Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 2631 insertions, 0 deletions

diff --git a/js/src/jit/Ion.cpp b/js/src/jit/Ion.cpp
new file mode 100644
index 0000000000..3d472aa85f
--- /dev/null
+++ b/js/src/jit/Ion.cpp
@@ -0,0 +1,2631 @@
+/* -*- 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 "jit/Ion.h"
+
+#include "mozilla/CheckedInt.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/ThreadLocal.h"
+
+#include "gc/GCContext.h"
+#include "gc/PublicIterators.h"
+#include "jit/AliasAnalysis.h"
+#include "jit/AlignmentMaskAnalysis.h"
+#include "jit/AutoWritableJitCode.h"
+#include "jit/BacktrackingAllocator.h"
+#include "jit/BaselineFrame.h"
+#include "jit/BaselineJIT.h"
+#include "jit/CodeGenerator.h"
+#include "jit/CompileInfo.h"
+#include "jit/EdgeCaseAnalysis.h"
+#include "jit/EffectiveAddressAnalysis.h"
+#include "jit/ExecutableAllocator.h"
+#include "jit/FoldLinearArithConstants.h"
+#include "jit/InlineScriptTree.h"
+#include "jit/InstructionReordering.h"
+#include "jit/Invalidation.h"
+#include "jit/IonAnalysis.h"
+#include "jit/IonCompileTask.h"
+#include "jit/IonIC.h"
+#include "jit/IonOptimizationLevels.h"
+#include "jit/IonScript.h"
+#include "jit/JitcodeMap.h"
+#include "jit/JitFrames.h"
+#include "jit/JitRealm.h"
+#include "jit/JitRuntime.h"
+#include "jit/JitSpewer.h"
+#include "jit/JitZone.h"
+#include "jit/LICM.h"
+#include "jit/Linker.h"
+#include "jit/LIR.h"
+#include "jit/Lowering.h"
+#include "jit/PerfSpewer.h"
+#include "jit/RangeAnalysis.h"
+#include "jit/ScalarReplacement.h"
+#include "jit/ScriptFromCalleeToken.h"
+#include "jit/Sink.h"
+#include "jit/ValueNumbering.h"
+#include "jit/WarpBuilder.h"
+#include "jit/WarpOracle.h"
+#include "jit/WasmBCE.h"
+#include "js/Printf.h"
+#include "js/UniquePtr.h"
+#include "util/Memory.h"
+#include "util/WindowsWrapper.h"
+#include "vm/HelperThreads.h"
+#include "vm/Realm.h"
+#ifdef MOZ_VTUNE
+#  include "vtune/VTuneWrapper.h"
+#endif
+
+#include "gc/GC-inl.h"
+#include "gc/StableCellHasher-inl.h"
+#include "jit/InlineScriptTree-inl.h"
+#include "jit/MacroAssembler-inl.h"
+#include "jit/SafepointIndex-inl.h"
+#include "vm/GeckoProfiler-inl.h"
+#include "vm/JSScript-inl.h"
+#include "vm/Realm-inl.h"
+
+#if defined(ANDROID)
+#  include <sys/system_properties.h>
+#endif
+
+using mozilla::CheckedInt;
+using mozilla::DebugOnly;
+
+using namespace js;
+using namespace js::jit;
+
+JitRuntime::~JitRuntime() {
+  MOZ_ASSERT(numFinishedOffThreadTasks_ == 0);
+  MOZ_ASSERT(ionLazyLinkListSize_ == 0);
+  MOZ_ASSERT(ionLazyLinkList_.ref().isEmpty());
+
+  // By this point, the jitcode global table should be empty.
+  MOZ_ASSERT_IF(jitcodeGlobalTable_, jitcodeGlobalTable_->empty());
+  js_delete(jitcodeGlobalTable_.ref());
+
+  // interpreterEntryMap should be cleared out during finishRoots()
+  MOZ_ASSERT_IF(interpreterEntryMap_, interpreterEntryMap_->empty());
+  js_delete(interpreterEntryMap_.ref());
+
+  js_delete(jitHintsMap_.ref());
+}
+
+uint32_t JitRuntime::startTrampolineCode(MacroAssembler& masm) {
+  AutoCreatedBy acb(masm, "startTrampolineCode");
+
+  masm.assumeUnreachable("Shouldn't get here");
+  masm.flushBuffer();
+  masm.haltingAlign(CodeAlignment);
+  masm.setFramePushed(0);
+  return masm.currentOffset();
+}
+
+bool JitRuntime::initialize(JSContext* cx) {
+  MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
+
+  AutoAllocInAtomsZone az(cx);
+  JitContext jctx(cx);
+
+  if (!generateTrampolines(cx)) {
+    return false;
+  }
+
+  if (!generateBaselineICFallbackCode(cx)) {
+    return false;
+  }
+
+  jitcodeGlobalTable_ = cx->new_<JitcodeGlobalTable>();
+  if (!jitcodeGlobalTable_) {
+    return false;
+  }
+
+  if (!JitOptions.disableJitHints) {
+    jitHintsMap_ = cx->new_<JitHintsMap>();
+    if (!jitHintsMap_) {
+      return false;
+    }
+  }
+
+  if (JitOptions.emitInterpreterEntryTrampoline) {
+    interpreterEntryMap_ = cx->new_<EntryTrampolineMap>();
+    if (!interpreterEntryMap_) {
+      return false;
+    }
+  }
+
+  if (!GenerateBaselineInterpreter(cx, baselineInterpreter_)) {
+    return false;
+  }
+
+  // Initialize the jitCodeRaw of the Runtime's canonical SelfHostedLazyScript
+  // to point to the interpreter trampoline.
+  cx->runtime()->selfHostedLazyScript.ref().jitCodeRaw_ =
+      interpreterStub().value;
+
+  return true;
+}
+
+bool JitRuntime::generateTrampolines(JSContext* cx) {
+  TempAllocator temp(&cx->tempLifoAlloc());
+  StackMacroAssembler masm(cx, temp);
+  PerfSpewerRangeRecorder rangeRecorder(masm);
+
+  Label bailoutTail;
+  JitSpew(JitSpew_Codegen, "# Emitting bailout tail stub");
+  generateBailoutTailStub(masm, &bailoutTail);
+
+  JitSpew(JitSpew_Codegen, "# Emitting bailout handler");
+  generateBailoutHandler(masm, &bailoutTail);
+  rangeRecorder.recordOffset("Trampoline: Bailout");
+
+  JitSpew(JitSpew_Codegen, "# Emitting invalidator");
+  generateInvalidator(masm, &bailoutTail);
+  rangeRecorder.recordOffset("Trampoline: Invalidator");
+
+  // The arguments rectifier has to use the same frame layout as the function
+  // frames it rectifies.
+  static_assert(std::is_base_of_v<JitFrameLayout, RectifierFrameLayout>,
+                "a rectifier frame can be used with jit frame");
+  static_assert(std::is_base_of_v<JitFrameLayout, WasmToJSJitFrameLayout>,
+                "wasm frames simply are jit frames");
+  static_assert(sizeof(JitFrameLayout) == sizeof(WasmToJSJitFrameLayout),
+                "thus a rectifier frame can be used with a wasm frame");
+
+  JitSpew(JitSpew_Codegen, "# Emitting arguments rectifier");
+  generateArgumentsRectifier(masm, ArgumentsRectifierKind::Normal);
+  rangeRecorder.recordOffset("Trampoline: Arguments Rectifier");
+
+  JitSpew(JitSpew_Codegen, "# Emitting trial inlining arguments rectifier");
+  generateArgumentsRectifier(masm, ArgumentsRectifierKind::TrialInlining);
+  rangeRecorder.recordOffset(
+      "Trampoline: Arguments Rectifier (Trial Inlining)");
+
+  JitSpew(JitSpew_Codegen, "# Emitting EnterJIT sequence");
+  generateEnterJIT(cx, masm);
+  rangeRecorder.recordOffset("Trampoline: EnterJIT");
+
+  JitSpew(JitSpew_Codegen, "# Emitting Pre Barrier for Value");
+  valuePreBarrierOffset_ = generatePreBarrier(cx, masm, MIRType::Value);
+  rangeRecorder.recordOffset("Trampoline: PreBarrier Value");
+
+  JitSpew(JitSpew_Codegen, "# Emitting Pre Barrier for String");
+  stringPreBarrierOffset_ = generatePreBarrier(cx, masm, MIRType::String);
+  rangeRecorder.recordOffset("Trampoline: PreBarrier String");
+
+  JitSpew(JitSpew_Codegen, "# Emitting Pre Barrier for Object");
+  objectPreBarrierOffset_ = generatePreBarrier(cx, masm, MIRType::Object);
+  rangeRecorder.recordOffset("Trampoline: PreBarrier Object");
+
+  JitSpew(JitSpew_Codegen, "# Emitting Pre Barrier for Shape");
+  shapePreBarrierOffset_ = generatePreBarrier(cx, masm, MIRType::Shape);
+  rangeRecorder.recordOffset("Trampoline: PreBarrier Shape");
+
+  JitSpew(JitSpew_Codegen, "# Emitting free stub");
+  generateFreeStub(masm);
+  rangeRecorder.recordOffset("Trampoline: FreeStub");
+
+  JitSpew(JitSpew_Codegen, "# Emitting lazy link stub");
+  generateLazyLinkStub(masm);
+  rangeRecorder.recordOffset("Trampoline: LazyLinkStub");
+
+  JitSpew(JitSpew_Codegen, "# Emitting interpreter stub");
+  generateInterpreterStub(masm);
+  rangeRecorder.recordOffset("Trampoline: Interpreter");
+
+  JitSpew(JitSpew_Codegen, "# Emitting double-to-int32-value stub");
+  generateDoubleToInt32ValueStub(masm);
+  rangeRecorder.recordOffset("Trampoline: DoubleToInt32ValueStub");
+
+  JitSpew(JitSpew_Codegen, "# Emitting VM function wrappers");
+  if (!generateVMWrappers(cx, masm)) {
+    return false;
+  }
+  rangeRecorder.recordOffset("Trampoline: VM Wrapper");
+
+  JitSpew(JitSpew_Codegen, "# Emitting profiler exit frame tail stub");
+  Label profilerExitTail;
+  generateProfilerExitFrameTailStub(masm, &profilerExitTail);
+  rangeRecorder.recordOffset("Trampoline: ProfilerExitFrameTailStub");
+
+  JitSpew(JitSpew_Codegen, "# Emitting exception tail stub");
+  generateExceptionTailStub(masm, &profilerExitTail, &bailoutTail);
+  rangeRecorder.recordOffset("Trampoline: ExceptionTailStub");
+
+  Linker linker(masm);
+  trampolineCode_ = linker.newCode(cx, CodeKind::Other);
+  if (!trampolineCode_) {
+    return false;
+  }
+
+  rangeRecorder.collectRangesForJitCode(trampolineCode_);
+#ifdef MOZ_VTUNE
+  vtune::MarkStub(trampolineCode_, "Trampolines");
+#endif
+
+  return true;
+}
+
+JitCode* JitRuntime::debugTrapHandler(JSContext* cx,
+                                      DebugTrapHandlerKind kind) {
+  if (!debugTrapHandlers_[kind]) {
+    // JitRuntime code stubs are shared across compartments and have to
+    // be allocated in the atoms zone.
