,
+                              uint32_t denseLen);
+
+  JSContext* cx() const { return cx_; }
+
+  JSObject* comparator() const {
+    MOZ_ASSERT(comparator_);
+    return comparator_;
+  }
+
+  Value returnValue() const { return callArgs[0]; }
+  void setReturnValue(JSObject* obj) { callArgs[0].setObject(*obj); }
+
+  Value comparatorArg(size_t index) {
+    MOZ_ASSERT(index < ComparatorActualArgs);
+    return callArgs[index];
+  }
+  Value comparatorThisValue() const { return thisv; }
+  Value comparatorReturnValue() const { return callArgs[0]; }
+  void setComparatorArgs(const Value& x, const Value& y) {
+    callArgs[0] = x;
+    callArgs[1] = y;
+  }
+  void setComparatorReturnValue(const Value& v) { callArgs[0] = v; }
+
+  ComparatorKind comparatorKind() const { return comparatorKind_; }
+
+  static ArraySortResult sortWithComparator(ArraySortData* d);
+
+  void freeMallocData();
+  void trace(JSTracer* trc);
+
+  static constexpr int32_t offsetOfDescriptor() {
+    return offsetof(ArraySortData, descriptor_);
+  }
+  static constexpr int32_t offsetOfComparator() {
+    return offsetof(ArraySortData, comparator_);
+  }
+  static constexpr int32_t offsetOfComparatorReturnValue() {
+    return offsetof(ArraySortData, callArgs[0]);
+  }
+  static constexpr int32_t offsetOfComparatorThis() {
+    return offsetof(ArraySortData, thisv);
+  }
+  static constexpr int32_t offsetOfComparatorArgs() {
+    return offsetof(ArraySortData, callArgs);
+  }
+};
+
+extern ArraySortResult ArraySortFromJit(
+    JSContext* cx, jit::TrampolineNativeFrameLayout* frame);
+
 class MOZ_NON_TEMPORARY_CLASS ArraySpeciesLookup final {
   /*
    * An ArraySpeciesLookup holds the following:
diff --git a/js/src/builtin/Array.js b/js/src/builtin/Array.js
index f831615041..b62edef7e9 100644
--- a/js/src/builtin/Array.js
+++ b/js/src/builtin/Array.js
@@ -76,85 +76,6 @@ function ArraySome(callbackfn /*, thisArg*/) {
 // Inlining this enables inlining of the callback function.
 SetIsInlinableLargeFunction(ArraySome);
 
-// ES2023 draft rev cb4224156c54156f30c18c50784c1b0148ebfae5
-// 23.1.3.30 Array.prototype.sort ( comparefn )
-function ArraySortCompare(comparefn) {
-  return function(x, y) {
-    // Steps 4.a-c.
-    if (x === undefined) {
-      if (y === undefined) {
-        return 0;
-      }
-      return 1;
-    }
-    if (y === undefined) {
-      return -1;
-    }
-
-    // Step 4.d.i.
-    var v = ToNumber(callContentFunction(comparefn, undefined, x, y));
-
-    // Steps 4.d.ii-iii.
-    return v !== v ? 0 : v;
-  };
-}
-
-// ES2023 draft rev cb4224156c54156f30c18c50784c1b0148ebfae5
-// 23.1.3.30 Array.prototype.sort ( comparefn )
-function ArraySort(comparefn) {
-  // Step 1.
-  if (comparefn !== undefined) {
-    if (!IsCallable(comparefn)) {
-      ThrowTypeError(JSMSG_BAD_SORT_ARG);
-    }
-  }
-
-  // Step 2.
-  var O = ToObject(this);
-
-  // First try to sort the array in native code, if that fails, indicated by
-  // returning |false| from ArrayNativeSort, sort it in self-hosted code.
-  if (callFunction(ArrayNativeSort, O, comparefn)) {
-    return O;
-  }
-
-  // Step 3.
-  var len = ToLength(O.length);
-
-  // Arrays with less than two elements remain unchanged when sorted.
-  if (len <= 1) {
-    return O;
-  }
-
-  // Step 4.
-  var wrappedCompareFn = ArraySortCompare(comparefn);
-
-  // Step 5.
-  // To save effort we will do all of our work on a dense list, then create
-  // holes at the end.
-  var denseList = [];
-  var denseLen = 0;
-
-  for (var i = 0; i < len; i++) {
-    if (i in O) {
-      DefineDataProperty(denseList, denseLen++, O[i]);
-    }
-  }
-
-  if (denseLen < 1) {
-    return O;
-  }
-
-  var sorted = MergeSort(denseList, denseLen, wrappedCompareFn);
-
-  assert(IsPackedArray(sorted), "sorted is a packed array");
-  assert(sorted.length === denseLen, "sorted array has the correct length");
-
-  MoveHoles(O, len, sorted, denseLen);
-
-  return O;
-}
-
 /* ES5 15.4.4.18. */
 function ArrayForEach(callbackfn /*, thisArg*/) {
   /* Step 1. */
@@ -1335,22 +1256,8 @@ function ArrayToSorted(comparefn) {
     return items;
   }
 
-  // First try to sort the array in native code, if that fails, indicated by
-  // returning |false| from ArrayNativeSort, sort it in self-hosted code.
-  if (callFunction(ArrayNativeSort, items, comparefn)) {
-    return items;
-  }
-
-  // Step 5.
-  var wrappedCompareFn = ArraySortCompare(comparefn);
-
-  // Steps 6-9.
-  var sorted = MergeSort(items, len, wrappedCompareFn);
-
-  assert(IsPackedArray(sorted), "sorted is a packed array");
-  assert(sorted.length === len, "sorted array has the correct length");
-
-  return sorted;
+  // Steps 5-9.
+  return callFunction(std_Array_sort, items, comparefn);
 }
 
 // https://github.com/tc39/proposal-array-find-from-last
diff --git a/js/src/builtin/JSON.cpp b/js/src/builtin/JSON.cpp
index dbfab8b43a..1423595937 100644
--- a/js/src/builtin/JSON.cpp
+++ b/js/src/builtin/JSON.cpp
@@ -20,15 +20,18 @@
 #include "builtin/Array.h"
 #include "builtin/BigInt.h"
 #include "builtin/ParseRecordObject.h"
+#include "builtin/RawJSONObject.h"
 #include "js/friend/ErrorMessages.h"  // js::GetErrorMessage, JSMSG_*
 #include "js/friend/StackLimits.h"    // js::AutoCheckRecursionLimit
 #include "js/Object.h"                // JS::GetBuiltinClass
+#include "js/Prefs.h"                 // JS::Prefs
 #include "js/PropertySpec.h"
 #include "js/StableStringChars.h"
 #include "js/TypeDecls.h"
 #include "js/Value.h"
 #include "util/StringBuffer.h"
-#include "vm/BooleanObject.h"  // js::BooleanObject
+#include "vm/BooleanObject.h"       // js::BooleanObject
+#include "vm/EqualityOperations.h"  // js::SameValue
 #include "vm/Interpreter.h"
 #include "vm/Iteration.h"
 #include "vm/JSAtomUtils.h"  // ToAtom
@@ -436,6 +439,16 @@ class CycleDetector {
   bool appended_;
 };
 
+static inline JSString* MaybeGetRawJSON(JSContext* cx, JSObject* obj) {
+  if (!obj->is<RawJSONObject>()) {
+    return nullptr;
+  }
+
+  JSString* rawJSON = obj->as<js::RawJSONObject>().rawJSON(cx);
+  MOZ_ASSERT(rawJSON);
+  return rawJSON;
+}
+
 #ifdef ENABLE_RECORD_TUPLE
 enum class JOType { Record, Object };
 template <JOType type = JOType::Object>
@@ -783,6 +796,12 @@ static bool SerializeJSONProperty(JSContext* cx, const Value& v,
   MOZ_ASSERT(v.hasObjectPayload());
   RootedObject obj(cx, &v.getObjectPayload());
 
+  /* https://tc39.es/proposal-json-parse-with-source/#sec-serializejsonproperty
+   * Step 4a.*/
+  if (JSString* rawJSON = MaybeGetRawJSON(cx, obj)) {
+    return scx->sb.append(rawJSON);
+  }
+
   MOZ_ASSERT(
       !scx->maybeSafely || obj->is<PlainObject>() || obj->is<ArrayObject>(),
       "input to JS::ToJSONMaybeSafely must not include reachable "
@@ -1233,6 +1252,10 @@ static bool FastSerializeJSONProperty(JSContext* cx, Handle<Value> v,
   MOZ_ASSERT(*whySlow == BailReason::NO_REASON);
   MOZ_ASSERT(v.isObject());
 
