Add m-esr52 at 52.6.0

1 files changed, 959 insertions, 0 deletions

diff --git a/js/src/vm/MemoryMetrics.cpp b/js/src/vm/MemoryMetrics.cpp
new file mode 100644
index 000000000..1012e808e
--- /dev/null
+++ b/js/src/vm/MemoryMetrics.cpp
@@ -0,0 +1,959 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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 "js/MemoryMetrics.h"
+
+#include "mozilla/DebugOnly.h"
+
+#include "jsapi.h"
+#include "jscompartment.h"
+#include "jsgc.h"
+#include "jsobj.h"
+#include "jsscript.h"
+
+#include "gc/Heap.h"
+#include "jit/BaselineJIT.h"
+#include "jit/Ion.h"
+#include "vm/ArrayObject.h"
+#include "vm/Runtime.h"
+#include "vm/Shape.h"
+#include "vm/String.h"
+#include "vm/Symbol.h"
+#include "vm/WrapperObject.h"
+#include "wasm/WasmInstance.h"
+#include "wasm/WasmJS.h"
+#include "wasm/WasmModule.h"
+
+using mozilla::DebugOnly;
+using mozilla::MallocSizeOf;
+using mozilla::Move;
+using mozilla::PodCopy;
+using mozilla::PodEqual;
+
+using namespace js;
+
+using JS::RuntimeStats;
+using JS::ObjectPrivateVisitor;
+using JS::ZoneStats;
+using JS::CompartmentStats;
+
+namespace js {
+
+JS_FRIEND_API(size_t)
+MemoryReportingSundriesThreshold()
+{
+    return 8 * 1024;
+}
+
+template <typename CharT>
+static uint32_t
+HashStringChars(JSString* s)
+{
+    ScopedJSFreePtr<CharT> ownedChars;
+    const CharT* chars;
+    JS::AutoCheckCannotGC nogc;
+    if (s->isLinear()) {
+        chars = s->asLinear().chars<CharT>(nogc);
+    } else {
+        // Slowest hash function evar!
+        if (!s->asRope().copyChars<CharT>(/* tcx */ nullptr, ownedChars))
+            MOZ_CRASH("oom");
+        chars = ownedChars;
+    }
+
+    return mozilla::HashString(chars, s->length());
+}
+
+/* static */ HashNumber
+InefficientNonFlatteningStringHashPolicy::hash(const Lookup& l)
+{
+    return l->hasLatin1Chars()
+           ? HashStringChars<Latin1Char>(l)
+           : HashStringChars<char16_t>(l);
+}
+
+template <typename Char1, typename Char2>
+static bool
+EqualStringsPure(JSString* s1, JSString* s2)
+{
+    if (s1->length() != s2->length())
+        return false;
+
+    const Char1* c1;
+    ScopedJSFreePtr<Char1> ownedChars1;
+    JS::AutoCheckCannotGC nogc;
+    if (s1->isLinear()) {
+        c1 = s1->asLinear().chars<Char1>(nogc);
+    } else {
+        if (!s1->asRope().copyChars<Char1>(/* tcx */ nullptr, ownedChars1))
+            MOZ_CRASH("oom");
+        c1 = ownedChars1;
+    }
+
+    const Char2* c2;
+    ScopedJSFreePtr<Char2> ownedChars2;
+    if (s2->isLinear()) {
+        c2 = s2->asLinear().chars<Char2>(nogc);
+    } else {
+        if (!s2->asRope().copyChars<Char2>(/* tcx */ nullptr, ownedChars2))
+            MOZ_CRASH("oom");
+        c2 = ownedChars2;
+    }
+
+    return EqualChars(c1, c2, s1->length());
+}
+
+/* static */ bool
+InefficientNonFlatteningStringHashPolicy::match(const JSString* const& k, const Lookup& l)
+{
+    // We can't use js::EqualStrings, because that flattens our strings.
