Adding upstream version 110.0.1.upstream/110.0.1upstream

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

1 files changed, 6222 insertions, 0 deletions

diff --git a/js/src/jit/MacroAssembler.cpp b/js/src/jit/MacroAssembler.cpp
new file mode 100644
index 0000000000..8f66c6218f
--- /dev/null
+++ b/js/src/jit/MacroAssembler.cpp
@@ -0,0 +1,6222 @@
+/* -*- 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/MacroAssembler-inl.h"
+
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/XorShift128PlusRNG.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "jit/AtomicOp.h"
+#include "jit/AtomicOperations.h"
+#include "jit/Bailouts.h"
+#include "jit/BaselineFrame.h"
+#include "jit/BaselineJIT.h"
+#include "jit/JitFrames.h"
+#include "jit/JitOptions.h"
+#include "jit/JitRuntime.h"
+#include "jit/JitScript.h"
+#include "jit/MoveEmitter.h"
+#include "jit/ReciprocalMulConstants.h"
+#include "jit/SharedICHelpers.h"
+#include "jit/SharedICRegisters.h"
+#include "jit/Simulator.h"
+#include "jit/VMFunctions.h"
+#include "js/Conversions.h"
+#include "js/friend/DOMProxy.h"  // JS::ExpandoAndGeneration
+#include "js/ScalarType.h"       // js::Scalar::Type
+#include "vm/ArgumentsObject.h"
+#include "vm/ArrayBufferViewObject.h"
+#include "vm/FunctionFlags.h"  // js::FunctionFlags
+#include "vm/Iteration.h"
+#include "vm/JSContext.h"
+#include "vm/TypedArrayObject.h"
+#include "wasm/WasmBuiltins.h"
+#include "wasm/WasmCodegenTypes.h"
+#include "wasm/WasmInstanceData.h"
+#include "wasm/WasmMemory.h"
+#include "wasm/WasmValidate.h"
+
+#include "jit/TemplateObject-inl.h"
+#include "vm/BytecodeUtil-inl.h"
+#include "vm/Interpreter-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+using JS::GenericNaN;
+using JS::ToInt32;
+
+using mozilla::CheckedInt;
+
+TrampolinePtr MacroAssembler::preBarrierTrampoline(MIRType type) {
+  const JitRuntime* rt = runtime()->jitRuntime();
+  return rt->preBarrier(type);
+}
+
+template <typename S, typename T>
+static void StoreToTypedFloatArray(MacroAssembler& masm, int arrayType,
+                                   const S& value, const T& dest) {
+  switch (arrayType) {
+    case Scalar::Float32:
+      masm.storeFloat32(value, dest);
+      break;
+    case Scalar::Float64:
+      masm.storeDouble(value, dest);
+      break;
+    default:
+      MOZ_CRASH("Invalid typed array type");
+  }
+}
+
+void MacroAssembler::storeToTypedFloatArray(Scalar::Type arrayType,
+                                            FloatRegister value,
+                                            const BaseIndex& dest) {
+  StoreToTypedFloatArray(*this, arrayType, value, dest);
+}
+void MacroAssembler::storeToTypedFloatArray(Scalar::Type arrayType,
+                                            FloatRegister value,
+                                            const Address& dest) {
+  StoreToTypedFloatArray(*this, arrayType, value, dest);
+}
+
+template <typename S, typename T>
+static void StoreToTypedBigIntArray(MacroAssembler& masm,
+                                    Scalar::Type arrayType, const S& value,
+                                    const T& dest) {
+  MOZ_ASSERT(Scalar::isBigIntType(arrayType));
+  masm.store64(value, dest);
+}
+
+void MacroAssembler::storeToTypedBigIntArray(Scalar::Type arrayType,
+                                             Register64 value,
+                                             const BaseIndex& dest) {
+  StoreToTypedBigIntArray(*this, arrayType, value, dest);
+}
+void MacroAssembler::storeToTypedBigIntArray(Scalar::Type arrayType,
+                                             Register64 value,
+                                             const Address& dest) {
+  StoreToTypedBigIntArray(*this, arrayType, value, dest);
+}
+
+void MacroAssembler::boxUint32(Register source, ValueOperand dest,
+                               Uint32Mode mode, Label* fail) {
+  switch (mode) {
+    // Fail if the value does not fit in an int32.
+    case Uint32Mode::FailOnDouble: {
+      branchTest32(Assembler::Signed, source, source, fail);
+      tagValue(JSVAL_TYPE_INT32, source, dest);
+      break;
+    }
+    case Uint32Mode::ForceDouble: {
+      // Always convert the value to double.
+      ScratchDoubleScope fpscratch(*this);
+      convertUInt32ToDouble(source, fpscratch);
+      boxDouble(fpscratch, dest, fpscratch);
+      break;
+    }
+  }
+}
+
+template <typename T>
+void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const T& src,
+                                        AnyRegister dest, Register temp,
+                                        Label* fail) {
+  switch (arrayType) {
+    case Scalar::Int8:
+      load8SignExtend(src, dest.gpr());
+      break;
+    case Scalar::Uint8:
+    case Scalar::Uint8Clamped:
+      load8ZeroExtend(src, dest.gpr());
+      break;
+    case Scalar::Int16:
+      load16SignExtend(src, dest.gpr());
+      break;
+    case Scalar::Uint16:
+      load16ZeroExtend(src, dest.gpr());
+      break;
+    case Scalar::Int32:
+      load32(src, dest.gpr());
+      break;
+    case Scalar::Uint32:
+      if (dest.isFloat()) {
+        load32(src, temp);
+        convertUInt32ToDouble(temp, dest.fpu());
+      } else {
+        load32(src, dest.gpr());
+
+        // Bail out if the value doesn't fit into a signed int32 value. This
+        // is what allows MLoadUnboxedScalar to have a type() of
+        // MIRType::Int32 for UInt32 array loads.
+        branchTest32(Assembler::Signed, dest.gpr(), dest.gpr(), fail);
+      }
+      break;
+    case Scalar::Float32:
+      loadFloat32(src, dest.fpu());
+      canonicalizeFloat(dest.fpu());
+      break;
+    case Scalar::Float64:
+      loadDouble(src, dest.fpu());
+      canonicalizeDouble(dest.fpu());
+      break;
+    case Scalar::BigInt64:
+    case Scalar::BigUint64:
+    default:
+      MOZ_CRASH("Invalid typed array type");
+  }
+}
+
+template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType,
+                                                 const Address& src,
+                                                 AnyRegister dest,
+                                                 Register temp, Label* fail);
+template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType,
+                                                 const BaseIndex& src,
+                                                 AnyRegister dest,
+                                                 Register temp, Label* fail);
+
+template <typename T>
+void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const T& src,
+                                        const ValueOperand& dest,
+                                        Uint32Mode uint32Mode, Register temp,
+                                        Label* fail) {
+  switch (arrayType) {
+    case Scalar::Int8:
+    case Scalar::Uint8:
+    case Scalar::Uint8Clamped:
+    case Scalar::Int16:
+    case Scalar::Uint16:
+    case Scalar::Int32:
+      loadFromTypedArray(arrayType, src, AnyRegister(dest.scratchReg()),
+                         InvalidReg, nullptr);
+      tagValue(JSVAL_TYPE_INT32, dest.scratchReg(), dest);
+      break;
+    case Scalar::Uint32:
+      // Don't clobber dest when we could fail, instead use temp.
+      load32(src, temp);
+      boxUint32(temp, dest, uint32Mode, fail);
+      break;
+    case Scalar::Float32: {
+      ScratchDoubleScope dscratch(*this);
+      FloatRegister fscratch = dscratch.asSingle();
+      loadFromTypedArray(arrayType, src, AnyRegister(fscratch),
+                         dest.scratchReg(), nullptr);
+      convertFloat32ToDouble(fscratch, dscratch);
+      boxDouble(dscratch, dest, dscratch);
+      break;
+    }
+    case Scalar::Float64: {
+      ScratchDoubleScope fpscratch(*this);
+      loadFromTypedArray(arrayType, src, AnyRegister(fpscratch),
+                         dest.scratchReg(), nullptr);
+      boxDouble(fpscratch, dest, fpscratch);
+      break;
+    }
+    case Scalar::BigInt64:
+    case Scalar::BigUint64:
+    default:
+      MOZ_CRASH("Invalid typed array type");
+  }
+}
+
+template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType,
+                                                 const Address& src,
+                                                 const ValueOperand& dest,
+                                                 Uint32Mode uint32Mode,
+                                                 Register temp, Label* fail);
+template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType,
+                                                 const BaseIndex& src,
+                                                 const ValueOperand& dest,
+                                                 Uint32Mode uint32Mode,
+                                                 Register temp, Label* fail);
+
+template <typename T>
+void MacroAssembler::loadFromTypedBigIntArray(Scalar::Type arrayType,
+                                              const T& src, Register bigInt,
+                                              Register64 temp) {
+  MOZ_ASSERT(Scalar::isBigIntType(arrayType));
+
+  load64(src, temp);
+  initializeBigInt64(arrayType, bigInt, temp);
+}
+
+template void MacroAssembler::loadFromTypedBigIntArray(Scalar::Type arrayType,
+                                                       const Address& src,
+                                                       Register bigInt,
+                                                       Register64 temp);
+template void MacroAssembler::loadFromTypedBigIntArray(Scalar::Type arrayType,
+                                                       const BaseIndex& src,
+                                                       Register bigInt,
+                                                       Register64 temp);
+
+// Inlined version of gc::CheckAllocatorState that checks the bare essentials
+// and bails for anything that cannot be handled with our jit allocators.
+void MacroAssembler::checkAllocatorState(Label* fail) {
+  // Don't execute the inline path if GC probes are built in.
+#ifdef JS_GC_PROBES
+  jump(fail);
+#endif
+
+#ifdef JS_GC_ZEAL
+  // Don't execute the inline path if gc zeal or tracing are active.
+  const uint32_t* ptrZealModeBits = runtime()->addressOfGCZealModeBits();
+  branch32(Assembler::NotEqual, AbsoluteAddress(ptrZealModeBits), Imm32(0),
+           fail);
+#endif
+
+  // Don't execute the inline path if the realm has an object metadata callback,
+  // as the metadata to use for the object may vary between executions of the
+  // op.
+  if (realm()->hasAllocationMetadataBuilder()) {
+    jump(fail);
+  }
+}
+
+bool MacroAssembler::shouldNurseryAllocate(gc::AllocKind allocKind,
+                                           gc::InitialHeap initialHeap) {
+  // Note that Ion elides barriers on writes to objects known to be in the
+  // nursery, so any allocation that can be made into the nursery must be made
+  // into the nursery, even if the nursery is disabled. At runtime these will
+  // take the out-of-line path, which is required to insert a barrier for the
+  // initializing writes.
+  return IsNurseryAllocable(allocKind) && initialHeap != gc::TenuredHeap;
+}
+
+// Inline version of Nursery::allocateObject. If the object has dynamic slots,
+// this fills in the slots_ pointer.
+void MacroAssembler::nurseryAllocateObject(Register result, Register temp,
+                                           gc::AllocKind allocKind,
+                                           size_t nDynamicSlots, Label* fail,
+                                           const AllocSiteInput& allocSite) {
+  MOZ_ASSERT(IsNurseryAllocable(allocKind));
+
+  // We still need to allocate in the nursery, per the comment in
+  // shouldNurseryAllocate; however, we need to insert into the
+  // mallocedBuffers set, so bail to do the nursery allocation in the
+  // interpreter.
+  if (nDynamicSlots >= Nursery::MaxNurseryBufferSize / sizeof(Value)) {
+    jump(fail);
+    return;
+  }
+
+  // Check whether this allocation site needs pretenuring. This dynamic check
+  // only happens for baseline code.
+  if (allocSite.is<Register>()) {
+    Register site = allocSite.as<Register>();
+    branchTestPtr(Assembler::NonZero,
+                  Address(site, gc::AllocSite::offsetOfScriptAndState()),
+                  Imm32(gc::AllocSite::LONG_LIVED_BIT), fail);
+  }
+
+  // No explicit check for nursery.isEnabled() is needed, as the comparison
+  // with the nursery's end will always fail in such cases.
+  CompileZone* zone = realm()->zone();
+  size_t thingSize = gc::Arena::thingSize(allocKind);
+  size_t totalSize = thingSize;
+  if (nDynamicSlots) {
+    totalSize += ObjectSlots::allocSize(nDynamicSlots);
+  }
+  MOZ_ASSERT(totalSize < INT32_MAX);
+  MOZ_ASSERT(totalSize % gc::CellAlignBytes == 0);
+
+  bumpPointerAllocate(result, temp, fail, zone,
+                      zone->addressOfNurseryPosition(),
+                      zone->addressOfNurseryCurrentEnd(), JS::TraceKind::Object,
+                      totalSize, allocSite);
+
+  if (nDynamicSlots) {
+    store32(Imm32(nDynamicSlots),
+            Address(result, thingSize + ObjectSlots::offsetOfCapacity()));
+    store32(
+        Imm32(0),
+        Address(result, thingSize + ObjectSlots::offsetOfDictionarySlotSpan()));
+    computeEffectiveAddress(
+        Address(result, thingSize + ObjectSlots::offsetOfSlots()), temp);
+    storePtr(temp, Address(result, NativeObject::offsetOfSlots()));
+  }
+}
+
+// Inlined version of FreeSpan::allocate. This does not fill in slots_.
+void MacroAssembler::freeListAllocate(Register result, Register temp,
+                                      gc::AllocKind allocKind, Label* fail) {
+  CompileZone* zone = realm()->zone();
+  int thingSize = int(gc::Arena::thingSize(allocKind));
+
+  Label fallback;
+  Label success;
+
+  // Load the first and last offsets of |zone|'s free list for |allocKind|.
+  // If there is no room remaining in the span, fall back to get the next one.
+  gc::FreeSpan** ptrFreeList = zone->addressOfFreeList(allocKind);
+  loadPtr(AbsoluteAddress(ptrFreeList), temp);
+  load16ZeroExtend(Address(temp, js::gc::FreeSpan::offsetOfFirst()), result);
+  load16ZeroExtend(Address(temp, js::gc::FreeSpan::offsetOfLast()), temp);
+  branch32(Assembler::AboveOrEqual, result, temp, &fallback);
+
+  // Bump the offset for the next allocation.
+  add32(Imm32(thingSize), result);
+  loadPtr(AbsoluteAddress(ptrFreeList), temp);
+  store16(result, Address(temp, js::gc::FreeSpan::offsetOfFirst()));
+  sub32(Imm32(thingSize), result);
+  addPtr(temp, result);  // Turn the offset into a pointer.
+  jump(&success);
+
+  bind(&fallback);
+  // If there are no free spans left, we bail to finish the allocation. The
+  // interpreter will call the GC allocator to set up a new arena to allocate
+  // from, after which we can resume allocating in the jit.
+  branchTest32(Assembler::Zero, result, result, fail);
+  loadPtr(AbsoluteAddress(ptrFreeList), temp);
+  addPtr(temp, result);  // Turn the offset into a pointer.
+  Push(result);
+  // Update the free list to point to the next span (which may be empty).
+  load32(Address(result, 0), result);
+  store32(result, Address(temp, js::gc::FreeSpan::offsetOfFirst()));
+  Pop(result);
+
+  bind(&success);
+
+  if (runtime()->geckoProfiler().enabled()) {
+    uint32_t* countAddress = zone->addressOfTenuredAllocCount();
+    movePtr(ImmPtr(countAddress), temp);
+    add32(Imm32(1), Address(temp, 0));
+  }
+}
+
+void MacroAssembler::callFreeStub(Register slots) {
+  // This register must match the one in JitRuntime::generateFreeStub.
+  const Register regSlots = CallTempReg0;
+
+  push(regSlots);
+  movePtr(slots, regSlots);
+  call(runtime()->jitRuntime()->freeStub());
+  pop(regSlots);
+}
+
+// Inlined equivalent of gc::AllocateObject, without failure case handling.
+void MacroAssembler::allocateObject(Register result, Register temp,
+                                    gc::AllocKind allocKind,
+                                    uint32_t nDynamicSlots,
+                                    gc::InitialHeap initialHeap, Label* fail,
+                                    const AllocSiteInput& allocSite) {
+  MOZ_ASSERT(gc::IsObjectAllocKind(allocKind));
+
+  checkAllocatorState(fail);
+
+  if (shouldNurseryAllocate(allocKind, initialHeap)) {
+    MOZ_ASSERT(initialHeap == gc::DefaultHeap);
+    return nurseryAllocateObject(result, temp, allocKind, nDynamicSlots, fail,
+                                 allocSite);
+  }
+
+  // Fall back to calling into the VM to allocate objects in the tenured heap
+  // that have dynamic slots.
+  if (nDynamicSlots) {
+    jump(fail);
+    return;
+  }
+
+  return freeListAllocate(result, temp, allocKind, fail);
+}
+
+void MacroAssembler::createGCObject(Register obj, Register temp,
+                                    const TemplateObject& templateObj,
+                                    gc::InitialHeap initialHeap, Label* fail,
+                                    bool initContents /* = true */) {
+  gc::AllocKind allocKind = templateObj.getAllocKind();
+  MOZ_ASSERT(gc::IsObjectAllocKind(allocKind));
+
+  uint32_t nDynamicSlots = 0;
+  if (templateObj.isNativeObject()) {
+    const TemplateNativeObject& ntemplate =
+        templateObj.asTemplateNativeObject();
+    nDynamicSlots = ntemplate.numDynamicSlots();
+  }
+
+  allocateObject(obj, temp, allocKind, nDynamicSlots, initialHeap, fail);
+  initGCThing(obj, temp, templateObj, initContents);
+}
+
+void MacroAssembler::createPlainGCObject(
+    Register result, Register shape, Register temp, Register temp2,
+    uint32_t numFixedSlots, uint32_t numDynamicSlots, gc::AllocKind allocKind,
+    gc::InitialHeap initialHeap, Label* fail, const AllocSiteInput& allocSite,
+    bool initContents /* = true */) {
+  MOZ_ASSERT(gc::IsObjectAllocKind(allocKind));
+  MOZ_ASSERT(shape != temp, "shape can overlap with temp2, but not temp");
+
+  // Allocate object.
+  allocateObject(result, temp, allocKind, numDynamicSlots, initialHeap, fail,
+                 allocSite);
+
+  // Initialize shape field.
+  storePtr(shape, Address(result, JSObject::offsetOfShape()));
+
+  // If the object has dynamic slots, allocateObject will initialize
+  // the slots field. If not, we must initialize it now.
+  if (numDynamicSlots == 0) {
+    storePtr(ImmPtr(emptyObjectSlots),
+             Address(result, NativeObject::offsetOfSlots()));
+  }
+
+  // Initialize elements field.
+  storePtr(ImmPtr(emptyObjectElements),
+           Address(result, NativeObject::offsetOfElements()));
+
+  // Initialize fixed slots.
+  if (initContents) {
+    fillSlotsWithUndefined(Address(result, NativeObject::getFixedSlotOffset(0)),
+                           temp, 0, numFixedSlots);
+  }
+
+  // Initialize dynamic slots.
+  if (numDynamicSlots > 0) {
+    loadPtr(Address(result, NativeObject::offsetOfSlots()), temp2);
+    fillSlotsWithUndefined(Address(temp2, 0), temp, 0, numDynamicSlots);
+  }
+}
+
+void MacroAssembler::createArrayWithFixedElements(
+    Register result, Register shape, Register temp, uint32_t arrayLength,
+    uint32_t arrayCapacity, gc::AllocKind allocKind,
+    gc::InitialHeap initialHeap, Label* fail, const AllocSiteInput& allocSite) {
+  MOZ_ASSERT(gc::IsObjectAllocKind(allocKind));
+  MOZ_ASSERT(shape != temp, "shape can overlap with temp2, but not temp");
+  MOZ_ASSERT(result != temp);
+
+  // This only supports allocating arrays with fixed elements and does not
+  // support any dynamic slots or elements.
+  MOZ_ASSERT(arrayCapacity >= arrayLength);
+  MOZ_ASSERT(gc::GetGCKindSlots(allocKind) >=
+             arrayCapacity + ObjectElements::VALUES_PER_HEADER);
+
+  // Allocate object.
+  allocateObject(result, temp, allocKind, 0, initialHeap, fail, allocSite);
+
+  // Initialize shape field.
+  storePtr(shape, Address(result, JSObject::offsetOfShape()));
+
+  // There are no dynamic slots.
+  storePtr(ImmPtr(emptyObjectSlots),
+           Address(result, NativeObject::offsetOfSlots()));
+
+  // Initialize elements pointer for fixed (inline) elements.
+  computeEffectiveAddress(
+      Address(result, NativeObject::offsetOfFixedElements()), temp);
+  storePtr(temp, Address(result, NativeObject::offsetOfElements()));
+
+  // Initialize elements header.