+  if (JSString* rawJSON = MaybeGetRawJSON(cx, &v.toObject())) {
+    return scx->sb.append(rawJSON);
+  }
+
   /*
    * FastSerializeJSONProperty is an optimistic fast path for the
    * SerializeJSONProperty algorithm that applies in limited situations. It
@@ -1356,19 +1379,24 @@ static bool FastSerializeJSONProperty(JSContext* cx, Handle<Value> v,
         }
 
         if (val.isObject()) {
-          if (stack.length() >= MAX_STACK_DEPTH - 1) {
-            *whySlow = BailReason::DEEP_RECURSION;
-            return true;
+          if (JSString* rawJSON = MaybeGetRawJSON(cx, &val.toObject())) {
+            if (!scx->sb.append(rawJSON)) {
+              return false;
+            }
+          } else {
+            if (stack.length() >= MAX_STACK_DEPTH - 1) {
+              *whySlow = BailReason::DEEP_RECURSION;
+              return true;
+            }
+            // Save the current iterator position on the stack and
+            // switch to processing the nested value.
+            stack.infallibleAppend(std::move(top));
+            top = FastStackEntry(&val.toObject().as<NativeObject>());
+            wroteMember = false;
+            nestedObject = true;  // Break out to the outer loop.
+            break;
           }
-          // Save the current iterator position on the stack and
-          // switch to processing the nested value.
-          stack.infallibleAppend(std::move(top));
-          top = FastStackEntry(&val.toObject().as<NativeObject>());
-          wroteMember = false;
-          nestedObject = true;  // Break out to the outer loop.
-          break;
-        }
-        if (!EmitSimpleValue(cx, scx->sb, val)) {
+        } else if (!EmitSimpleValue(cx, scx->sb, val)) {
           return false;
         }
       }
@@ -1433,19 +1461,24 @@ static bool FastSerializeJSONProperty(JSContext* cx, Handle<Value> v,
           return false;
         }
         if (val.isObject()) {
-          if (stack.length() >= MAX_STACK_DEPTH - 1) {
-            *whySlow = BailReason::DEEP_RECURSION;
-            return true;
+          if (JSString* rawJSON = MaybeGetRawJSON(cx, &val.toObject())) {
+            if (!scx->sb.append(rawJSON)) {
+              return false;
+            }
+          } else {
+            if (stack.length() >= MAX_STACK_DEPTH - 1) {
+              *whySlow = BailReason::DEEP_RECURSION;
+              return true;
+            }
+            // Save the current iterator position on the stack and
+            // switch to processing the nested value.
+            stack.infallibleAppend(std::move(top));
+            top = FastStackEntry(&val.toObject().as<NativeObject>());
+            wroteMember = false;
+            nesting = true;  // Break out to the outer loop.
+            break;
           }
-          // Save the current iterator position on the stack and
-          // switch to processing the nested value.
-          stack.infallibleAppend(std::move(top));
-          top = FastStackEntry(&val.toObject().as<NativeObject>());
-          wroteMember = false;
-          nesting = true;  // Break out to the outer loop.
-          break;
-        }
-        if (!EmitSimpleValue(cx, scx->sb, val)) {
+        } else if (!EmitSimpleValue(cx, scx->sb, val)) {
           return false;
         }
       }
@@ -1733,6 +1766,41 @@ static bool InternalizeJSONProperty(
     return false;
   }
 
+#ifdef ENABLE_JSON_PARSE_WITH_SOURCE
+  RootedObject context(cx);
+  Rooted<UniquePtr<ParseRecordObject::EntryMap>> entries(cx);
+  if (JS::Prefs::experimental_json_parse_with_source()) {
+    // https://tc39.es/proposal-json-parse-with-source/#sec-internalizejsonproperty
+    bool sameVal = false;
+    Rooted<Value> parsedValue(cx, parseRecord.get().value);
+    if (!SameValue(cx, parsedValue, val, &sameVal)) {
+      return false;
+    }
+    if (!parseRecord.get().isEmpty() && sameVal) {
+      if (parseRecord.get().parseNode) {
+        MOZ_ASSERT(!val.isObject());
+        Rooted<IdValueVector> props(cx, cx);
+        if (!props.emplaceBack(
+                IdValuePair(NameToId(cx->names().source),
+                            StringValue(parseRecord.get().parseNode)))) {
+          return false;
+        }
+        context = NewPlainObjectWithUniqueNames(cx, props);
+        if (!context) {
+          return false;
+        }
+      }
+      entries = std::move(parseRecord.get().entries);
+    }
+    if (!context) {
+      context = NewPlainObject(cx);
+      if (!context) {
+        return false;
+      }
+    }
+  }
+#endif
+
   /* Step 2. */
   if (val.isObject()) {
     RootedObject obj(cx, &val.toObject());
@@ -1763,6 +1831,13 @@ static bool InternalizeJSONProperty(
 
         /* Step 2a(iii)(1). */
         Rooted<ParseRecordObject> elementRecord(cx);
+#ifdef ENABLE_JSON_PARSE_WITH_SOURCE
+        if (entries) {
+          if (auto entry = entries->lookup(id)) {
+            elementRecord = std::move(entry->value());
+          }
+        }
+#endif
         if (!InternalizeJSONProperty(cx, obj, id, reviver, &elementRecord,
                                      &newElement)) {
           return false;
@@ -1804,6 +1879,13 @@ static bool InternalizeJSONProperty(
         /* Step 2c(ii)(1). */
         id = keys[i];
         Rooted<ParseRecordObject> entryRecord(cx);
+#ifdef ENABLE_JSON_PARSE_WITH_SOURCE
+        if (entries) {
+          if (auto entry = entries->lookup(id)) {
+            entryRecord = std::move(entry->value());
+          }
+        }
+#endif
         if (!InternalizeJSONProperty(cx, obj, id, reviver, &entryRecord,
                                      &newElement)) {
           return false;
@@ -1838,15 +1920,7 @@ static bool InternalizeJSONProperty(
 
   RootedValue keyVal(cx, StringValue(key));
 #ifdef ENABLE_JSON_PARSE_WITH_SOURCE
-  if (cx->realm()->creationOptions().getJSONParseWithSource()) {
-    RootedObject context(cx, NewPlainObject(cx));
-    if (!context) {
-      return false;
-    }
-    Rooted<Value> parseNode(cx, StringValue(parseRecord.get().parseNode));
-    if (!DefineDataProperty(cx, context, cx->names().source, parseNode)) {
-      return false;
-    }
+  if (JS::Prefs::experimental_json_parse_with_source()) {
     RootedValue contextVal(cx, ObjectValue(*context));
     return js::Call(cx, reviver, holder, keyVal, val, contextVal, vp);
   }
@@ -1867,7 +1941,7 @@ static bool Revive(JSContext* cx, HandleValue reviver,
   }
 
 #ifdef ENABLE_JSON_PARSE_WITH_SOURCE
-  MOZ_ASSERT_IF(cx->realm()->creationOptions().getJSONParseWithSource(),
+  MOZ_ASSERT_IF(JS::Prefs::experimental_json_parse_with_source(),
                 pro.get().value == vp.get());
 #endif
   Rooted<jsid> id(cx, NameToId(cx->names().empty_));
@@ -1876,10 +1950,10 @@ static bool Revive(JSContext* cx, HandleValue reviver,
 
 template <typename CharT>
 bool ParseJSON(JSContext* cx, const mozilla::Range<const CharT> chars,
-               MutableHandleValue vp, MutableHandle<ParseRecordObject> pro) {
+               MutableHandleValue vp) {
   Rooted<JSONParser<CharT>> parser(cx, cx, chars,
                                    JSONParser<CharT>::ParseType::JSONParse);
-  return parser.parse(vp, pro);
+  return parser.parse(vp);
 }
 
 template <typename CharT>
@@ -1888,7 +1962,15 @@ bool js::ParseJSONWithReviver(JSContext* cx,
                               HandleValue reviver, MutableHandleValue vp) {
   /* https://262.ecma-international.org/14.0/#sec-json.parse steps 2-10. */
   Rooted<ParseRecordObject> pro(cx);
-  if (!ParseJSON(cx, chars, vp, &pro)) {
+#ifdef ENABLE_JSON_PARSE_WITH_SOURCE
+  if (JS::Prefs::experimental_json_parse_with_source() && IsCallable(reviver)) {
+    Rooted<JSONReviveParser<CharT>> parser(cx, cx, chars);
+    if (!parser.get().parse(vp, &pro)) {
+      return false;
+    }
+  } else
+#endif
+      if (!ParseJSON(cx, chars, vp)) {
     return false;
   }
 
@@ -2086,14 +2168,13 @@ static bool json_parseImmutable(JSContext* cx, unsigned argc, Value* vp) {
 
   HandleValue reviver = args.get(1);
   RootedValue unfiltered(cx);
-  Rooted<ParseRecordObject> pro(cx);
 
   if (linearChars.isLatin1()) {
-    if (!ParseJSON(cx, linearChars.latin1Range(), &unfiltered, &pro)) {
+    if (!ParseJSON(cx, linearChars.latin1Range(), &unfiltered)) {
       return false;
     }
   } else {
-    if (!ParseJSON(cx, linearChars.twoByteRange(), &unfiltered, &pro)) {
+    if (!ParseJSON(cx, linearChars.twoByteRange(), &unfiltered)) {
       return false;
     }
   }
@@ -2103,6 +2184,104 @@ static bool json_parseImmutable(JSContext* cx, unsigned argc, Value* vp) {
 }
 #endif
 