+    JSString* s1 = const_cast<JSString*>(k);
+    if (k->hasLatin1Chars()) {
+        return l->hasLatin1Chars()
+               ? EqualStringsPure<Latin1Char, Latin1Char>(s1, l)
+               : EqualStringsPure<Latin1Char, char16_t>(s1, l);
+    }
+
+    return l->hasLatin1Chars()
+           ? EqualStringsPure<char16_t, Latin1Char>(s1, l)
+           : EqualStringsPure<char16_t, char16_t>(s1, l);
+}
+
+/* static */ HashNumber
+CStringHashPolicy::hash(const Lookup& l)
+{
+    return mozilla::HashString(l);
+}
+
+/* static */ bool
+CStringHashPolicy::match(const char* const& k, const Lookup& l)
+{
+    return strcmp(k, l) == 0;
+}
+
+} // namespace js
+
+namespace JS {
+
+NotableStringInfo::NotableStringInfo()
+  : StringInfo(),
+    buffer(0),
+    length(0)
+{
+}
+
+template <typename CharT>
+static void
+StoreStringChars(char* buffer, size_t bufferSize, JSString* str)
+{
+    const CharT* chars;
+    ScopedJSFreePtr<CharT> ownedChars;
+    JS::AutoCheckCannotGC nogc;
+    if (str->isLinear()) {
+        chars = str->asLinear().chars<CharT>(nogc);
+    } else {
+        if (!str->asRope().copyChars<CharT>(/* tcx */ nullptr, ownedChars))
+            MOZ_CRASH("oom");
+        chars = ownedChars;
+    }
+
+    // We might truncate |str| even if it's much shorter than 1024 chars, if
+    // |str| contains unicode chars.  Since this is just for a memory reporter,
+    // we don't care.
+    PutEscapedString(buffer, bufferSize, chars, str->length(), /* quote */ 0);
+}
+
+NotableStringInfo::NotableStringInfo(JSString* str, const StringInfo& info)
+  : StringInfo(info),
+    length(str->length())
+{
+    size_t bufferSize = Min(str->length() + 1, size_t(MAX_SAVED_CHARS));
+    buffer = js_pod_malloc<char>(bufferSize);
+    if (!buffer) {
+        MOZ_CRASH("oom");
+    }
+
+    if (str->hasLatin1Chars())
+        StoreStringChars<Latin1Char>(buffer, bufferSize, str);
+    else
+        StoreStringChars<char16_t>(buffer, bufferSize, str);
+}
+
+NotableStringInfo::NotableStringInfo(NotableStringInfo&& info)
+  : StringInfo(Move(info)),
+    length(info.length)
+{
+    buffer = info.buffer;
+    info.buffer = nullptr;
+}
+
+NotableStringInfo& NotableStringInfo::operator=(NotableStringInfo&& info)
+{
+    MOZ_ASSERT(this != &info, "self-move assignment is prohibited");
+    this->~NotableStringInfo();
+    new (this) NotableStringInfo(Move(info));
+    return *this;
+}
+
+NotableClassInfo::NotableClassInfo()
+  : ClassInfo(),
+    className_(nullptr)
+{
+}
+
+NotableClassInfo::NotableClassInfo(const char* className, const ClassInfo& info)
+  : ClassInfo(info)
+{
+    size_t bytes = strlen(className) + 1;
+    className_ = js_pod_malloc<char>(bytes);
+    if (!className_)
+        MOZ_CRASH("oom");
+    PodCopy(className_, className, bytes);
+}
+
+NotableClassInfo::NotableClassInfo(NotableClassInfo&& info)
+  : ClassInfo(Move(info))
+{
+    className_ = info.className_;
+    info.className_ = nullptr;
+}
+
+NotableClassInfo& NotableClassInfo::operator=(NotableClassInfo&& info)
+{
+    MOZ_ASSERT(this != &info, "self-move assignment is prohibited");
+    this->~NotableClassInfo();
+    new (this) NotableClassInfo(Move(info));
+    return *this;
+}
+
+NotableScriptSourceInfo::NotableScriptSourceInfo()
+  : ScriptSourceInfo(),
+    filename_(nullptr)
+{
+}
+
+NotableScriptSourceInfo::NotableScriptSourceInfo(const char* filename, const ScriptSourceInfo& info)
+  : ScriptSourceInfo(info)
+{
+    size_t bytes = strlen(filename) + 1;
+    filename_ = js_pod_malloc<char>(bytes);
+    if (!filename_)
+        MOZ_CRASH("oom");
+    PodCopy(filename_, filename, bytes);
+}
+
+NotableScriptSourceInfo::NotableScriptSourceInfo(NotableScriptSourceInfo&& info)
+  : ScriptSourceInfo(Move(info))
+{
+    filename_ = info.filename_;
+    info.filename_ = nullptr;
+}
+
+NotableScriptSourceInfo& NotableScriptSourceInfo::operator=(NotableScriptSourceInfo&& info)
+{
+    MOZ_ASSERT(this != &info, "self-move assignment is prohibited");
+    this->~NotableScriptSourceInfo();
+    new (this) NotableScriptSourceInfo(Move(info));
+    return *this;
+}
+
+
+} // namespace JS
+
+typedef HashSet<ScriptSource*, DefaultHasher<ScriptSource*>, SystemAllocPolicy> SourceSet;
+
+struct StatsClosure
+{
+    RuntimeStats* rtStats;
+    ObjectPrivateVisitor* opv;
+    SourceSet seenSources;
+    wasm::Metadata::SeenSet wasmSeenMetadata;
+    wasm::ShareableBytes::SeenSet wasmSeenBytes;
+    wasm::Table::SeenSet wasmSeenTables;
+    bool anonymize;
+
+    StatsClosure(RuntimeStats* rt, ObjectPrivateVisitor* v, bool anon)
+      : rtStats(rt),
+        opv(v),
+        anonymize(anon)
+    {}
+
+    bool init() {
+        return seenSources.init() &&
+               wasmSeenMetadata.init() &&
+               wasmSeenBytes.init() &&
+               wasmSeenTables.init();
+    }
+};
+
+static void
+DecommittedArenasChunkCallback(JSRuntime* rt, void* data, gc::Chunk* chunk)
+{
+    // This case is common and fast to check.  Do it first.