+    mozilla::Maybe<AutoAllocInAtomsZone> az;
+    if (!cx->zone()->isAtomsZone()) {
+      az.emplace(cx);
+    }
+    debugTrapHandlers_[kind] = generateDebugTrapHandler(cx, kind);
+  }
+  return debugTrapHandlers_[kind];
+}
+
+JitRuntime::IonCompileTaskList& JitRuntime::ionLazyLinkList(JSRuntime* rt) {
+  MOZ_ASSERT(CurrentThreadCanAccessRuntime(rt),
+             "Should only be mutated by the main thread.");
+  return ionLazyLinkList_.ref();
+}
+
+void JitRuntime::ionLazyLinkListRemove(JSRuntime* rt,
+                                       jit::IonCompileTask* task) {
+  MOZ_ASSERT(CurrentThreadCanAccessRuntime(rt),
+             "Should only be mutated by the main thread.");
+  MOZ_ASSERT(rt == task->script()->runtimeFromMainThread());
+  MOZ_ASSERT(ionLazyLinkListSize_ > 0);
+
+  task->removeFrom(ionLazyLinkList(rt));
+  ionLazyLinkListSize_--;
+
+  MOZ_ASSERT(ionLazyLinkList(rt).isEmpty() == (ionLazyLinkListSize_ == 0));
+}
+
+void JitRuntime::ionLazyLinkListAdd(JSRuntime* rt, jit::IonCompileTask* task) {
+  MOZ_ASSERT(CurrentThreadCanAccessRuntime(rt),
+             "Should only be mutated by the main thread.");
+  MOZ_ASSERT(rt == task->script()->runtimeFromMainThread());
+  ionLazyLinkList(rt).insertFront(task);
+  ionLazyLinkListSize_++;
+}
+
+uint8_t* JitRuntime::allocateIonOsrTempData(size_t size) {
+  // Free the old buffer (if needed) before allocating a new one. Note that we
+  // could use realloc here but it's likely not worth the complexity.
+  freeIonOsrTempData();
+  ionOsrTempData_.ref().reset(static_cast<uint8_t*>(js_malloc(size)));
+  return ionOsrTempData_.ref().get();
+}
+
+void JitRuntime::freeIonOsrTempData() { ionOsrTempData_.ref().reset(); }
+
+JitRealm::JitRealm() : initialStringHeap(gc::Heap::Tenured) {}
+
+void JitRealm::initialize(bool zoneHasNurseryStrings) {
+  setStringsCanBeInNursery(zoneHasNurseryStrings);
+}
+
+template <typename T>
+static T PopNextBitmaskValue(uint32_t* bitmask) {
+  MOZ_ASSERT(*bitmask);
+  uint32_t index = mozilla::CountTrailingZeroes32(*bitmask);
+  *bitmask ^= 1 << index;
+
+  MOZ_ASSERT(index < uint32_t(T::Count));
+  return T(index);
+}
+
+void JitRealm::performStubReadBarriers(uint32_t stubsToBarrier) const {
+  while (stubsToBarrier) {
+    auto stub = PopNextBitmaskValue<StubIndex>(&stubsToBarrier);
+    const WeakHeapPtr<JitCode*>& jitCode = stubs_[stub];
+    MOZ_ASSERT(jitCode);
+    jitCode.get();
+  }
+}
+
+static bool LinkCodeGen(JSContext* cx, CodeGenerator* codegen,
+                        HandleScript script, const WarpSnapshot* snapshot) {
+  if (!codegen->link(cx, snapshot)) {
+    return false;
+  }
+
+  return true;
+}
+
+static bool LinkBackgroundCodeGen(JSContext* cx, IonCompileTask* task) {
+  CodeGenerator* codegen = task->backgroundCodegen();
+  if (!codegen) {
+    return false;
+  }
+
+  JitContext jctx(cx);
+  RootedScript script(cx, task->script());
+  return LinkCodeGen(cx, codegen, script, task->snapshot());
+}
+
+void jit::LinkIonScript(JSContext* cx, HandleScript calleeScript) {
+  // Get the pending IonCompileTask from the script.
+  MOZ_ASSERT(calleeScript->hasBaselineScript());
+  IonCompileTask* task =
+      calleeScript->baselineScript()->pendingIonCompileTask();
+  calleeScript->baselineScript()->removePendingIonCompileTask(cx->runtime(),
+                                                              calleeScript);
+
+  // Remove from pending.
+  cx->runtime()->jitRuntime()->ionLazyLinkListRemove(cx->runtime(), task);
+
+  {
+    gc::AutoSuppressGC suppressGC(cx);
+    if (!LinkBackgroundCodeGen(cx, task)) {
+      // Silently ignore OOM during code generation. The assembly code
+      // doesn't have code to handle it after linking happened. So it's
+      // not OK to throw a catchable exception from there.
+      cx->clearPendingException();
+    }
+  }
+
+  {
+    AutoLockHelperThreadState lock;
+    FinishOffThreadTask(cx->runtime(), task, lock);
+  }
+}
+
+uint8_t* jit::LazyLinkTopActivation(JSContext* cx,
+                                    LazyLinkExitFrameLayout* frame) {
+  RootedScript calleeScript(
+      cx, ScriptFromCalleeToken(frame->jsFrame()->calleeToken()));
+
+  LinkIonScript(cx, calleeScript);
+
+  MOZ_ASSERT(calleeScript->hasBaselineScript());
+  MOZ_ASSERT(calleeScript->jitCodeRaw());
+
+  return calleeScript->jitCodeRaw();
+}
+
+/* static */
+void JitRuntime::TraceAtomZoneRoots(JSTracer* trc) {
+  MOZ_ASSERT(!JS::RuntimeHeapIsMinorCollecting());
+
+  // Shared stubs are allocated in the atoms zone, so do not iterate
+  // them after the atoms heap after it has been "finished."
+  if (trc->runtime()->atomsAreFinished()) {
+    return;
+  }
+
+  Zone* zone = trc->runtime()->atomsZone();
+  for (auto i = zone->cellIterUnsafe<JitCode>(); !i.done(); i.next()) {
+    JitCode* code = i;
+    TraceRoot(trc, &code, "wrapper");
+  }
+}
+
+/* static */
+bool JitRuntime::MarkJitcodeGlobalTableIteratively(GCMarker* marker) {
+  if (marker->runtime()->hasJitRuntime() &&
+      marker->runtime()->jitRuntime()->hasJitcodeGlobalTable()) {
+    return marker->runtime()
+        ->jitRuntime()
+        ->getJitcodeGlobalTable()
+        ->markIteratively(marker);
+  }
+  return false;
+}
+
+/* static */
+void JitRuntime::TraceWeakJitcodeGlobalTable(JSRuntime* rt, JSTracer* trc) {
+  if (rt->hasJitRuntime() && rt->jitRuntime()->hasJitcodeGlobalTable()) {
+    rt->jitRuntime()->getJitcodeGlobalTable()->traceWeak(rt, trc);
+  }
+}
+
+void JitRealm::traceWeak(JSTracer* trc, JS::Realm* realm) {
+  // Any outstanding compilations should have been cancelled by the GC.
+  MOZ_ASSERT(!HasOffThreadIonCompile(realm));
+
+  for (WeakHeapPtr<JitCode*>& stub : stubs_) {
+    TraceWeakEdge(trc, &stub, "JitRealm::stubs_");
+  }
+}
+
+bool JitZone::addInlinedCompilation(const RecompileInfo& info,
+                                    JSScript* inlined) {
+  MOZ_ASSERT(inlined != info.script());
+
+  auto p = inlinedCompilations_.lookupForAdd(inlined);
+  if (p) {
+    auto& compilations = p->value();
+    if (!compilations.empty() && compilations.back() == info) {
+      return true;
+    }
+    return compilations.append(info);
+  }
+
+  RecompileInfoVector compilations;
+  if (!compilations.append(info)) {
+    return false;
+  }
+  return inlinedCompilations_.add(p, inlined, std::move(compilations));
+}
+
+void jit::AddPendingInvalidation(RecompileInfoVector& invalid,
+                                 JSScript* script) {
+  MOZ_ASSERT(script);
+
+  CancelOffThreadIonCompile(script);
+
+  // Let the script warm up again before attempting another compile.
+  script->resetWarmUpCounterToDelayIonCompilation();
+
+  JitScript* jitScript = script->maybeJitScript();
+  if (!jitScript) {
+    return;
+  }
+
+  auto addPendingInvalidation = [&invalid](const RecompileInfo& info) {
+    AutoEnterOOMUnsafeRegion oomUnsafe;
+    if (!invalid.append(info)) {
+      // BUG 1536159: For diagnostics, compute the size of the failed
+      // allocation. This presumes the vector growth strategy is to double. This
+      // is only used for crash reporting so not a problem if we get it wrong.
+      size_t allocSize = 2 * sizeof(RecompileInfo) * invalid.capacity();
+      oomUnsafe.crash(allocSize, "Could not update RecompileInfoVector");
+    }
+  };
+
+  // Trigger invalidation of the IonScript.
+  if (jitScript->hasIonScript()) {
+    RecompileInfo info(script, jitScript->ionScript()->compilationId());
+    addPendingInvalidation(info);
+  }
+
+  // Trigger invalidation of any callers inlining this script.
+  auto* inlinedCompilations =
+      script->zone()->jitZone()->maybeInlinedCompilations(script);
+  if (inlinedCompilations) {
+    for (const RecompileInfo& info : *inlinedCompilations) {
+      addPendingInvalidation(info);
+    }
+    script->zone()->jitZone()->removeInlinedCompilations(script);
+  }
+}
+
+IonScript* RecompileInfo::maybeIonScriptToInvalidate() const {
+  // Make sure this is not called under CodeGenerator::link (before the
+  // IonScript is created).
+  MOZ_ASSERT_IF(
+      script_->zone()->jitZone()->currentCompilationId(),
+      script_->zone()->jitZone()->currentCompilationId().ref() != id_);
+
+  if (!script_->hasIonScript() ||
+      script_->ionScript()->compilationId() != id_) {
+    return nullptr;
+  }
+
+  return script_->ionScript();
+}
+
+bool RecompileInfo::traceWeak(JSTracer* trc) {
+  // Sweep the RecompileInfo if either the script is dead or the IonScript has
+  // been invalidated.
+
+  if (!TraceManuallyBarrieredWeakEdge(trc, &script_, "RecompileInfo::script")) {
+    return false;
+  }
+
+  return maybeIonScriptToInvalidate() != nullptr;
+}
+
+void JitZone::traceWeak(JSTracer* trc) {
+  baselineCacheIRStubCodes_.traceWeak(trc);
+  inlinedCompilations_.traceWeak(trc);
+
+  TraceWeakEdge(trc, &lastStubFoldingBailoutChild_,
+                "JitZone::lastStubFoldingBailoutChild_");
+  TraceWeakEdge(trc, &lastStubFoldingBailoutParent_,
+                "JitZone::lastStubFoldingBailoutParent_");
+}
+
+size_t JitRealm::sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+  return mallocSizeOf(this);
+}
+
+void JitZone::addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf,
+                                     JS::CodeSizes* code, size_t* jitZone,
+                                     size_t* baselineStubsOptimized) const {
+  *jitZone += mallocSizeOf(this);
+  *jitZone +=
+      baselineCacheIRStubCodes_.shallowSizeOfExcludingThis(mallocSizeOf);
+  *jitZone += ionCacheIRStubInfoSet_.shallowSizeOfExcludingThis(mallocSizeOf);
+
+  execAlloc().addSizeOfCode(code);
+
+  *baselineStubsOptimized +=
+      optimizedStubSpace_.sizeOfExcludingThis(mallocSizeOf);
+}
+
+void JitCodeHeader::init(JitCode* jitCode) {
+  // As long as JitCode isn't moveable, we can avoid tracing this and
+  // mutating executable data.
+  MOZ_ASSERT(!gc::IsMovableKind(gc::AllocKind::JITCODE));
+  jitCode_ = jitCode;
+}
+
+template <AllowGC allowGC>
+JitCode* JitCode::New(JSContext* cx, uint8_t* code, uint32_t totalSize,
+                      uint32_t headerSize, ExecutablePool* pool,
+                      CodeKind kind) {
+  uint32_t bufferSize = totalSize - headerSize;
+  JitCode* codeObj =
+      cx->newCell<JitCode, allowGC>(code, bufferSize, headerSize, pool, kind);
+  if (!codeObj) {
+    // The caller already allocated `totalSize` bytes of executable memory.
+    pool->release(totalSize, kind);
+    return nullptr;
+  }
+
+  cx->zone()->incJitMemory(totalSize);
+
+  return codeObj;
+}
+
+template JitCode* JitCode::New<CanGC>(JSContext* cx, uint8_t* code,
+                                      uint32_t bufferSize, uint32_t headerSize,
+                                      ExecutablePool* pool, CodeKind kind);
+
+template JitCode* JitCode::New<NoGC>(JSContext* cx, uint8_t* code,
+                                     uint32_t bufferSize, uint32_t headerSize,
+                                     ExecutablePool* pool, CodeKind kind);
+
+void JitCode::copyFrom(MacroAssembler& masm) {
+  // Store the JitCode pointer in the JitCodeHeader so we can recover the
+  // gcthing from relocation tables.