+  store32(Imm32(ObjectElements::FIXED),
+          Address(temp, ObjectElements::offsetOfFlags()));
+  store32(Imm32(0), Address(temp, ObjectElements::offsetOfInitializedLength()));
+  store32(Imm32(arrayCapacity),
+          Address(temp, ObjectElements::offsetOfCapacity()));
+  store32(Imm32(arrayLength), Address(temp, ObjectElements::offsetOfLength()));
+}
+
+// Inline version of Nursery::allocateString.
+void MacroAssembler::nurseryAllocateString(Register result, Register temp,
+                                           gc::AllocKind allocKind,
+                                           Label* fail) {
+  MOZ_ASSERT(IsNurseryAllocable(allocKind));
+
+  // No explicit check for nursery.isEnabled() is needed, as the comparison
+  // with the nursery's end will always fail in such cases.
+
+  CompileZone* zone = realm()->zone();
+  uint64_t* allocStrsPtr = &zone->zone()->nurseryAllocatedStrings.ref();
+  inc64(AbsoluteAddress(allocStrsPtr));
+  size_t thingSize = gc::Arena::thingSize(allocKind);
+
+  bumpPointerAllocate(result, temp, fail, zone,
+                      zone->addressOfStringNurseryPosition(),
+                      zone->addressOfStringNurseryCurrentEnd(),
+                      JS::TraceKind::String, thingSize);
+}
+
+// Inline version of Nursery::allocateBigInt.
+void MacroAssembler::nurseryAllocateBigInt(Register result, Register temp,
+                                           Label* fail) {
+  MOZ_ASSERT(IsNurseryAllocable(gc::AllocKind::BIGINT));
+
+  // No explicit check for nursery.isEnabled() is needed, as the comparison
+  // with the nursery's end will always fail in such cases.
+
+  CompileZone* zone = realm()->zone();
+  size_t thingSize = gc::Arena::thingSize(gc::AllocKind::BIGINT);
+
+  bumpPointerAllocate(result, temp, fail, zone,
+                      zone->addressOfBigIntNurseryPosition(),
+                      zone->addressOfBigIntNurseryCurrentEnd(),
+                      JS::TraceKind::BigInt, thingSize);
+}
+
+void MacroAssembler::bumpPointerAllocate(Register result, Register temp,
+                                         Label* fail, CompileZone* zone,
+                                         void* posAddr, const void* curEndAddr,
+                                         JS::TraceKind traceKind, uint32_t size,
+                                         const AllocSiteInput& allocSite) {
+  MOZ_ASSERT(size >= gc::MinCellSize);
+
+  uint32_t totalSize = size + Nursery::nurseryCellHeaderSize();
+  MOZ_ASSERT(totalSize < INT32_MAX, "Nursery allocation too large");
+  MOZ_ASSERT(totalSize % gc::CellAlignBytes == 0);
+
+  // The position (allocation pointer) and the end pointer are stored
+  // very close to each other -- specifically, easily within a 32 bit offset.
+  // Use relative offsets between them, to avoid 64-bit immediate loads.
+  //
+  // I tried to optimise this further by using an extra register to avoid
+  // the final subtraction and hopefully get some more instruction
+  // parallelism, but it made no difference.
+  movePtr(ImmPtr(posAddr), temp);
+  loadPtr(Address(temp, 0), result);
+  addPtr(Imm32(totalSize), result);
+  CheckedInt<int32_t> endOffset =
+      (CheckedInt<uintptr_t>(uintptr_t(curEndAddr)) -
+       CheckedInt<uintptr_t>(uintptr_t(posAddr)))
+          .toChecked<int32_t>();
+  MOZ_ASSERT(endOffset.isValid(), "Position and end pointers must be nearby");
+  branchPtr(Assembler::Below, Address(temp, endOffset.value()), result, fail);
+  storePtr(result, Address(temp, 0));
+  subPtr(Imm32(size), result);
+
+  if (runtime()->geckoProfiler().enabled()) {
+    uint32_t* countAddress = zone->addressOfNurseryAllocCount();
+    CheckedInt<int32_t> counterOffset =
+        (CheckedInt<uintptr_t>(uintptr_t(countAddress)) -
+         CheckedInt<uintptr_t>(uintptr_t(posAddr)))
+            .toChecked<int32_t>();
+    if (counterOffset.isValid()) {
+      add32(Imm32(1), Address(temp, counterOffset.value()));
+    } else {
+      movePtr(ImmPtr(countAddress), temp);
+      add32(Imm32(1), Address(temp, 0));
+    }
+  }
+
+  if (allocSite.is<gc::CatchAllAllocSite>()) {
+    // No allocation site supplied. This is the case when called from Warp, or
+    // from places that don't support pretenuring.
+    gc::CatchAllAllocSite siteKind = allocSite.as<gc::CatchAllAllocSite>();
+    storePtr(ImmWord(zone->nurseryCellHeader(traceKind, siteKind)),
+             Address(result, -js::Nursery::nurseryCellHeaderSize()));
+  } else {
+    // Update allocation site and store pointer in the nursery cell header. This
+    // is only used from baseline.
+    Register site = allocSite.as<Register>();
+    updateAllocSite(temp, result, zone, site);
+    // See NurseryCellHeader::MakeValue.
+    orPtr(Imm32(int32_t(traceKind)), site);
+    storePtr(site, Address(result, -js::Nursery::nurseryCellHeaderSize()));
+  }
+}
+
+// Update the allocation site in the same way as Nursery::allocateCell.
+void MacroAssembler::updateAllocSite(Register temp, Register result,
+                                     CompileZone* zone, Register site) {
+  Label done;
+
+  add32(Imm32(1), Address(site, gc::AllocSite::offsetOfNurseryAllocCount()));
+
+  branchPtr(Assembler::NotEqual,
+            Address(site, gc::AllocSite::offsetOfNextNurseryAllocated()),
+            ImmPtr(nullptr), &done);
+
+  loadPtr(AbsoluteAddress(zone->addressOfNurseryAllocatedSites()), temp);
+  storePtr(temp, Address(site, gc::AllocSite::offsetOfNextNurseryAllocated()));
+  storePtr(site, AbsoluteAddress(zone->addressOfNurseryAllocatedSites()));
+
+  bind(&done);
+}
+
+// Inlined equivalent of gc::AllocateString, jumping to fail if nursery
+// allocation requested but unsuccessful.
+void MacroAssembler::allocateString(Register result, Register temp,
+                                    gc::AllocKind allocKind,
+                                    gc::InitialHeap initialHeap, Label* fail) {
+  MOZ_ASSERT(allocKind == gc::AllocKind::STRING ||
+             allocKind == gc::AllocKind::FAT_INLINE_STRING);
+
+  checkAllocatorState(fail);
+
+  if (shouldNurseryAllocate(allocKind, initialHeap)) {
+    MOZ_ASSERT(initialHeap == gc::DefaultHeap);
+    return nurseryAllocateString(result, temp, allocKind, fail);
+  }
+
+  freeListAllocate(result, temp, allocKind, fail);
+}
+
+void MacroAssembler::newGCString(Register result, Register temp,
+                                 gc::InitialHeap initialHeap, Label* fail) {
+  allocateString(result, temp, js::gc::AllocKind::STRING, initialHeap, fail);
+}
+
+void MacroAssembler::newGCFatInlineString(Register result, Register temp,
+                                          gc::InitialHeap initialHeap,
+                                          Label* fail) {
+  allocateString(result, temp, js::gc::AllocKind::FAT_INLINE_STRING,
+                 initialHeap, fail);
+}
+
+void MacroAssembler::newGCBigInt(Register result, Register temp,
+                                 gc::InitialHeap initialHeap, Label* fail) {
+  checkAllocatorState(fail);
+
+  if (shouldNurseryAllocate(gc::AllocKind::BIGINT, initialHeap)) {
+    MOZ_ASSERT(initialHeap == gc::DefaultHeap);
+    return nurseryAllocateBigInt(result, temp, fail);
+  }
+
+  freeListAllocate(result, temp, gc::AllocKind::BIGINT, fail);
+}
+
+void MacroAssembler::copySlotsFromTemplate(
+    Register obj, const TemplateNativeObject& templateObj, uint32_t start,
+    uint32_t end) {
+  uint32_t nfixed = std::min(templateObj.numFixedSlots(), end);
+  for (unsigned i = start; i < nfixed; i++) {
+    // Template objects are not exposed to script and therefore immutable.
+    // However, regexp template objects are sometimes used directly (when
+    // the cloning is not observable), and therefore we can end up with a
+    // non-zero lastIndex. Detect this case here and just substitute 0, to
+    // avoid racing with the main thread updating this slot.
+    Value v;
+    if (templateObj.isRegExpObject() && i == RegExpObject::lastIndexSlot()) {
+      v = Int32Value(0);
+    } else {
+      v = templateObj.getSlot(i);
+    }
+    storeValue(v, Address(obj, NativeObject::getFixedSlotOffset(i)));
+  }
+}
+
+void MacroAssembler::fillSlotsWithConstantValue(Address base, Register temp,
+                                                uint32_t start, uint32_t end,
+                                                const Value& v) {
+  MOZ_ASSERT(v.isUndefined() || IsUninitializedLexical(v));
+
+  if (start >= end) {
+    return;
+  }
+
+#ifdef JS_NUNBOX32
+  // We only have a single spare register, so do the initialization as two
+  // strided writes of the tag and body.
+  Address addr = base;
+  move32(Imm32(v.toNunboxPayload()), temp);
+  for (unsigned i = start; i < end; ++i, addr.offset += sizeof(GCPtr<Value>)) {
+    store32(temp, ToPayload(addr));
+  }
+
+  addr = base;
+  move32(Imm32(v.toNunboxTag()), temp);
+  for (unsigned i = start; i < end; ++i, addr.offset += sizeof(GCPtr<Value>)) {
+    store32(temp, ToType(addr));
+  }
+#else
+  moveValue(v, ValueOperand(temp));
+  for (uint32_t i = start; i < end; ++i, base.offset += sizeof(GCPtr<Value>)) {
+    storePtr(temp, base);
+  }
+#endif
+}
+
+void MacroAssembler::fillSlotsWithUndefined(Address base, Register temp,
+                                            uint32_t start, uint32_t end) {
+  fillSlotsWithConstantValue(base, temp, start, end, UndefinedValue());
+}
+
+void MacroAssembler::fillSlotsWithUninitialized(Address base, Register temp,
+                                                uint32_t start, uint32_t end) {
+  fillSlotsWithConstantValue(base, temp, start, end,
+                             MagicValue(JS_UNINITIALIZED_LEXICAL));
+}
+
+static std::pair<uint32_t, uint32_t> FindStartOfUninitializedAndUndefinedSlots(
+    const TemplateNativeObject& templateObj, uint32_t nslots) {
+  MOZ_ASSERT(nslots == templateObj.slotSpan());
+  MOZ_ASSERT(nslots > 0);
+
+  uint32_t first = nslots;
+  for (; first != 0; --first) {
+    if (templateObj.getSlot(first - 1) != UndefinedValue()) {
+      break;
+    }
+  }
+  uint32_t startOfUndefined = first;
+
+  if (first != 0 && IsUninitializedLexical(templateObj.getSlot(first - 1))) {
+    for (; first != 0; --first) {
+      if (!IsUninitializedLexical(templateObj.getSlot(first - 1))) {
+        break;
+      }
+    }
+  }
+  uint32_t startOfUninitialized = first;
+
+  return {startOfUninitialized, startOfUndefined};
+}
+
+void MacroAssembler::initTypedArraySlots(Register obj, Register temp,
+                                         Register lengthReg,
+                                         LiveRegisterSet liveRegs, Label* fail,
+                                         TypedArrayObject* templateObj,
+                                         TypedArrayLength lengthKind) {
+  MOZ_ASSERT(!templateObj->hasBuffer());
+
+  constexpr size_t dataSlotOffset = ArrayBufferViewObject::dataOffset();
+  constexpr size_t dataOffset = dataSlotOffset + sizeof(HeapSlot);
+
+  static_assert(
+      TypedArrayObject::FIXED_DATA_START == TypedArrayObject::DATA_SLOT + 1,
+      "fixed inline element data assumed to begin after the data slot");
+
+  static_assert(
+      TypedArrayObject::INLINE_BUFFER_LIMIT ==
+          JSObject::MAX_BYTE_SIZE - dataOffset,
+      "typed array inline buffer is limited by the maximum object byte size");
+
+  // Initialise data elements to zero.
+  size_t length = templateObj->length();
+  MOZ_ASSERT(length <= INT32_MAX,
+             "Template objects are only created for int32 lengths");
+  size_t nbytes = length * templateObj->bytesPerElement();
+
+  if (lengthKind == TypedArrayLength::Fixed &&
+      nbytes <= TypedArrayObject::INLINE_BUFFER_LIMIT) {
+    MOZ_ASSERT(dataOffset + nbytes <= templateObj->tenuredSizeOfThis());
+
+    // Store data elements inside the remaining JSObject slots.
+    computeEffectiveAddress(Address(obj, dataOffset), temp);
+    storePrivateValue(temp, Address(obj, dataSlotOffset));
+
+    // Write enough zero pointers into fixed data to zero every
+    // element.  (This zeroes past the end of a byte count that's
+    // not a multiple of pointer size.  That's okay, because fixed
+    // data is a count of 8-byte HeapSlots (i.e. <= pointer size),
+    // and we won't inline unless the desired memory fits in that
+    // space.)
+    static_assert(sizeof(HeapSlot) == 8, "Assumed 8 bytes alignment");
+
+    size_t numZeroPointers = ((nbytes + 7) & ~0x7) / sizeof(char*);
+    for (size_t i = 0; i < numZeroPointers; i++) {
+      storePtr(ImmWord(0), Address(obj, dataOffset + i * sizeof(char*)));
+    }
+    MOZ_ASSERT(nbytes > 0, "Zero-length TypedArrays need ZeroLengthArrayData");
+  } else {
+    if (lengthKind == TypedArrayLength::Fixed) {
+      move32(Imm32(length), lengthReg);
+    }
+
+    // Ensure volatile |obj| is saved across the call.
+    if (obj.volatile_()) {
+      liveRegs.addUnchecked(obj);
+    }
+
+    // Allocate a buffer on the heap to store the data elements.
+    PushRegsInMask(liveRegs);
+    using Fn = void (*)(JSContext * cx, TypedArrayObject * obj, int32_t count);
+    setupUnalignedABICall(temp);
+    loadJSContext(temp);
+    passABIArg(temp);
+    passABIArg(obj);
+    passABIArg(lengthReg);
+    callWithABI<Fn, AllocateAndInitTypedArrayBuffer>();
+    PopRegsInMask(liveRegs);
+
+    // Fail when data slot is UndefinedValue.
+    branchTestUndefined(Assembler::Equal, Address(obj, dataSlotOffset), fail);
+  }
+}
+
+void MacroAssembler::initGCSlots(Register obj, Register temp,
+                                 const TemplateNativeObject& templateObj) {
+  MOZ_ASSERT(!templateObj.isArrayObject());
+
+  // Slots of non-array objects are required to be initialized.
+  // Use the values currently in the template object.
+  uint32_t nslots = templateObj.slotSpan();
+  if (nslots == 0) {
+    return;
+  }
+
+  uint32_t nfixed = templateObj.numUsedFixedSlots();
+  uint32_t ndynamic = templateObj.numDynamicSlots();
+
+  // Attempt to group slot writes such that we minimize the amount of
+  // duplicated data we need to embed in code and load into registers. In
+  // general, most template object slots will be undefined except for any
+  // reserved slots. Since reserved slots come first, we split the object
+  // logically into independent non-UndefinedValue writes to the head and
+  // duplicated writes of UndefinedValue to the tail. For the majority of
+  // objects, the "tail" will be the entire slot range.
+  //
+  // The template object may be a CallObject, in which case we need to
+  // account for uninitialized lexical slots as well as undefined
+  // slots. Uninitialized lexical slots appears in CallObjects if the function
+  // has parameter expressions, in which case closed over parameters have
+  // TDZ. Uninitialized slots come before undefined slots in CallObjects.
+  auto [startOfUninitialized, startOfUndefined] =
+      FindStartOfUninitializedAndUndefinedSlots(templateObj, nslots);
+  MOZ_ASSERT(startOfUninitialized <= nfixed);  // Reserved slots must be fixed.
+  MOZ_ASSERT(startOfUndefined >= startOfUninitialized);
+  MOZ_ASSERT_IF(!templateObj.isCallObject() &&
+                    !templateObj.isBlockLexicalEnvironmentObject(),
+                startOfUninitialized == startOfUndefined);
+
+  // Copy over any preserved reserved slots.
+  copySlotsFromTemplate(obj, templateObj, 0, startOfUninitialized);
+
+  // Fill the rest of the fixed slots with undefined and uninitialized.
+  size_t offset = NativeObject::getFixedSlotOffset(startOfUninitialized);
+  fillSlotsWithUninitialized(Address(obj, offset), temp, startOfUninitialized,
+                             std::min(startOfUndefined, nfixed));
+
+  if (startOfUndefined < nfixed) {
+    offset = NativeObject::getFixedSlotOffset(startOfUndefined);
+    fillSlotsWithUndefined(Address(obj, offset), temp, startOfUndefined,
+                           nfixed);
+  }
+
+  if (ndynamic) {
+    // We are short one register to do this elegantly. Borrow the obj
+    // register briefly for our slots base address.
+    push(obj);
+    loadPtr(Address(obj, NativeObject::offsetOfSlots()), obj);
+
+    // Fill uninitialized slots if necessary. Otherwise initialize all
+    // slots to undefined.
+    if (startOfUndefined > nfixed) {
+      MOZ_ASSERT(startOfUninitialized != startOfUndefined);
+      fillSlotsWithUninitialized(Address(obj, 0), temp, 0,
+                                 startOfUndefined - nfixed);
+      size_t offset = (startOfUndefined - nfixed) * sizeof(Value);
+      fillSlotsWithUndefined(Address(obj, offset), temp,
+                             startOfUndefined - nfixed, ndynamic);
+    } else {
+      fillSlotsWithUndefined(Address(obj, 0), temp, 0, ndynamic);
+    }
+
+    pop(obj);
+  }
+}
+
+void MacroAssembler::initGCThing(Register obj, Register temp,
+                                 const TemplateObject& templateObj,
+                                 bool initContents) {
+  // Fast initialization of an empty object returned by allocateObject().
+
+  storePtr(ImmGCPtr(templateObj.shape()),
+           Address(obj, JSObject::offsetOfShape()));
+
+  if (templateObj.isNativeObject()) {
+    const TemplateNativeObject& ntemplate =
+        templateObj.asTemplateNativeObject();
+    MOZ_ASSERT(!ntemplate.hasDynamicElements());
+
+    // If the object has dynamic slots, the slots member has already been
+    // filled in.
+    if (!ntemplate.hasDynamicSlots()) {
+      storePtr(ImmPtr(emptyObjectSlots),
+               Address(obj, NativeObject::offsetOfSlots()));
+    }
+
+    if (ntemplate.isArrayObject()) {
+      // Can't skip initializing reserved slots.
+      MOZ_ASSERT(initContents);
+
+      int elementsOffset = NativeObject::offsetOfFixedElements();
+
+      computeEffectiveAddress(Address(obj, elementsOffset), temp);
+      storePtr(temp, Address(obj, NativeObject::offsetOfElements()));
+
+      // Fill in the elements header.
+      store32(
+          Imm32(ntemplate.getDenseCapacity()),
+          Address(obj, elementsOffset + ObjectElements::offsetOfCapacity()));
+      store32(Imm32(ntemplate.getDenseInitializedLength()),
+              Address(obj, elementsOffset +
+                               ObjectElements::offsetOfInitializedLength()));
+      store32(Imm32(ntemplate.getArrayLength()),
+              Address(obj, elementsOffset + ObjectElements::offsetOfLength()));
+      store32(Imm32(ObjectElements::FIXED),
+              Address(obj, elementsOffset + ObjectElements::offsetOfFlags()));
+    } else if (ntemplate.isArgumentsObject()) {
+      // The caller will initialize the reserved slots.
+      MOZ_ASSERT(!initContents);
+      storePtr(ImmPtr(emptyObjectElements),
+               Address(obj, NativeObject::offsetOfElements()));
+    } else {
+      // If the target type could be a TypedArray that maps shared memory
+      // then this would need to store emptyObjectElementsShared in that case.
+      MOZ_ASSERT(!ntemplate.isSharedMemory());
+
+      // Can't skip initializing reserved slots.