+#ifdef ENABLE_JSON_PARSE_WITH_SOURCE
+/* https://tc39.es/proposal-json-parse-with-source/#sec-json.israwjson */
+static bool json_isRawJSON(JSContext* cx, unsigned argc, Value* vp) {
+  AutoJSMethodProfilerEntry pseudoFrame(cx, "JSON", "isRawJSON");
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  /* Step 1. */
+  if (args.get(0).isObject()) {
+    Rooted<JSObject*> obj(cx, &args[0].toObject());
+#  ifdef DEBUG
+    if (obj->is<RawJSONObject>()) {
+      bool objIsFrozen = false;
+      MOZ_ASSERT(js::TestIntegrityLevel(cx, obj, IntegrityLevel::Frozen,
+                                        &objIsFrozen));
+      MOZ_ASSERT(objIsFrozen);
+    }
+#  endif  // DEBUG
+    args.rval().setBoolean(obj->is<RawJSONObject>());
+    return true;
+  }
+
+  /* Step 2. */
+  args.rval().setBoolean(false);
+  return true;
+}
+
+static inline bool IsJSONWhitespace(char16_t ch) {
+  return ch == '\t' || ch == '\n' || ch == '\r' || ch == ' ';
+}
+
+/* https://tc39.es/proposal-json-parse-with-source/#sec-json.rawjson */
+static bool json_rawJSON(JSContext* cx, unsigned argc, Value* vp) {
+  AutoJSMethodProfilerEntry pseudoFrame(cx, "JSON", "rawJSON");
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  /* Step 1. */
+  JSString* jsonString = ToString<CanGC>(cx, args.get(0));
+  if (!jsonString) {
+    return false;
+  }
+
+  Rooted<JSLinearString*> linear(cx, jsonString->ensureLinear(cx));
+  if (!linear) {
+    return false;
+  }
+
+  AutoStableStringChars linearChars(cx);
+  if (!linearChars.init(cx, linear)) {
+    return false;
+  }
+
+  /* Step 2. */
+  if (linear->empty()) {
+    JS_ReportErrorNumberASCII(cx, js::GetErrorMessage, nullptr,
+                              JSMSG_JSON_RAW_EMPTY);
+    return false;
+  }
+  if (IsJSONWhitespace(linear->latin1OrTwoByteChar(0)) ||
+      IsJSONWhitespace(linear->latin1OrTwoByteChar(linear->length() - 1))) {
+    JS_ReportErrorNumberASCII(cx, js::GetErrorMessage, nullptr,
+                              JSMSG_JSON_RAW_WHITESPACE);
+    return false;
+  }
+
+  /* Step 3. */
+  RootedValue parsedValue(cx);
+  if (linearChars.isLatin1()) {
+    if (!ParseJSON(cx, linearChars.latin1Range(), &parsedValue)) {
+      return false;
+    }
+  } else {
+    if (!ParseJSON(cx, linearChars.twoByteRange(), &parsedValue)) {
+      return false;
+    }
+  }
+
+  if (parsedValue.isObject()) {
+    JS_ReportErrorNumberASCII(cx, js::GetErrorMessage, nullptr,
+                              JSMSG_JSON_RAW_ARRAY_OR_OBJECT);
+    return false;
+  }
+
+  /* Steps 4-6. */
+  Rooted<RawJSONObject*> obj(cx, RawJSONObject::create(cx, linear));
+  if (!obj) {
+    return false;
+  }
+
+  /* Step 7. */
+  if (!js::FreezeObject(cx, obj)) {
+    return false;
+  }
+
+  args.rval().setObject(*obj);
+  return true;
+}
+#endif  // ENABLE_JSON_PARSE_WITH_SOURCE
+
 /* https://262.ecma-international.org/14.0/#sec-json.stringify */
 bool json_stringify(JSContext* cx, unsigned argc, Value* vp) {
   AutoJSMethodProfilerEntry pseudoFrame(cx, "JSON", "stringify");
@@ -2141,11 +2320,16 @@ bool json_stringify(JSContext* cx, unsigned argc, Value* vp) {
 }
 
 static const JSFunctionSpec json_static_methods[] = {
-    JS_FN("toSource", json_toSource, 0, 0), JS_FN("parse", json_parse, 2, 0),
+    JS_FN("toSource", json_toSource, 0, 0),
+    JS_FN("parse", json_parse, 2, 0),
     JS_FN("stringify", json_stringify, 3, 0),
 #ifdef ENABLE_RECORD_TUPLE
     JS_FN("parseImmutable", json_parseImmutable, 2, 0),
 #endif
+#ifdef ENABLE_JSON_PARSE_WITH_SOURCE
+    JS_FN("isRawJSON", json_isRawJSON, 1, 0),
+    JS_FN("rawJSON", json_rawJSON, 1, 0),
+#endif
     JS_FS_END};
 
 static const JSPropertySpec json_static_properties[] = {
diff --git a/js/src/builtin/MapObject.cpp b/js/src/builtin/MapObject.cpp
index fd35b8e776..cd4ae7f46a 100644
--- a/js/src/builtin/MapObject.cpp
+++ b/js/src/builtin/MapObject.cpp
@@ -333,23 +333,42 @@ size_t MapIteratorObject::objectMoved(JSObject* obj, JSObject* old) {
   Nursery& nursery = iter->runtimeFromMainThread()->gc.nursery();
   if (!nursery.isInside(range)) {
     nursery.removeMallocedBufferDuringMinorGC(range);
-    return 0;
   }
 
+  size_t size = RoundUp(sizeof(ValueMap::Range), gc::CellAlignBytes);
   AutoEnterOOMUnsafeRegion oomUnsafe;
-  auto newRange = iter->zone()->new_<ValueMap::Range>(*range);
-  if (!newRange) {
-    oomUnsafe.crash(
-        "MapIteratorObject failed to allocate Range data while tenuring.");
+  void* buffer = nursery.allocateBufferSameLocation(obj, size, js::MallocArena);
+  if (!buffer) {
+    oomUnsafe.crash("MapIteratorObject::objectMoved");
   }
 
+  bool iteratorIsInNursery = IsInsideNursery(obj);
+  MOZ_ASSERT(iteratorIsInNursery == nursery.isInside(buffer));
+  auto* newRange = new (buffer) ValueMap::Range(*range, iteratorIsInNursery);
   range->~Range();
   iter->setReservedSlot(MapIteratorObject::RangeSlot, PrivateValue(newRange));
-  return sizeof(ValueMap::Range);
+
+  if (iteratorIsInNursery && iter->target()) {
+    SetHasNurseryMemory(iter->target(), true);
+  }
+
+  return size;
+}
+
+MapObject* MapIteratorObject::target() const {
+  Value value = getFixedSlot(TargetSlot);
+  if (value.isUndefined()) {
+    return nullptr;
+  }
+
+  return &MaybeForwarded(&value.toObject())->as<MapObject>();
 }
 
 template <typename Range>
 static void DestroyRange(JSObject* iterator, Range* range) {
+  MOZ_ASSERT(IsInsideNursery(iterator) ==
+             iterator->runtimeFromMainThread()->gc.nursery().isInside(range));
+
   range->~Range();
   if (!IsInsideNursery(iterator)) {
     js_free(range);
@@ -533,7 +552,7 @@ void MapObject::trace(JSTracer* trc, JSObject* obj) {
   }
 }
 
-using NurseryKeysVector = mozilla::Vector<Value, 0, SystemAllocPolicy>;
+using NurseryKeysVector = GCVector<Value, 0, SystemAllocPolicy>;
 
 template <typename TableObject>
 static NurseryKeysVector* GetNurseryKeys(TableObject* t) {
@@ -577,17 +596,34 @@ class js::OrderedHashTableRef : public gc::BufferableRef {
         reinterpret_cast<typename ObjectT::UnbarrieredTable*>(realTable);
     NurseryKeysVector* keys = GetNurseryKeys(object);
     MOZ_ASSERT(keys);
-    for (Value key : *keys) {
-      MOZ_ASSERT(unbarrieredTable->hash(key) ==
-                 realTable->hash(*reinterpret_cast<HashableValue*>(&key)));
-      // Note: we use a lambda to avoid tenuring keys that have been removed
-      // from the Map or Set.
-      unbarrieredTable->rekeyOneEntry(key, [trc](const Value& prior) {
-        Value key = prior;
-        TraceManuallyBarrieredEdge(trc, &key, "ordered hash table key");
-        return key;
-      });
+
+    keys->mutableEraseIf([&](Value& key) {
+      MOZ_ASSERT(
+          unbarrieredTable->hash(key) ==
+          realTable->hash(*reinterpret_cast<const HashableValue*>(&key)));
+      MOZ_ASSERT(IsInsideNursery(key.toGCThing()));
+
+      auto result =
+          unbarrieredTable->rekeyOneEntry(key, [trc](const Value& prior) {
+            Value key = prior;
+            TraceManuallyBarrieredEdge(trc, &key, "ordered hash table key");
+            return key;
+          });
+
+      if (result.isNothing()) {
+        return true;  // Key removed.
+      }
+
+      key = result.value();
+      return !IsInsideNursery(key.toGCThing());
+    });
+
+    if (!keys->empty()) {
+      trc->runtime()->gc.storeBuffer().putGeneric(
+          OrderedHashTableRef<ObjectT>(object));
+      return;
     }
+
     DeleteNurseryKeys(object);
   }
 };
@@ -739,6 +775,8 @@ void MapObject::finalize(JS::GCContext* gcx, JSObject* obj) {
     return;
   }
 