+  JitCodeHeader::FromExecutable(raw())->init(this);
+
+  insnSize_ = masm.instructionsSize();
+  masm.executableCopy(raw());
+
+  jumpRelocTableBytes_ = masm.jumpRelocationTableBytes();
+  masm.copyJumpRelocationTable(raw() + jumpRelocTableOffset());
+
+  dataRelocTableBytes_ = masm.dataRelocationTableBytes();
+  masm.copyDataRelocationTable(raw() + dataRelocTableOffset());
+
+  masm.processCodeLabels(raw());
+}
+
+void JitCode::traceChildren(JSTracer* trc) {
+  // Note that we cannot mark invalidated scripts, since we've basically
+  // corrupted the code stream by injecting bailouts.
+  if (invalidated()) {
+    return;
+  }
+
+  if (jumpRelocTableBytes_) {
+    uint8_t* start = raw() + jumpRelocTableOffset();
+    CompactBufferReader reader(start, start + jumpRelocTableBytes_);
+    MacroAssembler::TraceJumpRelocations(trc, this, reader);
+  }
+  if (dataRelocTableBytes_) {
+    uint8_t* start = raw() + dataRelocTableOffset();
+    CompactBufferReader reader(start, start + dataRelocTableBytes_);
+    MacroAssembler::TraceDataRelocations(trc, this, reader);
+  }
+}
+
+void JitCode::finalize(JS::GCContext* gcx) {
+  // If this jitcode had a bytecode map, it must have already been removed.
+#ifdef DEBUG
+  JSRuntime* rt = gcx->runtime();
+  if (hasBytecodeMap_) {
+    MOZ_ASSERT(rt->jitRuntime()->hasJitcodeGlobalTable());
+    MOZ_ASSERT(!rt->jitRuntime()->getJitcodeGlobalTable()->lookup(raw()));
+  }
+#endif
+
+#ifdef MOZ_VTUNE
+  vtune::UnmarkCode(this);
+#endif
+
+  MOZ_ASSERT(pool_);
+
+  // With W^X JIT code, reprotecting memory for each JitCode instance is
+  // slow, so we record the ranges and poison them later all at once. It's
+  // safe to ignore OOM here, it just means we won't poison the code.
+  if (gcx->appendJitPoisonRange(JitPoisonRange(pool_, raw() - headerSize_,
+                                               headerSize_ + bufferSize_))) {
+    pool_->addRef();
+  }
+  setHeaderPtr(nullptr);
+
+#ifdef JS_ION_PERF
+  // Code buffers are stored inside ExecutablePools. Pools are refcounted.
+  // Releasing the pool may free it. Horrible hack: if we are using perf
+  // integration, we don't want to reuse code addresses, so we just leak the
+  // memory instead.
+  if (!PerfEnabled()) {
+    pool_->release(headerSize_ + bufferSize_, CodeKind(kind_));
+  }
+#else
+  pool_->release(headerSize_ + bufferSize_, CodeKind(kind_));
+#endif
+
+  zone()->decJitMemory(headerSize_ + bufferSize_);
+
+  pool_ = nullptr;
+}
+
+IonScript::IonScript(IonCompilationId compilationId, uint32_t localSlotsSize,
+                     uint32_t argumentSlotsSize, uint32_t frameSize)
+    : localSlotsSize_(localSlotsSize),
+      argumentSlotsSize_(argumentSlotsSize),
+      frameSize_(frameSize),
+      compilationId_(compilationId) {}
+
+IonScript* IonScript::New(JSContext* cx, IonCompilationId compilationId,
+                          uint32_t localSlotsSize, uint32_t argumentSlotsSize,
+                          uint32_t frameSize, size_t snapshotsListSize,
+                          size_t snapshotsRVATableSize, size_t recoversSize,
+                          size_t constants, size_t nurseryObjects,
+                          size_t safepointIndices, size_t osiIndices,
+                          size_t icEntries, size_t runtimeSize,
+                          size_t safepointsSize) {
+  if (snapshotsListSize >= MAX_BUFFER_SIZE) {
+    ReportOutOfMemory(cx);
+    return nullptr;
+  }
+
+  // Verify the hardcoded sizes in header are accurate.
+  static_assert(SizeOf_OsiIndex == sizeof(OsiIndex),
+                "IonScript has wrong size for OsiIndex");
+  static_assert(SizeOf_SafepointIndex == sizeof(SafepointIndex),
+                "IonScript has wrong size for SafepointIndex");
+
+  CheckedInt<Offset> allocSize = sizeof(IonScript);
+  allocSize += CheckedInt<Offset>(constants) * sizeof(Value);
+  allocSize += CheckedInt<Offset>(runtimeSize);
+  allocSize += CheckedInt<Offset>(nurseryObjects) * sizeof(HeapPtr<JSObject*>);
+  allocSize += CheckedInt<Offset>(osiIndices) * sizeof(OsiIndex);
+  allocSize += CheckedInt<Offset>(safepointIndices) * sizeof(SafepointIndex);
+  allocSize += CheckedInt<Offset>(icEntries) * sizeof(uint32_t);
+  allocSize += CheckedInt<Offset>(safepointsSize);
+  allocSize += CheckedInt<Offset>(snapshotsListSize);
+  allocSize += CheckedInt<Offset>(snapshotsRVATableSize);
+  allocSize += CheckedInt<Offset>(recoversSize);
+
+  if (!allocSize.isValid()) {
+    ReportAllocationOverflow(cx);
+    return nullptr;
+  }
+
+  void* raw = cx->pod_malloc<uint8_t>(allocSize.value());
+  MOZ_ASSERT(uintptr_t(raw) % alignof(IonScript) == 0);
+  if (!raw) {
+    return nullptr;
+  }
+  IonScript* script = new (raw)
+      IonScript(compilationId, localSlotsSize, argumentSlotsSize, frameSize);
+
+  Offset offsetCursor = sizeof(IonScript);
+
+  MOZ_ASSERT(offsetCursor % alignof(Value) == 0);
+  script->constantTableOffset_ = offsetCursor;
+  offsetCursor += constants * sizeof(Value);
+
+  MOZ_ASSERT(offsetCursor % alignof(uint64_t) == 0);
+  script->runtimeDataOffset_ = offsetCursor;
+  offsetCursor += runtimeSize;
+
+  MOZ_ASSERT(offsetCursor % alignof(HeapPtr<JSObject*>) == 0);
+  script->initElements<HeapPtr<JSObject*>>(offsetCursor, nurseryObjects);
+  script->nurseryObjectsOffset_ = offsetCursor;
+  offsetCursor += nurseryObjects * sizeof(HeapPtr<JSObject*>);
+
+  MOZ_ASSERT(offsetCursor % alignof(OsiIndex) == 0);
+  script->osiIndexOffset_ = offsetCursor;
+  offsetCursor += osiIndices * sizeof(OsiIndex);
+
+  MOZ_ASSERT(offsetCursor % alignof(SafepointIndex) == 0);
+  script->safepointIndexOffset_ = offsetCursor;
+  offsetCursor += safepointIndices * sizeof(SafepointIndex);
+
+  MOZ_ASSERT(offsetCursor % alignof(uint32_t) == 0);
+  script->icIndexOffset_ = offsetCursor;
+  offsetCursor += icEntries * sizeof(uint32_t);
+
+  script->safepointsOffset_ = offsetCursor;
+  offsetCursor += safepointsSize;
+
+  script->snapshotsOffset_ = offsetCursor;
+  offsetCursor += snapshotsListSize;
+
+  script->rvaTableOffset_ = offsetCursor;
+  offsetCursor += snapshotsRVATableSize;
+
+  script->recoversOffset_ = offsetCursor;
+  offsetCursor += recoversSize;
+
+  script->allocBytes_ = offsetCursor;
+
+  MOZ_ASSERT(script->numConstants() == constants);
+  MOZ_ASSERT(script->runtimeSize() == runtimeSize);
+  MOZ_ASSERT(script->numNurseryObjects() == nurseryObjects);
+  MOZ_ASSERT(script->numOsiIndices() == osiIndices);
+  MOZ_ASSERT(script->numSafepointIndices() == safepointIndices);
+  MOZ_ASSERT(script->numICs() == icEntries);
+  MOZ_ASSERT(script->safepointsSize() == safepointsSize);
+  MOZ_ASSERT(script->snapshotsListSize() == snapshotsListSize);
+  MOZ_ASSERT(script->snapshotsRVATableSize() == snapshotsRVATableSize);
+  MOZ_ASSERT(script->recoversSize() == recoversSize);
+  MOZ_ASSERT(script->endOffset() == offsetCursor);
+
+  return script;
+}
+
+void IonScript::trace(JSTracer* trc) {
+  if (method_) {
+    TraceEdge(trc, &method_, "method");
+  }
+
+  for (size_t i = 0; i < numConstants(); i++) {
+    TraceEdge(trc, &getConstant(i), "constant");
+  }
+
+  for (size_t i = 0; i < numNurseryObjects(); i++) {
+    TraceEdge(trc, &nurseryObjects()[i], "nursery-object");
+  }
+
+  // Trace caches so that the JSScript pointer can be updated if moved.
+  for (size_t i = 0; i < numICs(); i++) {
+    getICFromIndex(i).trace(trc, this);
+  }
+}
+
+/* static */
+void IonScript::preWriteBarrier(Zone* zone, IonScript* ionScript) {
+  PreWriteBarrier(zone, ionScript);
+}
+
+void IonScript::copySnapshots(const SnapshotWriter* writer) {
+  MOZ_ASSERT(writer->listSize() == snapshotsListSize());
+  memcpy(offsetToPointer<uint8_t>(snapshotsOffset()), writer->listBuffer(),
+         snapshotsListSize());
+
+  MOZ_ASSERT(snapshotsRVATableSize());
+  MOZ_ASSERT(writer->RVATableSize() == snapshotsRVATableSize());
+  memcpy(offsetToPointer<uint8_t>(rvaTableOffset()), writer->RVATableBuffer(),
+         snapshotsRVATableSize());
+}
+
+void IonScript::copyRecovers(const RecoverWriter* writer) {
+  MOZ_ASSERT(writer->size() == recoversSize());
+  memcpy(offsetToPointer<uint8_t>(recoversOffset()), writer->buffer(),
+         recoversSize());
+}
+
+void IonScript::copySafepoints(const SafepointWriter* writer) {
+  MOZ_ASSERT(writer->size() == safepointsSize());
+  memcpy(offsetToPointer<uint8_t>(safepointsOffset()), writer->buffer(),
+         safepointsSize());
+}
+
+void IonScript::copyConstants(const Value* vp) {
+  for (size_t i = 0; i < numConstants(); i++) {
+    constants()[i].init(vp[i]);
+  }
+}
+
+void IonScript::copySafepointIndices(const CodegenSafepointIndex* si) {
+  // Convert CodegenSafepointIndex to more compact form.
+  SafepointIndex* table = safepointIndices();
+  for (size_t i = 0; i < numSafepointIndices(); ++i) {
+    table[i] = SafepointIndex(si[i]);
+  }
+}
+
+void IonScript::copyOsiIndices(const OsiIndex* oi) {
+  memcpy(osiIndices(), oi, numOsiIndices() * sizeof(OsiIndex));
+}
+
+void IonScript::copyRuntimeData(const uint8_t* data) {
+  memcpy(runtimeData(), data, runtimeSize());
+}
+
+void IonScript::copyICEntries(const uint32_t* icEntries) {
+  memcpy(icIndex(), icEntries, numICs() * sizeof(uint32_t));
+
+  // Update the codeRaw_ field in the ICs now that we know the code address.
+  for (size_t i = 0; i < numICs(); i++) {
+    getICFromIndex(i).resetCodeRaw(this);
+  }
+}
+
+const SafepointIndex* IonScript::getSafepointIndex(uint32_t disp) const {
+  MOZ_ASSERT(numSafepointIndices() > 0);
+
+  const SafepointIndex* table = safepointIndices();
+  if (numSafepointIndices() == 1) {
+    MOZ_ASSERT(disp == table[0].displacement());
+    return &table[0];
+  }
+
+  size_t minEntry = 0;
+  size_t maxEntry = numSafepointIndices() - 1;
+  uint32_t min = table[minEntry].displacement();
+  uint32_t max = table[maxEntry].displacement();
+
+  // Raise if the element is not in the list.