+      MOZ_ASSERT(initContents);
+
+      storePtr(ImmPtr(emptyObjectElements),
+               Address(obj, NativeObject::offsetOfElements()));
+
+      initGCSlots(obj, temp, ntemplate);
+    }
+  } else {
+    MOZ_CRASH("Unknown object");
+  }
+
+#ifdef JS_GC_PROBES
+  AllocatableRegisterSet regs(RegisterSet::Volatile());
+  LiveRegisterSet save(regs.asLiveSet());
+  PushRegsInMask(save);
+
+  regs.takeUnchecked(obj);
+  Register temp2 = regs.takeAnyGeneral();
+
+  using Fn = void (*)(JSObject * obj);
+  setupUnalignedABICall(temp2);
+  passABIArg(obj);
+  callWithABI<Fn, TraceCreateObject>();
+
+  PopRegsInMask(save);
+#endif
+}
+
+void MacroAssembler::compareStrings(JSOp op, Register left, Register right,
+                                    Register result, Label* fail) {
+  MOZ_ASSERT(left != result);
+  MOZ_ASSERT(right != result);
+  MOZ_ASSERT(IsEqualityOp(op) || IsRelationalOp(op));
+
+  Label notPointerEqual;
+  // If operands point to the same instance, the strings are trivially equal.
+  branchPtr(Assembler::NotEqual, left, right,
+            IsEqualityOp(op) ? &notPointerEqual : fail);
+  move32(Imm32(op == JSOp::Eq || op == JSOp::StrictEq || op == JSOp::Le ||
+               op == JSOp::Ge),
+         result);
+
+  if (IsEqualityOp(op)) {
+    Label done;
+    jump(&done);
+
+    bind(&notPointerEqual);
+
+    Label leftIsNotAtom;
+    Label setNotEqualResult;
+    // Atoms cannot be equal to each other if they point to different strings.
+    Imm32 atomBit(JSString::ATOM_BIT);
+    branchTest32(Assembler::Zero, Address(left, JSString::offsetOfFlags()),
+                 atomBit, &leftIsNotAtom);
+    branchTest32(Assembler::NonZero, Address(right, JSString::offsetOfFlags()),
+                 atomBit, &setNotEqualResult);
+
+    bind(&leftIsNotAtom);
+    // Strings of different length can never be equal.
+    loadStringLength(left, result);
+    branch32(Assembler::Equal, Address(right, JSString::offsetOfLength()),
+             result, fail);
+
+    bind(&setNotEqualResult);
+    move32(Imm32(op == JSOp::Ne || op == JSOp::StrictNe), result);
+
+    bind(&done);
+  }
+}
+
+void MacroAssembler::loadStringChars(Register str, Register dest,
+                                     CharEncoding encoding) {
+  MOZ_ASSERT(str != dest);
+
+  if (JitOptions.spectreStringMitigations) {
+    if (encoding == CharEncoding::Latin1) {
+      // If the string is a rope, zero the |str| register. The code below
+      // depends on str->flags so this should block speculative execution.
+      movePtr(ImmWord(0), dest);
+      test32MovePtr(Assembler::Zero, Address(str, JSString::offsetOfFlags()),
+                    Imm32(JSString::LINEAR_BIT), dest, str);
+    } else {
+      // If we're loading TwoByte chars, there's an additional risk:
+      // if the string has Latin1 chars, we could read out-of-bounds. To
+      // prevent this, we check both the Linear and Latin1 bits. We don't
+      // have a scratch register, so we use these flags also to block
+      // speculative execution, similar to the use of 0 above.
+      MOZ_ASSERT(encoding == CharEncoding::TwoByte);
+      static constexpr uint32_t Mask =
+          JSString::LINEAR_BIT | JSString::LATIN1_CHARS_BIT;
+      static_assert(Mask < 1024,
+                    "Mask should be a small, near-null value to ensure we "
+                    "block speculative execution when it's used as string "
+                    "pointer");
+      move32(Imm32(Mask), dest);
+      and32(Address(str, JSString::offsetOfFlags()), dest);
+      cmp32MovePtr(Assembler::NotEqual, dest, Imm32(JSString::LINEAR_BIT), dest,
+                   str);
+    }
+  }
+
+  // Load the inline chars.
+  computeEffectiveAddress(Address(str, JSInlineString::offsetOfInlineStorage()),
+                          dest);
+
+  // If it's not an inline string, load the non-inline chars. Use a
+  // conditional move to prevent speculative execution.
+  test32LoadPtr(Assembler::Zero, Address(str, JSString::offsetOfFlags()),
+                Imm32(JSString::INLINE_CHARS_BIT),
+                Address(str, JSString::offsetOfNonInlineChars()), dest);
+}
+
+void MacroAssembler::loadNonInlineStringChars(Register str, Register dest,
+                                              CharEncoding encoding) {
+  MOZ_ASSERT(str != dest);
+
+  if (JitOptions.spectreStringMitigations) {
+    // If the string is a rope, has inline chars, or has a different
+    // character encoding, set str to a near-null value to prevent
+    // speculative execution below (when reading str->nonInlineChars).
+
+    static constexpr uint32_t Mask = JSString::LINEAR_BIT |
+                                     JSString::INLINE_CHARS_BIT |
+                                     JSString::LATIN1_CHARS_BIT;
+    static_assert(Mask < 1024,
+                  "Mask should be a small, near-null value to ensure we "
+                  "block speculative execution when it's used as string "
+                  "pointer");
+
+    uint32_t expectedBits = JSString::LINEAR_BIT;
+    if (encoding == CharEncoding::Latin1) {
+      expectedBits |= JSString::LATIN1_CHARS_BIT;
+    }
+
+    move32(Imm32(Mask), dest);
+    and32(Address(str, JSString::offsetOfFlags()), dest);
+
+    cmp32MovePtr(Assembler::NotEqual, dest, Imm32(expectedBits), dest, str);
+  }
+
+  loadPtr(Address(str, JSString::offsetOfNonInlineChars()), dest);
+}
+
+void MacroAssembler::storeNonInlineStringChars(Register chars, Register str) {
+  MOZ_ASSERT(chars != str);
+  storePtr(chars, Address(str, JSString::offsetOfNonInlineChars()));
+}
+
+void MacroAssembler::loadInlineStringCharsForStore(Register str,
+                                                   Register dest) {
+  computeEffectiveAddress(Address(str, JSInlineString::offsetOfInlineStorage()),
+                          dest);
+}
+
+void MacroAssembler::loadInlineStringChars(Register str, Register dest,
+                                           CharEncoding encoding) {
+  MOZ_ASSERT(str != dest);
+
+  if (JitOptions.spectreStringMitigations) {
+    // Making this Spectre-safe is a bit complicated: using
+    // computeEffectiveAddress and then zeroing the output register if
+    // non-inline is not sufficient: when the index is very large, it would
+    // allow reading |nullptr + index|. Just fall back to loadStringChars
+    // for now.
+    loadStringChars(str, dest, encoding);
+  } else {
+    computeEffectiveAddress(
+        Address(str, JSInlineString::offsetOfInlineStorage()), dest);
+  }
+}
+
+void MacroAssembler::loadRopeLeftChild(Register str, Register dest) {
+  MOZ_ASSERT(str != dest);
+
+  if (JitOptions.spectreStringMitigations) {
+    // Zero the output register if the input was not a rope.
+    movePtr(ImmWord(0), dest);
+    test32LoadPtr(Assembler::Zero, Address(str, JSString::offsetOfFlags()),
+                  Imm32(JSString::LINEAR_BIT),
+                  Address(str, JSRope::offsetOfLeft()), dest);
+  } else {
+    loadPtr(Address(str, JSRope::offsetOfLeft()), dest);
+  }
+}
+
+void MacroAssembler::loadRopeRightChild(Register str, Register dest) {
+  MOZ_ASSERT(str != dest);
+
+  if (JitOptions.spectreStringMitigations) {
+    // Zero the output register if the input was not a rope.
+    movePtr(ImmWord(0), dest);
+    test32LoadPtr(Assembler::Zero, Address(str, JSString::offsetOfFlags()),
+                  Imm32(JSString::LINEAR_BIT),
+                  Address(str, JSRope::offsetOfRight()), dest);
+  } else {
+    loadPtr(Address(str, JSRope::offsetOfRight()), dest);
+  }
+}
+
+void MacroAssembler::storeRopeChildren(Register left, Register right,
+                                       Register str) {
+  storePtr(left, Address(str, JSRope::offsetOfLeft()));
+  storePtr(right, Address(str, JSRope::offsetOfRight()));
+}
+
+void MacroAssembler::loadDependentStringBase(Register str, Register dest) {
+  MOZ_ASSERT(str != dest);
+
+  if (JitOptions.spectreStringMitigations) {
+    // If the string is not a dependent string, zero the |str| register.
+    // The code below loads str->base so this should block speculative
+    // execution.
+    movePtr(ImmWord(0), dest);
+    test32MovePtr(Assembler::Zero, Address(str, JSString::offsetOfFlags()),
+                  Imm32(JSString::DEPENDENT_BIT), dest, str);
+  }
+
+  loadPtr(Address(str, JSDependentString::offsetOfBase()), dest);
+}
+
+void MacroAssembler::storeDependentStringBase(Register base, Register str) {
+  storePtr(base, Address(str, JSDependentString::offsetOfBase()));
+}
+
+void MacroAssembler::loadRopeChild(Register str, Register index,
+                                   Register output, Label* isLinear) {
+  // This follows JSString::getChar.
+  branchIfNotRope(str, isLinear);
+
+  loadRopeLeftChild(str, output);
+
+  // Check if the index is contained in the leftChild.
+  Label loadedChild;
+  branch32(Assembler::Above, Address(output, JSString::offsetOfLength()), index,
+           &loadedChild);
+
+  // The index must be in the rightChild.
+  loadRopeRightChild(str, output);
+
+  bind(&loadedChild);
+}
+
+void MacroAssembler::branchIfCanLoadStringChar(Register str, Register index,
+                                               Register scratch, Label* label) {
+  loadRopeChild(str, index, scratch, label);
+
+  // Branch if the left resp. right side is linear.
+  branchIfNotRope(scratch, label);
+}
+
+void MacroAssembler::branchIfNotCanLoadStringChar(Register str, Register index,
+                                                  Register scratch,
+                                                  Label* label) {
+  Label done;
+  loadRopeChild(str, index, scratch, &done);
+
+  // Branch if the left or right side is another rope.
+  branchIfRope(scratch, label);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadStringChar(Register str, Register index,
+                                    Register output, Register scratch1,
+                                    Register scratch2, Label* fail) {
+  MOZ_ASSERT(str != output);
+  MOZ_ASSERT(str != index);
+  MOZ_ASSERT(index != output);
+  MOZ_ASSERT(output != scratch1);
+  MOZ_ASSERT(output != scratch2);
+
+  // Use scratch1 for the index (adjusted below).
+  move32(index, scratch1);
+  movePtr(str, output);
+
+  // This follows JSString::getChar.
+  Label notRope;
+  branchIfNotRope(str, &notRope);
+
+  loadRopeLeftChild(str, output);
+
+  // Check if the index is contained in the leftChild.
+  Label loadedChild, notInLeft;
+  spectreBoundsCheck32(scratch1, Address(output, JSString::offsetOfLength()),
+                       scratch2, &notInLeft);
+  jump(&loadedChild);
+
+  // The index must be in the rightChild.
+  // index -= rope->leftChild()->length()
+  bind(&notInLeft);
+  sub32(Address(output, JSString::offsetOfLength()), scratch1);
+  loadRopeRightChild(str, output);
+
+  // If the left or right side is another rope, give up.
+  bind(&loadedChild);
+  branchIfRope(output, fail);
+
+  bind(&notRope);
+
+  Label isLatin1, done;
+  // We have to check the left/right side for ropes,
+  // because a TwoByte rope might have a Latin1 child.
+  branchLatin1String(output, &isLatin1);
+  loadStringChars(output, scratch2, CharEncoding::TwoByte);
+  loadChar(scratch2, scratch1, output, CharEncoding::TwoByte);
+  jump(&done);
+
+  bind(&isLatin1);
+  loadStringChars(output, scratch2, CharEncoding::Latin1);
+  loadChar(scratch2, scratch1, output, CharEncoding::Latin1);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadStringIndexValue(Register str, Register dest,
+                                          Label* fail) {
+  MOZ_ASSERT(str != dest);
+
+  load32(Address(str, JSString::offsetOfFlags()), dest);
+
+  // Does not have a cached index value.
+  branchTest32(Assembler::Zero, dest, Imm32(JSString::INDEX_VALUE_BIT), fail);
+
+  // Extract the index.
+  rshift32(Imm32(JSString::INDEX_VALUE_SHIFT), dest);
+}
+
+void MacroAssembler::loadChar(Register chars, Register index, Register dest,
+                              CharEncoding encoding, int32_t offset /* = 0 */) {
+  if (encoding == CharEncoding::Latin1) {
+    loadChar(BaseIndex(chars, index, TimesOne, offset), dest, encoding);
+  } else {
+    loadChar(BaseIndex(chars, index, TimesTwo, offset), dest, encoding);
+  }
+}
+
+void MacroAssembler::addToCharPtr(Register chars, Register index,
+                                  CharEncoding encoding) {
+  if (encoding == CharEncoding::Latin1) {
+    static_assert(sizeof(char) == 1,
+                  "Latin-1 string index shouldn't need scaling");
+    addPtr(index, chars);
+  } else {
+    computeEffectiveAddress(BaseIndex(chars, index, TimesTwo), chars);
+  }
+}
+
+void MacroAssembler::loadStringFromUnit(Register unit, Register dest,
+                                        const StaticStrings& staticStrings) {
+  movePtr(ImmPtr(&staticStrings.unitStaticTable), dest);
+  loadPtr(BaseIndex(dest, unit, ScalePointer), dest);
+}
+
+void MacroAssembler::loadLengthTwoString(Register c1, Register c2,
+                                         Register dest,
+                                         const StaticStrings& staticStrings) {
+  // Compute (toSmallCharTable[c1] << SMALL_CHAR_BITS) + toSmallCharTable[c2]
+  // to obtain the index into `StaticStrings::length2StaticTable`.
+  static_assert(sizeof(StaticStrings::SmallChar) == 1);
+
+  movePtr(ImmPtr(&StaticStrings::toSmallCharTable.storage), dest);
+  load8ZeroExtend(BaseIndex(dest, c1, Scale::TimesOne), c1);
+  load8ZeroExtend(BaseIndex(dest, c2, Scale::TimesOne), c2);
+
+  lshift32(Imm32(StaticStrings::SMALL_CHAR_BITS), c1);
+  add32(c2, c1);
+
+  // Look up the string from the computed index.
+  movePtr(ImmPtr(&staticStrings.length2StaticTable), dest);
+  loadPtr(BaseIndex(dest, c1, ScalePointer), dest);
+}
+
+void MacroAssembler::loadInt32ToStringWithBase(
+    Register input, Register base, Register dest, Register scratch1,
+    Register scratch2, const StaticStrings& staticStrings,
+    const LiveRegisterSet& volatileRegs, Label* fail) {
+#ifdef DEBUG
+  Label baseBad, baseOk;
+  branch32(Assembler::LessThan, base, Imm32(2), &baseBad);
+  branch32(Assembler::LessThanOrEqual, base, Imm32(36), &baseOk);
+  bind(&baseBad);
+  assumeUnreachable("base must be in range [2, 36]");
+  bind(&baseOk);
+#endif
+
+  // Compute |"0123456789abcdefghijklmnopqrstuvwxyz"[r]|.
+  auto toChar = [this, base](Register r) {
+#ifdef DEBUG
+    Label ok;
+    branch32(Assembler::Below, r, base, &ok);
+    assumeUnreachable("bad digit");
+    bind(&ok);
+#else
+    // Silence unused lambda capture warning.
+    (void)base;
+#endif
+
+    Label done;
+    add32(Imm32('0'), r);
+    branch32(Assembler::BelowOrEqual, r, Imm32('9'), &done);
+    add32(Imm32('a' - '0' - 10), r);
+    bind(&done);
+  };
+
+  // Perform a "unit" lookup when |unsigned(input) < unsigned(base)|.
+  Label lengthTwo, done;
+  branch32(Assembler::AboveOrEqual, input, base, &lengthTwo);
+  {
+    move32(input, scratch1);
+    toChar(scratch1);
+
+    loadStringFromUnit(scratch1, dest, staticStrings);
+
+    jump(&done);
+  }
+  bind(&lengthTwo);
+
+  // Compute |base * base|.
+  move32(base, scratch1);
+  mul32(scratch1, scratch1);
+
+  // Perform a "length2" lookup when |unsigned(input) < unsigned(base * base)|.
+  branch32(Assembler::AboveOrEqual, input, scratch1, fail);
+  {
+    // Compute |scratch1 = input / base| and |scratch2 = input % base|.
+    move32(input, scratch1);
+    flexibleDivMod32(base, scratch1, scratch2, true, volatileRegs);
+
+    // Compute the digits of the divisor and remainder.
+    toChar(scratch1);
+    toChar(scratch2);
+
+    // Look up the 2-character digit string in the small-char table.
+    loadLengthTwoString(scratch1, scratch2, dest, staticStrings);
+  }
+  bind(&done);
+}
+
+void MacroAssembler::loadInt32ToStringWithBase(
+    Register input, int32_t base, Register dest, Register scratch1,
+    Register scratch2, const StaticStrings& staticStrings, Label* fail) {
+  MOZ_ASSERT(2 <= base && base <= 36, "base must be in range [2, 36]");
+
+  // Compute |"0123456789abcdefghijklmnopqrstuvwxyz"[r]|.
+  auto toChar = [this, base](Register r) {
+#ifdef DEBUG
+    Label ok;
+    branch32(Assembler::Below, r, Imm32(base), &ok);
+    assumeUnreachable("bad digit");
+    bind(&ok);
+#endif
+
+    if (base <= 10) {
+      add32(Imm32('0'), r);
+    } else {
+      Label done;
+      add32(Imm32('0'), r);
+      branch32(Assembler::BelowOrEqual, r, Imm32('9'), &done);
+      add32(Imm32('a' - '0' - 10), r);
+      bind(&done);
+    }
+  };
+
+  // Perform a "unit" lookup when |unsigned(input) < unsigned(base)|.
+  Label lengthTwo, done;
+  branch32(Assembler::AboveOrEqual, input, Imm32(base), &lengthTwo);
+  {
+    move32(input, scratch1);
+    toChar(scratch1);
+
+    loadStringFromUnit(scratch1, dest, staticStrings);
+
+    jump(&done);
+  }
+  bind(&lengthTwo);
+
+  // Perform a "length2" lookup when |unsigned(input) < unsigned(base * base)|.
+  branch32(Assembler::AboveOrEqual, input, Imm32(base * base), fail);
+  {
+    // Compute |scratch1 = input / base| and |scratch2 = input % base|.
+    if (mozilla::IsPowerOfTwo(uint32_t(base))) {
+      uint32_t shift = mozilla::FloorLog2(base);
+
+      move32(input, scratch1);
+      rshift32(Imm32(shift), scratch1);
+
+      move32(input, scratch2);
+      and32(Imm32((uint32_t(1) << shift) - 1), scratch2);
+    } else {
+      // The following code matches CodeGenerator::visitUDivOrModConstant()
+      // for x86-shared. Also see Hacker's Delight 2nd edition, chapter 10-8
+      // "Unsigned Division by 7" for the case when |rmc.multiplier| exceeds
+      // UINT32_MAX and we need to adjust the shift amount.
+
+      auto rmc = ReciprocalMulConstants::computeUnsignedDivisionConstants(base);
+
+      // We first compute |q = (M * n) >> 32), where M = rmc.multiplier.
+      mulHighUnsigned32(Imm32(rmc.multiplier), input, scratch1);
+
+      if (rmc.multiplier > UINT32_MAX) {
+        // M >= 2^32 and shift == 0 is impossible, as d >= 2 implies that
+        // ((M * n) >> (32 + shift)) >= n > floor(n/d) whenever n >= d,
+        // contradicting the proof of correctness in computeDivisionConstants.
+        MOZ_ASSERT(rmc.shiftAmount > 0);
+        MOZ_ASSERT(rmc.multiplier < (int64_t(1) << 33));
+
+        // Compute |t = (n - q) / 2|.
+        move32(input, scratch2);
+        sub32(scratch1, scratch2);
+        rshift32(Imm32(1), scratch2);
+
+        // Compute |t = (n - q) / 2 + q = (n + q) / 2|.
+        add32(scratch2, scratch1);
+
+        // Finish the computation |q = floor(n / d)|.
+        rshift32(Imm32(rmc.shiftAmount - 1), scratch1);
+      } else {
+        rshift32(Imm32(rmc.shiftAmount), scratch1);
+      }
+
+      // Compute the remainder from |r = n - q * d|.
+      move32(scratch1, dest);
+      mul32(Imm32(base), dest);
+      move32(input, scratch2);
+      sub32(dest, scratch2);
+    }
+
+    // Compute the digits of the divisor and remainder.
+    toChar(scratch1);
+    toChar(scratch2);
+
+    // Look up the 2-character digit string in the small-char table.
+    loadLengthTwoString(scratch1, scratch2, dest, staticStrings);
+  }
+  bind(&done);
+}
+
+void MacroAssembler::loadBigIntDigits(Register bigInt, Register digits) {
+  MOZ_ASSERT(digits != bigInt);
+
+  // Load the inline digits.