+  MOZ_ASSERT_IF(obj->isTenured(), !table->hasNurseryRanges());
+
   bool needsPostBarriers = obj->isTenured();
   if (needsPostBarriers) {
     // Use the ValueMap representation which has post barriers.
@@ -750,21 +788,36 @@ void MapObject::finalize(JS::GCContext* gcx, JSObject* obj) {
   }
 }
 
+void MapObject::clearNurseryRangesBeforeMinorGC() {
+  getTableUnchecked()->destroyNurseryRanges();
+  SetHasNurseryMemory(this, false);
+}
+
 /* static */
-void MapObject::sweepAfterMinorGC(JS::GCContext* gcx, MapObject* mapobj) {
-  bool wasInsideNursery = IsInsideNursery(mapobj);
-  if (wasInsideNursery && !IsForwarded(mapobj)) {
+MapObject* MapObject::sweepAfterMinorGC(JS::GCContext* gcx, MapObject* mapobj) {
+  Nursery& nursery = gcx->runtime()->gc.nursery();
+  bool wasInCollectedRegion = nursery.inCollectedRegion(mapobj);
+  if (wasInCollectedRegion && !IsForwarded(mapobj)) {
     finalize(gcx, mapobj);
-    return;
+    return nullptr;
   }
 
   mapobj = MaybeForwarded(mapobj);
-  mapobj->getTableUnchecked()->destroyNurseryRanges();
-  SetHasNurseryMemory(mapobj, false);
 
-  if (wasInsideNursery) {
+  bool insideNursery = IsInsideNursery(mapobj);
+  if (insideNursery) {
+    SetHasNurseryMemory(mapobj, true);
+  }
+
+  if (wasInCollectedRegion && mapobj->isTenured()) {
     AddCellMemory(mapobj, sizeof(ValueMap), MemoryUse::MapObjectTable);
   }
+
+  if (!HasNurseryMemory(mapobj)) {
+    return nullptr;
+  }
+
+  return mapobj;
 }
 
 bool MapObject::construct(JSContext* cx, unsigned argc, Value* vp) {
@@ -1199,19 +1252,36 @@ size_t SetIteratorObject::objectMoved(JSObject* obj, JSObject* old) {
   Nursery& nursery = iter->runtimeFromMainThread()->gc.nursery();
   if (!nursery.isInside(range)) {
     nursery.removeMallocedBufferDuringMinorGC(range);
-    return 0;
   }
 
+  size_t size = RoundUp(sizeof(ValueSet::Range), gc::CellAlignBytes);
+  ;
   AutoEnterOOMUnsafeRegion oomUnsafe;
-  auto newRange = iter->zone()->new_<ValueSet::Range>(*range);
-  if (!newRange) {
-    oomUnsafe.crash(
-        "SetIteratorObject failed to allocate Range data while tenuring.");
+  void* buffer = nursery.allocateBufferSameLocation(obj, size, js::MallocArena);
+  if (!buffer) {
+    oomUnsafe.crash("SetIteratorObject::objectMoved");
   }
 
+  bool iteratorIsInNursery = IsInsideNursery(obj);
+  MOZ_ASSERT(iteratorIsInNursery == nursery.isInside(buffer));
+  auto* newRange = new (buffer) ValueSet::Range(*range, iteratorIsInNursery);
   range->~Range();
   iter->setReservedSlot(SetIteratorObject::RangeSlot, PrivateValue(newRange));
-  return sizeof(ValueSet::Range);
+
+  if (iteratorIsInNursery && iter->target()) {
+    SetHasNurseryMemory(iter->target(), true);
+  }
+
+  return size;
+}
+
+SetObject* SetIteratorObject::target() const {
+  Value value = getFixedSlot(TargetSlot);
+  if (value.isUndefined()) {
+    return nullptr;
+  }
+
+  return &MaybeForwarded(&value.toObject())->as<SetObject>();
 }
 
 bool SetIteratorObject::next(SetIteratorObject* setIterator,
@@ -1449,25 +1519,41 @@ void SetObject::finalize(JS::GCContext* gcx, JSObject* obj) {
   MOZ_ASSERT(gcx->onMainThread());
   SetObject* setobj = static_cast<SetObject*>(obj);
   if (ValueSet* set = setobj->getData()) {
+    MOZ_ASSERT_IF(obj->isTenured(), !set->hasNurseryRanges());
     gcx->delete_(obj, set, MemoryUse::MapObjectTable);
   }
 }
 
+void SetObject::clearNurseryRangesBeforeMinorGC() {
+  getTableUnchecked()->destroyNurseryRanges();
+  SetHasNurseryMemory(this, false);
+}
+
 /* static */
-void SetObject::sweepAfterMinorGC(JS::GCContext* gcx, SetObject* setobj) {
-  bool wasInsideNursery = IsInsideNursery(setobj);
-  if (wasInsideNursery && !IsForwarded(setobj)) {
+SetObject* SetObject::sweepAfterMinorGC(JS::GCContext* gcx, SetObject* setobj) {
+  Nursery& nursery = gcx->runtime()->gc.nursery();
+  bool wasInCollectedRegion = nursery.inCollectedRegion(setobj);
+  if (wasInCollectedRegion && !IsForwarded(setobj)) {
     finalize(gcx, setobj);
-    return;
+    return nullptr;
   }
 
   setobj = MaybeForwarded(setobj);
-  setobj->getData()->destroyNurseryRanges();
-  SetHasNurseryMemory(setobj, false);
 
-  if (wasInsideNursery) {
+  bool insideNursery = IsInsideNursery(setobj);
+  if (insideNursery) {
+    SetHasNurseryMemory(setobj, true);
+  }
+
+  if (wasInCollectedRegion && setobj->isTenured()) {
     AddCellMemory(setobj, sizeof(ValueSet), MemoryUse::MapObjectTable);
   }
+
+  if (!HasNurseryMemory(setobj)) {
+    return nullptr;
+  }
+
+  return setobj;
 }
 
 bool SetObject::isBuiltinAdd(HandleValue add) {
diff --git a/js/src/builtin/MapObject.h b/js/src/builtin/MapObject.h
index ef37b9912e..d47797eff7 100644
--- a/js/src/builtin/MapObject.h
+++ b/js/src/builtin/MapObject.h
@@ -168,7 +168,14 @@ class MapObject : public NativeObject {
       OrderedHashMap<Value, Value, UnbarrieredHashPolicy, CellAllocPolicy>;
   friend class OrderedHashTableRef<MapObject>;
 
-  static void sweepAfterMinorGC(JS::GCContext* gcx, MapObject* mapobj);
+  void clearNurseryRangesBeforeMinorGC();
+
+  // Sweeps a map that had nursery memory associated with it after a minor
+  // GC. This may finalize the map if it was in the nursery and has died.
+  //
+  // Returns a pointer to the map if it still has nursery memory associated with
+  // it, or nullptr.
+  static MapObject* sweepAfterMinorGC(JS::GCContext* gcx, MapObject* mapobj);
 
   size_t sizeOfData(mozilla::MallocSizeOf mallocSizeOf);
 
@@ -276,6 +283,7 @@ class MapIteratorObject : public NativeObject {
 
  private:
   inline MapObject::IteratorKind kind() const;
+  MapObject* target() const;
 };
 
 class SetObject : public NativeObject {
@@ -326,7 +334,14 @@ class SetObject : public NativeObject {
       OrderedHashSet<Value, UnbarrieredHashPolicy, CellAllocPolicy>;
   friend class OrderedHashTableRef<SetObject>;
 
-  static void sweepAfterMinorGC(JS::GCContext* gcx, SetObject* setobj);
+  void clearNurseryRangesBeforeMinorGC();
+
+  // Sweeps a set that had nursery memory associated with it after a minor
+  // GC. This may finalize the set if it was in the nursery and has died.
+  //
+  // Returns a pointer to the set if it still has nursery memory associated with
+  // it, or nullptr.
+  static SetObject* sweepAfterMinorGC(JS::GCContext* gcx, SetObject* setobj);
 
   size_t sizeOfData(mozilla::MallocSizeOf mallocSizeOf);
 
@@ -414,6 +429,7 @@ class SetIteratorObject : public NativeObject {
 
  private:
   inline SetObject::IteratorKind kind() const;
+  SetObject* target() const;
 };
 
 using SetInitGetPrototypeOp = NativeObject* (*)(JSContext*,
diff --git a/js/src/builtin/ModuleObject.cpp b/js/src/builtin/ModuleObject.cpp
index b9db9bf02d..0365f744a6 100644
--- a/js/src/builtin/ModuleObject.cpp
+++ b/js/src/builtin/ModuleObject.cpp
@@ -1109,6 +1109,17 @@ JSScript* ModuleObject::script() const {
   return ptr;
 }
 