+  MOZ_ASSERT(min <= disp && disp <= max);
+
+  // Approximate the location of the FrameInfo.
+  size_t guess = (disp - min) * (maxEntry - minEntry) / (max - min) + minEntry;
+  uint32_t guessDisp = table[guess].displacement();
+
+  if (table[guess].displacement() == disp) {
+    return &table[guess];
+  }
+
+  // Doing a linear scan from the guess should be more efficient in case of
+  // small group which are equally distributed on the code.
+  //
+  // such as:  <...      ...    ...  ...  .   ...    ...>
+  if (guessDisp > disp) {
+    while (--guess >= minEntry) {
+      guessDisp = table[guess].displacement();
+      MOZ_ASSERT(guessDisp >= disp);
+      if (guessDisp == disp) {
+        return &table[guess];
+      }
+    }
+  } else {
+    while (++guess <= maxEntry) {
+      guessDisp = table[guess].displacement();
+      MOZ_ASSERT(guessDisp <= disp);
+      if (guessDisp == disp) {
+        return &table[guess];
+      }
+    }
+  }
+
+  MOZ_CRASH("displacement not found.");
+}
+
+const OsiIndex* IonScript::getOsiIndex(uint32_t disp) const {
+  const OsiIndex* end = osiIndices() + numOsiIndices();
+  for (const OsiIndex* it = osiIndices(); it != end; ++it) {
+    if (it->returnPointDisplacement() == disp) {
+      return it;
+    }
+  }
+
+  MOZ_CRASH("Failed to find OSI point return address");
+}
+
+const OsiIndex* IonScript::getOsiIndex(uint8_t* retAddr) const {
+  JitSpew(JitSpew_IonInvalidate, "IonScript %p has method %p raw %p",
+          (void*)this, (void*)method(), method()->raw());
+
+  MOZ_ASSERT(containsCodeAddress(retAddr));
+  uint32_t disp = retAddr - method()->raw();
+  return getOsiIndex(disp);
+}
+
+void IonScript::Destroy(JS::GCContext* gcx, IonScript* script) {
+  // Make sure there are no pointers into the IonScript's nursery objects list
+  // in the store buffer. Because this can be called during sweeping when
+  // discarding JIT code, we have to lock the store buffer when we find an
+  // object that's (still) in the nursery.
+  mozilla::Maybe<gc::AutoLockStoreBuffer> lock;
+  for (size_t i = 0, len = script->numNurseryObjects(); i < len; i++) {
+    JSObject* obj = script->nurseryObjects()[i];
+    if (!IsInsideNursery(obj)) {
+      continue;
+    }
+    if (lock.isNothing()) {
+      lock.emplace(&gcx->runtime()->gc.storeBuffer());
+    }
+    script->nurseryObjects()[i] = HeapPtr<JSObject*>();
+  }
+
+  // This allocation is tracked by JSScript::setIonScriptImpl.
+  gcx->deleteUntracked(script);
+}
+
+void JS::DeletePolicy<js::jit::IonScript>::operator()(
+    const js::jit::IonScript* script) {
+  IonScript::Destroy(rt_->gcContext(), const_cast<IonScript*>(script));
+}
+
+void IonScript::purgeICs(Zone* zone) {
+  for (size_t i = 0; i < numICs(); i++) {
+    getICFromIndex(i).reset(zone, this);
+  }
+}
+
+namespace js {
+namespace jit {
+
+bool OptimizeMIR(MIRGenerator* mir) {
+  MIRGraph& graph = mir->graph();
+  GraphSpewer& gs = mir->graphSpewer();
+
+  if (mir->shouldCancel("Start")) {
+    return false;
+  }
+
+  gs.spewPass("BuildSSA");
+  AssertBasicGraphCoherency(graph);
+
+  if (JitSpewEnabled(JitSpew_MIRExpressions)) {
+    JitSpewCont(JitSpew_MIRExpressions, "\n");
+    DumpMIRExpressions(JitSpewPrinter(), graph, mir->outerInfo(),
+                       "BuildSSA (== input to OptimizeMIR)");
+  }
+
+  if (!JitOptions.disablePruning && !mir->compilingWasm()) {
+    JitSpewCont(JitSpew_Prune, "\n");
+    if (!PruneUnusedBranches(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Prune Unused Branches");
+    AssertBasicGraphCoherency(graph);
+
+    if (mir->shouldCancel("Prune Unused Branches")) {
+      return false;
+    }
+  }
+
+  {
+    if (!FoldEmptyBlocks(graph)) {
+      return false;
+    }
+    gs.spewPass("Fold Empty Blocks");
+    AssertBasicGraphCoherency(graph);
+
+    if (mir->shouldCancel("Fold Empty Blocks")) {
+      return false;
+    }
+  }
+
+  // Remove trivially dead resume point operands before folding tests, so the
+  // latter pass can optimize more aggressively.
+  if (!mir->compilingWasm()) {
+    if (!EliminateTriviallyDeadResumePointOperands(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Eliminate trivially dead resume point operands");
+    AssertBasicGraphCoherency(graph);
+
+    if (mir->shouldCancel("Eliminate trivially dead resume point operands")) {
+      return false;
+    }
+  }
+
+  {
+    if (!FoldTests(graph)) {
+      return false;
+    }
+    gs.spewPass("Fold Tests");
+    AssertBasicGraphCoherency(graph);
+
+    if (mir->shouldCancel("Fold Tests")) {
+      return false;
+    }
+  }
+
+  {
+    if (!SplitCriticalEdges(graph)) {
+      return false;
+    }
+    gs.spewPass("Split Critical Edges");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("Split Critical Edges")) {
+      return false;
+    }
+  }
+
+  {
+    RenumberBlocks(graph);
+    gs.spewPass("Renumber Blocks");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("Renumber Blocks")) {
+      return false;
+    }
+  }
+
+  {
+    if (!BuildDominatorTree(graph)) {
+      return false;
+    }
+    // No spew: graph not changed.
+
+    if (mir->shouldCancel("Dominator Tree")) {
+      return false;
+    }
+  }
+
+  {
+    // Aggressive phi elimination must occur before any code elimination. If the
+    // script contains a try-statement, we only compiled the try block and not
+    // the catch or finally blocks, so in this case it's also invalid to use
+    // aggressive phi elimination.
+    Observability observability = graph.hasTryBlock()
+                                      ? ConservativeObservability
+                                      : AggressiveObservability;
+    if (!EliminatePhis(mir, graph, observability)) {
+      return false;
+    }
+    gs.spewPass("Eliminate phis");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("Eliminate phis")) {
+      return false;
+    }
+
+    if (!BuildPhiReverseMapping(graph)) {
+      return false;
+    }
+    AssertExtendedGraphCoherency(graph);
+    // No spew: graph not changed.
+
+    if (mir->shouldCancel("Phi reverse mapping")) {
+      return false;
+    }
+  }
+
+  if (!mir->compilingWasm() && !JitOptions.disableIteratorIndices) {
+    if (!OptimizeIteratorIndices(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Iterator Indices");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("Iterator Indices")) {
+      return false;
+    }
+  }
+
+  if (!JitOptions.disableRecoverIns &&
+      mir->optimizationInfo().scalarReplacementEnabled()) {
+    JitSpewCont(JitSpew_Escape, "\n");
+    if (!ScalarReplacement(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Scalar Replacement");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("Scalar Replacement")) {
+      return false;
+    }
+  }
+
+  if (!mir->compilingWasm()) {
+    if (!ApplyTypeInformation(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Apply types");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Apply types")) {
+      return false;
+    }
+  }
+
+  if (mir->optimizationInfo().amaEnabled()) {
+    AlignmentMaskAnalysis ama(graph);
+    if (!ama.analyze()) {
+      return false;
+    }
+    gs.spewPass("Alignment Mask Analysis");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Alignment Mask Analysis")) {
+      return false;
+    }
+  }
+
+  ValueNumberer gvn(mir, graph);
+
+  // Alias analysis is required for LICM and GVN so that we don't move
+  // loads across stores. We also use alias information when removing
+  // redundant shapeguards.
+  if (mir->optimizationInfo().licmEnabled() ||
+      mir->optimizationInfo().gvnEnabled() ||
+      mir->optimizationInfo().eliminateRedundantShapeGuardsEnabled()) {
+    {
+      AliasAnalysis analysis(mir, graph);
+      JitSpewCont(JitSpew_Alias, "\n");
+      if (!analysis.analyze()) {
+        return false;
+      }
+
+      gs.spewPass("Alias analysis");
+      AssertExtendedGraphCoherency(graph);
+
+      if (mir->shouldCancel("Alias analysis")) {
+        return false;
+      }
+    }
+
+    if (!mir->compilingWasm()) {
+      // Eliminating dead resume point operands requires basic block
+      // instructions to be numbered. Reuse the numbering computed during
+      // alias analysis.
+      if (!EliminateDeadResumePointOperands(mir, graph)) {
+        return false;
+      }
+
+      gs.spewPass("Eliminate dead resume point operands");
+      AssertExtendedGraphCoherency(graph);
+
+      if (mir->shouldCancel("Eliminate dead resume point operands")) {
+        return false;
+      }
+    }
+  }
+
+  if (mir->optimizationInfo().gvnEnabled()) {
+    JitSpewCont(JitSpew_GVN, "\n");
+    if (!gvn.run(ValueNumberer::UpdateAliasAnalysis)) {
+      return false;
+    }
+    gs.spewPass("GVN");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("GVN")) {
+      return false;
+    }
+  }
+
+  // LICM can hoist instructions from conditional branches and
+  // trigger bailouts. Disable it if bailing out of a hoisted
+  // instruction has previously invalidated this script.
+  if (mir->licmEnabled()) {
+    JitSpewCont(JitSpew_LICM, "\n");
+    if (!LICM(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("LICM");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("LICM")) {
+      return false;
+    }
+  }
+
+  RangeAnalysis r(mir, graph);
+  if (mir->optimizationInfo().rangeAnalysisEnabled()) {
+    JitSpewCont(JitSpew_Range, "\n");
+    if (!r.addBetaNodes()) {
+      return false;
+    }
+    gs.spewPass("Beta");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("RA Beta")) {
+      return false;
+    }
+
+    if (!r.analyze() || !r.addRangeAssertions()) {
+      return false;
+    }
+    gs.spewPass("Range Analysis");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Range Analysis")) {
+      return false;
+    }
+
+    if (!r.removeBetaNodes()) {
+      return false;
+    }
+    gs.spewPass("De-Beta");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("RA De-Beta")) {
+      return false;
+    }
+
+    if (mir->optimizationInfo().gvnEnabled()) {
+      bool shouldRunUCE = false;
+      if (!r.prepareForUCE(&shouldRunUCE)) {
+        return false;
+      }
+      gs.spewPass("RA check UCE");
+      AssertExtendedGraphCoherency(graph);
+
+      if (mir->shouldCancel("RA check UCE")) {
+        return false;
+      }
+
+      if (shouldRunUCE) {
+        if (!gvn.run(ValueNumberer::DontUpdateAliasAnalysis)) {
+          return false;
+        }
+        gs.spewPass("UCE After RA");
+        AssertExtendedGraphCoherency(graph);
+
+        if (mir->shouldCancel("UCE After RA")) {
+          return false;
+        }
+      }
+    }
+
+    if (mir->optimizationInfo().autoTruncateEnabled()) {
+      if (!r.truncate()) {
+        return false;
+      }
+      gs.spewPass("Truncate Doubles");
+      AssertExtendedGraphCoherency(graph);
+
+      if (mir->shouldCancel("Truncate Doubles")) {
+        return false;
+      }
+    }
+  }
+
+  if (!JitOptions.disableRecoverIns) {
+    JitSpewCont(JitSpew_Sink, "\n");
+    if (!Sink(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Sink");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Sink")) {
+      return false;
+    }
+  }
+
+  if (!JitOptions.disableRecoverIns &&
+      mir->optimizationInfo().rangeAnalysisEnabled()) {
+    JitSpewCont(JitSpew_Range, "\n");
+    if (!r.removeUnnecessaryBitops()) {
+      return false;
+    }
+    gs.spewPass("Remove Unnecessary Bitops");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Remove Unnecessary Bitops")) {
+      return false;
+    }
+  }
+
+  {
+    JitSpewCont(JitSpew_FLAC, "\n");
+    if (!FoldLinearArithConstants(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Fold Linear Arithmetic Constants");
+    AssertBasicGraphCoherency(graph);
+
+    if (mir->shouldCancel("Fold Linear Arithmetic Constants")) {
+      return false;
+    }
+  }
+
+  if (mir->optimizationInfo().eaaEnabled()) {
+    EffectiveAddressAnalysis eaa(mir, graph);
+    JitSpewCont(JitSpew_EAA, "\n");
+    if (!eaa.analyze()) {
+      return false;
+    }
+    gs.spewPass("Effective Address Analysis");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Effective Address Analysis")) {
+      return false;
+    }
+  }
+
+  // BCE marks bounds checks as dead, so do BCE before DCE.