+  computeEffectiveAddress(Address(bigInt, BigInt::offsetOfInlineDigits()),
+                          digits);
+
+  // If inline digits aren't used, load the heap digits. Use a conditional move
+  // to prevent speculative execution.
+  cmp32LoadPtr(Assembler::Above, Address(bigInt, BigInt::offsetOfLength()),
+               Imm32(int32_t(BigInt::inlineDigitsLength())),
+               Address(bigInt, BigInt::offsetOfHeapDigits()), digits);
+}
+
+void MacroAssembler::loadBigInt64(Register bigInt, Register64 dest) {
+  // This code follows the implementation of |BigInt::toUint64()|. We're also
+  // using it for inline callers of |BigInt::toInt64()|, which works, because
+  // all supported Jit architectures use a two's complement representation for
+  // int64 values, which means the WrapToSigned call in toInt64() is a no-op.
+
+  Label done, nonZero;
+
+  branchIfBigIntIsNonZero(bigInt, &nonZero);
+  {
+    move64(Imm64(0), dest);
+    jump(&done);
+  }
+  bind(&nonZero);
+
+#ifdef JS_PUNBOX64
+  Register digits = dest.reg;
+#else
+  Register digits = dest.high;
+#endif
+
+  loadBigIntDigits(bigInt, digits);
+
+#if JS_PUNBOX64
+  // Load the first digit into the destination register.
+  load64(Address(digits, 0), dest);
+#else
+  // Load the first digit into the destination register's low value.
+  load32(Address(digits, 0), dest.low);
+
+  // And conditionally load the second digit into the high value register.
+  Label twoDigits, digitsDone;
+  branch32(Assembler::Above, Address(bigInt, BigInt::offsetOfLength()),
+           Imm32(1), &twoDigits);
+  {
+    move32(Imm32(0), dest.high);
+    jump(&digitsDone);
+  }
+  {
+    bind(&twoDigits);
+    load32(Address(digits, sizeof(BigInt::Digit)), dest.high);
+  }
+  bind(&digitsDone);
+#endif
+
+  branchTest32(Assembler::Zero, Address(bigInt, BigInt::offsetOfFlags()),
+               Imm32(BigInt::signBitMask()), &done);
+  neg64(dest);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadFirstBigIntDigitOrZero(Register bigInt,
+                                                Register dest) {
+  Label done, nonZero;
+  branchIfBigIntIsNonZero(bigInt, &nonZero);
+  {
+    movePtr(ImmWord(0), dest);
+    jump(&done);
+  }
+  bind(&nonZero);
+
+  loadBigIntDigits(bigInt, dest);
+
+  // Load the first digit into the destination register.
+  loadPtr(Address(dest, 0), dest);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadBigInt(Register bigInt, Register dest, Label* fail) {
+  Label done, nonZero;
+  branchIfBigIntIsNonZero(bigInt, &nonZero);
+  {
+    movePtr(ImmWord(0), dest);
+    jump(&done);
+  }
+  bind(&nonZero);
+
+  loadBigIntNonZero(bigInt, dest, fail);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadBigIntNonZero(Register bigInt, Register dest,
+                                       Label* fail) {
+  MOZ_ASSERT(bigInt != dest);
+
+#ifdef DEBUG
+  Label nonZero;
+  branchIfBigIntIsNonZero(bigInt, &nonZero);
+  assumeUnreachable("Unexpected zero BigInt");
+  bind(&nonZero);
+#endif
+
+  branch32(Assembler::Above, Address(bigInt, BigInt::offsetOfLength()),
+           Imm32(1), fail);
+
+  static_assert(BigInt::inlineDigitsLength() > 0,
+                "Single digit BigInts use inline storage");
+
+  // Load the first inline digit into the destination register.
+  loadPtr(Address(bigInt, BigInt::offsetOfInlineDigits()), dest);
+
+  // Return as a signed pointer.
+  bigIntDigitToSignedPtr(bigInt, dest, fail);
+}
+
+void MacroAssembler::bigIntDigitToSignedPtr(Register bigInt, Register digit,
+                                            Label* fail) {
+  // BigInt digits are stored as absolute numbers. Take the failure path when
+  // the digit can't be stored in intptr_t.
+  branchTestPtr(Assembler::Signed, digit, digit, fail);
+
+  // Negate |dest| when the BigInt is negative.
+  Label nonNegative;
+  branchIfBigIntIsNonNegative(bigInt, &nonNegative);
+  negPtr(digit);
+  bind(&nonNegative);
+}
+
+void MacroAssembler::loadBigIntAbsolute(Register bigInt, Register dest,
+                                        Label* fail) {
+  MOZ_ASSERT(bigInt != dest);
+
+  branch32(Assembler::Above, Address(bigInt, BigInt::offsetOfLength()),
+           Imm32(1), fail);
+
+  static_assert(BigInt::inlineDigitsLength() > 0,
+                "Single digit BigInts use inline storage");
+
+  // Load the first inline digit into the destination register.
+  movePtr(ImmWord(0), dest);
+  cmp32LoadPtr(Assembler::NotEqual, Address(bigInt, BigInt::offsetOfLength()),
+               Imm32(0), Address(bigInt, BigInt::offsetOfInlineDigits()), dest);
+}
+
+void MacroAssembler::initializeBigInt64(Scalar::Type type, Register bigInt,
+                                        Register64 val) {
+  MOZ_ASSERT(Scalar::isBigIntType(type));
+
+  store32(Imm32(0), Address(bigInt, BigInt::offsetOfFlags()));
+
+  Label done, nonZero;
+  branch64(Assembler::NotEqual, val, Imm64(0), &nonZero);
+  {
+    store32(Imm32(0), Address(bigInt, BigInt::offsetOfLength()));
+    jump(&done);
+  }
+  bind(&nonZero);
+
+  if (type == Scalar::BigInt64) {
+    // Set the sign-bit for negative values and then continue with the two's
+    // complement.
+    Label isPositive;
+    branch64(Assembler::GreaterThan, val, Imm64(0), &isPositive);
+    {
+      store32(Imm32(BigInt::signBitMask()),
+              Address(bigInt, BigInt::offsetOfFlags()));
+      neg64(val);
+    }
+    bind(&isPositive);
+  }
+
+  store32(Imm32(1), Address(bigInt, BigInt::offsetOfLength()));
+
+  static_assert(sizeof(BigInt::Digit) == sizeof(uintptr_t),
+                "BigInt Digit size matches uintptr_t, so there's a single "
+                "store on 64-bit and up to two stores on 32-bit");
+
+#ifndef JS_PUNBOX64
+  Label singleDigit;
+  branchTest32(Assembler::Zero, val.high, val.high, &singleDigit);
+  store32(Imm32(2), Address(bigInt, BigInt::offsetOfLength()));
+  bind(&singleDigit);
+
+  // We can perform a single store64 on 32-bit platforms, because inline
+  // storage can store at least two 32-bit integers.
+  static_assert(BigInt::inlineDigitsLength() >= 2,
+                "BigInt inline storage can store at least two digits");
+#endif
+
+  store64(val, Address(bigInt, js::BigInt::offsetOfInlineDigits()));
+
+  bind(&done);
+}
+
+void MacroAssembler::initializeBigInt(Register bigInt, Register val) {
+  store32(Imm32(0), Address(bigInt, BigInt::offsetOfFlags()));
+
+  Label done, nonZero;
+  branchTestPtr(Assembler::NonZero, val, val, &nonZero);
+  {
+    store32(Imm32(0), Address(bigInt, BigInt::offsetOfLength()));
+    jump(&done);
+  }
+  bind(&nonZero);
+
+  // Set the sign-bit for negative values and then continue with the two's
+  // complement.
+  Label isPositive;
+  branchTestPtr(Assembler::NotSigned, val, val, &isPositive);
+  {
+    store32(Imm32(BigInt::signBitMask()),
+            Address(bigInt, BigInt::offsetOfFlags()));
+    negPtr(val);
+  }
+  bind(&isPositive);
+
+  store32(Imm32(1), Address(bigInt, BigInt::offsetOfLength()));
+
+  static_assert(sizeof(BigInt::Digit) == sizeof(uintptr_t),
+                "BigInt Digit size matches uintptr_t");
+
+  storePtr(val, Address(bigInt, js::BigInt::offsetOfInlineDigits()));
+
+  bind(&done);
+}
+
+void MacroAssembler::initializeBigIntAbsolute(Register bigInt, Register val) {
+  store32(Imm32(0), Address(bigInt, BigInt::offsetOfFlags()));
+
+  Label done, nonZero;
+  branchTestPtr(Assembler::NonZero, val, val, &nonZero);
+  {
+    store32(Imm32(0), Address(bigInt, BigInt::offsetOfLength()));
+    jump(&done);
+  }
+  bind(&nonZero);
+
+  store32(Imm32(1), Address(bigInt, BigInt::offsetOfLength()));
+
+  static_assert(sizeof(BigInt::Digit) == sizeof(uintptr_t),
+                "BigInt Digit size matches uintptr_t");
+
+  storePtr(val, Address(bigInt, js::BigInt::offsetOfInlineDigits()));
+
+  bind(&done);
+}
+
+void MacroAssembler::copyBigIntWithInlineDigits(Register src, Register dest,
+                                                Register temp,
+                                                gc::InitialHeap initialHeap,
+                                                Label* fail) {
+  branch32(Assembler::Above, Address(src, BigInt::offsetOfLength()),
+           Imm32(int32_t(BigInt::inlineDigitsLength())), fail);
+
+  newGCBigInt(dest, temp, initialHeap, fail);
+
+  // Copy the sign-bit, but not any of the other bits used by the GC.
+  load32(Address(src, BigInt::offsetOfFlags()), temp);
+  and32(Imm32(BigInt::signBitMask()), temp);
+  store32(temp, Address(dest, BigInt::offsetOfFlags()));
+
+  // Copy the length.
+  load32(Address(src, BigInt::offsetOfLength()), temp);
+  store32(temp, Address(dest, BigInt::offsetOfLength()));
+
+  // Copy the digits.
+  Address srcDigits(src, js::BigInt::offsetOfInlineDigits());
+  Address destDigits(dest, js::BigInt::offsetOfInlineDigits());
+
+  for (size_t i = 0; i < BigInt::inlineDigitsLength(); i++) {
+    static_assert(sizeof(BigInt::Digit) == sizeof(uintptr_t),
+                  "BigInt Digit size matches uintptr_t");
+
+    loadPtr(srcDigits, temp);
+    storePtr(temp, destDigits);
+
+    srcDigits = Address(src, srcDigits.offset + sizeof(BigInt::Digit));
+    destDigits = Address(dest, destDigits.offset + sizeof(BigInt::Digit));
+  }
+}
+
+void MacroAssembler::compareBigIntAndInt32(JSOp op, Register bigInt,
+                                           Register int32, Register scratch1,
+                                           Register scratch2, Label* ifTrue,
+                                           Label* ifFalse) {
+  MOZ_ASSERT(IsLooseEqualityOp(op) || IsRelationalOp(op));
+
+  static_assert(std::is_same_v<BigInt::Digit, uintptr_t>,
+                "BigInt digit can be loaded in a pointer-sized register");
+  static_assert(sizeof(BigInt::Digit) >= sizeof(uint32_t),
+                "BigInt digit stores at least an uint32");
+
+  // Test for too large numbers.
+  //
+  // If the absolute value of the BigInt can't be expressed in an uint32/uint64,
+  // the result of the comparison is a constant.
+  if (op == JSOp::Eq || op == JSOp::Ne) {
+    Label* tooLarge = op == JSOp::Eq ? ifFalse : ifTrue;
+    branch32(Assembler::GreaterThan,
+             Address(bigInt, BigInt::offsetOfDigitLength()), Imm32(1),
+             tooLarge);
+  } else {
+    Label doCompare;
+    branch32(Assembler::LessThanOrEqual,
+             Address(bigInt, BigInt::offsetOfDigitLength()), Imm32(1),
+             &doCompare);
+
+    // Still need to take the sign-bit into account for relational operations.
+    if (op == JSOp::Lt || op == JSOp::Le) {
+      branchIfBigIntIsNegative(bigInt, ifTrue);
+      jump(ifFalse);
+    } else {
+      branchIfBigIntIsNegative(bigInt, ifFalse);
+      jump(ifTrue);
+    }
+
+    bind(&doCompare);
+  }
+
+  // Test for mismatched signs and, if the signs are equal, load |abs(x)| in
+  // |scratch1| and |abs(y)| in |scratch2| and then compare the absolute numbers
+  // against each other.
+  {
+    // Jump to |ifTrue| resp. |ifFalse| if the BigInt is strictly less than
+    // resp. strictly greater than the int32 value, depending on the comparison
+    // operator.
+    Label* greaterThan;
+    Label* lessThan;
+    if (op == JSOp::Eq) {
+      greaterThan = ifFalse;
+      lessThan = ifFalse;
+    } else if (op == JSOp::Ne) {
+      greaterThan = ifTrue;
+      lessThan = ifTrue;
+    } else if (op == JSOp::Lt || op == JSOp::Le) {
+      greaterThan = ifFalse;
+      lessThan = ifTrue;
+    } else {
+      MOZ_ASSERT(op == JSOp::Gt || op == JSOp::Ge);
+      greaterThan = ifTrue;
+      lessThan = ifFalse;
+    }
+
+    // BigInt digits are always stored as an absolute number.
+    loadFirstBigIntDigitOrZero(bigInt, scratch1);
+
+    // Load the int32 into |scratch2| and negate it for negative numbers.
+    move32(int32, scratch2);
+
+    Label isNegative, doCompare;
+    branchIfBigIntIsNegative(bigInt, &isNegative);
+    branch32(Assembler::LessThan, int32, Imm32(0), greaterThan);
+    jump(&doCompare);
+
+    // We rely on |neg32(INT32_MIN)| staying INT32_MIN, because we're using an
+    // unsigned comparison below.
+    bind(&isNegative);
+    branch32(Assembler::GreaterThanOrEqual, int32, Imm32(0), lessThan);
+    neg32(scratch2);
+
+    // Not all supported platforms (e.g. MIPS64) zero-extend 32-bit operations,
+    // so we need to explicitly clear any high 32-bits.
+    move32ZeroExtendToPtr(scratch2, scratch2);
+
+    // Reverse the relational comparator for negative numbers.
+    // |-x < -y| <=> |+x > +y|.
+    // |-x ≤ -y| <=> |+x ≥ +y|.
+    // |-x > -y| <=> |+x < +y|.
+    // |-x ≥ -y| <=> |+x ≤ +y|.
+    JSOp reversed = ReverseCompareOp(op);
+    if (reversed != op) {
+      branchPtr(JSOpToCondition(reversed, /* isSigned = */ false), scratch1,
+                scratch2, ifTrue);
+      jump(ifFalse);
+    }
+
+    bind(&doCompare);
+    branchPtr(JSOpToCondition(op, /* isSigned = */ false), scratch1, scratch2,
+              ifTrue);
+  }
+}
+
+void MacroAssembler::equalBigInts(Register left, Register right, Register temp1,
+                                  Register temp2, Register temp3,
+                                  Register temp4, Label* notSameSign,
+                                  Label* notSameLength, Label* notSameDigit) {
+  MOZ_ASSERT(left != temp1);
+  MOZ_ASSERT(right != temp1);
+  MOZ_ASSERT(right != temp2);
+
+  // Jump to |notSameSign| when the sign aren't the same.
+  load32(Address(left, BigInt::offsetOfFlags()), temp1);
+  xor32(Address(right, BigInt::offsetOfFlags()), temp1);
+  branchTest32(Assembler::NonZero, temp1, Imm32(BigInt::signBitMask()),
+               notSameSign);
+
+  // Jump to |notSameLength| when the digits length is different.
+  load32(Address(right, BigInt::offsetOfLength()), temp1);
+  branch32(Assembler::NotEqual, Address(left, BigInt::offsetOfLength()), temp1,
+           notSameLength);
+
+  // Both BigInts have the same sign and the same number of digits. Loop
+  // over each digit, starting with the left-most one, and break from the
+  // loop when the first non-matching digit was found.
+
+  loadBigIntDigits(left, temp2);
+  loadBigIntDigits(right, temp3);
+
+  static_assert(sizeof(BigInt::Digit) == sizeof(void*),
+                "BigInt::Digit is pointer sized");
+
+  computeEffectiveAddress(BaseIndex(temp2, temp1, ScalePointer), temp2);
+  computeEffectiveAddress(BaseIndex(temp3, temp1, ScalePointer), temp3);
+
+  Label start, loop;
+  jump(&start);
+  bind(&loop);
+
+  subPtr(Imm32(sizeof(BigInt::Digit)), temp2);
+  subPtr(Imm32(sizeof(BigInt::Digit)), temp3);
+
+  loadPtr(Address(temp3, 0), temp4);
+  branchPtr(Assembler::NotEqual, Address(temp2, 0), temp4, notSameDigit);
+
+  bind(&start);
+  branchSub32(Assembler::NotSigned, Imm32(1), temp1, &loop);
+
+  // No different digits were found, both BigInts are equal to each other.
+}
+
+void MacroAssembler::typeOfObject(Register obj, Register scratch, Label* slow,
+                                  Label* isObject, Label* isCallable,
+                                  Label* isUndefined) {
+  loadObjClassUnsafe(obj, scratch);
+
+  // Proxies can emulate undefined and have complex isCallable behavior.
+  branchTestClassIsProxy(true, scratch, slow);
+
+  // JSFunctions are always callable.
+  branchTestClassIsFunction(Assembler::Equal, scratch, isCallable);
+
+  // Objects that emulate undefined.
+  Address flags(scratch, JSClass::offsetOfFlags());
+  branchTest32(Assembler::NonZero, flags, Imm32(JSCLASS_EMULATES_UNDEFINED),
+               isUndefined);
+
+  // Handle classes with a call hook.
+  branchPtr(Assembler::Equal, Address(scratch, offsetof(JSClass, cOps)),
+            ImmPtr(nullptr), isObject);
+
+  loadPtr(Address(scratch, offsetof(JSClass, cOps)), scratch);
+  branchPtr(Assembler::Equal, Address(scratch, offsetof(JSClassOps, call)),
+            ImmPtr(nullptr), isObject);
+
+  jump(isCallable);
+}
+
+void MacroAssembler::isCallableOrConstructor(bool isCallable, Register obj,
+                                             Register output, Label* isProxy) {
+  MOZ_ASSERT(obj != output);
+
+  Label notFunction, hasCOps, done;
+  loadObjClassUnsafe(obj, output);
+
+  // An object is callable iff:
+  //   is<JSFunction>() || (getClass()->cOps && getClass()->cOps->call).
+  // An object is constructor iff:
+  //  ((is<JSFunction>() && as<JSFunction>().isConstructor) ||
+  //   (getClass()->cOps && getClass()->cOps->construct)).
+  branchTestClassIsFunction(Assembler::NotEqual, output, &notFunction);
+  if (isCallable) {
+    move32(Imm32(1), output);
+  } else {
+    static_assert(mozilla::IsPowerOfTwo(uint32_t(FunctionFlags::CONSTRUCTOR)),
+                  "FunctionFlags::CONSTRUCTOR has only one bit set");
+
+    load32(Address(obj, JSFunction::offsetOfFlagsAndArgCount()), output);
+    rshift32(Imm32(mozilla::FloorLog2(uint32_t(FunctionFlags::CONSTRUCTOR))),
+             output);
+    and32(Imm32(1), output);
+  }
+  jump(&done);
+
+  bind(&notFunction);
+
+  // Just skim proxies off. Their notion of isCallable()/isConstructor() is
+  // more complicated.