+    if (chunk->decommittedArenas.isAllClear())
+        return;
+
+    size_t n = 0;
+    for (size_t i = 0; i < gc::ArenasPerChunk; i++) {
+        if (chunk->decommittedArenas.get(i))
+            n += gc::ArenaSize;
+    }
+    MOZ_ASSERT(n > 0);
+    *static_cast<size_t*>(data) += n;
+}
+
+static void
+StatsZoneCallback(JSRuntime* rt, void* data, Zone* zone)
+{
+    // Append a new CompartmentStats to the vector.
+    RuntimeStats* rtStats = static_cast<StatsClosure*>(data)->rtStats;
+
+    // CollectRuntimeStats reserves enough space.
+    MOZ_ALWAYS_TRUE(rtStats->zoneStatsVector.growBy(1));
+    ZoneStats& zStats = rtStats->zoneStatsVector.back();
+    if (!zStats.initStrings(rt))
+        MOZ_CRASH("oom");
+    rtStats->initExtraZoneStats(zone, &zStats);
+    rtStats->currZoneStats = &zStats;
+
+    zone->addSizeOfIncludingThis(rtStats->mallocSizeOf_,
+                                 &zStats.typePool,
+                                 &zStats.baselineStubsOptimized,
+                                 &zStats.uniqueIdMap,
+                                 &zStats.shapeTables);
+}
+
+static void
+StatsCompartmentCallback(JSContext* cx, void* data, JSCompartment* compartment)
+{
+    // Append a new CompartmentStats to the vector.
+    RuntimeStats* rtStats = static_cast<StatsClosure*>(data)->rtStats;
+
+    // CollectRuntimeStats reserves enough space.
+    MOZ_ALWAYS_TRUE(rtStats->compartmentStatsVector.growBy(1));
+    CompartmentStats& cStats = rtStats->compartmentStatsVector.back();
+    if (!cStats.initClasses(cx))
+        MOZ_CRASH("oom");
+    rtStats->initExtraCompartmentStats(compartment, &cStats);
+
+    compartment->setCompartmentStats(&cStats);
+
+    // Measure the compartment object itself, and things hanging off it.
+    compartment->addSizeOfIncludingThis(rtStats->mallocSizeOf_,
+                                        &cStats.typeInferenceAllocationSiteTables,
+                                        &cStats.typeInferenceArrayTypeTables,
+                                        &cStats.typeInferenceObjectTypeTables,
+                                        &cStats.compartmentObject,
+                                        &cStats.compartmentTables,
+                                        &cStats.innerViewsTable,
+                                        &cStats.lazyArrayBuffersTable,
+                                        &cStats.objectMetadataTable,
+                                        &cStats.crossCompartmentWrappersTable,
+                                        &cStats.regexpCompartment,
+                                        &cStats.savedStacksSet,
+                                        &cStats.varNamesSet,
+                                        &cStats.nonSyntacticLexicalScopesTable,
+                                        &cStats.jitCompartment,
+                                        &cStats.privateData);
+}
+
+static void
+StatsArenaCallback(JSRuntime* rt, void* data, gc::Arena* arena,
+                   JS::TraceKind traceKind, size_t thingSize)
+{
+    RuntimeStats* rtStats = static_cast<StatsClosure*>(data)->rtStats;
+
+    // The admin space includes (a) the header fields and (b) the padding
+    // between the end of the header fields and the first GC thing.
+    size_t allocationSpace = gc::Arena::thingsSpan(arena->getAllocKind());
+    rtStats->currZoneStats->gcHeapArenaAdmin += gc::ArenaSize - allocationSpace;
+
+    // We don't call the callback on unused things.  So we compute the
+    // unused space like this:  arenaUnused = maxArenaUnused - arenaUsed.