+  if (mir->compilingWasm()) {
+    JitSpewCont(JitSpew_WasmBCE, "\n");
+    if (!EliminateBoundsChecks(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("Redundant Bounds Check Elimination");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("BCE")) {
+      return false;
+    }
+  }
+
+  {
+    if (!EliminateDeadCode(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("DCE");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("DCE")) {
+      return false;
+    }
+  }
+
+  if (mir->optimizationInfo().instructionReorderingEnabled() &&
+      !mir->outerInfo().hadReorderingBailout()) {
+    if (!ReorderInstructions(graph)) {
+      return false;
+    }
+    gs.spewPass("Reordering");
+
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Reordering")) {
+      return false;
+    }
+  }
+
+  // Make loops contiguous. We do this after GVN/UCE and range analysis,
+  // which can remove CFG edges, exposing more blocks that can be moved.
+  {
+    if (!MakeLoopsContiguous(graph)) {
+      return false;
+    }
+    gs.spewPass("Make loops contiguous");
+    AssertExtendedGraphCoherency(graph);
+
+    if (mir->shouldCancel("Make loops contiguous")) {
+      return false;
+    }
+  }
+  AssertExtendedGraphCoherency(graph, /* underValueNumberer = */ false,
+                               /* force = */ true);
+
+  // Remove unreachable blocks created by MBasicBlock::NewFakeLoopPredecessor
+  // to ensure every loop header has two predecessors. (This only happens due
+  // to OSR.)  After this point, it is no longer possible to build the
+  // dominator tree.
+  if (!mir->compilingWasm() && graph.osrBlock()) {
+    graph.removeFakeLoopPredecessors();
+    gs.spewPass("Remove fake loop predecessors");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("Remove fake loop predecessors")) {
+      return false;
+    }
+  }
+
+  // Passes after this point must not move instructions; these analyses
+  // depend on knowing the final order in which instructions will execute.
+
+  if (mir->optimizationInfo().edgeCaseAnalysisEnabled()) {
+    EdgeCaseAnalysis edgeCaseAnalysis(mir, graph);
+    if (!edgeCaseAnalysis.analyzeLate()) {
+      return false;
+    }
+    gs.spewPass("Edge Case Analysis (Late)");
+    AssertGraphCoherency(graph);
+
+    if (mir->shouldCancel("Edge Case Analysis (Late)")) {
+      return false;
+    }
+  }
+
+  if (mir->optimizationInfo().eliminateRedundantChecksEnabled()) {
+    // Note: check elimination has to run after all other passes that move
+    // instructions. Since check uses are replaced with the actual index,
+    // code motion after this pass could incorrectly move a load or store
+    // before its bounds check.
+    if (!EliminateRedundantChecks(graph)) {
+      return false;
+    }
+    gs.spewPass("Bounds Check Elimination");
+    AssertGraphCoherency(graph);
+  }
+
+  if (mir->optimizationInfo().eliminateRedundantShapeGuardsEnabled()) {
+    if (!EliminateRedundantShapeGuards(graph)) {
+      return false;
+    }
+    gs.spewPass("Shape Guard Elimination");
+    AssertGraphCoherency(graph);
+  }
+
+  // Run the GC Barrier Elimination pass after instruction reordering, to
+  // ensure we don't move instructions that can trigger GC between stores we
+  // optimize here.
+  if (mir->optimizationInfo().eliminateRedundantGCBarriersEnabled()) {
+    if (!EliminateRedundantGCBarriers(graph)) {
+      return false;
+    }
+    gs.spewPass("GC Barrier Elimination");
+    AssertGraphCoherency(graph);
+  }
+
+  if (!mir->compilingWasm() && !mir->outerInfo().hadUnboxFoldingBailout()) {
+    if (!FoldLoadsWithUnbox(mir, graph)) {
+      return false;
+    }
+    gs.spewPass("FoldLoadsWithUnbox");
+    AssertGraphCoherency(graph);
+  }
+
+  if (!mir->compilingWasm()) {
+    if (!AddKeepAliveInstructions(graph)) {
+      return false;
+    }
+    gs.spewPass("Add KeepAlive Instructions");
+    AssertGraphCoherency(graph);
+  }
+
+  AssertGraphCoherency(graph, /* force = */ true);
+
+  if (JitSpewEnabled(JitSpew_MIRExpressions)) {
+    JitSpewCont(JitSpew_MIRExpressions, "\n");
+    DumpMIRExpressions(JitSpewPrinter(), graph, mir->outerInfo(),
+                       "BeforeLIR (== result of OptimizeMIR)");
+  }
+
+  return true;
+}
+
+LIRGraph* GenerateLIR(MIRGenerator* mir) {
+  MIRGraph& graph = mir->graph();
+  GraphSpewer& gs = mir->graphSpewer();
+
+  LIRGraph* lir = mir->alloc().lifoAlloc()->new_<LIRGraph>(&graph);
+  if (!lir || !lir->init()) {
+    return nullptr;
+  }
+
+  LIRGenerator lirgen(mir, graph, *lir);
+  {
+    if (!lirgen.generate()) {
+      return nullptr;
+    }
+    gs.spewPass("Generate LIR");
+
+    if (mir->shouldCancel("Generate LIR")) {
+      return nullptr;
+    }
+  }
+
+#ifdef DEBUG
+  AllocationIntegrityState integrity(*lir);
+#endif
+
+  {
+    IonRegisterAllocator allocator =
+        mir->optimizationInfo().registerAllocator();
+
+    switch (allocator) {
+      case RegisterAllocator_Backtracking:
+      case RegisterAllocator_Testbed: {
+#ifdef DEBUG
+        if (JitOptions.fullDebugChecks) {
+          if (!integrity.record()) {
+            return nullptr;
+          }
+        }
+#endif
+
+        BacktrackingAllocator regalloc(mir, &lirgen, *lir,
+                                       allocator == RegisterAllocator_Testbed);
+        if (!regalloc.go()) {
+          return nullptr;
+        }
+
+#ifdef DEBUG
+        if (JitOptions.fullDebugChecks) {
+          if (!integrity.check()) {
+            return nullptr;
+          }
+        }
+#endif
+
+        gs.spewPass("Allocate Registers [Backtracking]");
+        break;
+      }
+
+      default:
+        MOZ_CRASH("Bad regalloc");
+    }
+
+    if (mir->shouldCancel("Allocate Registers")) {
+      return nullptr;
+    }
+  }
+
+  return lir;
+}
+
+CodeGenerator* GenerateCode(MIRGenerator* mir, LIRGraph* lir) {
+  auto codegen = MakeUnique<CodeGenerator>(mir, lir);
+  if (!codegen) {
+    return nullptr;
+  }
+
+  if (!codegen->generate()) {
+    return nullptr;
+  }
+
+  return codegen.release();
+}
+
+CodeGenerator* CompileBackEnd(MIRGenerator* mir, WarpSnapshot* snapshot) {
+  // Everything in CompileBackEnd can potentially run on a helper thread.
+  AutoEnterIonBackend enter;
+  AutoSpewEndFunction spewEndFunction(mir);
+
+  {
+    WarpCompilation comp(mir->alloc());
+    WarpBuilder builder(*snapshot, *mir, &comp);
+    if (!builder.build()) {
+      return nullptr;
+    }
+  }
+
+  if (!OptimizeMIR(mir)) {
+    return nullptr;
+  }
+
+  LIRGraph* lir = GenerateLIR(mir);
+  if (!lir) {
+    return nullptr;
+  }
+
+  return GenerateCode(mir, lir);
+}
+
+static AbortReasonOr<WarpSnapshot*> CreateWarpSnapshot(JSContext* cx,
+                                                       MIRGenerator* mirGen,
+                                                       HandleScript script) {
+  // Suppress GC during compilation.
+  gc::AutoSuppressGC suppressGC(cx);
+
+  SpewBeginFunction(mirGen, script);
+
+  WarpOracle oracle(cx, *mirGen, script);
+
+  AbortReasonOr<WarpSnapshot*> result = oracle.createSnapshot();
+
+  MOZ_ASSERT_IF(result.isErr(), result.unwrapErr() == AbortReason::Alloc ||
+                                    result.unwrapErr() == AbortReason::Error ||
+                                    result.unwrapErr() == AbortReason::Disable);
+  MOZ_ASSERT_IF(!result.isErr(), result.unwrap());
+
+  return result;
+}
+
+static AbortReason IonCompile(JSContext* cx, HandleScript script,
+                              jsbytecode* osrPc) {
+  cx->check(script);
+
+  auto alloc =
+      cx->make_unique<LifoAlloc>(TempAllocator::PreferredLifoChunkSize);
+  if (!alloc) {
+    return AbortReason::Error;
+  }
+
+  if (!cx->realm()->ensureJitRealmExists(cx)) {
+    return AbortReason::Error;
+  }
+
+  if (!cx->realm()->jitRealm()->ensureIonStubsExist(cx)) {
+    return AbortReason::Error;
+  }
+
+  TempAllocator* temp = alloc->new_<TempAllocator>(alloc.get());
+  if (!temp) {
+    return AbortReason::Alloc;
+  }
+
+  MIRGraph* graph = alloc->new_<MIRGraph>(temp);
+  if (!graph) {
+    return AbortReason::Alloc;
+  }
+
+  InlineScriptTree* inlineScriptTree =
+      InlineScriptTree::New(temp, nullptr, nullptr, script);
+  if (!inlineScriptTree) {
+    return AbortReason::Alloc;
+  }
+
+  CompileInfo* info = alloc->new_<CompileInfo>(
+      CompileRuntime::get(cx->runtime()), script, script->function(), osrPc,
+      script->needsArgsObj(), inlineScriptTree);
+  if (!info) {
+    return AbortReason::Alloc;
+  }
+
+  const OptimizationInfo* optimizationInfo =
+      IonOptimizations.get(OptimizationLevel::Normal);
+  const JitCompileOptions options(cx);
+
+  MIRGenerator* mirGen =
+      alloc->new_<MIRGenerator>(CompileRealm::get(cx->realm()), options, temp,
+                                graph, info, optimizationInfo);
+  if (!mirGen) {
+    return AbortReason::Alloc;
+  }
+
+  MOZ_ASSERT(!script->baselineScript()->hasPendingIonCompileTask());
+  MOZ_ASSERT(!script->hasIonScript());
+  MOZ_ASSERT(script->canIonCompile());
+
+  if (osrPc) {
+    script->jitScript()->setHadIonOSR();
+  }
+
+  AbortReasonOr<WarpSnapshot*> result = CreateWarpSnapshot(cx, mirGen, script);
+  if (result.isErr()) {
+    return result.unwrapErr();
+  }
+  WarpSnapshot* snapshot = result.unwrap();
+
+  // If possible, compile the script off thread.