+const char* ModuleObject::filename() const {
+  // The ScriptSlot will be cleared once the module is evaluated, so we try to
+  // get the filename from cyclicModuleFields().
+
+  // TODO: Bug 1885483: Provide filename for JSON modules
+  if (!hasCyclicModuleFields()) {
+    return "(JSON module)";
+  }
+  return cyclicModuleFields()->scriptSourceObject->source()->filename();
+}
+
 static inline void AssertValidModuleStatus(ModuleStatus status) {
   MOZ_ASSERT(status >= ModuleStatus::Unlinked &&
              status <= ModuleStatus::Evaluated_Error);
diff --git a/js/src/builtin/ModuleObject.h b/js/src/builtin/ModuleObject.h
index d39d65b18c..cb74d67c40 100644
--- a/js/src/builtin/ModuleObject.h
+++ b/js/src/builtin/ModuleObject.h
@@ -360,6 +360,7 @@ class ModuleObject : public NativeObject {
 
   JSScript* maybeScript() const;
   JSScript* script() const;
+  const char* filename() const;
   ModuleEnvironmentObject& initialEnvironment() const;
   ModuleEnvironmentObject* environment() const;
   ModuleNamespaceObject* namespace_();
diff --git a/js/src/builtin/ParseRecordObject.cpp b/js/src/builtin/ParseRecordObject.cpp
index a453c30c0e..efb05d1845 100644
--- a/js/src/builtin/ParseRecordObject.cpp
+++ b/js/src/builtin/ParseRecordObject.cpp
@@ -19,8 +19,24 @@ ParseRecordObject::ParseRecordObject(Handle<js::JSONParseNode*> parseNode,
                                      const Value& val)
     : parseNode(parseNode), key(JS::PropertyKey::Void()), value(val) {}
 
+bool ParseRecordObject::addEntries(JSContext* cx, EntryMap&& appendEntries) {
+  if (!entries) {
+    entries = js::MakeUnique<EntryMap>(std::move(appendEntries));
+    return !!entries;
+  }
+  for (auto iter = appendEntries.iter(); !iter.done(); iter.next()) {
+    if (!entries->put(iter.get().key(), std::move(iter.get().value()))) {
+      return false;
+    }
+  }
+  return true;
+}
+
 void ParseRecordObject::trace(JSTracer* trc) {
   JS::TraceRoot(trc, &parseNode, "ParseRecordObject parse node");
   JS::TraceRoot(trc, &key, "ParseRecordObject key");
   JS::TraceRoot(trc, &value, "ParseRecordObject value");
+  if (entries) {
+    entries->trace(trc);
+  }
 }
diff --git a/js/src/builtin/ParseRecordObject.h b/js/src/builtin/ParseRecordObject.h
index 60a902f19b..7e3176a23f 100644
--- a/js/src/builtin/ParseRecordObject.h
+++ b/js/src/builtin/ParseRecordObject.h
@@ -7,7 +7,8 @@
 #ifndef builtin_ParseRecordObject_h
 #define builtin_ParseRecordObject_h
 
-#include "js/TraceKind.h"
+#include "js/HashTable.h"
+#include "js/TracingAPI.h"
 #include "vm/JSContext.h"
 
 namespace js {
@@ -16,24 +17,40 @@ using JSONParseNode = JSString;
 
 class ParseRecordObject {
  public:
+  using EntryMap = js::GCHashMap<PropertyKey, ParseRecordObject>;
+
+  // The source text that was parsed for this record. According to the spec, we
+  // don't track this for objects and arrays, so it will be a null pointer.
   JSONParseNode* parseNode;
+  // For object members, the member key. For arrays, the index. For JSON
+  // primitives, it will be undefined.
   JS::PropertyKey key;
+  // The original value corresponding to this record, used to determine if the
+  // reviver function has modified it.
   Value value;
+  // For objects and arrays, the records for the members and elements
+  // (respectively). If there are none, or for JSON primitives, we won't
+  // allocate an EntryMap.
+  UniquePtr<EntryMap> entries;
 
   ParseRecordObject();
   ParseRecordObject(Handle<js::JSONParseNode*> parseNode, const Value& val);
   ParseRecordObject(ParseRecordObject&& other)
       : parseNode(std::move(other.parseNode)),
         key(std::move(other.key)),
-        value(std::move(other.value)) {}
+        value(std::move(other.value)),
+        entries(std::move(other.entries)) {}
 
   bool isEmpty() const { return value.isUndefined(); }
 
+  bool addEntries(JSContext* cx, EntryMap&& appendEntries);
+
   // move assignment
   ParseRecordObject& operator=(ParseRecordObject&& other) noexcept {
     parseNode = other.parseNode;
     key = other.key;
     value = other.value;
+    entries = std::move(other.entries);
     return *this;
   }
 
diff --git a/js/src/builtin/Promise.cpp b/js/src/builtin/Promise.cpp
index bd40add77f..92e72b9cb9 100644
--- a/js/src/builtin/Promise.cpp
+++ b/js/src/builtin/Promise.cpp
@@ -940,13 +940,7 @@ static JSFunction* GetRejectFunctionFromResolve(JSFunction* resolve);
 /**
  * Returns Promise Resolve Function's [[AlreadyResolved]].[[Value]].
  */
-static bool IsAlreadyResolvedMaybeWrappedResolveFunction(
-    JSObject* resolveFunObj) {
-  if (IsWrapper(resolveFunObj)) {
-    resolveFunObj = UncheckedUnwrap(resolveFunObj);
-  }
-
-  JSFunction* resolveFun = &resolveFunObj->as<JSFunction>();
+static bool IsAlreadyResolvedResolveFunction(JSFunction* resolveFun) {
   MOZ_ASSERT(resolveFun->maybeNative() == ResolvePromiseFunction);
 
   bool alreadyResolved =
@@ -970,13 +964,7 @@ static bool IsAlreadyResolvedMaybeWrappedResolveFunction(
 /**
  * Returns Promise Reject Function's [[AlreadyResolved]].[[Value]].
  */
-static bool IsAlreadyResolvedMaybeWrappedRejectFunction(
-    JSObject* rejectFunObj) {
-  if (IsWrapper(rejectFunObj)) {
-    rejectFunObj = UncheckedUnwrap(rejectFunObj);
-  }
-
-  JSFunction* rejectFun = &rejectFunObj->as<JSFunction>();
+static bool IsAlreadyResolvedRejectFunction(JSFunction* rejectFun) {
   MOZ_ASSERT(rejectFun->maybeNative() == RejectPromiseFunction);
 
   bool alreadyResolved =
@@ -1023,8 +1011,8 @@ static void SetAlreadyResolvedResolutionFunction(JSFunction* resolutionFun) {
   reject->setExtendedSlot(RejectFunctionSlot_Promise, UndefinedValue());
   reject->setExtendedSlot(RejectFunctionSlot_ResolveFunction, UndefinedValue());
 
-  MOZ_ASSERT(IsAlreadyResolvedMaybeWrappedResolveFunction(resolve));
-  MOZ_ASSERT(IsAlreadyResolvedMaybeWrappedRejectFunction(reject));
+  MOZ_ASSERT(IsAlreadyResolvedResolveFunction(resolve));
+  MOZ_ASSERT(IsAlreadyResolvedRejectFunction(reject));
 }
 
 /**
@@ -1132,8 +1120,8 @@ void js::SetAlreadyResolvedPromiseWithDefaultResolvingFunction(
   rejectFun->initExtendedSlot(RejectFunctionSlot_ResolveFunction,
                               ObjectValue(*resolveFun));
 
-  MOZ_ASSERT(!IsAlreadyResolvedMaybeWrappedResolveFunction(resolveFun));
-  MOZ_ASSERT(!IsAlreadyResolvedMaybeWrappedRejectFunction(rejectFun));
+  MOZ_ASSERT(!IsAlreadyResolvedResolveFunction(resolveFun));
+  MOZ_ASSERT(!IsAlreadyResolvedRejectFunction(rejectFun));
 
   // Step 12. Return the Record { [[Resolve]]: resolve, [[Reject]]: reject }.
   return true;
@@ -1181,8 +1169,7 @@ static bool RejectPromiseFunction(JSContext* cx, unsigned argc, Value* vp) {
   // If the Promise isn't available anymore, it has been resolved and the
   // reference to it removed to make it eligible for collection.
   bool alreadyResolved = promiseVal.isUndefined();
-  MOZ_ASSERT(IsAlreadyResolvedMaybeWrappedRejectFunction(reject) ==
-             alreadyResolved);
+  MOZ_ASSERT(IsAlreadyResolvedRejectFunction(reject) == alreadyResolved);
   if (alreadyResolved) {
     args.rval().setUndefined();
     return true;
@@ -1362,8 +1349,7 @@ static bool ResolvePromiseFunction(JSContext* cx, unsigned argc, Value* vp) {
   //
   // NOTE: We use the reference to the reject function as [[AlreadyResolved]].
   bool alreadyResolved = promiseVal.isUndefined();
-  MOZ_ASSERT(IsAlreadyResolvedMaybeWrappedResolveFunction(resolve) ==
-             alreadyResolved);
+  MOZ_ASSERT(IsAlreadyResolvedResolveFunction(resolve) == alreadyResolved);
   if (alreadyResolved) {
     args.rval().setUndefined();
     return true;
@@ -3164,7 +3150,8 @@ static bool PromiseAllResolveElementFunction(JSContext* cx, unsigned argc,
   for (size_t i = 0, len = promises.length(); i < len; i++) {
     JSObject* obj = promises[i];
     cx->check(obj);
-    MOZ_ASSERT(UncheckedUnwrap(obj)->is<PromiseObject>());
+    JSObject* unwrapped = UncheckedUnwrap(obj);
+    MOZ_ASSERT(unwrapped->is<PromiseObject>() || JS_IsDeadWrapper(unwrapped));
   }
 #endif
 