+  branchTestClassIsProxy(true, output, isProxy);
+
+  branchPtr(Assembler::NonZero, Address(output, offsetof(JSClass, cOps)),
+            ImmPtr(nullptr), &hasCOps);
+  move32(Imm32(0), output);
+  jump(&done);
+
+  bind(&hasCOps);
+  loadPtr(Address(output, offsetof(JSClass, cOps)), output);
+  size_t opsOffset =
+      isCallable ? offsetof(JSClassOps, call) : offsetof(JSClassOps, construct);
+  cmpPtrSet(Assembler::NonZero, Address(output, opsOffset), ImmPtr(nullptr),
+            output);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadJSContext(Register dest) {
+  movePtr(ImmPtr(runtime()->mainContextPtr()), dest);
+}
+
+static const uint8_t* ContextRealmPtr(CompileRuntime* rt) {
+  return (static_cast<const uint8_t*>(rt->mainContextPtr()) +
+          JSContext::offsetOfRealm());
+}
+
+void MacroAssembler::switchToRealm(Register realm) {
+  storePtr(realm, AbsoluteAddress(ContextRealmPtr(runtime())));
+}
+
+void MacroAssembler::switchToRealm(const void* realm, Register scratch) {
+  MOZ_ASSERT(realm);
+
+  movePtr(ImmPtr(realm), scratch);
+  switchToRealm(scratch);
+}
+
+void MacroAssembler::switchToObjectRealm(Register obj, Register scratch) {
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch);
+  loadPtr(Address(scratch, Shape::offsetOfBaseShape()), scratch);
+  loadPtr(Address(scratch, BaseShape::offsetOfRealm()), scratch);
+  switchToRealm(scratch);
+}
+
+void MacroAssembler::switchToBaselineFrameRealm(Register scratch) {
+  Address envChain(FramePointer,
+                   BaselineFrame::reverseOffsetOfEnvironmentChain());
+  loadPtr(envChain, scratch);
+  switchToObjectRealm(scratch, scratch);
+}
+
+void MacroAssembler::switchToWasmInstanceRealm(Register scratch1,
+                                               Register scratch2) {
+  loadPtr(Address(InstanceReg, wasm::Instance::offsetOfCx()), scratch1);
+  loadPtr(Address(InstanceReg, wasm::Instance::offsetOfRealm()), scratch2);
+  storePtr(scratch2, Address(scratch1, JSContext::offsetOfRealm()));
+}
+
+void MacroAssembler::debugAssertContextRealm(const void* realm,
+                                             Register scratch) {
+#ifdef DEBUG
+  Label ok;
+  movePtr(ImmPtr(realm), scratch);
+  branchPtr(Assembler::Equal, AbsoluteAddress(ContextRealmPtr(runtime())),
+            scratch, &ok);
+  assumeUnreachable("Unexpected context realm");
+  bind(&ok);
+#endif
+}
+
+void MacroAssembler::setIsCrossRealmArrayConstructor(Register obj,
+                                                     Register output) {
+#ifdef DEBUG
+  Label notProxy;
+  branchTestObjectIsProxy(false, obj, output, &notProxy);
+  assumeUnreachable("Unexpected proxy in setIsCrossRealmArrayConstructor");
+  bind(&notProxy);
+#endif
+
+  // The object's realm must not be cx->realm.
+  Label isFalse, done;
+  loadPtr(Address(obj, JSObject::offsetOfShape()), output);
+  loadPtr(Address(output, Shape::offsetOfBaseShape()), output);
+  loadPtr(Address(output, BaseShape::offsetOfRealm()), output);
+  branchPtr(Assembler::Equal, AbsoluteAddress(ContextRealmPtr(runtime())),
+            output, &isFalse);
+
+  // The object must be a function.
+  branchTestObjIsFunction(Assembler::NotEqual, obj, output, obj, &isFalse);
+
+  // The function must be the ArrayConstructor native.
+  branchPtr(Assembler::NotEqual,
+            Address(obj, JSFunction::offsetOfNativeOrEnv()),
+            ImmPtr(js::ArrayConstructor), &isFalse);
+
+  move32(Imm32(1), output);
+  jump(&done);
+
+  bind(&isFalse);
+  move32(Imm32(0), output);
+
+  bind(&done);
+}
+
+void MacroAssembler::setIsDefinitelyTypedArrayConstructor(Register obj,
+                                                          Register output) {
+  Label isFalse, isTrue, done;
+
+  // The object must be a function. (Wrappers are not supported.)
+  branchTestObjIsFunction(Assembler::NotEqual, obj, output, obj, &isFalse);
+
+  // Load the native into |output|.
+  loadPtr(Address(obj, JSFunction::offsetOfNativeOrEnv()), output);
+
+  auto branchIsTypedArrayCtor = [&](Scalar::Type type) {
+    // The function must be a TypedArrayConstructor native (from any realm).
+    JSNative constructor = TypedArrayConstructorNative(type);
+    branchPtr(Assembler::Equal, output, ImmPtr(constructor), &isTrue);
+  };
+
+#define TYPED_ARRAY_CONSTRUCTOR_NATIVE(_, T, N) \
+  branchIsTypedArrayCtor(Scalar::N);
+  JS_FOR_EACH_TYPED_ARRAY(TYPED_ARRAY_CONSTRUCTOR_NATIVE)
+#undef TYPED_ARRAY_CONSTRUCTOR_NATIVE
+
+  // Falls through to the false case.
+
+  bind(&isFalse);
+  move32(Imm32(0), output);
+  jump(&done);
+
+  bind(&isTrue);
+  move32(Imm32(1), output);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadMegamorphicCache(Register dest) {
+  movePtr(ImmPtr(runtime()->addressOfMegamorphicCache()), dest);
+}
+
+void MacroAssembler::loadStringToAtomCacheLastLookups(Register dest) {
+  uintptr_t cachePtr = uintptr_t(runtime()->addressOfStringToAtomCache());
+  void* offset = (void*)(cachePtr + StringToAtomCache::offsetOfLastLookups());
+  movePtr(ImmPtr(offset), dest);
+}
+
+void MacroAssembler::loadAtomOrSymbolAndHash(ValueOperand value, Register outId,
+                                             Register outHash,
+                                             Label* cacheMiss) {
+  Label isString, fatInline, done, nonAtom, atom, lastLookupAtom;
+
+  {
+    ScratchTagScope tag(*this, value);
+    splitTagForTest(value, tag);
+    branchTestString(Assembler::Equal, tag, &isString);
+
+    branchTestSymbol(Assembler::NotEqual, tag, cacheMiss);
+
+    unboxSymbol(value, outId);
+    load32(Address(outId, JS::Symbol::offsetOfHash()), outHash);
+    jump(&done);
+  }
+
+  bind(&isString);
+  unboxString(value, outId);
+  branchTest32(Assembler::Zero, Address(outId, JSString::offsetOfFlags()),
+               Imm32(JSString::ATOM_BIT), &nonAtom);
+
+  bind(&atom);
+  move32(Imm32(JSString::FAT_INLINE_MASK), outHash);
+  and32(Address(outId, JSString::offsetOfFlags()), outHash);
+
+  branch32(Assembler::Equal, outHash, Imm32(JSString::FAT_INLINE_MASK),
+           &fatInline);
+  load32(Address(outId, NormalAtom::offsetOfHash()), outHash);
+  jump(&done);
+  bind(&fatInline);
+  load32(Address(outId, FatInlineAtom::offsetOfHash()), outHash);
+  jump(&done);
+
+  bind(&nonAtom);
+  loadStringToAtomCacheLastLookups(outHash);
+
+  // Compare each entry in the StringToAtomCache's lastLookups_ array
+  size_t stringOffset = StringToAtomCache::LastLookup::offsetOfString();
+  branchPtr(Assembler::Equal, Address(outHash, stringOffset), outId,
+            &lastLookupAtom);
+  for (size_t i = 0; i < StringToAtomCache::NumLastLookups - 1; ++i) {
+    addPtr(Imm32(sizeof(StringToAtomCache::LastLookup)), outHash);
+    branchPtr(Assembler::Equal, Address(outHash, stringOffset), outId,
+              &lastLookupAtom);
+  }
+
+  // Couldn't find us in the cache, so fall back to the C++ call
+  jump(cacheMiss);
+
+  // We found a hit in the lastLookups_ array! Load the associated atom
+  // and jump back up to our usual atom handling code
+  bind(&lastLookupAtom);
+  size_t atomOffset = StringToAtomCache::LastLookup::offsetOfAtom();
+  loadPtr(Address(outHash, atomOffset), outId);
+  jump(&atom);
+
+  bind(&done);
+}
+
+void MacroAssembler::emitExtractValueFromMegamorphicCacheEntry(
+    Register obj, Register entry, Register scratch1, Register scratch2,
+    ValueOperand output, Label* cacheHit, Label* cacheMiss) {
+  Label isMissing, dynamicSlot, protoLoopHead, protoLoopTail;
+
+  // scratch2 = entry->numHops_
+  load8ZeroExtend(Address(entry, MegamorphicCache::Entry::offsetOfNumHops()),
+                  scratch2);
+  // if (scratch2 == NumHopsForMissingOwnProperty) goto cacheMiss
+  branch32(Assembler::Equal, scratch2,
+           Imm32(MegamorphicCache::Entry::NumHopsForMissingOwnProperty),
+           cacheMiss);
+  // if (scratch2 == NumHopsForMissingProperty) goto isMissing
+  branch32(Assembler::Equal, scratch2,
+           Imm32(MegamorphicCache::Entry::NumHopsForMissingProperty),
+           &isMissing);
+
+  // NOTE: Where this is called, `output` can actually alias `obj`, and before
+  // the last cacheMiss branch above we can't write to `obj`, so we can't
+  // use `output`'s scratch register there. However a cache miss is impossible
+  // now, so we're free to use `output` as we like.
+  Register outputScratch = output.scratchReg();
+  if (!outputScratch.aliases(obj)) {
+    // We're okay with paying this very slight extra cost to avoid a potential
+    // footgun of writing to what callers understand as only an input register.
+    movePtr(obj, outputScratch);
+  }
+  branchTest32(Assembler::Zero, scratch2, scratch2, &protoLoopTail);
+  bind(&protoLoopHead);
+  loadObjProto(outputScratch, outputScratch);
+  branchSub32(Assembler::NonZero, Imm32(1), scratch2, &protoLoopHead);
+  bind(&protoLoopTail);
+
+  // scratch1 = outputScratch->numFixedSlots()
+  loadPtr(Address(outputScratch, JSObject::offsetOfShape()), scratch1);
+  load32(Address(scratch1, Shape::offsetOfImmutableFlags()), scratch1);
+  and32(Imm32(NativeShape::fixedSlotsMask()), scratch1);
+  rshift32(Imm32(NativeShape::fixedSlotsShift()), scratch1);
+
+  // scratch2 = entry->slot()
+  load16ZeroExtend(Address(entry, MegamorphicCache::Entry::offsetOfSlot()),
+                   scratch2);
+  // if (scratch2 >= scratch1) goto dynamicSlot
+  branch32(Assembler::GreaterThanOrEqual, scratch2, scratch1, &dynamicSlot);
+
+  static_assert(sizeof(HeapSlot) == 8);
+  // output = outputScratch->fixedSlots()[scratch2]
+  loadValue(BaseValueIndex(outputScratch, scratch2, sizeof(NativeObject)),
+            output);
+  jump(cacheHit);
+
+  bind(&dynamicSlot);
+  // scratch2 -= scratch1
+  sub32(scratch1, scratch2);
+  // output = outputScratch->slots_[scratch2]
+  loadPtr(Address(outputScratch, NativeObject::offsetOfSlots()), outputScratch);
+  loadValue(BaseValueIndex(outputScratch, scratch2, 0), output);
+  jump(cacheHit);
+
+  bind(&isMissing);
+  // output = undefined
+  moveValue(UndefinedValue(), output);
+  jump(cacheHit);
+}
+
+void MacroAssembler::emitMegamorphicCacheLookupByValueCommon(
+    ValueOperand id, Register obj, Register scratch1, Register scratch2,
+    Register outEntryPtr, Label* cacheMiss) {
+  // A lot of this code is shared with emitMegamorphicCacheLookup. It would
+  // be nice to be able to avoid the duplication here, but due to a few
+  // differences like taking the id in a ValueOperand instead of being able
+  // to bake it in as an immediate, and only needing a Register for the output
+  // value, it seemed more awkward to read once it was deduplicated.
+
+  // outEntryPtr = obj->shape()
+  loadPtr(Address(obj, JSObject::offsetOfShape()), outEntryPtr);
+
+  movePtr(outEntryPtr, scratch2);
+
+  // outEntryPtr = (outEntryPtr >> 3) ^ (outEntryPtr >> 13) + idHash
+  rshiftPtr(Imm32(MegamorphicCache::ShapeHashShift1), outEntryPtr);
+  rshiftPtr(Imm32(MegamorphicCache::ShapeHashShift2), scratch2);
+  xorPtr(scratch2, outEntryPtr);
+
+  loadAtomOrSymbolAndHash(id, scratch1, scratch2, cacheMiss);
+  addPtr(scratch2, outEntryPtr);
+
+  // outEntryPtr %= MegamorphicCache::NumEntries
+  constexpr size_t cacheSize = MegamorphicCache::NumEntries;
+  static_assert(mozilla::IsPowerOfTwo(cacheSize));
+  size_t cacheMask = cacheSize - 1;
+  and32(Imm32(cacheMask), outEntryPtr);
+
+  loadMegamorphicCache(scratch2);
+  // outEntryPtr = &scratch2->entries_[outEntryPtr]
+  constexpr size_t entrySize = sizeof(MegamorphicCache::Entry);
+  static_assert(sizeof(void*) == 4 || entrySize == 24);
+  if constexpr (sizeof(void*) == 4) {
+    mul32(Imm32(entrySize), outEntryPtr);
+    computeEffectiveAddress(BaseIndex(scratch2, outEntryPtr, TimesOne,
+                                      MegamorphicCache::offsetOfEntries()),
+                            outEntryPtr);
+  } else {
+    computeEffectiveAddress(BaseIndex(outEntryPtr, outEntryPtr, TimesTwo),
+                            outEntryPtr);
+    computeEffectiveAddress(BaseIndex(scratch2, outEntryPtr, TimesEight,
+                                      MegamorphicCache::offsetOfEntries()),
+                            outEntryPtr);
+  }
+
+  // if (outEntryPtr->key_ != scratch1) goto cacheMiss
+  branchPtr(Assembler::NotEqual,
+            Address(outEntryPtr, MegamorphicCache::Entry::offsetOfKey()),
+            scratch1, cacheMiss);
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch1);
+
+  // if (outEntryPtr->shape_ != scratch1) goto cacheMiss
+  branchPtr(Assembler::NotEqual,
+            Address(outEntryPtr, MegamorphicCache::Entry::offsetOfShape()),
+            scratch1, cacheMiss);
+
+  // scratch2 = scratch2->generation_
+  load16ZeroExtend(Address(scratch2, MegamorphicCache::offsetOfGeneration()),
+                   scratch2);
+  load16ZeroExtend(
+      Address(outEntryPtr, MegamorphicCache::Entry::offsetOfGeneration()),
+      scratch1);
+  // if (outEntryPtr->generation_ != scratch2) goto cacheMiss
+  branch32(Assembler::NotEqual, scratch1, scratch2, cacheMiss);
+}
+
+void MacroAssembler::emitMegamorphicCacheLookup(
+    PropertyKey id, Register obj, Register scratch1, Register scratch2,
+    Register scratch3, ValueOperand output, Label* cacheHit) {
+  Label cacheMiss, isMissing, dynamicSlot, protoLoopHead, protoLoopTail;
+
+  // scratch1 = obj->shape()
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch1);
+
+  movePtr(scratch1, scratch2);
+  movePtr(scratch1, scratch3);
+
+  // scratch2 = (scratch1 >> 3) ^ (scratch1 >> 13) + hash(id)
+  rshiftPtr(Imm32(MegamorphicCache::ShapeHashShift1), scratch2);
+  rshiftPtr(Imm32(MegamorphicCache::ShapeHashShift2), scratch3);
+  xorPtr(scratch3, scratch2);
+  addPtr(Imm32(HashAtomOrSymbolPropertyKey(id)), scratch2);
+
+  // scratch2 %= MegamorphicCache::NumEntries
+  constexpr size_t cacheSize = MegamorphicCache::NumEntries;
+  static_assert(mozilla::IsPowerOfTwo(cacheSize));
+  size_t cacheMask = cacheSize - 1;
+  and32(Imm32(cacheMask), scratch2);
+
+  loadMegamorphicCache(scratch3);
+  // scratch2 = &scratch3->entries_[scratch2]
+  constexpr size_t entrySize = sizeof(MegamorphicCache::Entry);
+  static_assert(sizeof(void*) == 4 || entrySize == 24);
+  if constexpr (sizeof(void*) == 4) {
+    mul32(Imm32(entrySize), scratch2);
+    computeEffectiveAddress(BaseIndex(scratch3, scratch2, TimesOne,
+                                      MegamorphicCache::offsetOfEntries()),
+                            scratch2);
+  } else {
+    computeEffectiveAddress(BaseIndex(scratch2, scratch2, TimesTwo), scratch2);
+    computeEffectiveAddress(BaseIndex(scratch3, scratch2, TimesEight,
+                                      MegamorphicCache::offsetOfEntries()),
+                            scratch2);
+  }
+
+  // if (scratch2->shape_ != scratch1) goto cacheMiss
+  branchPtr(Assembler::NotEqual,
+            Address(scratch2, MegamorphicCache::Entry::offsetOfShape()),
+            scratch1, &cacheMiss);
+
+  // if (scratch2->key_ != id) goto cacheMiss
+  movePropertyKey(id, scratch1);
+  branchPtr(Assembler::NotEqual,
+            Address(scratch2, MegamorphicCache::Entry::offsetOfKey()), scratch1,
+            &cacheMiss);
+
+  // scratch3 = scratch3->generation_
+  load16ZeroExtend(Address(scratch3, MegamorphicCache::offsetOfGeneration()),
+                   scratch3);
+  load16ZeroExtend(
+      Address(scratch2, MegamorphicCache::Entry::offsetOfGeneration()),
+      scratch1);
+  // if (scratch2->generation_ != scratch3) goto cacheMiss
+  branch32(Assembler::NotEqual, scratch1, scratch3, &cacheMiss);
+
+  emitExtractValueFromMegamorphicCacheEntry(obj, scratch2, scratch1, scratch3,
+                                            output, cacheHit, &cacheMiss);
+
+  bind(&cacheMiss);
+}
+
+void MacroAssembler::emitMegamorphicCacheLookupByValue(
+    ValueOperand id, Register obj, Register scratch1, Register scratch2,
+    Register scratch3, ValueOperand output, Label* cacheHit) {
+  Label cacheMiss;
+  emitMegamorphicCacheLookupByValueCommon(id, obj, scratch1, scratch2, scratch3,
+                                          &cacheMiss);
+  emitExtractValueFromMegamorphicCacheEntry(obj, scratch3, scratch1, scratch2,
+                                            output, cacheHit, &cacheMiss);
+  bind(&cacheMiss);
+}
+
+void MacroAssembler::emitMegamorphicCacheLookupExists(
+    ValueOperand id, Register obj, Register scratch1, Register scratch2,
+    Register scratch3, Register output, Label* cacheHit, bool hasOwn) {
+  Label cacheMiss, cacheHitFalse;
+  emitMegamorphicCacheLookupByValueCommon(id, obj, scratch1, scratch2, scratch3,
+                                          &cacheMiss);
+
+  // scratch3 = scratch3->numHops_
+  load8ZeroExtend(Address(scratch3, MegamorphicCache::Entry::offsetOfNumHops()),
+                  scratch3);
+
+  branch32(Assembler::Equal, scratch3,
+           Imm32(MegamorphicCache::Entry::NumHopsForMissingProperty),
+           &cacheHitFalse);
+
+  if (hasOwn) {
+    branch32(Assembler::NotEqual, scratch3, Imm32(0), &cacheHitFalse);
+  } else {
+    branch32(Assembler::Equal, scratch3,
+             Imm32(MegamorphicCache::Entry::NumHopsForMissingOwnProperty),
+             &cacheMiss);
+  }
+
+  move32(Imm32(1), output);
+  jump(cacheHit);
+
+  bind(&cacheHitFalse);
+  xor32(output, output);
+  jump(cacheHit);
+
+  bind(&cacheMiss);
+}
+
+void MacroAssembler::guardNonNegativeIntPtrToInt32(Register reg, Label* fail) {
+#ifdef DEBUG
+  Label ok;
+  branchPtr(Assembler::NotSigned, reg, reg, &ok);
+  assumeUnreachable("Unexpected negative value");
+  bind(&ok);
+#endif
+
+#ifdef JS_64BIT
+  branchPtr(Assembler::Above, reg, Imm32(INT32_MAX), fail);
+#endif
+}
+
+void MacroAssembler::loadArrayBufferByteLengthIntPtr(Register obj,
+                                                     Register output) {
+  Address slotAddr(obj, ArrayBufferObject::offsetOfByteLengthSlot());
+  loadPrivate(slotAddr, output);
+}
+
+void MacroAssembler::loadArrayBufferViewByteOffsetIntPtr(Register obj,
+                                                         Register output) {
+  Address slotAddr(obj, ArrayBufferViewObject::byteOffsetOffset());
+  loadPrivate(slotAddr, output);
+}
+
+void MacroAssembler::loadArrayBufferViewLengthIntPtr(Register obj,
+                                                     Register output) {
+  Address slotAddr(obj, ArrayBufferViewObject::lengthOffset());
+  loadPrivate(slotAddr, output);
+}
+
+void MacroAssembler::loadDOMExpandoValueGuardGeneration(
+    Register obj, ValueOperand output,
+    JS::ExpandoAndGeneration* expandoAndGeneration, uint64_t generation,
+    Label* fail) {
+  loadPtr(Address(obj, ProxyObject::offsetOfReservedSlots()),
+          output.scratchReg());
+  loadValue(Address(output.scratchReg(),
+                    js::detail::ProxyReservedSlots::offsetOfPrivateSlot()),
+            output);
+
+  // Guard the ExpandoAndGeneration* matches the proxy's ExpandoAndGeneration
+  // privateSlot.