+    // We do this by setting arenaUnused to maxArenaUnused here, and then
+    // subtracting thingSize for every used cell, in StatsCellCallback().
+    rtStats->currZoneStats->unusedGCThings.addToKind(traceKind, allocationSpace);
+}
+
+// FineGrained is used for normal memory reporting.  CoarseGrained is used by
+// AddSizeOfTab(), which aggregates all the measurements into a handful of
+// high-level numbers, which means that fine-grained reporting would be a waste
+// of effort.
+enum Granularity {
+    FineGrained,
+    CoarseGrained
+};
+
+static void
+AddClassInfo(Granularity granularity, CompartmentStats& cStats, const char* className,
+             JS::ClassInfo& info)
+{
+    if (granularity == FineGrained) {
+        if (!className)
+            className = "<no class name>";
+        CompartmentStats::ClassesHashMap::AddPtr p = cStats.allClasses->lookupForAdd(className);
+        if (!p) {
+            bool ok = cStats.allClasses->add(p, className, info);
+            // Ignore failure -- we just won't record the
+            // object/shape/base-shape as notable.
+            (void)ok;
+        } else {
+            p->value().add(info);
+        }
+    }
+}
+
+template <Granularity granularity>
+static void
+CollectScriptSourceStats(StatsClosure* closure, ScriptSource* ss)
+{
+    RuntimeStats* rtStats = closure->rtStats;
+
+    SourceSet::AddPtr entry = closure->seenSources.lookupForAdd(ss);
+    if (entry)
+        return;
+
+    bool ok = closure->seenSources.add(entry, ss);
+    (void)ok; // Not much to be done on failure.
+
+    JS::ScriptSourceInfo info;  // This zeroes all the sizes.
+    ss->addSizeOfIncludingThis(rtStats->mallocSizeOf_, &info);
+
+    rtStats->runtime.scriptSourceInfo.add(info);
+
+    if (granularity == FineGrained) {
+        const char* filename = ss->filename();
+        if (!filename)
+            filename = "<no filename>";
+
+        JS::RuntimeSizes::ScriptSourcesHashMap::AddPtr p =
+            rtStats->runtime.allScriptSources->lookupForAdd(filename);
+        if (!p) {
+            bool ok = rtStats->runtime.allScriptSources->add(p, filename, info);
+            // Ignore failure -- we just won't record the script source as notable.
+            (void)ok;
+        } else {
+            p->value().add(info);
+        }
+    }
+}
+
+
+// The various kinds of hashing are expensive, and the results are unused when
+// doing coarse-grained measurements. Skipping them more than doubles the
+// profile speed for complex pages such as gmail.com.
+template <Granularity granularity>
+static void
+StatsCellCallback(JSRuntime* rt, void* data, void* thing, JS::TraceKind traceKind,
+                  size_t thingSize)
+{
+    StatsClosure* closure = static_cast<StatsClosure*>(data);
+    RuntimeStats* rtStats = closure->rtStats;
+    ZoneStats* zStats = rtStats->currZoneStats;
+    switch (traceKind) {
+      case JS::TraceKind::Object: {
+        JSObject* obj = static_cast<JSObject*>(thing);
+        CompartmentStats& cStats = obj->compartment()->compartmentStats();
+        JS::ClassInfo info;        // This zeroes all the sizes.
+        info.objectsGCHeap += thingSize;
+
+        obj->addSizeOfExcludingThis(rtStats->mallocSizeOf_, &info);
+
+        // These classes require special handling due to shared resources which
+        // we must be careful not to report twice.