@@ -3265,7 +3252,13 @@ static bool PromiseAllResolveElementFunction(JSContext* cx, unsigned argc,
       // compartments with principals inaccessible from the current
       // compartment. To make that work, it unwraps promises with
       // UncheckedUnwrap,
-      nextPromise = &UncheckedUnwrap(nextPromiseObj)->as<PromiseObject>();
+      JSObject* unwrapped = UncheckedUnwrap(nextPromiseObj);
+      if (JS_IsDeadWrapper(unwrapped)) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                                  JSMSG_DEAD_OBJECT);
+        return nullptr;
+      }
+      nextPromise = &unwrapped->as<PromiseObject>();
 
       if (!PerformPromiseThen(cx, nextPromise, resolveFunVal, rejectFunVal,
                               resultCapabilityWithoutResolving)) {
@@ -5036,7 +5029,8 @@ static PromiseReactionRecord* NewReactionRecord(
       // This is the only case where we allow `resolve` and `reject` to
       // be null when the `promise` field is not a PromiseObject.
       JSObject* unwrappedPromise = UncheckedUnwrap(resultCapability.promise());
-      MOZ_ASSERT(unwrappedPromise->is<PromiseObject>());
+      MOZ_ASSERT(unwrappedPromise->is<PromiseObject>() ||
+                 JS_IsDeadWrapper(unwrappedPromise));
       MOZ_ASSERT(!resultCapability.resolve());
       MOZ_ASSERT(!resultCapability.reject());
     }
@@ -6218,6 +6212,11 @@ bool js::Promise_then(JSContext* cx, unsigned argc, Value* vp) {
     return true;
   }
 
+  if (JS_IsDeadWrapper(UncheckedUnwrap(dependentPromise))) {
+    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_DEAD_OBJECT);
+    return false;
+  }
+
   // `dependentPromise` should be a maybe-wrapped Promise.
   MOZ_ASSERT(UncheckedUnwrap(dependentPromise)->is<PromiseObject>());
 
@@ -6934,7 +6933,8 @@ JS::AutoDebuggerJobQueueInterruption::AutoDebuggerJobQueueInterruption()
     : cx(nullptr) {}
 
 JS::AutoDebuggerJobQueueInterruption::~AutoDebuggerJobQueueInterruption() {
-  MOZ_ASSERT_IF(initialized(), cx->jobQueue->empty());
+  MOZ_ASSERT_IF(initialized() && !cx->jobQueue->isDrainingStopped(),
+                cx->jobQueue->empty());
 }
 
 bool JS::AutoDebuggerJobQueueInterruption::init(JSContext* cx) {
diff --git a/js/src/builtin/RawJSONObject.cpp b/js/src/builtin/RawJSONObject.cpp
new file mode 100644
index 0000000000..08a98835c1
--- /dev/null
+++ b/js/src/builtin/RawJSONObject.cpp
@@ -0,0 +1,41 @@
+/* -*- 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/. */
+
+#include "builtin/RawJSONObject.h"
+#include "js/PropertyDescriptor.h"
+
+#include "vm/JSObject-inl.h"
+
+using namespace js;
+
+const JSClass RawJSONObject::class_ = {"RawJSON",
+                                       JSCLASS_HAS_RESERVED_SLOTS(SlotCount)};
+
+/* static */
+RawJSONObject* RawJSONObject::create(JSContext* cx,
+                                     Handle<JSString*> jsonString) {
+  Rooted<RawJSONObject*> obj(
+      cx, NewObjectWithGivenProto<RawJSONObject>(cx, nullptr));
+  if (!obj) {
+    return nullptr;
+  }
+  Rooted<PropertyKey> id(cx, NameToId(cx->names().rawJSON));
+  Rooted<Value> jsonStringVal(cx, StringValue(jsonString));
+  if (!NativeDefineDataProperty(cx, obj, id, jsonStringVal, 0)) {
+    return nullptr;
+  }
+  return obj;
+}
+
+JSString* RawJSONObject::rawJSON(JSContext* cx) {
+  // RawJSONObjects are frozen on creation, so must always have a rawJSON string
+  // property.
+  PropertyKey id(NameToId(cx->names().rawJSON));
+  JS::Value vp;
+  MOZ_ALWAYS_TRUE(GetPropertyNoGC(cx, this, ObjectValue(*this), id, &vp));
+  MOZ_ASSERT(vp.isString());
+  return vp.toString();
+}
diff --git a/js/src/builtin/RawJSONObject.h b/js/src/builtin/RawJSONObject.h
new file mode 100644
index 0000000000..cf8821a844
--- /dev/null
+++ b/js/src/builtin/RawJSONObject.h
@@ -0,0 +1,27 @@
+/* -*- 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 builtin_RawJSONObject_h
+#define builtin_RawJSONObject_h
+
+#include "vm/NativeObject.h"
+
+namespace js {
+
+class RawJSONObject : public NativeObject {
+  enum { SlotCount = 0 };
+
+ public:
+  static const JSClass class_;
+
+  static RawJSONObject* create(JSContext* cx, Handle<JSString*> jsonString);
+
+  JSString* rawJSON(JSContext* cx);
+};
+
+}  // namespace js
+
+#endif /* builtin_RawJSONObject_h */
diff --git a/js/src/builtin/Reflect.js b/js/src/builtin/Reflect.js
index f56d603ca3..34ca34af60 100644
--- a/js/src/builtin/Reflect.js
+++ b/js/src/builtin/Reflect.js
@@ -52,6 +52,8 @@ function Reflect_apply(target, thisArgument, argumentsList) {
   // Steps 2-4.
   return callFunction(std_Function_apply, target, thisArgument, argumentsList);
 }
+// This function is only barely too long for normal inlining.
+SetIsInlinableLargeFunction(Reflect_apply);
 
 // ES2017 draft rev a785b0832b071f505a694e1946182adeab84c972
 // 26.1.2 Reflect.construct ( target, argumentsList [ , newTarget ] )
diff --git a/js/src/builtin/Sorting.js b/js/src/builtin/Sorting.js
index 4530a82818..175b506192 100644
--- a/js/src/builtin/Sorting.js
+++ b/js/src/builtin/Sorting.js
@@ -6,7 +6,7 @@
 // consolidated here to avoid confusion and re-implementation of existing
 // algorithms.
 
-// For sorting small arrays.
+// For sorting small typed arrays.
 function InsertionSort(array, from, to, comparefn) {
   var item, swap, i, j;
   for (i = from + 1; i <= to; i++) {
@@ -22,101 +22,6 @@ function InsertionSort(array, from, to, comparefn) {
   }
 }
 