+  if (options.offThreadCompilationAvailable()) {
+    JitSpew(JitSpew_IonSyncLogs,
+            "Can't log script %s:%u:%u"
+            ". (Compiled on background thread.)",
+            script->filename(), script->lineno(), script->column());
+
+    IonCompileTask* task = alloc->new_<IonCompileTask>(cx, *mirGen, snapshot);
+    if (!task) {
+      return AbortReason::Alloc;
+    }
+
+    AutoLockHelperThreadState lock;
+    if (!StartOffThreadIonCompile(task, lock)) {
+      JitSpew(JitSpew_IonAbort, "Unable to start off-thread ion compilation.");
+      mirGen->graphSpewer().endFunction();
+      return AbortReason::Alloc;
+    }
+
+    script->jitScript()->setIsIonCompilingOffThread(script);
+
+    // The allocator and associated data will be destroyed after being
+    // processed in the finishedOffThreadCompilations list.
+    (void)alloc.release();
+
+    return AbortReason::NoAbort;
+  }
+
+  bool succeeded = false;
+  {
+    gc::AutoSuppressGC suppressGC(cx);
+    JitContext jctx(cx);
+    UniquePtr<CodeGenerator> codegen(CompileBackEnd(mirGen, snapshot));
+    if (!codegen) {
+      JitSpew(JitSpew_IonAbort, "Failed during back-end compilation.");
+      if (cx->isExceptionPending()) {
+        return AbortReason::Error;
+      }
+      return AbortReason::Disable;
+    }
+
+    succeeded = LinkCodeGen(cx, codegen.get(), script, snapshot);
+  }
+
+  if (succeeded) {
+    return AbortReason::NoAbort;
+  }
+  if (cx->isExceptionPending()) {
+    return AbortReason::Error;
+  }
+  return AbortReason::Disable;
+}
+
+static bool CheckFrame(JSContext* cx, BaselineFrame* frame) {
+  MOZ_ASSERT(!frame->isDebuggerEvalFrame());
+  MOZ_ASSERT(!frame->isEvalFrame());
+
+  // This check is to not overrun the stack.
+  if (frame->isFunctionFrame()) {
+    if (TooManyActualArguments(frame->numActualArgs())) {
+      JitSpew(JitSpew_IonAbort, "too many actual arguments");
+      return false;
+    }
+
+    if (TooManyFormalArguments(frame->numFormalArgs())) {
+      JitSpew(JitSpew_IonAbort, "too many arguments");
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static bool CanIonCompileOrInlineScript(JSScript* script, const char** reason) {
+  if (script->isForEval()) {
+    // Eval frames are not yet supported. Supporting this will require new
+    // logic in pushBailoutFrame to deal with linking prev.
+    // Additionally, JSOp::GlobalOrEvalDeclInstantiation support will require
+    // baking in isEvalFrame().
+    *reason = "eval script";
+    return false;
+  }
+
+  if (script->isAsync()) {
+    if (script->isModule()) {
+      *reason = "async module";
+      return false;
+    }
+  }
+
+  if (script->hasNonSyntacticScope() && !script->function()) {
+    // Support functions with a non-syntactic global scope but not other
+    // scripts. For global scripts, WarpBuilder currently uses the global
+    // object as scope chain, this is not valid when the script has a
+    // non-syntactic global scope.
+    *reason = "has non-syntactic global scope";
+    return false;
+  }
+
+  return true;
+}  // namespace jit
+
+static bool ScriptIsTooLarge(JSContext* cx, JSScript* script) {
+  if (!JitOptions.limitScriptSize) {
+    return false;
+  }
+
+  size_t numLocalsAndArgs = NumLocalsAndArgs(script);
+
+  bool canCompileOffThread = OffThreadCompilationAvailable(cx);
+  size_t maxScriptSize = canCompileOffThread
+                             ? JitOptions.ionMaxScriptSize
+                             : JitOptions.ionMaxScriptSizeMainThread;
+  size_t maxLocalsAndArgs = canCompileOffThread
+                                ? JitOptions.ionMaxLocalsAndArgs
+                                : JitOptions.ionMaxLocalsAndArgsMainThread;
+
+  if (script->length() > maxScriptSize || numLocalsAndArgs > maxLocalsAndArgs) {
+    JitSpew(JitSpew_IonAbort,
+            "Script too large (%zu bytes) (%zu locals/args) @ %s:%u:%u",
+            script->length(), numLocalsAndArgs, script->filename(),
+            script->lineno(), script->column());
+    return true;
+  }
+
+  return false;
+}
+
+bool CanIonCompileScript(JSContext* cx, JSScript* script) {
+  if (!script->canIonCompile()) {
+    return false;
+  }
+
+  const char* reason = nullptr;
+  if (!CanIonCompileOrInlineScript(script, &reason)) {
+    JitSpew(JitSpew_IonAbort, "%s", reason);
+    return false;
+  }
+
+  if (ScriptIsTooLarge(cx, script)) {
+    return false;
+  }
+
+  return true;
+}
+
+bool CanIonInlineScript(JSScript* script) {
+  if (!script->canIonCompile()) {
+    return false;
+  }
+
+  const char* reason = nullptr;
+  if (!CanIonCompileOrInlineScript(script, &reason)) {
+    JitSpew(JitSpew_Inlining, "Cannot Ion compile script (%s)", reason);
+    return false;
+  }
+
+  return true;
+}
+
+static MethodStatus Compile(JSContext* cx, HandleScript script,
+                            BaselineFrame* osrFrame, jsbytecode* osrPc) {
+  MOZ_ASSERT(jit::IsIonEnabled(cx));
+  MOZ_ASSERT(jit::IsBaselineJitEnabled(cx));
+
+  MOZ_ASSERT(script->hasBaselineScript());
+  MOZ_ASSERT(!script->baselineScript()->hasPendingIonCompileTask());
+  MOZ_ASSERT(!script->hasIonScript());
+
+  AutoGeckoProfilerEntry pseudoFrame(
+      cx, "Ion script compilation",
+      JS::ProfilingCategoryPair::JS_IonCompilation);
+
+  if (script->isDebuggee() || (osrFrame && osrFrame->isDebuggee())) {
+    JitSpew(JitSpew_IonAbort, "debugging");
+    return Method_Skipped;
+  }
+
+  if (!CanIonCompileScript(cx, script)) {
+    JitSpew(JitSpew_IonAbort, "Aborted compilation of %s:%u:%u",
+            script->filename(), script->lineno(), script->column());
+    return Method_CantCompile;
+  }
+
+  OptimizationLevel optimizationLevel =
+      IonOptimizations.levelForScript(script, osrPc);
+  if (optimizationLevel == OptimizationLevel::DontCompile) {
+    return Method_Skipped;
+  }
+
+  MOZ_ASSERT(optimizationLevel == OptimizationLevel::Normal);
+
+  if (!CanLikelyAllocateMoreExecutableMemory()) {
+    script->resetWarmUpCounterToDelayIonCompilation();
+    return Method_Skipped;
+  }
+
+  MOZ_ASSERT(!script->hasIonScript());
+
+  AbortReason reason = IonCompile(cx, script, osrPc);
+  if (reason == AbortReason::Error) {
+    MOZ_ASSERT(cx->isExceptionPending());
+    return Method_Error;
+  }
+
+  if (reason == AbortReason::Disable) {
+    return Method_CantCompile;
+  }
+
+  if (reason == AbortReason::Alloc) {
+    ReportOutOfMemory(cx);
+    return Method_Error;
+  }
+
+  // Compilation succeeded or we invalidated right away or an inlining/alloc
+  // abort
+  if (script->hasIonScript()) {
+    return Method_Compiled;
+  }
+  return Method_Skipped;
+}
+
+}  // namespace jit
+}  // namespace js
+
+bool jit::OffThreadCompilationAvailable(JSContext* cx) {
+  // Even if off thread compilation is enabled, compilation must still occur
+  // on the main thread in some cases.
+  //
+  // Require cpuCount > 1 so that Ion compilation jobs and active-thread
+  // execution are not competing for the same resources.
+  return cx->runtime()->canUseOffthreadIonCompilation() &&
+         GetHelperThreadCPUCount() > 1 && CanUseExtraThreads();
+}
+
+MethodStatus jit::CanEnterIon(JSContext* cx, RunState& state) {
+  MOZ_ASSERT(jit::IsIonEnabled(cx));
+
+  HandleScript script = state.script();
+  MOZ_ASSERT(!script->hasIonScript());
+
+  // Skip if the script has been disabled.
+  if (!script->canIonCompile()) {
+    return Method_Skipped;
+  }
+
+  // Skip if the script is being compiled off thread.
+  if (script->isIonCompilingOffThread()) {
+    return Method_Skipped;
+  }
+
+  if (state.isInvoke()) {
+    InvokeState& invoke = *state.asInvoke();
+
+    if (TooManyActualArguments(invoke.args().length())) {
+      JitSpew(JitSpew_IonAbort, "too many actual args");
+      ForbidCompilation(cx, script);
+      return Method_CantCompile;
+    }
+
+    if (TooManyFormalArguments(
+            invoke.args().callee().as<JSFunction>().nargs())) {
+      JitSpew(JitSpew_IonAbort, "too many args");
+      ForbidCompilation(cx, script);
+      return Method_CantCompile;
+    }
+  }
+
+  // If --ion-eager is used, compile with Baseline first, so that we
+  // can directly enter IonMonkey.
+  if (JitOptions.eagerIonCompilation() && !script->hasBaselineScript()) {
+    MethodStatus status =
+        CanEnterBaselineMethod<BaselineTier::Compiler>(cx, state);
+    if (status != Method_Compiled) {
+      return status;
+    }
+    // Bytecode analysis may forbid compilation for a script.
+    if (!script->canIonCompile()) {
+      return Method_CantCompile;
+    }
+  }
+
+  if (!script->hasBaselineScript()) {
+    return Method_Skipped;
+  }
+
+  MOZ_ASSERT(!script->isIonCompilingOffThread());
+  MOZ_ASSERT(script->canIonCompile());
+
+  // Attempt compilation. Returns Method_Compiled if already compiled.
+  MethodStatus status = Compile(cx, script, /* osrFrame = */ nullptr,
+                                /* osrPc = */ nullptr);
+  if (status != Method_Compiled) {
+    if (status == Method_CantCompile) {
+      ForbidCompilation(cx, script);
+    }
+    return status;
+  }
+
+  if (state.script()->baselineScript()->hasPendingIonCompileTask()) {
+    LinkIonScript(cx, state.script());
+    if (!state.script()->hasIonScript()) {
+      return jit::Method_Skipped;
+    }
+  }
+
+  return Method_Compiled;
+}
+
+static MethodStatus BaselineCanEnterAtEntry(JSContext* cx, HandleScript script,
+                                            BaselineFrame* frame) {
+  MOZ_ASSERT(jit::IsIonEnabled(cx));
+  MOZ_ASSERT(script->canIonCompile());
+  MOZ_ASSERT(!script->isIonCompilingOffThread());
+  MOZ_ASSERT(!script->hasIonScript());
+  MOZ_ASSERT(frame->isFunctionFrame());
+
+  // Mark as forbidden if frame can't be handled.
+  if (!CheckFrame(cx, frame)) {
+    ForbidCompilation(cx, script);
+    return Method_CantCompile;
+  }
+
+  if (script->baselineScript()->hasPendingIonCompileTask()) {
+    LinkIonScript(cx, script);
+    if (script->hasIonScript()) {
+      return Method_Compiled;
+    }
+  }
+
+  // Attempt compilation. Returns Method_Compiled if already compiled.
+  MethodStatus status = Compile(cx, script, frame, nullptr);
+  if (status != Method_Compiled) {
+    if (status == Method_CantCompile) {
+      ForbidCompilation(cx, script);
+    }
+    return status;
+  }
+
+  return Method_Compiled;
+}
+
+// Decide if a transition from baseline execution to Ion code should occur.
+// May compile or recompile the target JSScript.
+static MethodStatus BaselineCanEnterAtBranch(JSContext* cx, HandleScript script,
+                                             BaselineFrame* osrFrame,
+                                             jsbytecode* pc) {
+  MOZ_ASSERT(jit::IsIonEnabled(cx));
+  MOZ_ASSERT((JSOp)*pc == JSOp::LoopHead);
+
+  // Skip if the script has been disabled.
+  if (!script->canIonCompile()) {
+    return Method_Skipped;
+  }
+
+  // Skip if the script is being compiled off thread.
+  if (script->isIonCompilingOffThread()) {
+    return Method_Skipped;
+  }
+
+  // Optionally ignore on user request.