+        if (obj->is<WasmModuleObject>()) {
+            wasm::Module& module = obj->as<WasmModuleObject>().module();
+            if (ScriptSource* ss = module.metadata().maybeScriptSource())
+                CollectScriptSourceStats<granularity>(closure, ss);
+            module.addSizeOfMisc(rtStats->mallocSizeOf_,
+                                 &closure->wasmSeenMetadata,
+                                 &closure->wasmSeenBytes,
+                                 &info.objectsNonHeapCodeWasm,
+                                 &info.objectsMallocHeapMisc);
+        } else if (obj->is<WasmInstanceObject>()) {
+            wasm::Instance& instance = obj->as<WasmInstanceObject>().instance();
+            if (ScriptSource* ss = instance.metadata().maybeScriptSource())
+                CollectScriptSourceStats<granularity>(closure, ss);
+            instance.addSizeOfMisc(rtStats->mallocSizeOf_,
+                                   &closure->wasmSeenMetadata,
+                                   &closure->wasmSeenBytes,
+                                   &closure->wasmSeenTables,
+                                   &info.objectsNonHeapCodeWasm,
+                                   &info.objectsMallocHeapMisc);
+        }
+
+        cStats.classInfo.add(info);
+
+        const Class* clasp = obj->getClass();
+        const char* className = clasp->name;
+        AddClassInfo(granularity, cStats, className, info);
+
+        if (ObjectPrivateVisitor* opv = closure->opv) {
+            nsISupports* iface;
+            if (opv->getISupports_(obj, &iface) && iface)
+                cStats.objectsPrivate += opv->sizeOfIncludingThis(iface);
+        }
+        break;
+      }
+
+      case JS::TraceKind::Script: {
+        JSScript* script = static_cast<JSScript*>(thing);
+        CompartmentStats& cStats = script->compartment()->compartmentStats();
+        cStats.scriptsGCHeap += thingSize;
+        cStats.scriptsMallocHeapData += script->sizeOfData(rtStats->mallocSizeOf_);
+        cStats.typeInferenceTypeScripts += script->sizeOfTypeScript(rtStats->mallocSizeOf_);
+        jit::AddSizeOfBaselineData(script, rtStats->mallocSizeOf_, &cStats.baselineData,
+                                   &cStats.baselineStubsFallback);
+        cStats.ionData += jit::SizeOfIonData(script, rtStats->mallocSizeOf_);
+        CollectScriptSourceStats<granularity>(closure, script->scriptSource());
+        break;
+      }
+
+      case JS::TraceKind::String: {
+        JSString* str = static_cast<JSString*>(thing);
+
+        JS::StringInfo info;
+        if (str->hasLatin1Chars()) {
+            info.gcHeapLatin1 = thingSize;
+            info.mallocHeapLatin1 = str->sizeOfExcludingThis(rtStats->mallocSizeOf_);
+        } else {
+            info.gcHeapTwoByte = thingSize;
+            info.mallocHeapTwoByte = str->sizeOfExcludingThis(rtStats->mallocSizeOf_);
+        }
+        info.numCopies = 1;
+
+        zStats->stringInfo.add(info);
+
+        // The primary use case for anonymization is automated crash submission
+        // (to help detect OOM crashes). In that case, we don't want to pay the
+        // memory cost required to do notable string detection.
+        if (granularity == FineGrained && !closure->anonymize) {
+            ZoneStats::StringsHashMap::AddPtr p = zStats->allStrings->lookupForAdd(str);
+            if (!p) {
+                bool ok = zStats->allStrings->add(p, str, info);
+                // Ignore failure -- we just won't record the string as notable.
+                (void)ok;
+            } else {
+                p->value().add(info);
+            }
+        }
+        break;
+      }
+
+      case JS::TraceKind::Symbol:
+        zStats->symbolsGCHeap += thingSize;
+        break;
+
+      case JS::TraceKind::BaseShape: {
+        JS::ShapeInfo info;        // This zeroes all the sizes.
+        info.shapesGCHeapBase += thingSize;
+        // No malloc-heap measurements.
+
+        zStats->shapeInfo.add(info);
+        break;
+      }
+
+      case JS::TraceKind::JitCode: {
+        zStats->jitCodesGCHeap += thingSize;
+        // The code for a script is counted in ExecutableAllocator::sizeOfCode().
+        break;
+      }
+
+      case JS::TraceKind::LazyScript: {
+        LazyScript* lazy = static_cast<LazyScript*>(thing);
+        zStats->lazyScriptsGCHeap += thingSize;
+        zStats->lazyScriptsMallocHeap += lazy->sizeOfExcludingThis(rtStats->mallocSizeOf_);
+        break;
+      }
+
+      case JS::TraceKind::Shape: {
+        Shape* shape = static_cast<Shape*>(thing);
+
+        JS::ShapeInfo info;        // This zeroes all the sizes.
+        if (shape->inDictionary())
+            info.shapesGCHeapDict += thingSize;
+        else
+            info.shapesGCHeapTree += thingSize;
+        shape->addSizeOfExcludingThis(rtStats->mallocSizeOf_, &info);
+        zStats->shapeInfo.add(info);
+        break;
+      }
+
+      case JS::TraceKind::ObjectGroup: {
+        ObjectGroup* group = static_cast<ObjectGroup*>(thing);
+        zStats->objectGroupsGCHeap += thingSize;
+        zStats->objectGroupsMallocHeap += group->sizeOfExcludingThis(rtStats->mallocSizeOf_);
+        break;
+      }
+
+      case JS::TraceKind::Scope: {
+        Scope* scope = static_cast<Scope*>(thing);
+        zStats->scopesGCHeap += thingSize;
+        zStats->scopesMallocHeap += scope->sizeOfExcludingThis(rtStats->mallocSizeOf_);
+        break;
+      }
+
+      default:
+        MOZ_CRASH("invalid traceKind in StatsCellCallback");
+    }
+
+    // Yes, this is a subtraction:  see StatsArenaCallback() for details.