+  branchTestValue(Assembler::NotEqual, output,
+                  PrivateValue(expandoAndGeneration), fail);
+
+  // Guard expandoAndGeneration->generation matches the expected generation.
+  Address generationAddr(output.payloadOrValueReg(),
+                         JS::ExpandoAndGeneration::offsetOfGeneration());
+  branch64(Assembler::NotEqual, generationAddr, Imm64(generation), fail);
+
+  // Load expandoAndGeneration->expando into the output Value register.
+  loadValue(Address(output.payloadOrValueReg(),
+                    JS::ExpandoAndGeneration::offsetOfExpando()),
+            output);
+}
+
+void MacroAssembler::loadJitActivation(Register dest) {
+  loadJSContext(dest);
+  loadPtr(Address(dest, offsetof(JSContext, activation_)), dest);
+}
+
+void MacroAssembler::guardSpecificAtom(Register str, JSAtom* atom,
+                                       Register scratch,
+                                       const LiveRegisterSet& volatileRegs,
+                                       Label* fail) {
+  Label done;
+  branchPtr(Assembler::Equal, str, ImmGCPtr(atom), &done);
+
+  // The pointers are not equal, so if the input string is also an atom it
+  // must be a different string.
+  branchTest32(Assembler::NonZero, Address(str, JSString::offsetOfFlags()),
+               Imm32(JSString::ATOM_BIT), fail);
+
+  // Check the length.
+  branch32(Assembler::NotEqual, Address(str, JSString::offsetOfLength()),
+           Imm32(atom->length()), fail);
+
+  // We have a non-atomized string with the same length. Call a helper
+  // function to do the comparison.
+  PushRegsInMask(volatileRegs);
+
+  using Fn = bool (*)(JSString * str1, JSString * str2);
+  setupUnalignedABICall(scratch);
+  movePtr(ImmGCPtr(atom), scratch);
+  passABIArg(scratch);
+  passABIArg(str);
+  callWithABI<Fn, EqualStringsHelperPure>();
+  storeCallPointerResult(scratch);
+
+  MOZ_ASSERT(!volatileRegs.has(scratch));
+  PopRegsInMask(volatileRegs);
+  branchIfFalseBool(scratch, fail);
+
+  bind(&done);
+}
+
+void MacroAssembler::guardStringToInt32(Register str, Register output,
+                                        Register scratch,
+                                        LiveRegisterSet volatileRegs,
+                                        Label* fail) {
+  Label vmCall, done;
+  // Use indexed value as fast path if possible.
+  loadStringIndexValue(str, output, &vmCall);
+  jump(&done);
+  {
+    bind(&vmCall);
+
+    // Reserve space for holding the result int32_t of the call. Use
+    // pointer-size to avoid misaligning the stack on 64-bit platforms.
+    reserveStack(sizeof(uintptr_t));
+    moveStackPtrTo(output);
+
+    volatileRegs.takeUnchecked(scratch);
+    if (output.volatile_()) {
+      volatileRegs.addUnchecked(output);
+    }
+    PushRegsInMask(volatileRegs);
+
+    using Fn = bool (*)(JSContext * cx, JSString * str, int32_t * result);
+    setupUnalignedABICall(scratch);
+    loadJSContext(scratch);
+    passABIArg(scratch);
+    passABIArg(str);
+    passABIArg(output);
+    callWithABI<Fn, GetInt32FromStringPure>();
+    storeCallPointerResult(scratch);
+
+    PopRegsInMask(volatileRegs);
+
+    Label ok;
+    branchIfTrueBool(scratch, &ok);
+    {
+      // OOM path, recovered by GetInt32FromStringPure.
+      //
+      // Use addToStackPtr instead of freeStack as freeStack tracks stack height
+      // flow-insensitively, and using it twice would confuse the stack height
+      // tracking.
+      addToStackPtr(Imm32(sizeof(uintptr_t)));
+      jump(fail);
+    }
+    bind(&ok);
+    load32(Address(output, 0), output);
+    freeStack(sizeof(uintptr_t));
+  }
+  bind(&done);
+}
+
+void MacroAssembler::generateBailoutTail(Register scratch,
+                                         Register bailoutInfo) {
+  Label bailoutFailed;
+  branchIfFalseBool(ReturnReg, &bailoutFailed);
+
+  // Finish bailing out to Baseline.
+  {
+    // Prepare a register set for use in this case.
+    AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+    MOZ_ASSERT_IF(!IsHiddenSP(getStackPointer()),
+                  !regs.has(AsRegister(getStackPointer())));
+    regs.take(bailoutInfo);
+
+    Register temp = regs.takeAny();
+
+#ifdef DEBUG
+    // Assert the stack pointer points to the JitFrameLayout header. Copying
+    // starts here.
+    Label ok;
+    loadPtr(Address(bailoutInfo, offsetof(BaselineBailoutInfo, incomingStack)),
+            temp);
+    branchStackPtr(Assembler::Equal, temp, &ok);
+    assumeUnreachable("Unexpected stack pointer value");
+    bind(&ok);
+#endif
+
+    Register copyCur = regs.takeAny();
+    Register copyEnd = regs.takeAny();
+
+    // Copy data onto stack.
+    loadPtr(Address(bailoutInfo, offsetof(BaselineBailoutInfo, copyStackTop)),
+            copyCur);
+    loadPtr(
+        Address(bailoutInfo, offsetof(BaselineBailoutInfo, copyStackBottom)),
+        copyEnd);
+    {
+      Label copyLoop;
+      Label endOfCopy;
+      bind(&copyLoop);
+      branchPtr(Assembler::BelowOrEqual, copyCur, copyEnd, &endOfCopy);
+      subPtr(Imm32(sizeof(uintptr_t)), copyCur);
+      subFromStackPtr(Imm32(sizeof(uintptr_t)));
+      loadPtr(Address(copyCur, 0), temp);
+      storePtr(temp, Address(getStackPointer(), 0));
+      jump(&copyLoop);
+      bind(&endOfCopy);
+    }
+
+    loadPtr(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeFramePtr)),
+            FramePointer);
+
+    // Enter exit frame for the FinishBailoutToBaseline call.
+    pushFrameDescriptor(FrameType::BaselineJS);
+    push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeAddr)));
+    push(FramePointer);
+    // No GC things to mark on the stack, push a bare token.
+    loadJSContext(scratch);
+    enterFakeExitFrame(scratch, scratch, ExitFrameType::Bare);
+
+    // Save needed values onto stack temporarily.
+    push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeAddr)));
+
+    // Call a stub to free allocated memory and create arguments objects.
+    using Fn = bool (*)(BaselineBailoutInfo * bailoutInfoArg);
+    setupUnalignedABICall(temp);
+    passABIArg(bailoutInfo);
+    callWithABI<Fn, FinishBailoutToBaseline>(
+        MoveOp::GENERAL, CheckUnsafeCallWithABI::DontCheckHasExitFrame);
+    branchIfFalseBool(ReturnReg, exceptionLabel());
+
+    // Restore values where they need to be and resume execution.
+    AllocatableGeneralRegisterSet enterRegs(GeneralRegisterSet::All());
+    MOZ_ASSERT(!enterRegs.has(FramePointer));
+    Register jitcodeReg = enterRegs.takeAny();
+
+    pop(jitcodeReg);
+
+    // Discard exit frame.
+    addToStackPtr(Imm32(ExitFrameLayout::SizeWithFooter()));
+
+    jump(jitcodeReg);
+  }
+
+  bind(&bailoutFailed);
+  {
+    // jit::Bailout or jit::InvalidationBailout failed and returned false. The
+    // Ion frame has already been discarded and the stack pointer points to the
+    // JitFrameLayout header. Turn it into an ExitFrameLayout, similar to
+    // EnsureUnwoundJitExitFrame, and call the exception handler.
+    loadJSContext(scratch);
+    enterFakeExitFrame(scratch, scratch, ExitFrameType::UnwoundJit);
+    jump(exceptionLabel());
+  }
+}
+
+void MacroAssembler::loadJitCodeRaw(Register func, Register dest) {
+  static_assert(BaseScript::offsetOfJitCodeRaw() ==
+                    SelfHostedLazyScript::offsetOfJitCodeRaw(),
+                "SelfHostedLazyScript and BaseScript must use same layout for "
+                "jitCodeRaw_");
+  loadPrivate(Address(func, JSFunction::offsetOfJitInfoOrScript()), dest);
+  loadPtr(Address(dest, BaseScript::offsetOfJitCodeRaw()), dest);
+}
+
+void MacroAssembler::loadBaselineJitCodeRaw(Register func, Register dest,
+                                            Label* failure) {
+  // Load JitScript
+  loadPrivate(Address(func, JSFunction::offsetOfJitInfoOrScript()), dest);
+  if (failure) {
+    branchIfScriptHasNoJitScript(dest, failure);
+  }
+  loadJitScript(dest, dest);
+
+  // Load BaselineScript
+  loadPtr(Address(dest, JitScript::offsetOfBaselineScript()), dest);
+  if (failure) {
+    static_assert(BaselineDisabledScript == 0x1);
+    branchPtr(Assembler::BelowOrEqual, dest, ImmWord(BaselineDisabledScript),
+              failure);
+  }
+
+  // Load Baseline jitcode
+  loadPtr(Address(dest, BaselineScript::offsetOfMethod()), dest);
+  loadPtr(Address(dest, JitCode::offsetOfCode()), dest);
+}
+
+void MacroAssembler::loadBaselineFramePtr(Register framePtr, Register dest) {
+  if (framePtr != dest) {
+    movePtr(framePtr, dest);
+  }
+  subPtr(Imm32(BaselineFrame::Size()), dest);
+}
+
+static const uint8_t* ContextInlinedICScriptPtr(CompileRuntime* rt) {
+  return (static_cast<const uint8_t*>(rt->mainContextPtr()) +
+          JSContext::offsetOfInlinedICScript());
+}
+
+void MacroAssembler::storeICScriptInJSContext(Register icScript) {
+  storePtr(icScript, AbsoluteAddress(ContextInlinedICScriptPtr(runtime())));
+}
+
+void MacroAssembler::handleFailure() {
+  // Re-entry code is irrelevant because the exception will leave the
+  // running function and never come back
+  TrampolinePtr excTail = runtime()->jitRuntime()->getExceptionTail();
+  jump(excTail);
+}
+
+void MacroAssembler::assumeUnreachable(const char* output) {
+#ifdef JS_MASM_VERBOSE
+  if (!IsCompilingWasm()) {
+    AllocatableRegisterSet regs(RegisterSet::Volatile());
+    LiveRegisterSet save(regs.asLiveSet());
+    PushRegsInMask(save);
+    Register temp = regs.takeAnyGeneral();
+
+    using Fn = void (*)(const char* output);
+    setupUnalignedABICall(temp);
+    movePtr(ImmPtr(output), temp);
+    passABIArg(temp);
+    callWithABI<Fn, AssumeUnreachable>(MoveOp::GENERAL,
+                                       CheckUnsafeCallWithABI::DontCheckOther);
+
+    PopRegsInMask(save);
+  }
+#endif
+
+  breakpoint();
+}
+
+void MacroAssembler::printf(const char* output) {
+#ifdef JS_MASM_VERBOSE
+  AllocatableRegisterSet regs(RegisterSet::Volatile());
+  LiveRegisterSet save(regs.asLiveSet());
+  PushRegsInMask(save);
+
+  Register temp = regs.takeAnyGeneral();
+
+  using Fn = void (*)(const char* output);
+  setupUnalignedABICall(temp);
+  movePtr(ImmPtr(output), temp);
+  passABIArg(temp);
+  callWithABI<Fn, Printf0>();
+
+  PopRegsInMask(save);
+#endif
+}
+
+void MacroAssembler::printf(const char* output, Register value) {
+#ifdef JS_MASM_VERBOSE
+  AllocatableRegisterSet regs(RegisterSet::Volatile());
+  LiveRegisterSet save(regs.asLiveSet());
+  PushRegsInMask(save);
+
+  regs.takeUnchecked(value);
+
+  Register temp = regs.takeAnyGeneral();
+
+  using Fn = void (*)(const char* output, uintptr_t value);
+  setupUnalignedABICall(temp);
+  movePtr(ImmPtr(output), temp);
+  passABIArg(temp);
+  passABIArg(value);
+  callWithABI<Fn, Printf1>();
+
+  PopRegsInMask(save);
+#endif
+}
+
+void MacroAssembler::convertInt32ValueToDouble(ValueOperand val) {
+  Label done;
+  branchTestInt32(Assembler::NotEqual, val, &done);
+  unboxInt32(val, val.scratchReg());
+  ScratchDoubleScope fpscratch(*this);
+  convertInt32ToDouble(val.scratchReg(), fpscratch);
+  boxDouble(fpscratch, val, fpscratch);
+  bind(&done);
+}
+
+void MacroAssembler::convertValueToFloatingPoint(ValueOperand value,
+                                                 FloatRegister output,
+                                                 Label* fail,
+                                                 MIRType outputType) {
+  Label isDouble, isInt32, isBool, isNull, done;
+
+  {
+    ScratchTagScope tag(*this, value);
+    splitTagForTest(value, tag);
+
+    branchTestDouble(Assembler::Equal, tag, &isDouble);
+    branchTestInt32(Assembler::Equal, tag, &isInt32);
+    branchTestBoolean(Assembler::Equal, tag, &isBool);
+    branchTestNull(Assembler::Equal, tag, &isNull);
+    branchTestUndefined(Assembler::NotEqual, tag, fail);
+  }
+
+  // fall-through: undefined
+  loadConstantFloatingPoint(GenericNaN(), float(GenericNaN()), output,
+                            outputType);
+  jump(&done);
+
+  bind(&isNull);
+  loadConstantFloatingPoint(0.0, 0.0f, output, outputType);
+  jump(&done);
+
+  bind(&isBool);
+  boolValueToFloatingPoint(value, output, outputType);
+  jump(&done);
+
+  bind(&isInt32);
+  int32ValueToFloatingPoint(value, output, outputType);
+  jump(&done);
+
+  // On some non-multiAlias platforms, unboxDouble may use the scratch register,
+  // so do not merge code paths here.
+  bind(&isDouble);
+  if (outputType == MIRType::Float32 && hasMultiAlias()) {
+    ScratchDoubleScope tmp(*this);
+    unboxDouble(value, tmp);
+    convertDoubleToFloat32(tmp, output);
+  } else {
+    FloatRegister tmp = output.asDouble();
+    unboxDouble(value, tmp);
+    if (outputType == MIRType::Float32) {
+      convertDoubleToFloat32(tmp, output);
+    }
+  }
+
+  bind(&done);
+}
+
+void MacroAssembler::outOfLineTruncateSlow(FloatRegister src, Register dest,
+                                           bool widenFloatToDouble,
+                                           bool compilingWasm,
+                                           wasm::BytecodeOffset callOffset) {
+  if (compilingWasm) {
+    Push(InstanceReg);
+  }
+  int32_t framePushedAfterInstance = framePushed();
+
+#if defined(JS_CODEGEN_ARM) || defined(JS_CODEGEN_ARM64) ||     \
+    defined(JS_CODEGEN_MIPS32) || defined(JS_CODEGEN_MIPS64) || \
+    defined(JS_CODEGEN_LOONG64)
+  ScratchDoubleScope fpscratch(*this);
+  if (widenFloatToDouble) {
+    convertFloat32ToDouble(src, fpscratch);
+    src = fpscratch;
+  }
+#elif defined(JS_CODEGEN_X86) || defined(JS_CODEGEN_X64)
+  FloatRegister srcSingle;
+  if (widenFloatToDouble) {
+    MOZ_ASSERT(src.isSingle());
+    srcSingle = src;
+    src = src.asDouble();
+    Push(srcSingle);
+    convertFloat32ToDouble(srcSingle, src);
+  }
+#else
+  // Also see below
+  MOZ_CRASH("MacroAssembler platform hook: outOfLineTruncateSlow");
+#endif
+
+  MOZ_ASSERT(src.isDouble());
+
+  if (compilingWasm) {
+    int32_t instanceOffset = framePushed() - framePushedAfterInstance;
+    setupWasmABICall();
+    passABIArg(src, MoveOp::DOUBLE);
+    callWithABI(callOffset, wasm::SymbolicAddress::ToInt32,
+                mozilla::Some(instanceOffset));
+  } else {
+    using Fn = int32_t (*)(double);
+    setupUnalignedABICall(dest);
+    passABIArg(src, MoveOp::DOUBLE);
+    callWithABI<Fn, JS::ToInt32>(MoveOp::GENERAL,
+                                 CheckUnsafeCallWithABI::DontCheckOther);
+  }
+  storeCallInt32Result(dest);
+
+#if defined(JS_CODEGEN_ARM) || defined(JS_CODEGEN_ARM64) ||     \
+    defined(JS_CODEGEN_MIPS32) || defined(JS_CODEGEN_MIPS64) || \
+    defined(JS_CODEGEN_LOONG64)
+  // Nothing
+#elif defined(JS_CODEGEN_X86) || defined(JS_CODEGEN_X64)
+  if (widenFloatToDouble) {
+    Pop(srcSingle);
+  }
+#else
+  MOZ_CRASH("MacroAssembler platform hook: outOfLineTruncateSlow");
+#endif
+
+  if (compilingWasm) {
+    Pop(InstanceReg);
+  }
+}
+
+void MacroAssembler::convertDoubleToInt(FloatRegister src, Register output,
+                                        FloatRegister temp, Label* truncateFail,
+                                        Label* fail,
+                                        IntConversionBehavior behavior) {
+  switch (behavior) {
+    case IntConversionBehavior::Normal:
+    case IntConversionBehavior::NegativeZeroCheck:
+      convertDoubleToInt32(
+          src, output, fail,
+          behavior == IntConversionBehavior::NegativeZeroCheck);
+      break;
+    case IntConversionBehavior::Truncate:
+      branchTruncateDoubleMaybeModUint32(src, output,
+                                         truncateFail ? truncateFail : fail);
+      break;
+    case IntConversionBehavior::TruncateNoWrap:
+      branchTruncateDoubleToInt32(src, output,
+                                  truncateFail ? truncateFail : fail);
+      break;
+    case IntConversionBehavior::ClampToUint8:
+      // Clamping clobbers the input register, so use a temp.
+      if (src != temp) {
+        moveDouble(src, temp);
+      }
+      clampDoubleToUint8(temp, output);
+      break;
+  }
+}
+
+void MacroAssembler::convertValueToInt(
+    ValueOperand value, Label* handleStringEntry, Label* handleStringRejoin,
+    Label* truncateDoubleSlow, Register stringReg, FloatRegister temp,
+    Register output, Label* fail, IntConversionBehavior behavior,
+    IntConversionInputKind conversion) {
+  Label done, isInt32, isBool, isDouble, isNull, isString;
+
+  bool handleStrings = (behavior == IntConversionBehavior::Truncate ||
+                        behavior == IntConversionBehavior::ClampToUint8) &&
+                       handleStringEntry && handleStringRejoin;
+
+  MOZ_ASSERT_IF(handleStrings, conversion == IntConversionInputKind::Any);
+
+  {
+    ScratchTagScope tag(*this, value);
+    splitTagForTest(value, tag);
+
+    branchTestInt32(Equal, tag, &isInt32);
+    if (conversion == IntConversionInputKind::Any ||
+        conversion == IntConversionInputKind::NumbersOrBoolsOnly) {
+      branchTestBoolean(Equal, tag, &isBool);
+    }
+    branchTestDouble(Equal, tag, &isDouble);
+
+    if (conversion == IntConversionInputKind::Any) {
+      // If we are not truncating, we fail for anything that's not
+      // null. Otherwise we might be able to handle strings and undefined.
+      switch (behavior) {
+        case IntConversionBehavior::Normal:
+        case IntConversionBehavior::NegativeZeroCheck:
+          branchTestNull(Assembler::NotEqual, tag, fail);
+          break;
+
+        case IntConversionBehavior::Truncate:
+        case IntConversionBehavior::TruncateNoWrap:
+        case IntConversionBehavior::ClampToUint8:
+          branchTestNull(Equal, tag, &isNull);
+          if (handleStrings) {
+            branchTestString(Equal, tag, &isString);
+          }
+          branchTestUndefined(Assembler::NotEqual, tag, fail);
+          break;
+      }
+    } else {
+      jump(fail);
+    }
+  }
+
+  // The value is null or undefined in truncation contexts - just emit 0.
+  if (conversion == IntConversionInputKind::Any) {
+    if (isNull.used()) {
+      bind(&isNull);
+    }
+    mov(ImmWord(0), output);
+    jump(&done);
+  }
+
+  // |output| needs to be different from |stringReg| to load string indices.
+  bool handleStringIndices = handleStrings && output != stringReg;
+
+  // First try loading a string index. If that fails, try converting a string
+  // into a double, then jump to the double case.