+  if (!JitOptions.osr) {
+    return Method_Skipped;
+  }
+
+  // Mark as forbidden if frame can't be handled.
+  if (!CheckFrame(cx, osrFrame)) {
+    ForbidCompilation(cx, script);
+    return Method_CantCompile;
+  }
+
+  // Check if the jitcode still needs to get linked and do this
+  // to have a valid IonScript.
+  if (script->baselineScript()->hasPendingIonCompileTask()) {
+    LinkIonScript(cx, script);
+  }
+
+  // By default a recompilation doesn't happen on osr mismatch.
+  // Decide if we want to force a recompilation if this happens too much.
+  if (script->hasIonScript()) {
+    if (pc == script->ionScript()->osrPc()) {
+      return Method_Compiled;
+    }
+
+    uint32_t count = script->ionScript()->incrOsrPcMismatchCounter();
+    if (count <= JitOptions.osrPcMismatchesBeforeRecompile &&
+        !JitOptions.eagerIonCompilation()) {
+      return Method_Skipped;
+    }
+
+    JitSpew(JitSpew_IonScripts, "Forcing OSR Mismatch Compilation");
+    Invalidate(cx, script);
+  }
+
+  // Attempt compilation.
+  // - Returns Method_Compiled if the right ionscript is present
+  //   (Meaning it was present or a sequantial compile finished)
+  // - Returns Method_Skipped if pc doesn't match
+  //   (This means a background thread compilation with that pc could have
+  //   started or not.)
+  MethodStatus status = Compile(cx, script, osrFrame, pc);
+  if (status != Method_Compiled) {
+    if (status == Method_CantCompile) {
+      ForbidCompilation(cx, script);
+    }
+    return status;
+  }
+
+  // Return the compilation was skipped when the osr pc wasn't adjusted.
+  // This can happen when there was still an IonScript available and a
+  // background compilation started, but hasn't finished yet.
+  // Or when we didn't force a recompile.
+  if (script->hasIonScript() && pc != script->ionScript()->osrPc()) {
+    return Method_Skipped;
+  }
+
+  return Method_Compiled;
+}
+
+static bool IonCompileScriptForBaseline(JSContext* cx, BaselineFrame* frame,
+                                        jsbytecode* pc) {
+  MOZ_ASSERT(IsIonEnabled(cx));
+
+  RootedScript script(cx, frame->script());
+  bool isLoopHead = JSOp(*pc) == JSOp::LoopHead;
+
+  // The Baseline JIT code checks for Ion disabled or compiling off-thread.
+  MOZ_ASSERT(script->canIonCompile());
+  MOZ_ASSERT(!script->isIonCompilingOffThread());
+
+  // If Ion script exists, but PC is not at a loop entry, then Ion will be
+  // entered for this script at an appropriate LOOPENTRY or the next time this
+  // function is called.
+  if (script->hasIonScript() && !isLoopHead) {
+    JitSpew(JitSpew_BaselineOSR, "IonScript exists, but not at loop entry!");
+    // TODO: ASSERT that a ion-script-already-exists checker stub doesn't exist.
+    // TODO: Clear all optimized stubs.
+    // TODO: Add a ion-script-already-exists checker stub.
+    return true;
+  }
+
+  // Ensure that Ion-compiled code is available.
+  JitSpew(JitSpew_BaselineOSR,
+          "WarmUpCounter for %s:%u:%u reached %d at pc %p, trying to switch to "
+          "Ion!",
+          script->filename(), script->lineno(), script->column(),
+          (int)script->getWarmUpCount(), (void*)pc);
+
+  MethodStatus stat;
+  if (isLoopHead) {
+    JitSpew(JitSpew_BaselineOSR, "  Compile at loop head!");
+    stat = BaselineCanEnterAtBranch(cx, script, frame, pc);
+  } else if (frame->isFunctionFrame()) {
+    JitSpew(JitSpew_BaselineOSR,
+            "  Compile function from top for later entry!");
+    stat = BaselineCanEnterAtEntry(cx, script, frame);
+  } else {
+    return true;
+  }
+
+  if (stat == Method_Error) {
+    JitSpew(JitSpew_BaselineOSR, "  Compile with Ion errored!");
+    return false;
+  }
+
+  if (stat == Method_CantCompile) {
+    MOZ_ASSERT(!script->canIonCompile());
+    JitSpew(JitSpew_BaselineOSR, "  Can't compile with Ion!");
+  } else if (stat == Method_Skipped) {
+    JitSpew(JitSpew_BaselineOSR, "  Skipped compile with Ion!");
+  } else if (stat == Method_Compiled) {
+    JitSpew(JitSpew_BaselineOSR, "  Compiled with Ion!");
+  } else {
+    MOZ_CRASH("Invalid MethodStatus!");
+  }
+
+  return true;
+}
+
+bool jit::IonCompileScriptForBaselineAtEntry(JSContext* cx,
+                                             BaselineFrame* frame) {
+  JSScript* script = frame->script();
+  return IonCompileScriptForBaseline(cx, frame, script->code());
+}
+
+/* clang-format off */
+// The following data is kept in a temporary heap-allocated buffer, stored in
+// JitRuntime (high memory addresses at top, low at bottom):
+//
+//     +----->+=================================+  --      <---- High Address
+//     |      |                                 |   |
+//     |      |     ...BaselineFrame...         |   |-- Copy of BaselineFrame + stack values
+//     |      |                                 |   |
+//     |      +---------------------------------+   |
+//     |      |                                 |   |
+//     |      |     ...Locals/Stack...          |   |
+//     |      |                                 |   |
+//     |      +=================================+  --
+//     |      |     Padding(Maybe Empty)        |
+//     |      +=================================+  --
+//     +------|-- baselineFrame                 |   |-- IonOsrTempData
+//            |   jitcode                       |   |
+//            +=================================+  --      <---- Low Address
+//
+// A pointer to the IonOsrTempData is returned.
+/* clang-format on */
+
+static IonOsrTempData* PrepareOsrTempData(JSContext* cx, BaselineFrame* frame,
+                                          uint32_t frameSize, void* jitcode) {
+  uint32_t numValueSlots = frame->numValueSlots(frameSize);
+
+  // Calculate the amount of space to allocate:
+  //      BaselineFrame space:
+  //          (sizeof(Value) * numValueSlots)
+  //        + sizeof(BaselineFrame)
+  //
+  //      IonOsrTempData space:
+  //          sizeof(IonOsrTempData)
+
+  size_t frameSpace = sizeof(BaselineFrame) + sizeof(Value) * numValueSlots;
+  size_t ionOsrTempDataSpace = sizeof(IonOsrTempData);
+
+  size_t totalSpace = AlignBytes(frameSpace, sizeof(Value)) +
+                      AlignBytes(ionOsrTempDataSpace, sizeof(Value));
+
+  JitRuntime* jrt = cx->runtime()->jitRuntime();
+  uint8_t* buf = jrt->allocateIonOsrTempData(totalSpace);
+  if (!buf) {
+    ReportOutOfMemory(cx);
+    return nullptr;
+  }
+
+  IonOsrTempData* info = new (buf) IonOsrTempData();
+  info->jitcode = jitcode;
+
+  // Copy the BaselineFrame + local/stack Values to the buffer. Arguments and
+  // |this| are not copied but left on the stack: the Baseline and Ion frame
+  // share the same frame prefix and Ion won't clobber these values. Note
+  // that info->baselineFrame will point to the *end* of the frame data, like
+  // the frame pointer register in baseline frames.
+  uint8_t* frameStart =
+      (uint8_t*)info + AlignBytes(ionOsrTempDataSpace, sizeof(Value));
+  info->baselineFrame = frameStart + frameSpace;
+
+  memcpy(frameStart, (uint8_t*)frame - numValueSlots * sizeof(Value),
+         frameSpace);
+
+  JitSpew(JitSpew_BaselineOSR, "Allocated IonOsrTempData at %p", info);
+  JitSpew(JitSpew_BaselineOSR, "Jitcode is %p", info->jitcode);
+
+  // All done.
+  return info;
+}
+
+bool jit::IonCompileScriptForBaselineOSR(JSContext* cx, BaselineFrame* frame,
+                                         uint32_t frameSize, jsbytecode* pc,
+                                         IonOsrTempData** infoPtr) {
+  MOZ_ASSERT(infoPtr);
+  *infoPtr = nullptr;
+
+  MOZ_ASSERT(frame->debugFrameSize() == frameSize);
+  MOZ_ASSERT(JSOp(*pc) == JSOp::LoopHead);
+
+  if (!IonCompileScriptForBaseline(cx, frame, pc)) {
+    return false;
+  }
+
+  RootedScript script(cx, frame->script());
+  if (!script->hasIonScript() || script->ionScript()->osrPc() != pc ||
+      frame->isDebuggee()) {
+    return true;
+  }
+
+  IonScript* ion = script->ionScript();
+  MOZ_ASSERT(cx->runtime()->geckoProfiler().enabled() ==
+             ion->hasProfilingInstrumentation());
+  MOZ_ASSERT(ion->osrPc() == pc);
+
+  ion->resetOsrPcMismatchCounter();
+
+  JitSpew(JitSpew_BaselineOSR, "  OSR possible!");
+  void* jitcode = ion->method()->raw() + ion->osrEntryOffset();
+
+  // Prepare the temporary heap copy of the fake InterpreterFrame and actual
+  // args list.
+  JitSpew(JitSpew_BaselineOSR, "Got jitcode.  Preparing for OSR into ion.");
+  IonOsrTempData* info = PrepareOsrTempData(cx, frame, frameSize, jitcode);
+  if (!info) {
+    return false;
+  }
+
+  *infoPtr = info;
+  return true;
+}
+
+static void InvalidateActivation(JS::GCContext* gcx,
+                                 const JitActivationIterator& activations,
+                                 bool invalidateAll) {
+  JitSpew(JitSpew_IonInvalidate, "BEGIN invalidating activation");
+
+#ifdef CHECK_OSIPOINT_REGISTERS
+  if (JitOptions.checkOsiPointRegisters) {
+    activations->asJit()->setCheckRegs(false);
+  }
+#endif
+
+  size_t frameno = 1;
+
+  for (OnlyJSJitFrameIter iter(activations); !iter.done(); ++iter, ++frameno) {
+    const JSJitFrameIter& frame = iter.frame();
+    MOZ_ASSERT_IF(frameno == 1, frame.isExitFrame() ||
+                                    frame.type() == FrameType::Bailout ||
+                                    frame.type() == FrameType::JSJitToWasm);
+
+#ifdef JS_JITSPEW
+    switch (frame.type()) {
+      case FrameType::Exit:
+        JitSpew(JitSpew_IonInvalidate, "#%zu exit frame @ %p", frameno,
+                frame.fp());
+        break;
+      case FrameType::JSJitToWasm:
+        JitSpew(JitSpew_IonInvalidate, "#%zu wasm exit frame @ %p", frameno,
+                frame.fp());
+        break;
+      case FrameType::BaselineJS:
+      case FrameType::IonJS:
+      case FrameType::Bailout: {
+        MOZ_ASSERT(frame.isScripted());
+        const char* type = "Unknown";
+        if (frame.isIonJS()) {
+          type = "Optimized";
+        } else if (frame.isBaselineJS()) {
+          type = "Baseline";
+        } else if (frame.isBailoutJS()) {
+          type = "Bailing";
+        }
+        JSScript* script = frame.maybeForwardedScript();
+        JitSpew(JitSpew_IonInvalidate,
+                "#%zu %s JS frame @ %p, %s:%u:%u (fun: %p, script: %p, pc %p)",
+                frameno, type, frame.fp(), script->maybeForwardedFilename(),
+                script->lineno(), script->column(), frame.maybeCallee(), script,
+                frame.resumePCinCurrentFrame());
+        break;
+      }
+      case FrameType::BaselineStub:
+        JitSpew(JitSpew_IonInvalidate, "#%zu baseline stub frame @ %p", frameno,
+                frame.fp());
+        break;
+      case FrameType::BaselineInterpreterEntry:
+        JitSpew(JitSpew_IonInvalidate,
+                "#%zu baseline interpreter entry frame @ %p", frameno,
+                frame.fp());
+        break;
+      case FrameType::Rectifier:
+        JitSpew(JitSpew_IonInvalidate, "#%zu rectifier frame @ %p", frameno,
+                frame.fp());
+        break;
+      case FrameType::IonICCall:
+        JitSpew(JitSpew_IonInvalidate, "#%zu ion IC call frame @ %p", frameno,
+                frame.fp());
+        break;
+      case FrameType::CppToJSJit:
+        JitSpew(JitSpew_IonInvalidate, "#%zu entry frame @ %p", frameno,
+                frame.fp());
+        break;
+      case FrameType::WasmToJSJit:
+        JitSpew(JitSpew_IonInvalidate, "#%zu wasm frames @ %p", frameno,
+                frame.fp());
+        break;
+    }
+#endif  // JS_JITSPEW
+
+    if (!frame.isIonScripted()) {
+      continue;
+    }
+
+    // See if the frame has already been invalidated.