+    zStats->unusedGCThings.addToKind(traceKind, -thingSize);
+}
+
+bool
+ZoneStats::initStrings(JSRuntime* rt)
+{
+    isTotals = false;
+    allStrings = rt->new_<StringsHashMap>();
+    if (!allStrings || !allStrings->init()) {
+        js_delete(allStrings);
+        allStrings = nullptr;
+        return false;
+    }
+    return true;
+}
+
+bool
+CompartmentStats::initClasses(JSRuntime* rt)
+{
+    isTotals = false;
+    allClasses = rt->new_<ClassesHashMap>();
+    if (!allClasses || !allClasses->init()) {
+        js_delete(allClasses);
+        allClasses = nullptr;
+        return false;
+    }
+    return true;
+}
+
+static bool
+FindNotableStrings(ZoneStats& zStats)
+{
+    using namespace JS;
+
+    // We should only run FindNotableStrings once per ZoneStats object.
+    MOZ_ASSERT(zStats.notableStrings.empty());
+
+    for (ZoneStats::StringsHashMap::Range r = zStats.allStrings->all(); !r.empty(); r.popFront()) {
+
+        JSString* str = r.front().key();
+        StringInfo& info = r.front().value();
+
+        if (!info.isNotable())
+            continue;
+
+        if (!zStats.notableStrings.growBy(1))
+            return false;
+
+        zStats.notableStrings.back() = NotableStringInfo(str, info);
+
+        // We're moving this string from a non-notable to a notable bucket, so
+        // subtract it out of the non-notable tallies.
+        zStats.stringInfo.subtract(info);
+    }
+    // Delete |allStrings| now, rather than waiting for zStats's destruction,
+    // to reduce peak memory consumption during reporting.
+    js_delete(zStats.allStrings);
+    zStats.allStrings = nullptr;
+    return true;
+}
+
+static bool
+FindNotableClasses(CompartmentStats& cStats)
+{
+    using namespace JS;
+
+    // We should only run FindNotableClasses once per ZoneStats object.
+    MOZ_ASSERT(cStats.notableClasses.empty());
+
+    for (CompartmentStats::ClassesHashMap::Range r = cStats.allClasses->all();
+         !r.empty();
+         r.popFront())
+    {
+        const char* className = r.front().key();
+        ClassInfo& info = r.front().value();
+
+        // If this class isn't notable, or if we can't grow the notableStrings
+        // vector, skip this string.
+        if (!info.isNotable())
+            continue;
+
+        if (!cStats.notableClasses.growBy(1))
+            return false;
+
+        cStats.notableClasses.back() = NotableClassInfo(className, info);
+
+        // We're moving this class from a non-notable to a notable bucket, so
+        // subtract it out of the non-notable tallies.
+        cStats.classInfo.subtract(info);
+    }
+    // Delete |allClasses| now, rather than waiting for zStats's destruction,
+    // to reduce peak memory consumption during reporting.
+    js_delete(cStats.allClasses);
+    cStats.allClasses = nullptr;
+    return true;
+}
+
+static bool
+FindNotableScriptSources(JS::RuntimeSizes& runtime)
+{
+    using namespace JS;
+
+    // We should only run FindNotableScriptSources once per RuntimeSizes.
+    MOZ_ASSERT(runtime.notableScriptSources.empty());
+
+    for (RuntimeSizes::ScriptSourcesHashMap::Range r = runtime.allScriptSources->all();
+         !r.empty();
+         r.popFront())
+    {
+        const char* filename = r.front().key();
+        ScriptSourceInfo& info = r.front().value();
+
+        if (!info.isNotable())
+            continue;
+
+        if (!runtime.notableScriptSources.growBy(1))
+            return false;
+
+        runtime.notableScriptSources.back() = NotableScriptSourceInfo(filename, info);
+
+        // We're moving this script source from a non-notable to a notable
+        // bucket, so subtract its sizes from the non-notable tallies.
+        runtime.scriptSourceInfo.subtract(info);
+    }
+    // Delete |allScriptSources| now, rather than waiting for zStats's
+    // destruction, to reduce peak memory consumption during reporting.