+  Label handleStringIndex;
+  if (handleStrings) {
+    bind(&isString);
+    unboxString(value, stringReg);
+    if (handleStringIndices) {
+      loadStringIndexValue(stringReg, output, handleStringEntry);
+      jump(&handleStringIndex);
+    } else {
+      jump(handleStringEntry);
+    }
+  }
+
+  // Try converting double into integer.
+  if (isDouble.used() || handleStrings) {
+    if (isDouble.used()) {
+      bind(&isDouble);
+      unboxDouble(value, temp);
+    }
+
+    if (handleStrings) {
+      bind(handleStringRejoin);
+    }
+
+    convertDoubleToInt(temp, output, temp, truncateDoubleSlow, fail, behavior);
+    jump(&done);
+  }
+
+  // Just unbox a bool, the result is 0 or 1.
+  if (isBool.used()) {
+    bind(&isBool);
+    unboxBoolean(value, output);
+    jump(&done);
+  }
+
+  // Integers can be unboxed.
+  if (isInt32.used() || handleStringIndices) {
+    if (isInt32.used()) {
+      bind(&isInt32);
+      unboxInt32(value, output);
+    }
+
+    if (handleStringIndices) {
+      bind(&handleStringIndex);
+    }
+
+    if (behavior == IntConversionBehavior::ClampToUint8) {
+      clampIntToUint8(output);
+    }
+  }
+
+  bind(&done);
+}
+
+void MacroAssembler::finish() {
+  if (failureLabel_.used()) {
+    bind(&failureLabel_);
+    handleFailure();
+  }
+
+  MacroAssemblerSpecific::finish();
+
+  MOZ_RELEASE_ASSERT(
+      size() <= MaxCodeBytesPerProcess,
+      "AssemblerBuffer should ensure we don't exceed MaxCodeBytesPerProcess");
+
+  if (bytesNeeded() > MaxCodeBytesPerProcess) {
+    setOOM();
+  }
+}
+
+void MacroAssembler::link(JitCode* code) {
+  MOZ_ASSERT(!oom());
+  linkProfilerCallSites(code);
+}
+
+MacroAssembler::AutoProfilerCallInstrumentation::
+    AutoProfilerCallInstrumentation(MacroAssembler& masm) {
+  if (!masm.emitProfilingInstrumentation_) {
+    return;
+  }
+
+  Register reg = CallTempReg0;
+  Register reg2 = CallTempReg1;
+  masm.push(reg);
+  masm.push(reg2);
+
+  CodeOffset label = masm.movWithPatch(ImmWord(uintptr_t(-1)), reg);
+  masm.loadJSContext(reg2);
+  masm.loadPtr(Address(reg2, offsetof(JSContext, profilingActivation_)), reg2);
+  masm.storePtr(reg,
+                Address(reg2, JitActivation::offsetOfLastProfilingCallSite()));
+
+  masm.appendProfilerCallSite(label);
+
+  masm.pop(reg2);
+  masm.pop(reg);
+}
+
+void MacroAssembler::linkProfilerCallSites(JitCode* code) {
+  for (size_t i = 0; i < profilerCallSites_.length(); i++) {
+    CodeOffset offset = profilerCallSites_[i];
+    CodeLocationLabel location(code, offset);
+    PatchDataWithValueCheck(location, ImmPtr(location.raw()),
+                            ImmPtr((void*)-1));
+  }
+}
+
+void MacroAssembler::alignJitStackBasedOnNArgs(Register nargs,
+                                               bool countIncludesThis) {
+  // The stack should already be aligned to the size of a value.
+  assertStackAlignment(sizeof(Value), 0);
+
+  static_assert(JitStackValueAlignment == 1 || JitStackValueAlignment == 2,
+                "JitStackValueAlignment is either 1 or 2.");
+  if (JitStackValueAlignment == 1) {
+    return;
+  }
+  // A jit frame is composed of the following:
+  //
+  // [padding?] [argN] .. [arg1] [this] [[argc] [callee] [descr] [raddr]]
+  //                                    \________JitFrameLayout_________/
+  // (The stack grows this way --->)
+  //
+  // We want to ensure that |raddr|, the return address, is 16-byte aligned.
+  // (Note: if 8-byte alignment was sufficient, we would have already
+  // returned above.)
+
+  // JitFrameLayout does not affect the alignment, so we can ignore it.
+  static_assert(sizeof(JitFrameLayout) % JitStackAlignment == 0,
+                "JitFrameLayout doesn't affect stack alignment");
+
+  // Therefore, we need to ensure that |this| is aligned.
+  // This implies that |argN| must be aligned if N is even,
+  // and offset by |sizeof(Value)| if N is odd.
+
+  // Depending on the context of the caller, it may be easier to pass in a
+  // register that has already been modified to include |this|. If that is the
+  // case, we want to flip the direction of the test.
+  Assembler::Condition condition =
+      countIncludesThis ? Assembler::NonZero : Assembler::Zero;
+
+  Label alignmentIsOffset, end;
+  branchTestPtr(condition, nargs, Imm32(1), &alignmentIsOffset);
+
+  // |argN| should be aligned to 16 bytes.
+  andToStackPtr(Imm32(~(JitStackAlignment - 1)));
+  jump(&end);
+
+  // |argN| should be offset by 8 bytes from 16-byte alignment.
+  // We already know that it is 8-byte aligned, so the only possibilities are:
+  // a) It is 16-byte aligned, and we must offset it by 8 bytes.
+  // b) It is not 16-byte aligned, and therefore already has the right offset.
+  // Therefore, we test to see if it is 16-byte aligned, and adjust it if it is.
+  bind(&alignmentIsOffset);
+  branchTestStackPtr(Assembler::NonZero, Imm32(JitStackAlignment - 1), &end);
+  subFromStackPtr(Imm32(sizeof(Value)));
+
+  bind(&end);
+}
+
+void MacroAssembler::alignJitStackBasedOnNArgs(uint32_t argc,
+                                               bool countIncludesThis) {
+  // The stack should already be aligned to the size of a value.
+  assertStackAlignment(sizeof(Value), 0);
+
+  static_assert(JitStackValueAlignment == 1 || JitStackValueAlignment == 2,
+                "JitStackValueAlignment is either 1 or 2.");
+  if (JitStackValueAlignment == 1) {
+    return;
+  }
+
+  // See above for full explanation.
+  uint32_t nArgs = argc + !countIncludesThis;
+  if (nArgs % 2 == 0) {
+    // |argN| should be 16-byte aligned
+    andToStackPtr(Imm32(~(JitStackAlignment - 1)));
+  } else {
+    // |argN| must be 16-byte aligned if argc is even,
+    // and offset by 8 if argc is odd.
+    Label end;
+    branchTestStackPtr(Assembler::NonZero, Imm32(JitStackAlignment - 1), &end);
+    subFromStackPtr(Imm32(sizeof(Value)));
+    bind(&end);
+    assertStackAlignment(JitStackAlignment, sizeof(Value));
+  }
+}
+
+// ===============================================================
+
+MacroAssembler::MacroAssembler(TempAllocator& alloc,
+                               CompileRuntime* maybeRuntime,
+                               CompileRealm* maybeRealm)
+    : maybeRuntime_(maybeRuntime),
+      maybeRealm_(maybeRealm),
+      wasmMaxOffsetGuardLimit_(0),
+      framePushed_(0),
+#ifdef DEBUG
+      inCall_(false),
+#endif
+      dynamicAlignment_(false),
+      emitProfilingInstrumentation_(false) {
+  moveResolver_.setAllocator(alloc);
+}
+
+StackMacroAssembler::StackMacroAssembler(JSContext* cx, TempAllocator& alloc)
+    : MacroAssembler(alloc, CompileRuntime::get(cx->runtime()),
+                     CompileRealm::get(cx->realm())) {}
+
+IonHeapMacroAssembler::IonHeapMacroAssembler(TempAllocator& alloc,
+                                             CompileRealm* realm)
+    : MacroAssembler(alloc, realm->runtime(), realm) {
+  MOZ_ASSERT(CurrentThreadIsIonCompiling());
+}
+
+WasmMacroAssembler::WasmMacroAssembler(TempAllocator& alloc, bool limitedSize)
+    : MacroAssembler(alloc) {
+#if defined(JS_CODEGEN_ARM64)
+  // Stubs + builtins + the baseline compiler all require the native SP,
+  // not the PSP.
+  SetStackPointer64(sp);
+#endif
+  if (!limitedSize) {
+    setUnlimitedBuffer();
+  }
+}
+
+WasmMacroAssembler::WasmMacroAssembler(TempAllocator& alloc,
+                                       const wasm::ModuleEnvironment& env,
+                                       bool limitedSize)
+    : MacroAssembler(alloc) {
+#if defined(JS_CODEGEN_ARM64)
+  // Stubs + builtins + the baseline compiler all require the native SP,
+  // not the PSP.
+  SetStackPointer64(sp);
+#endif
+  setWasmMaxOffsetGuardLimit(
+      wasm::GetMaxOffsetGuardLimit(env.hugeMemoryEnabled()));
+  if (!limitedSize) {
+    setUnlimitedBuffer();
+  }
+}
+
+bool MacroAssembler::icBuildOOLFakeExitFrame(void* fakeReturnAddr,
+                                             AutoSaveLiveRegisters& save) {
+  return buildOOLFakeExitFrame(fakeReturnAddr);
+}
+
+#ifndef JS_CODEGEN_ARM64
+void MacroAssembler::subFromStackPtr(Register reg) {
+  subPtr(reg, getStackPointer());
+}
+#endif  // JS_CODEGEN_ARM64
+
+//{{{ check_macroassembler_style
+// ===============================================================
+// Stack manipulation functions.
+
+void MacroAssembler::PushRegsInMask(LiveGeneralRegisterSet set) {
+  PushRegsInMask(LiveRegisterSet(set.set(), FloatRegisterSet()));
+}
+
+void MacroAssembler::PopRegsInMask(LiveRegisterSet set) {
+  PopRegsInMaskIgnore(set, LiveRegisterSet());
+}
+
+void MacroAssembler::PopRegsInMask(LiveGeneralRegisterSet set) {
+  PopRegsInMask(LiveRegisterSet(set.set(), FloatRegisterSet()));
+}
+
+void MacroAssembler::Push(PropertyKey key, Register scratchReg) {
+  if (key.isGCThing()) {
+    // If we're pushing a gcthing, then we can't just push the tagged key
+    // value since the GC won't have any idea that the push instruction
+    // carries a reference to a gcthing.  Need to unpack the pointer,
+    // push it using ImmGCPtr, and then rematerialize the PropertyKey at
+    // runtime.
+
+    if (key.isString()) {
+      JSString* str = key.toString();
+      MOZ_ASSERT((uintptr_t(str) & PropertyKey::TypeMask) == 0);
+      static_assert(PropertyKey::StringTypeTag == 0,
+                    "need to orPtr StringTypeTag if it's not 0");
+      Push(ImmGCPtr(str));
+    } else {
+      MOZ_ASSERT(key.isSymbol());
+      movePropertyKey(key, scratchReg);
+      Push(scratchReg);
+    }
+  } else {
+    MOZ_ASSERT(key.isInt());
+    Push(ImmWord(key.asRawBits()));
+  }
+}
+
+void MacroAssembler::movePropertyKey(PropertyKey key, Register dest) {
+  if (key.isGCThing()) {
+    // See comment in |Push(PropertyKey, ...)| above for an explanation.
+    if (key.isString()) {
+      JSString* str = key.toString();
+      MOZ_ASSERT((uintptr_t(str) & PropertyKey::TypeMask) == 0);
+      static_assert(PropertyKey::StringTypeTag == 0,
+                    "need to orPtr JSID_TYPE_STRING tag if it's not 0");
+      movePtr(ImmGCPtr(str), dest);
+    } else {
+      MOZ_ASSERT(key.isSymbol());
+      JS::Symbol* sym = key.toSymbol();
+      movePtr(ImmGCPtr(sym), dest);
+      orPtr(Imm32(PropertyKey::SymbolTypeTag), dest);
+    }
+  } else {
+    MOZ_ASSERT(key.isInt());
+    movePtr(ImmWord(key.asRawBits()), dest);
+  }
+}
+
+void MacroAssembler::Push(TypedOrValueRegister v) {
+  if (v.hasValue()) {
+    Push(v.valueReg());
+  } else if (IsFloatingPointType(v.type())) {
+    FloatRegister reg = v.typedReg().fpu();
+    if (v.type() == MIRType::Float32) {
+      ScratchDoubleScope fpscratch(*this);
+      convertFloat32ToDouble(reg, fpscratch);
+      PushBoxed(fpscratch);
+    } else {
+      PushBoxed(reg);
+    }
+  } else {
+    Push(ValueTypeFromMIRType(v.type()), v.typedReg().gpr());
+  }
+}
+
+void MacroAssembler::Push(const ConstantOrRegister& v) {
+  if (v.constant()) {
+    Push(v.value());
+  } else {
+    Push(v.reg());
+  }
+}
+
+void MacroAssembler::Push(const Address& addr) {
+  push(addr);
+  framePushed_ += sizeof(uintptr_t);
+}
+
+void MacroAssembler::Push(const ValueOperand& val) {
+  pushValue(val);
+  framePushed_ += sizeof(Value);
+}
+
+void MacroAssembler::Push(const Value& val) {
+  pushValue(val);
+  framePushed_ += sizeof(Value);
+}
+
+void MacroAssembler::Push(JSValueType type, Register reg) {
+  pushValue(type, reg);
+  framePushed_ += sizeof(Value);
+}
+
+void MacroAssembler::Push(const Register64 reg) {
+#if JS_BITS_PER_WORD == 64
+  Push(reg.reg);
+#else
+  MOZ_ASSERT(MOZ_LITTLE_ENDIAN(), "Big-endian not supported.");
+  Push(reg.high);
+  Push(reg.low);
+#endif
+}
+
+void MacroAssembler::PushEmptyRooted(VMFunctionData::RootType rootType) {
+  switch (rootType) {
+    case VMFunctionData::RootNone:
+      MOZ_CRASH("Handle must have root type");
+    case VMFunctionData::RootObject:
+    case VMFunctionData::RootString:
+    case VMFunctionData::RootCell:
+    case VMFunctionData::RootBigInt:
+      Push(ImmPtr(nullptr));
+      break;
+    case VMFunctionData::RootValue:
+      Push(UndefinedValue());
+      break;
+    case VMFunctionData::RootId:
+      Push(ImmWord(JS::PropertyKey::Void().asRawBits()));
+      break;
+  }
+}
+
+void MacroAssembler::popRooted(VMFunctionData::RootType rootType,
+                               Register cellReg, const ValueOperand& valueReg) {
+  switch (rootType) {
+    case VMFunctionData::RootNone:
+      MOZ_CRASH("Handle must have root type");
+    case VMFunctionData::RootObject:
+    case VMFunctionData::RootString:
+    case VMFunctionData::RootCell:
+    case VMFunctionData::RootId:
+    case VMFunctionData::RootBigInt:
+      Pop(cellReg);
+      break;
+    case VMFunctionData::RootValue:
+      Pop(valueReg);
+      break;
+  }
+}
+
+void MacroAssembler::adjustStack(int amount) {
+  if (amount > 0) {
+    freeStack(amount);
+  } else if (amount < 0) {
+    reserveStack(-amount);
+  }
+}
+
+void MacroAssembler::freeStack(uint32_t amount) {
+  MOZ_ASSERT(amount <= framePushed_);
+  if (amount) {
+    addToStackPtr(Imm32(amount));
+  }
+  framePushed_ -= amount;
+}
+
+void MacroAssembler::freeStack(Register amount) { addToStackPtr(amount); }
+
+// ===============================================================
+// ABI function calls.
+template <class ABIArgGeneratorT>
+void MacroAssembler::setupABICallHelper() {
+#ifdef DEBUG
+  MOZ_ASSERT(!inCall_);
+  inCall_ = true;
+#endif
+
+#ifdef JS_SIMULATOR
+  signature_ = 0;
+#endif
+
+  // Reinitialize the ABIArg generator.
+  abiArgs_ = ABIArgGeneratorT();
+
+#if defined(JS_CODEGEN_ARM)
+  // On ARM, we need to know what ABI we are using, either in the
+  // simulator, or based on the configure flags.
+#  if defined(JS_SIMULATOR_ARM)
+  abiArgs_.setUseHardFp(UseHardFpABI());
+#  elif defined(JS_CODEGEN_ARM_HARDFP)
+  abiArgs_.setUseHardFp(true);
+#  else
+  abiArgs_.setUseHardFp(false);
+#  endif
+#endif
+
+#if defined(JS_CODEGEN_MIPS32)
+  // On MIPS, the system ABI use general registers pairs to encode double
+  // arguments, after one or 2 integer-like arguments. Unfortunately, the
+  // Lowering phase is not capable to express it at the moment. So we enforce
+  // the system ABI here.
+  abiArgs_.enforceO32ABI();
+#endif
+}
+
+void MacroAssembler::setupNativeABICall() {
+  setupABICallHelper<ABIArgGenerator>();
+}
+
+void MacroAssembler::setupWasmABICall() {
+  MOZ_ASSERT(IsCompilingWasm(), "non-wasm should use setupAlignedABICall");
+  setupABICallHelper<WasmABIArgGenerator>();
+
+#if defined(JS_CODEGEN_ARM)
+  // The builtin thunk does the FP -> GPR moving on soft-FP, so
+  // use hard fp unconditionally.
+  abiArgs_.setUseHardFp(true);
+#endif
+  dynamicAlignment_ = false;
+}
+
+void MacroAssembler::setupAlignedABICall() {
+  MOZ_ASSERT(!IsCompilingWasm(), "wasm should use setupWasmABICall");
+  setupNativeABICall();
+  dynamicAlignment_ = false;
+}
+
+void MacroAssembler::passABIArg(const MoveOperand& from, MoveOp::Type type) {
+  MOZ_ASSERT(inCall_);
+  appendSignatureType(type);
+
+  ABIArg arg;
+  switch (type) {
+    case MoveOp::FLOAT32:
+      arg = abiArgs_.next(MIRType::Float32);
+      break;
+    case MoveOp::DOUBLE:
+      arg = abiArgs_.next(MIRType::Double);
+      break;
+    case MoveOp::GENERAL:
+      arg = abiArgs_.next(MIRType::Pointer);
+      break;
+    default:
+      MOZ_CRASH("Unexpected argument type");
+  }
+
+  MoveOperand to(*this, arg);
+  if (from == to) {
+    return;
+  }
+
+  if (oom()) {
+    return;
+  }
+  propagateOOM(moveResolver_.addMove(from, to, type));
+}
+
+void MacroAssembler::callWithABINoProfiler(void* fun, MoveOp::Type result,
+                                           CheckUnsafeCallWithABI check) {
+  appendSignatureType(result);
+#ifdef JS_SIMULATOR
+  fun = Simulator::RedirectNativeFunction(fun, signature());
+#endif
+
+  uint32_t stackAdjust;
+  callWithABIPre(&stackAdjust);
+
+#ifdef DEBUG
+  if (check == CheckUnsafeCallWithABI::Check) {
+    push(ReturnReg);
+    loadJSContext(ReturnReg);
+    Address flagAddr(ReturnReg, JSContext::offsetOfInUnsafeCallWithABI());
+    store32(Imm32(1), flagAddr);
+    pop(ReturnReg);
+    // On arm64, SP may be < PSP now (that's OK).
+    // eg testcase: tests/bug1375074.js
+  }
+#endif
+
+  call(ImmPtr(fun));
+
+  callWithABIPost(stackAdjust, result);
+
+#ifdef DEBUG
+  if (check == CheckUnsafeCallWithABI::Check) {
+    Label ok;
+    push(ReturnReg);
+    loadJSContext(ReturnReg);
+    Address flagAddr(ReturnReg, JSContext::offsetOfInUnsafeCallWithABI());
+    branch32(Assembler::Equal, flagAddr, Imm32(0), &ok);
+    assumeUnreachable("callWithABI: callee did not use AutoUnsafeCallWithABI");
+    bind(&ok);
+    pop(ReturnReg);
+    // On arm64, SP may be < PSP now (that's OK).
+    // eg testcase: tests/bug1375074.js
+  }
+#endif
+}
+
+CodeOffset MacroAssembler::callWithABI(wasm::BytecodeOffset bytecode,
+                                       wasm::SymbolicAddress imm,
+                                       mozilla::Maybe<int32_t> instanceOffset,
+                                       MoveOp::Type result) {
+  MOZ_ASSERT(wasm::NeedsBuiltinThunk(imm));
+
+  uint32_t stackAdjust;
+  callWithABIPre(&stackAdjust, /* callFromWasm = */ true);
+
+  // The instance register is used in builtin thunks and must be set.