+    if (frame.checkInvalidation()) {
+      continue;
+    }
+
+    JSScript* script = frame.maybeForwardedScript();
+    if (!script->hasIonScript()) {
+      continue;
+    }
+
+    if (!invalidateAll && !script->ionScript()->invalidated()) {
+      continue;
+    }
+
+    IonScript* ionScript = script->ionScript();
+
+    // Purge ICs before we mark this script as invalidated. This will
+    // prevent lastJump_ from appearing to be a bogus pointer, just
+    // in case anyone tries to read it.
+    ionScript->purgeICs(script->zone());
+
+    // This frame needs to be invalidated. We do the following:
+    //
+    // 1. Increment the reference counter to keep the ionScript alive
+    //    for the invalidation bailout or for the exception handler.
+    // 2. Determine safepoint that corresponds to the current call.
+    // 3. From safepoint, get distance to the OSI-patchable offset.
+    // 4. From the IonScript, determine the distance between the
+    //    call-patchable offset and the invalidation epilogue.
+    // 5. Patch the OSI point with a call-relative to the
+    //    invalidation epilogue.
+    //
+    // The code generator ensures that there's enough space for us
+    // to patch in a call-relative operation at each invalidation
+    // point.
+    //
+    // Note: you can't simplify this mechanism to "just patch the
+    // instruction immediately after the call" because things may
+    // need to move into a well-defined register state (using move
+    // instructions after the call) in to capture an appropriate
+    // snapshot after the call occurs.
+
+    ionScript->incrementInvalidationCount();
+
+    JitCode* ionCode = ionScript->method();
+
+    // We're about to remove edges from the JSScript to GC things embedded in
+    // the JitCode. Perform a barrier to let the GC know about those edges.
+    PreWriteBarrier(script->zone(), ionCode, [](JSTracer* trc, JitCode* code) {
+      code->traceChildren(trc);
+    });
+
+    ionCode->setInvalidated();
+
+    // Don't adjust OSI points in a bailout path.
+    if (frame.isBailoutJS()) {
+      continue;
+    }
+
+    // Write the delta (from the return address offset to the
+    // IonScript pointer embedded into the invalidation epilogue)
+    // where the safepointed call instruction used to be. We rely on
+    // the call sequence causing the safepoint being >= the size of
+    // a uint32, which is checked during safepoint index
+    // construction.
+    AutoWritableJitCode awjc(ionCode);
+    const SafepointIndex* si =
+        ionScript->getSafepointIndex(frame.resumePCinCurrentFrame());
+    CodeLocationLabel dataLabelToMunge(frame.resumePCinCurrentFrame());
+    ptrdiff_t delta = ionScript->invalidateEpilogueDataOffset() -
+                      (frame.resumePCinCurrentFrame() - ionCode->raw());
+    Assembler::PatchWrite_Imm32(dataLabelToMunge, Imm32(delta));
+
+    CodeLocationLabel osiPatchPoint =
+        SafepointReader::InvalidationPatchPoint(ionScript, si);
+    CodeLocationLabel invalidateEpilogue(
+        ionCode, CodeOffset(ionScript->invalidateEpilogueOffset()));
+
+    JitSpew(
+        JitSpew_IonInvalidate,
+        "   ! Invalidate ionScript %p (inv count %zu) -> patching osipoint %p",
+        ionScript, ionScript->invalidationCount(), (void*)osiPatchPoint.raw());
+    Assembler::PatchWrite_NearCall(osiPatchPoint, invalidateEpilogue);
+  }
+
+  JitSpew(JitSpew_IonInvalidate, "END invalidating activation");
+}
+
+void jit::InvalidateAll(JS::GCContext* gcx, Zone* zone) {
+  // The caller should previously have cancelled off thread compilation.
+#ifdef DEBUG
+  for (RealmsInZoneIter realm(zone); !realm.done(); realm.next()) {
+    MOZ_ASSERT(!HasOffThreadIonCompile(realm));
+  }
+#endif
+  if (zone->isAtomsZone()) {
+    return;
+  }
+  JSContext* cx = TlsContext.get();
+  for (JitActivationIterator iter(cx); !iter.done(); ++iter) {
+    if (iter->compartment()->zone() == zone) {
+      JitSpew(JitSpew_IonInvalidate, "Invalidating all frames for GC");
+      InvalidateActivation(gcx, iter, true);
+    }
+  }
+}
+
+static void ClearIonScriptAfterInvalidation(JSContext* cx, JSScript* script,
+                                            IonScript* ionScript,
+                                            bool resetUses) {
+  // Null out the JitScript's IonScript pointer. The caller is responsible for
+  // destroying the IonScript using the invalidation count mechanism.
+  DebugOnly<IonScript*> clearedIonScript =
+      script->jitScript()->clearIonScript(cx->gcContext(), script);
+  MOZ_ASSERT(clearedIonScript == ionScript);
+
+  // Wait for the scripts to get warm again before doing another
+  // compile, unless we are recompiling *because* a script got hot
+  // (resetUses is false).
+  if (resetUses) {
+    script->resetWarmUpCounterToDelayIonCompilation();
+  }
+}
+
+void jit::Invalidate(JSContext* cx, const RecompileInfoVector& invalid,
+                     bool resetUses, bool cancelOffThread) {
+  JitSpew(JitSpew_IonInvalidate, "Start invalidation.");
+
+  // Add an invalidation reference to all invalidated IonScripts to indicate
+  // to the traversal which frames have been invalidated.
+  size_t numInvalidations = 0;
+  for (const RecompileInfo& info : invalid) {
+    if (cancelOffThread) {
+      CancelOffThreadIonCompile(info.script());
+    }
+
+    IonScript* ionScript = info.maybeIonScriptToInvalidate();
+    if (!ionScript) {
+      continue;
+    }
+
+    JitSpew(JitSpew_IonInvalidate, " Invalidate %s:%u:%u, IonScript %p",
+            info.script()->filename(), info.script()->lineno(),
+            info.script()->column(), ionScript);
+
+    // Keep the ion script alive during the invalidation and flag this
+    // ionScript as being invalidated.  This increment is removed by the
+    // loop after the calls to InvalidateActivation.
+    ionScript->incrementInvalidationCount();
+    numInvalidations++;
+  }
+
+  if (!numInvalidations) {
+    JitSpew(JitSpew_IonInvalidate, " No IonScript invalidation.");
+    return;
+  }
+
+  JS::GCContext* gcx = cx->gcContext();
+  for (JitActivationIterator iter(cx); !iter.done(); ++iter) {
+    InvalidateActivation(gcx, iter, false);
+  }
+
+  // Drop the references added above. If a script was never active, its
+  // IonScript will be immediately destroyed. Otherwise, it will be held live
+  // until its last invalidated frame is destroyed.
+  for (const RecompileInfo& info : invalid) {
+    IonScript* ionScript = info.maybeIonScriptToInvalidate();
+    if (!ionScript) {
+      continue;
+    }
+
+    if (ionScript->invalidationCount() == 1) {
+      // decrementInvalidationCount will destroy the IonScript so null out
+      // jitScript->ionScript_ now. We don't want to do this unconditionally
+      // because maybeIonScriptToInvalidate depends on script->ionScript() (we
+      // would leak the IonScript if |invalid| contains duplicates).
+      ClearIonScriptAfterInvalidation(cx, info.script(), ionScript, resetUses);
+    }
+
+    ionScript->decrementInvalidationCount(gcx);
+    numInvalidations--;
+  }
+
+  // Make sure we didn't leak references by invalidating the same IonScript
+  // multiple times in the above loop.
+  MOZ_ASSERT(!numInvalidations);
+
+  // Finally, null out jitScript->ionScript_ for IonScripts that are still on
+  // the stack.
+  for (const RecompileInfo& info : invalid) {
+    if (IonScript* ionScript = info.maybeIonScriptToInvalidate()) {
+      ClearIonScriptAfterInvalidation(cx, info.script(), ionScript, resetUses);
+    }
+  }
+}
+
+void jit::IonScript::invalidate(JSContext* cx, JSScript* script, bool resetUses,
+                                const char* reason) {
+  // Note: we could short circuit here if we already invalidated this
+  // IonScript, but jit::Invalidate also cancels off-thread compilations of
+  // |script|.
+  MOZ_RELEASE_ASSERT(invalidated() || script->ionScript() == this);
+
+  JitSpew(JitSpew_IonInvalidate, " Invalidate IonScript %p: %s", this, reason);
+
+  // RecompileInfoVector has inline space for at least one element.
+  RecompileInfoVector list;
+  MOZ_RELEASE_ASSERT(list.reserve(1));
+  list.infallibleEmplaceBack(script, compilationId());
+
+  Invalidate(cx, list, resetUses, true);
+}
+
+void jit::Invalidate(JSContext* cx, JSScript* script, bool resetUses,
+                     bool cancelOffThread) {
+  MOZ_ASSERT(script->hasIonScript());
+
+  if (cx->runtime()->geckoProfiler().enabled()) {
+    // Register invalidation with profiler.
+    // Format of event payload string:
+    //      "<filename>:<lineno>"
+
+    // Get the script filename, if any, and its length.
+    const char* filename = script->filename();
+    if (filename == nullptr) {
+      filename = "<unknown>";
+    }
+
+    // Construct the descriptive string.
+    UniqueChars buf =
+        JS_smprintf("%s:%u:%u", filename, script->lineno(), script->column());
+
+    // Ignore the event on allocation failure.
+    if (buf) {
+      cx->runtime()->geckoProfiler().markEvent("Invalidate", buf.get());
+    }
+  }
+
+  // RecompileInfoVector has inline space for at least one element.
+  RecompileInfoVector scripts;
+  MOZ_ASSERT(script->hasIonScript());
+  MOZ_RELEASE_ASSERT(scripts.reserve(1));
+  scripts.infallibleEmplaceBack(script, script->ionScript()->compilationId());
+
+  Invalidate(cx, scripts, resetUses, cancelOffThread);
+}
+
+void jit::FinishInvalidation(JS::GCContext* gcx, JSScript* script) {
+  if (!script->hasIonScript()) {
+    return;
+  }
+
+  // In all cases, null out jitScript->ionScript_ to avoid re-entry.
+  IonScript* ion = script->jitScript()->clearIonScript(gcx, script);
+
+  // If this script has Ion code on the stack, invalidated() will return
+  // true. In this case we have to wait until destroying it.
+  if (!ion->invalidated()) {
+    jit::IonScript::Destroy(gcx, ion);
+  }
+}
+
+void jit::ForbidCompilation(JSContext* cx, JSScript* script) {
+  JitSpew(JitSpew_IonAbort, "Disabling Ion compilation of script %s:%u:%u",
+          script->filename(), script->lineno(), script->column());
+
+  CancelOffThreadIonCompile(script);
+
+  if (script->hasIonScript()) {
+    Invalidate(cx, script, false);
+  }
+
+  script->disableIon();
+}
+
+size_t jit::SizeOfIonData(JSScript* script,
+                          mozilla::MallocSizeOf mallocSizeOf) {
+  size_t result = 0;
+
+  if (script->hasIonScript()) {
+    result += script->ionScript()->sizeOfIncludingThis(mallocSizeOf);
+  }
+
+  return result;
+}
+
+// If you change these, please also change the comment in TempAllocator.
+/* static */ const size_t TempAllocator::BallastSize = 16 * 1024;
+/* static */ const size_t TempAllocator::PreferredLifoChunkSize = 32 * 1024;