+    js_delete(runtime.allScriptSources);
+    runtime.allScriptSources = nullptr;
+    return true;
+}
+
+static bool
+CollectRuntimeStatsHelper(JSContext* cx, RuntimeStats* rtStats, ObjectPrivateVisitor* opv,
+                          bool anonymize, IterateCellCallback statsCellCallback)
+{
+    JSRuntime* rt = cx;
+    if (!rtStats->compartmentStatsVector.reserve(rt->numCompartments))
+        return false;
+
+    if (!rtStats->zoneStatsVector.reserve(rt->gc.zones.length()))
+        return false;
+
+    rtStats->gcHeapChunkTotal =
+        size_t(JS_GetGCParameter(cx, JSGC_TOTAL_CHUNKS)) * gc::ChunkSize;
+
+    rtStats->gcHeapUnusedChunks =
+        size_t(JS_GetGCParameter(cx, JSGC_UNUSED_CHUNKS)) * gc::ChunkSize;
+
+    IterateChunks(cx, &rtStats->gcHeapDecommittedArenas,
+                  DecommittedArenasChunkCallback);
+
+    // Take the per-compartment measurements.
+    StatsClosure closure(rtStats, opv, anonymize);
+    if (!closure.init())
+        return false;
+    IterateZonesCompartmentsArenasCells(cx, &closure,
+                                        StatsZoneCallback,
+                                        StatsCompartmentCallback,
+                                        StatsArenaCallback,
+                                        statsCellCallback);
+
+    // Take the "explicit/js/runtime/" measurements.
+    rt->addSizeOfIncludingThis(rtStats->mallocSizeOf_, &rtStats->runtime);
+
+    if (!FindNotableScriptSources(rtStats->runtime))
+        return false;
+
+    JS::ZoneStatsVector& zs = rtStats->zoneStatsVector;
+    ZoneStats& zTotals = rtStats->zTotals;
+
+    // We don't look for notable strings for zTotals. So we first sum all the
+    // zones' measurements to get the totals. Then we find the notable strings
+    // within each zone.
+    for (size_t i = 0; i < zs.length(); i++)
+        zTotals.addSizes(zs[i]);
+
+    for (size_t i = 0; i < zs.length(); i++)
+        if (!FindNotableStrings(zs[i]))
+            return false;
+
+    MOZ_ASSERT(!zTotals.allStrings);
+
+    JS::CompartmentStatsVector& cs = rtStats->compartmentStatsVector;
+    CompartmentStats& cTotals = rtStats->cTotals;
+
+    // As with the zones, we sum all compartments first, and then get the
+    // notable classes within each zone.
+    for (size_t i = 0; i < cs.length(); i++)
+        cTotals.addSizes(cs[i]);
+
+    for (size_t i = 0; i < cs.length(); i++) {
+        if (!FindNotableClasses(cs[i]))
+            return false;
+    }
+
+    MOZ_ASSERT(!cTotals.allClasses);
+
+    rtStats->gcHeapGCThings = rtStats->zTotals.sizeOfLiveGCThings() +
+                              rtStats->cTotals.sizeOfLiveGCThings();
+
+#ifdef DEBUG
+    // Check that the in-arena measurements look ok.
+    size_t totalArenaSize = rtStats->zTotals.gcHeapArenaAdmin +
+                            rtStats->zTotals.unusedGCThings.totalSize() +
+                            rtStats->gcHeapGCThings;
+    MOZ_ASSERT(totalArenaSize % gc::ArenaSize == 0);
+#endif
+
+    for (CompartmentsIter comp(rt, WithAtoms); !comp.done(); comp.next())
+        comp->nullCompartmentStats();
+
+    size_t numDirtyChunks =
+        (rtStats->gcHeapChunkTotal - rtStats->gcHeapUnusedChunks) / gc::ChunkSize;
+    size_t perChunkAdmin =
+        sizeof(gc::Chunk) - (sizeof(gc::Arena) * gc::ArenasPerChunk);
+    rtStats->gcHeapChunkAdmin = numDirtyChunks * perChunkAdmin;
+
+    // |gcHeapUnusedArenas| is the only thing left.  Compute it in terms of
+    // all the others.  See the comment in RuntimeStats for explanation.