-// A helper function for MergeSort.
-//
-// Merge comparefn-sorted slices list[start..<=mid] and list[mid+1..<=end],
-// storing the merged sequence in out[start..<=end].
-function Merge(list, out, start, mid, end, comparefn) {
-  // Skip lopsided runs to avoid doing useless work.
-  // Skip calling the comparator if the sub-list is already sorted.
-  if (
-    mid >= end ||
-    callContentFunction(comparefn, undefined, list[mid], list[mid + 1]) <= 0
-  ) {
-    for (var i = start; i <= end; i++) {
-      DefineDataProperty(out, i, list[i]);
-    }
-    return;
-  }
-
-  var i = start;
-  var j = mid + 1;
-  var k = start;
-  while (i <= mid && j <= end) {
-    var lvalue = list[i];
-    var rvalue = list[j];
-    if (callContentFunction(comparefn, undefined, lvalue, rvalue) <= 0) {
-      DefineDataProperty(out, k++, lvalue);
-      i++;
-    } else {
-      DefineDataProperty(out, k++, rvalue);
-      j++;
-    }
-  }
-
-  // Empty out any remaining elements.
-  while (i <= mid) {
-    DefineDataProperty(out, k++, list[i++]);
-  }
-  while (j <= end) {
-    DefineDataProperty(out, k++, list[j++]);
-  }
-}
-
-// Helper function for overwriting a sparse array with a
-// dense array, filling remaining slots with holes.
-function MoveHoles(sparse, sparseLen, dense, denseLen) {
-  for (var i = 0; i < denseLen; i++) {
-    sparse[i] = dense[i];
-  }
-  for (var j = denseLen; j < sparseLen; j++) {
-    delete sparse[j];
-  }
-}
-
-// Iterative, bottom up, mergesort.
-function MergeSort(array, len, comparefn) {
-  assert(IsPackedArray(array), "array is packed");
-  assert(array.length === len, "length mismatch");
-  assert(len > 0, "array should be non-empty");
-
-  // Insertion sort for small arrays, where "small" is defined by performance
-  // testing.
-  if (len < 24) {
-    InsertionSort(array, 0, len - 1, comparefn);
-    return array;
-  }
-
-  // We do all of our allocating up front
-  var lBuffer = array;
-  var rBuffer = [];
-
-  // Use insertion sort for initial ranges.
-  var windowSize = 4;
-  for (var start = 0; start < len - 1; start += windowSize) {
-    var end = std_Math_min(start + windowSize - 1, len - 1);
-    InsertionSort(lBuffer, start, end, comparefn);
-  }
-
-  for (; windowSize < len; windowSize = 2 * windowSize) {
-    for (var start = 0; start < len; start += 2 * windowSize) {
-      // The midpoint between the two subarrays.
-      var mid = start + windowSize - 1;
-
-      // To keep from going over the edge.
-      var end = std_Math_min(start + 2 * windowSize - 1, len - 1);
-
-      Merge(lBuffer, rBuffer, start, mid, end, comparefn);
-    }
-
-    // Swap both lists.
-    var swap = lBuffer;
-    lBuffer = rBuffer;
-    rBuffer = swap;
-  }
-  return lBuffer;
-}
-
 // A helper function for MergeSortTypedArray.
 //
 // Merge comparefn-sorted slices list[start..<=mid] and list[mid+1..<=end],
diff --git a/js/src/builtin/TestingFunctions.cpp b/js/src/builtin/TestingFunctions.cpp
index 498fa1746d..da7efd2fcc 100644
--- a/js/src/builtin/TestingFunctions.cpp
+++ b/js/src/builtin/TestingFunctions.cpp
@@ -604,15 +604,6 @@ static bool GetBuildConfiguration(JSContext* cx, unsigned argc, Value* vp) {
     return false;
   }
 
-#ifdef ENABLE_JSON_PARSE_WITH_SOURCE
-  value = BooleanValue(true);
-#else
-  value = BooleanValue(false);
-#endif
-  if (!JS_SetProperty(cx, info, "json-parse-with-source", value)) {
-    return false;
-  }
-
 #ifdef FUZZING
   value = BooleanValue(true);
 #else
@@ -1620,7 +1611,7 @@ static bool WasmLosslessInvoke(JSContext* cx, unsigned argc, Value* vp) {
   if (!wasmCallFrame.resize(len)) {
     return false;
   }
-  wasmCallFrame[0].set(args.calleev());
+  wasmCallFrame[0].set(ObjectValue(*func));
   wasmCallFrame[1].set(args.thisv());
   // Copy over the arguments needed to invoke the provided wasm function,
   // skipping the wasm function we're calling that is at `args.get(0)`.
@@ -3714,6 +3705,85 @@ static bool NewString(JSContext* cx, unsigned argc, Value* vp) {
   return true;
 }
 
+static bool NewDependentString(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  RootedString src(cx, ToString(cx, args.get(0)));
+  if (!src) {
+    return false;
+  }
+
+  uint64_t indexStart = 0;
+  mozilla::Maybe<uint64_t> indexEnd;
+  gc::Heap heap = gc::Heap::Default;
+  mozilla::Maybe<gc::Heap> requiredHeap;
+
+  if (!ToIndex(cx, args.get(1), &indexStart)) {
+    return false;
+  }
+
+  Rooted<Value> options(cx);
+  if (args.get(2).isObject()) {
+    options = args[2];
+  } else {
+    uint64_t idx;
+    if (args.hasDefined(2)) {
+      if (!ToIndex(cx, args.get(2), &idx)) {
+        return false;
+      }
+      indexEnd.emplace(idx);
+    }
+    options = args.get(3);
+  }
+
+  if (options.isObject()) {
+    Rooted<Value> v(cx);
+    Rooted<JSObject*> optObj(cx, &options.toObject());
+    if (!JS_GetProperty(cx, optObj, "tenured", &v)) {
+      return false;
+    }
+    if (v.isBoolean()) {
+      requiredHeap.emplace(v.toBoolean() ? gc::Heap::Tenured
+                                         : gc::Heap::Default);
+      heap = *requiredHeap;
+    }
+  }
+
+  if (indexEnd.isNothing()) {
+    // Read the length now that no more JS code can run.
+    indexEnd.emplace(src->length());
+  }
+  if (indexStart > src->length() || *indexEnd > src->length() ||
+      indexStart >= *indexEnd) {
+    JS_ReportErrorASCII(cx, "invalid dependent string bounds");
+    return false;
+  }
+  if (!src->ensureLinear(cx)) {
+    return false;
+  }
+  Rooted<JSString*> result(
+      cx, js::NewDependentString(cx, src, indexStart, *indexEnd - indexStart,
+                                 heap));
+  if (!result) {
+    return false;
+  }
+  if (!result->isDependent()) {
+    JS_ReportErrorASCII(cx, "resulting string is not dependent (too short?)");
+    return false;
+  }
+
+  if (requiredHeap.isSome()) {
+    MOZ_ASSERT_IF(*requiredHeap == gc::Heap::Tenured, result->isTenured());
+    if ((*requiredHeap == gc::Heap::Default) && result->isTenured()) {
+      JS_ReportErrorASCII(cx, "nursery string created in tenured heap");
+      return false;
+    }
+  }
+
+  args.rval().setString(result);
+  return true;
+}
+
 // Warning! This will let you create ropes that I'm not sure would be possible
 // otherwise, specifically:
 //
@@ -7183,7 +7253,7 @@ static bool SetImmutablePrototype(JSContext* cx, unsigned argc, Value* vp) {
   return true;
 }
 
-#ifdef DEBUG
+#if defined(DEBUG) || defined(JS_JITSPEW)
 static bool DumpStringRepresentation(JSContext* cx, unsigned argc, Value* vp) {
   CallArgs args = CallArgsFromVp(argc, vp);
 
@@ -7221,7 +7291,6 @@ static bool GetStringRepresentation(JSContext* cx, unsigned argc, Value* vp) {
   args.rval().setString(rep);
   return true;
 }
-
 #endif
 
 static bool ParseCompileOptionsForModule(JSContext* cx,
@@ -7237,9 +7306,7 @@ static bool ParseCompileOptionsForModule(JSContext* cx,
     options.setModule();
     isModule = true;
 
-    // js::ParseCompileOptions should already be called.
-    if (options.lineno == 0) {
-      JS_ReportErrorASCII(cx, "Module cannot be compiled with lineNumber == 0");
+    if (!ValidateModuleCompileOptions(cx, options)) {
       return false;
     }
   } else {
@@ -9435,6 +9502,15 @@ static const JSFunctionSpecWithHelp TestingFunctions[] = {
 "   - maybeExternal: create an external string, unless the data fits within an\n"
 "     inline string. Inline strings may be nursery-allocated."),
 
+    JS_FN_HELP("newDependentString", NewDependentString, 2, 0,
+"newDependentString(str, indexStart[, indexEnd] [, options])",
+"  Essentially the same as str.substring() but insist on\n"
+"  creating a dependent string and failing if not. Also has options to\n"
+"  control the heap the string object is allocated into:\n"
+"  \n"
+"   - tenured: if true, allocate in the tenured heap or throw. If false,\n"
+"     allocate in the nursery or throw."),
+
     JS_FN_HELP("ensureLinearString", EnsureLinearString, 1, 0,
 "ensureLinearString(str)",
 "  Ensures str is a linear (non-rope) string and returns it."),
@@ -10058,20 +10134,6 @@ JS_FOR_WASM_FEATURES(WASM_FEATURE)
 "wasmMetadataAnalysis(wasmObject)",
 "  Prints an analysis of the size of metadata on this wasm object.\n"),
 
-#if defined(DEBUG) || defined(JS_JITSPEW)
-    JS_FN_HELP("dumpObject", DumpObject, 1, 0,
-"dumpObject(obj)",
-"  Dump an internal representation of an object."),
-
-    JS_FN_HELP("dumpValue", DumpValue, 1, 0,
-"dumpValue(v)",
-"  Dump an internal representation of a value."),
-
-    JS_FN_HELP("dumpValueToString", DumpValueToString, 1, 0,
-"dumpValue(v)",
-"  Return a dump of an internal representation of a value."),
-#endif
-
     JS_FN_HELP("sharedMemoryEnabled", SharedMemoryEnabled, 0, 0,
 "sharedMemoryEnabled()",
 "  Return true if SharedArrayBuffer and Atomics are enabled"),
@@ -10129,17 +10191,6 @@ JS_FOR_WASM_FEATURES(WASM_FEATURE)
 "  of internal error, or if the operation doesn't even make sense (for example,\n"
 "  because the object is a revoked proxy)."),
 