+    rtStats->gcHeapUnusedArenas = rtStats->gcHeapChunkTotal -
+                                  rtStats->gcHeapDecommittedArenas -
+                                  rtStats->gcHeapUnusedChunks -
+                                  rtStats->zTotals.unusedGCThings.totalSize() -
+                                  rtStats->gcHeapChunkAdmin -
+                                  rtStats->zTotals.gcHeapArenaAdmin -
+                                  rtStats->gcHeapGCThings;
+    return true;
+}
+
+JS_PUBLIC_API(bool)
+JS::CollectRuntimeStats(JSContext* cx, RuntimeStats *rtStats, ObjectPrivateVisitor *opv,
+                        bool anonymize)
+{
+    return CollectRuntimeStatsHelper(cx, rtStats, opv, anonymize, StatsCellCallback<FineGrained>);
+}
+
+JS_PUBLIC_API(size_t)
+JS::SystemCompartmentCount(JSContext* cx)
+{
+    size_t n = 0;
+    for (CompartmentsIter comp(cx, WithAtoms); !comp.done(); comp.next()) {
+        if (comp->isSystem())
+            ++n;
+    }
+    return n;
+}
+
+JS_PUBLIC_API(size_t)
+JS::UserCompartmentCount(JSContext* cx)
+{
+    size_t n = 0;
+    for (CompartmentsIter comp(cx, WithAtoms); !comp.done(); comp.next()) {
+        if (!comp->isSystem())
+            ++n;
+    }
+    return n;
+}
+
+JS_PUBLIC_API(size_t)
+JS::PeakSizeOfTemporary(const JSContext* cx)
+{
+    return cx->JSRuntime::tempLifoAlloc.peakSizeOfExcludingThis();
+}
+
+namespace JS {
+
+class SimpleJSRuntimeStats : public JS::RuntimeStats
+{
+  public:
+    explicit SimpleJSRuntimeStats(MallocSizeOf mallocSizeOf)
+      : JS::RuntimeStats(mallocSizeOf)
+    {}
+
+    virtual void initExtraZoneStats(JS::Zone* zone, JS::ZoneStats* zStats)
+        override
+    {}
+
+    virtual void initExtraCompartmentStats(
+        JSCompartment* c, JS::CompartmentStats* cStats) override
+    {}
+};
+
+JS_PUBLIC_API(bool)
+AddSizeOfTab(JSContext* cx, HandleObject obj, MallocSizeOf mallocSizeOf, ObjectPrivateVisitor* opv,
+             TabSizes* sizes)
+{
+    SimpleJSRuntimeStats rtStats(mallocSizeOf);
+
+    JS::Zone* zone = GetObjectZone(obj);
+
+    if (!rtStats.compartmentStatsVector.reserve(zone->compartments.length()))
+        return false;
+
+    if (!rtStats.zoneStatsVector.reserve(1))
+        return false;
+
+    // Take the per-compartment measurements. No need to anonymize because
+    // these measurements will be aggregated.
+    StatsClosure closure(&rtStats, opv, /* anonymize = */ false);
+    if (!closure.init())
+        return false;
+    IterateZoneCompartmentsArenasCells(cx, zone, &closure,
+                                       StatsZoneCallback,
+                                       StatsCompartmentCallback,
+                                       StatsArenaCallback,
+                                       StatsCellCallback<CoarseGrained>);
+
+    MOZ_ASSERT(rtStats.zoneStatsVector.length() == 1);
+    rtStats.zTotals.addSizes(rtStats.zoneStatsVector[0]);
+
+    for (size_t i = 0; i < rtStats.compartmentStatsVector.length(); i++)
+        rtStats.cTotals.addSizes(rtStats.compartmentStatsVector[i]);
+
+    for (CompartmentsInZoneIter comp(zone); !comp.done(); comp.next())
+        comp->nullCompartmentStats();
+
+    rtStats.zTotals.addToTabSizes(sizes);
+    rtStats.cTotals.addToTabSizes(sizes);
+
+    return true;
+}
+
+JS_PUBLIC_API(bool)
+AddServoSizeOf(JSContext* cx, MallocSizeOf mallocSizeOf, ObjectPrivateVisitor *opv,
+               ServoSizes *sizes)
+{
+    SimpleJSRuntimeStats rtStats(mallocSizeOf);
+
+    // No need to anonymize because the results will be aggregated.
+    if (!CollectRuntimeStatsHelper(cx, &rtStats, opv, /* anonymize = */ false,
+                                   StatsCellCallback<CoarseGrained>))
+        return false;
+
+#ifdef DEBUG
+    size_t gcHeapTotalOriginal = sizes->gcHeapUsed +
+                                 sizes->gcHeapUnused +
+                                 sizes->gcHeapAdmin +
+                                 sizes->gcHeapDecommitted;
+#endif
+
+    rtStats.addToServoSizes(sizes);
+    rtStats.zTotals.addToServoSizes(sizes);
+    rtStats.cTotals.addToServoSizes(sizes);
+
+#ifdef DEBUG
+    size_t gcHeapTotal = sizes->gcHeapUsed +
+                         sizes->gcHeapUnused +
+                         sizes->gcHeapAdmin +
+                         sizes->gcHeapDecommitted;
+    MOZ_ASSERT(rtStats.gcHeapChunkTotal == gcHeapTotal - gcHeapTotalOriginal);
+#endif
+
+    return true;
+}
+
+} // namespace JS