-#ifdef DEBUG
-    JS_FN_HELP("dumpStringRepresentation", DumpStringRepresentation, 1, 0,
-"dumpStringRepresentation(str)",
-"  Print a human-readable description of how the string |str| is represented.\n"),
-
-    JS_FN_HELP("stringRepresentation", GetStringRepresentation, 1, 0,
-"stringRepresentation(str)",
-"  Return a human-readable description of how the string |str| is represented.\n"),
-
-#endif
-
     JS_FN_HELP("allocationMarker", AllocationMarker, 0, 0,
 "allocationMarker([options])",
 "  Return a freshly allocated object whose [[Class]] name is\n"
@@ -10428,6 +10479,29 @@ JS_FN_HELP("getEnvironmentObjectType", GetEnvironmentObjectType, 1, 0,
       "  Return an object describing the calling realm's fuse state, "
       "as well as the state of any runtime fuses."),
 
+#if defined(DEBUG) || defined(JS_JITSPEW)
+    JS_FN_HELP("dumpObject", DumpObject, 1, 0,
+"dumpObject(obj)",
+"  Dump an internal representation of an object."),
+
+    JS_FN_HELP("dumpValue", DumpValue, 1, 0,
+"dumpValue(v)",
+"  Dump an internal representation of a value."),
+
+    JS_FN_HELP("dumpValueToString", DumpValueToString, 1, 0,
+"dumpValue(v)",
+"  Return a dump of an internal representation of a value."),
+
+    JS_FN_HELP("dumpStringRepresentation", DumpStringRepresentation, 1, 0,
+"dumpStringRepresentation(str)",
+"  Print a human-readable description of how the string |str| is represented.\n"),
+
+    JS_FN_HELP("stringRepresentation", GetStringRepresentation, 1, 0,
+"stringRepresentation(str)",
+"  Return a human-readable description of how the string |str| is represented.\n"),
+
+#endif
+
     JS_FS_HELP_END
 };
 // clang-format on
diff --git a/js/src/builtin/TestingUtility.cpp b/js/src/builtin/TestingUtility.cpp
index 12a99c7f08..9d4af5897c 100644
--- a/js/src/builtin/TestingUtility.cpp
+++ b/js/src/builtin/TestingUtility.cpp
@@ -308,3 +308,18 @@ bool js::ValidateLazinessOfStencilAndGlobal(
 
   return true;
 }
+
+bool js::ValidateModuleCompileOptions(JSContext* cx,
+                                      JS::CompileOptions& options) {
+  if (options.lineno == 0) {
+    JS_ReportErrorASCII(cx, "Module cannot be compiled with lineNumber == 0");
+    return false;
+  }
+
+  if (!options.filename()) {
+    JS_ReportErrorASCII(cx, "Module should have filename");
+    return false;
+  }
+
+  return true;
+}
diff --git a/js/src/builtin/TestingUtility.h b/js/src/builtin/TestingUtility.h
index 4c666540f7..82225068a1 100644
--- a/js/src/builtin/TestingUtility.h
+++ b/js/src/builtin/TestingUtility.h
@@ -72,6 +72,8 @@ JSObject* CreateScriptPrivate(JSContext* cx,
 bool ValidateLazinessOfStencilAndGlobal(
     JSContext* cx, const frontend::CompilationStencil& stencil);
 
+bool ValidateModuleCompileOptions(JSContext* cx, JS::CompileOptions& options);
+
 } /* namespace js */
 
 #endif /* builtin_TestingUtility_h */
diff --git a/js/src/builtin/Tuple.js b/js/src/builtin/Tuple.js
index 98177ac35d..bade1739d0 100644
--- a/js/src/builtin/Tuple.js
+++ b/js/src/builtin/Tuple.js
@@ -25,7 +25,7 @@ function TupleToSorted(comparefn) {
 
   /* Step 3. */
   var items = TupleToArray(T);
-  var sorted = callFunction(ArraySort, items, comparefn);
+  var sorted = callFunction(std_Array_sort, items, comparefn);
   return std_Tuple_unchecked(sorted);
 }
 
diff --git a/js/src/builtin/WeakMapObject-inl.h b/js/src/builtin/WeakMapObject-inl.h
index 28ab1abeb2..3c5f2ceb27 100644
--- a/js/src/builtin/WeakMapObject-inl.h
+++ b/js/src/builtin/WeakMapObject-inl.h
@@ -92,6 +92,21 @@ static MOZ_ALWAYS_INLINE bool CanBeHeldWeakly(JSContext* cx,
   return false;
 }
 
+static unsigned GetErrorNumber(bool isWeakMap) {
+#ifdef NIGHTLY_BUILD
+  bool symbolsAsWeakMapKeysEnabled =
+      JS::Prefs::experimental_symbols_as_weakmap_keys();
+
+  if (symbolsAsWeakMapKeysEnabled) {
+    return isWeakMap ? JSMSG_WEAKMAP_KEY_CANT_BE_HELD_WEAKLY
+                     : JSMSG_WEAKSET_VAL_CANT_BE_HELD_WEAKLY;
+  }
+#endif
+
+  return isWeakMap ? JSMSG_WEAKMAP_KEY_MUST_BE_AN_OBJECT
+                   : JSMSG_WEAKSET_VAL_MUST_BE_AN_OBJECT;
+}
+
 }  // namespace js
 
 #endif /* builtin_WeakMapObject_inl_h */
diff --git a/js/src/builtin/WeakMapObject.cpp b/js/src/builtin/WeakMapObject.cpp
index 680f49bc3e..a9d7dcdedc 100644
--- a/js/src/builtin/WeakMapObject.cpp
+++ b/js/src/builtin/WeakMapObject.cpp
@@ -122,8 +122,8 @@ bool WeakMapObject::delete_(JSContext* cx, unsigned argc, Value* vp) {
   MOZ_ASSERT(WeakMapObject::is(args.thisv()));
 
   if (!CanBeHeldWeakly(cx, args.get(0))) {
-    ReportValueError(cx, JSMSG_WEAKMAP_KEY_CANT_BE_HELD_WEAKLY,
-                     JSDVG_IGNORE_STACK, args.get(0), nullptr);
+    unsigned errorNum = GetErrorNumber(true);
+    ReportValueError(cx, errorNum, JSDVG_IGNORE_STACK, args.get(0), nullptr);
     return false;
   }
 
@@ -238,8 +238,8 @@ JS_PUBLIC_API bool JS::SetWeakMapEntry(JSContext* cx, HandleObject mapObj,
   CHECK_THREAD(cx);
   cx->check(key, val);
   if (!CanBeHeldWeakly(cx, key)) {
-    ReportValueError(cx, JSMSG_WEAKMAP_KEY_CANT_BE_HELD_WEAKLY,
-                     JSDVG_IGNORE_STACK, key, nullptr);
+    unsigned errorNum = GetErrorNumber(true);
+    ReportValueError(cx, errorNum, JSDVG_IGNORE_STACK, key, nullptr);
     return false;
   }
 
diff --git a/js/src/builtin/WeakSetObject.cpp b/js/src/builtin/WeakSetObject.cpp
index 06e190f51e..3705e94218 100644
--- a/js/src/builtin/WeakSetObject.cpp
+++ b/js/src/builtin/WeakSetObject.cpp
@@ -31,8 +31,8 @@ using namespace js;
 
   // Step 4.
   if (!CanBeHeldWeakly(cx, args.get(0))) {
-    ReportValueError(cx, JSMSG_WEAKSET_VAL_CANT_BE_HELD_WEAKLY,
-                     JSDVG_IGNORE_STACK, args.get(0), nullptr);
+    unsigned errorNum = GetErrorNumber(false);
+    ReportValueError(cx, errorNum, JSDVG_IGNORE_STACK, args.get(0), nullptr);
     return false;
   }
 
@@ -198,8 +198,9 @@ bool WeakSetObject::construct(JSContext* cx, unsigned argc, Value* vp) {
         MOZ_ASSERT(!keyVal.isMagic(JS_ELEMENTS_HOLE));
 
         if (!CanBeHeldWeakly(cx, keyVal)) {
-          ReportValueError(cx, JSMSG_WEAKSET_VAL_CANT_BE_HELD_WEAKLY,
-                           JSDVG_IGNORE_STACK, keyVal, nullptr);
+          unsigned errorNum = GetErrorNumber(false);
+          ReportValueError(cx, errorNum, JSDVG_IGNORE_STACK, args.get(0),
+                           nullptr);
           return false;
         }
 
diff --git a/js/src/builtin/embedjs.py b/js/src/builtin/embedjs.py
index 6a2c25b999..685f511e49 100644
--- a/js/src/builtin/embedjs.py
+++ b/js/src/builtin/embedjs.py
@@ -142,7 +142,9 @@ def preprocess(cxx, preprocessorOption, source, args=[]):
 
     with open(tmpIn, "wb") as input:
         input.write(source.encode("utf-8"))
-    print(" ".join(cxx + outputArg + args + [tmpIn]))
+
+    if os.environ.get("BUILD_VERBOSE_LOG"):
+        print("Executing:", " ".join(cxx + outputArg + args + [tmpIn]))
     result = subprocess.Popen(cxx + outputArg + args + [tmpIn]).wait()
     if result != 0:
         sys.exit(result)