+  if (instanceOffset) {
+    loadPtr(Address(getStackPointer(), *instanceOffset + stackAdjust),
+            InstanceReg);
+  } else {
+    MOZ_CRASH("instanceOffset is Nothing only for unsupported abi calls.");
+  }
+  CodeOffset raOffset = call(
+      wasm::CallSiteDesc(bytecode.offset(), wasm::CallSite::Symbolic), imm);
+
+  callWithABIPost(stackAdjust, result, /* callFromWasm = */ true);
+
+  return raOffset;
+}
+
+void MacroAssembler::callDebugWithABI(wasm::SymbolicAddress imm,
+                                      MoveOp::Type result) {
+  MOZ_ASSERT(!wasm::NeedsBuiltinThunk(imm));
+  uint32_t stackAdjust;
+  callWithABIPre(&stackAdjust, /* callFromWasm = */ false);
+  call(imm);
+  callWithABIPost(stackAdjust, result, /* callFromWasm = */ false);
+}
+
+// ===============================================================
+// Exit frame footer.
+
+void MacroAssembler::linkExitFrame(Register cxreg, Register scratch) {
+  loadPtr(Address(cxreg, JSContext::offsetOfActivation()), scratch);
+  storeStackPtr(Address(scratch, JitActivation::offsetOfPackedExitFP()));
+}
+
+// ===============================================================
+// Simple value-shuffling helpers, to hide MoveResolver verbosity
+// in common cases.
+
+void MacroAssembler::moveRegPair(Register src0, Register src1, Register dst0,
+                                 Register dst1, MoveOp::Type type) {
+  MoveResolver& moves = moveResolver();
+  if (src0 != dst0) {
+    propagateOOM(moves.addMove(MoveOperand(src0), MoveOperand(dst0), type));
+  }
+  if (src1 != dst1) {
+    propagateOOM(moves.addMove(MoveOperand(src1), MoveOperand(dst1), type));
+  }
+  propagateOOM(moves.resolve());
+  if (oom()) {
+    return;
+  }
+
+  MoveEmitter emitter(*this);
+  emitter.emit(moves);
+  emitter.finish();
+}
+
+// ===============================================================
+// Arithmetic functions
+
+void MacroAssembler::pow32(Register base, Register power, Register dest,
+                           Register temp1, Register temp2, Label* onOver) {
+  // Inline int32-specialized implementation of js::powi with overflow
+  // detection.
+
+  move32(Imm32(1), dest);  // result = 1
+
+  // x^y where x == 1 returns 1 for any y.
+  Label done;
+  branch32(Assembler::Equal, base, Imm32(1), &done);
+
+  move32(base, temp1);   // runningSquare = x
+  move32(power, temp2);  // n = y
+
+  // x^y where y < 0 returns a non-int32 value for any x != 1. Except when y is
+  // large enough so that the result is no longer representable as a double with
+  // fractional parts. We can't easily determine when y is too large, so we bail
+  // here.
+  // Note: it's important for this condition to match the code in CacheIR.cpp
+  // (CanAttachInt32Pow) to prevent failure loops.
+  Label start;
+  branchTest32(Assembler::NotSigned, power, power, &start);
+  jump(onOver);
+
+  Label loop;
+  bind(&loop);
+
+  // runningSquare *= runningSquare
+  branchMul32(Assembler::Overflow, temp1, temp1, onOver);
+
+  bind(&start);
+
+  // if ((n & 1) != 0) result *= runningSquare
+  Label even;
+  branchTest32(Assembler::Zero, temp2, Imm32(1), &even);
+  branchMul32(Assembler::Overflow, temp1, dest, onOver);
+  bind(&even);
+
+  // n >>= 1
+  // if (n == 0) return result
+  branchRshift32(Assembler::NonZero, Imm32(1), temp2, &loop);
+
+  bind(&done);
+}
+
+void MacroAssembler::signInt32(Register input, Register output) {
+  MOZ_ASSERT(input != output);
+
+  Label done;
+  move32(input, output);
+  rshift32Arithmetic(Imm32(31), output);
+  branch32(Assembler::LessThanOrEqual, input, Imm32(0), &done);
+  move32(Imm32(1), output);
+  bind(&done);
+}
+
+void MacroAssembler::signDouble(FloatRegister input, FloatRegister output) {
+  MOZ_ASSERT(input != output);
+
+  Label done, zeroOrNaN, negative;
+  loadConstantDouble(0.0, output);
+  branchDouble(Assembler::DoubleEqualOrUnordered, input, output, &zeroOrNaN);
+  branchDouble(Assembler::DoubleLessThan, input, output, &negative);
+
+  loadConstantDouble(1.0, output);
+  jump(&done);
+
+  bind(&negative);
+  loadConstantDouble(-1.0, output);
+  jump(&done);
+
+  bind(&zeroOrNaN);
+  moveDouble(input, output);
+
+  bind(&done);
+}
+
+void MacroAssembler::signDoubleToInt32(FloatRegister input, Register output,
+                                       FloatRegister temp, Label* fail) {
+  MOZ_ASSERT(input != temp);
+
+  Label done, zeroOrNaN, negative;
+  loadConstantDouble(0.0, temp);
+  branchDouble(Assembler::DoubleEqualOrUnordered, input, temp, &zeroOrNaN);
+  branchDouble(Assembler::DoubleLessThan, input, temp, &negative);
+
+  move32(Imm32(1), output);
+  jump(&done);
+
+  bind(&negative);
+  move32(Imm32(-1), output);
+  jump(&done);
+
+  // Fail for NaN and negative zero.
+  bind(&zeroOrNaN);
+  branchDouble(Assembler::DoubleUnordered, input, input, fail);
+
+  // The easiest way to distinguish -0.0 from 0.0 is that 1.0/-0.0
+  // is -Infinity instead of Infinity.
+  loadConstantDouble(1.0, temp);
+  divDouble(input, temp);
+  branchDouble(Assembler::DoubleLessThan, temp, input, fail);
+  move32(Imm32(0), output);
+
+  bind(&done);
+}
+
+void MacroAssembler::randomDouble(Register rng, FloatRegister dest,
+                                  Register64 temp0, Register64 temp1) {
+  using mozilla::non_crypto::XorShift128PlusRNG;
+
+  static_assert(
+      sizeof(XorShift128PlusRNG) == 2 * sizeof(uint64_t),
+      "Code below assumes XorShift128PlusRNG contains two uint64_t values");
+
+  Address state0Addr(rng, XorShift128PlusRNG::offsetOfState0());
+  Address state1Addr(rng, XorShift128PlusRNG::offsetOfState1());
+
+  Register64 s0Reg = temp0;
+  Register64 s1Reg = temp1;
+
+  // uint64_t s1 = mState[0];
+  load64(state0Addr, s1Reg);
+
+  // s1 ^= s1 << 23;
+  move64(s1Reg, s0Reg);
+  lshift64(Imm32(23), s1Reg);
+  xor64(s0Reg, s1Reg);
+
+  // s1 ^= s1 >> 17
+  move64(s1Reg, s0Reg);
+  rshift64(Imm32(17), s1Reg);
+  xor64(s0Reg, s1Reg);
+
+  // const uint64_t s0 = mState[1];
+  load64(state1Addr, s0Reg);
+
+  // mState[0] = s0;
+  store64(s0Reg, state0Addr);
+
+  // s1 ^= s0
+  xor64(s0Reg, s1Reg);
+
+  // s1 ^= s0 >> 26
+  rshift64(Imm32(26), s0Reg);
+  xor64(s0Reg, s1Reg);
+
+  // mState[1] = s1
+  store64(s1Reg, state1Addr);
+
+  // s1 += mState[0]
+  load64(state0Addr, s0Reg);
+  add64(s0Reg, s1Reg);
+
+  // See comment in XorShift128PlusRNG::nextDouble().
+  static constexpr int MantissaBits =
+      mozilla::FloatingPoint<double>::kExponentShift + 1;
+  static constexpr double ScaleInv = double(1) / (1ULL << MantissaBits);
+
+  and64(Imm64((1ULL << MantissaBits) - 1), s1Reg);
+
+  // Note: we know s1Reg isn't signed after the and64 so we can use the faster
+  // convertInt64ToDouble instead of convertUInt64ToDouble.
+  convertInt64ToDouble(s1Reg, dest);
+
+  // dest *= ScaleInv
+  mulDoublePtr(ImmPtr(&ScaleInv), s0Reg.scratchReg(), dest);
+}
+
+void MacroAssembler::sameValueDouble(FloatRegister left, FloatRegister right,
+                                     FloatRegister temp, Register dest) {
+  Label nonEqual, isSameValue, isNotSameValue;
+  branchDouble(Assembler::DoubleNotEqualOrUnordered, left, right, &nonEqual);
+  {
+    // First, test for being equal to 0.0, which also includes -0.0.
+    loadConstantDouble(0.0, temp);
+    branchDouble(Assembler::DoubleNotEqual, left, temp, &isSameValue);
+
+    // The easiest way to distinguish -0.0 from 0.0 is that 1.0/-0.0
+    // is -Infinity instead of Infinity.
+    Label isNegInf;
+    loadConstantDouble(1.0, temp);
+    divDouble(left, temp);
+    branchDouble(Assembler::DoubleLessThan, temp, left, &isNegInf);
+    {
+      loadConstantDouble(1.0, temp);
+      divDouble(right, temp);
+      branchDouble(Assembler::DoubleGreaterThan, temp, right, &isSameValue);
+      jump(&isNotSameValue);
+    }
+    bind(&isNegInf);
+    {
+      loadConstantDouble(1.0, temp);
+      divDouble(right, temp);
+      branchDouble(Assembler::DoubleLessThan, temp, right, &isSameValue);
+      jump(&isNotSameValue);
+    }
+  }
+  bind(&nonEqual);
+  {
+    // Test if both values are NaN.
+    branchDouble(Assembler::DoubleOrdered, left, left, &isNotSameValue);
+    branchDouble(Assembler::DoubleOrdered, right, right, &isNotSameValue);
+  }
+
+  Label done;
+  bind(&isSameValue);
+  move32(Imm32(1), dest);
+  jump(&done);
+
+  bind(&isNotSameValue);
+  move32(Imm32(0), dest);
+
+  bind(&done);
+}
+
+void MacroAssembler::minMaxArrayInt32(Register array, Register result,
+                                      Register temp1, Register temp2,
+                                      Register temp3, bool isMax, Label* fail) {
+  // array must be a packed array. Load its elements.
+  Register elements = temp1;
+  loadPtr(Address(array, NativeObject::offsetOfElements()), elements);
+
+  // Load the length and guard that it is non-zero.
+  Address lengthAddr(elements, ObjectElements::offsetOfInitializedLength());
+  load32(lengthAddr, temp3);
+  branchTest32(Assembler::Zero, temp3, temp3, fail);
+
+  // Compute the address of the last element.
+  Register elementsEnd = temp2;
+  BaseObjectElementIndex elementsEndAddr(elements, temp3,
+                                         -int32_t(sizeof(Value)));
+  computeEffectiveAddress(elementsEndAddr, elementsEnd);
+
+  // Load the first element into result.
+  fallibleUnboxInt32(Address(elements, 0), result, fail);
+
+  Label loop, done;
+  bind(&loop);
+
+  // Check whether we're done.
+  branchPtr(Assembler::Equal, elements, elementsEnd, &done);
+
+  // If not, advance to the next element and load it.
+  addPtr(Imm32(sizeof(Value)), elements);
+  fallibleUnboxInt32(Address(elements, 0), temp3, fail);
+
+  // Update result if necessary.
+  Assembler::Condition cond =
+      isMax ? Assembler::GreaterThan : Assembler::LessThan;
+  cmp32Move32(cond, temp3, result, temp3, result);
+
+  jump(&loop);
+  bind(&done);
+}
+
+void MacroAssembler::minMaxArrayNumber(Register array, FloatRegister result,
+                                       FloatRegister floatTemp, Register temp1,
+                                       Register temp2, bool isMax,
+                                       Label* fail) {
+  // array must be a packed array. Load its elements.
+  Register elements = temp1;
+  loadPtr(Address(array, NativeObject::offsetOfElements()), elements);
+
+  // Load the length and check if the array is empty.
+  Label isEmpty;
+  Address lengthAddr(elements, ObjectElements::offsetOfInitializedLength());
+  load32(lengthAddr, temp2);
+  branchTest32(Assembler::Zero, temp2, temp2, &isEmpty);
+
+  // Compute the address of the last element.
+  Register elementsEnd = temp2;
+  BaseObjectElementIndex elementsEndAddr(elements, temp2,
+                                         -int32_t(sizeof(Value)));
+  computeEffectiveAddress(elementsEndAddr, elementsEnd);
+
+  // Load the first element into result.
+  ensureDouble(Address(elements, 0), result, fail);
+
+  Label loop, done;
+  bind(&loop);
+
+  // Check whether we're done.
+  branchPtr(Assembler::Equal, elements, elementsEnd, &done);
+
+  // If not, advance to the next element and load it into floatTemp.
+  addPtr(Imm32(sizeof(Value)), elements);
+  ensureDouble(Address(elements, 0), floatTemp, fail);
+
+  // Update result if necessary.
+  if (isMax) {
+    maxDouble(floatTemp, result, /* handleNaN = */ true);
+  } else {
+    minDouble(floatTemp, result, /* handleNaN = */ true);
+  }
+  jump(&loop);
+
+  // With no arguments, min/max return +Infinity/-Infinity respectively.
+  bind(&isEmpty);
+  if (isMax) {
+    loadConstantDouble(mozilla::NegativeInfinity<double>(), result);
+  } else {
+    loadConstantDouble(mozilla::PositiveInfinity<double>(), result);
+  }
+
+  bind(&done);
+}
+
+void MacroAssembler::branchIfNotRegExpPrototypeOptimizable(Register proto,
+                                                           Register temp,
+                                                           Label* fail) {
+  loadJSContext(temp);
+  loadPtr(Address(temp, JSContext::offsetOfRealm()), temp);
+  size_t offset = Realm::offsetOfRegExps() +
+                  RegExpRealm::offsetOfOptimizableRegExpPrototypeShape();
+  loadPtr(Address(temp, offset), temp);
+  branchTestObjShapeUnsafe(Assembler::NotEqual, proto, temp, fail);
+}
+
+void MacroAssembler::branchIfNotRegExpInstanceOptimizable(Register regexp,
+                                                          Register temp,
+                                                          Label* label) {
+  loadJSContext(temp);
+  loadPtr(Address(temp, JSContext::offsetOfRealm()), temp);
+  size_t offset = Realm::offsetOfRegExps() +
+                  RegExpRealm::offsetOfOptimizableRegExpInstanceShape();
+  loadPtr(Address(temp, offset), temp);
+  branchTestObjShapeUnsafe(Assembler::NotEqual, regexp, temp, label);
+}
+
+// ===============================================================
+// Branch functions
+
+void MacroAssembler::loadFunctionLength(Register func,
+                                        Register funFlagsAndArgCount,
+                                        Register output, Label* slowPath) {
+#ifdef DEBUG
+  {
+    // These flags should already have been checked by caller.
+    Label ok;
+    uint32_t FlagsToCheck =
+        FunctionFlags::SELFHOSTLAZY | FunctionFlags::RESOLVED_LENGTH;
+    branchTest32(Assembler::Zero, funFlagsAndArgCount, Imm32(FlagsToCheck),
+                 &ok);
+    assumeUnreachable("The function flags should already have been checked.");
+    bind(&ok);
+  }
+#endif  // DEBUG
+
+  // NOTE: `funFlagsAndArgCount` and `output` must be allowed to alias.
+
+  // Load the target function's length.
+  Label isInterpreted, isBound, lengthLoaded;
+  branchTest32(Assembler::NonZero, funFlagsAndArgCount,
+               Imm32(FunctionFlags::BOUND_FUN), &isBound);
+  branchTest32(Assembler::NonZero, funFlagsAndArgCount,
+               Imm32(FunctionFlags::BASESCRIPT), &isInterpreted);
+  {
+    // The length property of a native function stored with the flags.
+    move32(funFlagsAndArgCount, output);
+    rshift32(Imm32(JSFunction::ArgCountShift), output);
+    jump(&lengthLoaded);
+  }
+  bind(&isBound);
+  {
+    // Load the length property of a bound function.
+    Address boundLength(func,
+                        FunctionExtended::offsetOfBoundFunctionLengthSlot());
+    fallibleUnboxInt32(boundLength, output, slowPath);
+    jump(&lengthLoaded);
+  }
+  bind(&isInterpreted);
+  {
+    // Load the length property of an interpreted function.
+    loadPrivate(Address(func, JSFunction::offsetOfJitInfoOrScript()), output);
+    loadPtr(Address(output, JSScript::offsetOfSharedData()), output);
+    branchTestPtr(Assembler::Zero, output, output, slowPath);
+    loadPtr(Address(output, SharedImmutableScriptData::offsetOfISD()), output);
+    load16ZeroExtend(Address(output, ImmutableScriptData::offsetOfFunLength()),
+                     output);
+  }
+  bind(&lengthLoaded);
+}
+
+void MacroAssembler::loadFunctionName(Register func, Register output,
+                                      ImmGCPtr emptyString, Label* slowPath) {
+  MOZ_ASSERT(func != output);
+
+  // Get the JSFunction flags.
+  load32(Address(func, JSFunction::offsetOfFlagsAndArgCount()), output);
+
+  // If the name was previously resolved, the name property may be shadowed.
+  branchTest32(Assembler::NonZero, output, Imm32(FunctionFlags::RESOLVED_NAME),
+               slowPath);
+
+  Label notBoundTarget, loadName;
+  branchTest32(Assembler::Zero, output, Imm32(FunctionFlags::BOUND_FUN),
+               &notBoundTarget);
+  {
+    // Call into the VM if the target's name atom doesn't contain the bound
+    // function prefix.
+    branchTest32(Assembler::Zero, output,
+                 Imm32(FunctionFlags::HAS_BOUND_FUNCTION_NAME_PREFIX),
+                 slowPath);
+
+    // Bound functions reuse HAS_GUESSED_ATOM for
+    // HAS_BOUND_FUNCTION_NAME_PREFIX, so skip the guessed atom check below.
+    static_assert(
+        FunctionFlags::HAS_BOUND_FUNCTION_NAME_PREFIX ==
+            FunctionFlags::HAS_GUESSED_ATOM,
+        "HAS_BOUND_FUNCTION_NAME_PREFIX is shared with HAS_GUESSED_ATOM");
+    jump(&loadName);
+  }
+  bind(&notBoundTarget);
+
+  Label noName, done;
+  branchTest32(Assembler::NonZero, output,
+               Imm32(FunctionFlags::HAS_GUESSED_ATOM), &noName);
+
+  bind(&loadName);
+  Address atomAddr(func, JSFunction::offsetOfAtom());
+  branchTestUndefined(Assembler::Equal, atomAddr, &noName);
+  unboxString(atomAddr, output);
+  jump(&done);
+
+  {
+    bind(&noName);
+
+    // An absent name property defaults to the empty string.
+    movePtr(emptyString, output);
+  }
+
+  bind(&done);
+}
+
+void MacroAssembler::assertFunctionIsExtended(Register func) {
+#ifdef DEBUG
+  Label extended;
+  branchTestFunctionFlags(func, FunctionFlags::EXTENDED, Assembler::NonZero,
+                          &extended);
+  assumeUnreachable("Function is not extended");
+  bind(&extended);
+#endif
+}
+
+void MacroAssembler::branchTestType(Condition cond, Register tag,
+                                    JSValueType type, Label* label) {
+  switch (type) {
+    case JSVAL_TYPE_DOUBLE:
+      branchTestDouble(cond, tag, label);
+      break;
+    case JSVAL_TYPE_INT32:
+      branchTestInt32(cond, tag, label);
+      break;
+    case JSVAL_TYPE_BOOLEAN:
+      branchTestBoolean(cond, tag, label);
+      break;
+    case JSVAL_TYPE_UNDEFINED:
+      branchTestUndefined(cond, tag, label);
+      break;
+    case JSVAL_TYPE_NULL:
+      branchTestNull(cond, tag, label);
+      break;
+    case JSVAL_TYPE_MAGIC:
+      branchTestMagic(cond, tag, label);
+      break;
+    case JSVAL_TYPE_STRING:
+      branchTestString(cond, tag, label);
+      break;
+    case JSVAL_TYPE_SYMBOL:
+      branchTestSymbol(cond, tag, label);
+      break;
+    case JSVAL_TYPE_BIGINT:
+      branchTestBigInt(cond, tag, label);
+      break;
+    case JSVAL_TYPE_OBJECT:
+      branchTestObject(cond, tag, label);
+      break;
+    default:
+      MOZ_CRASH("Unexpected value type");
+  }
+}
+
+void MacroAssembler::branchTestObjShapeList(
+    Condition cond, Register obj, Register shapeElements, Register shapeScratch,
+    Register endScratch, Register spectreScratch, Label* label) {
+  MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+
+  bool needSpectreMitigations = spectreScratch != InvalidReg;
+
+  Label done;
+  Label* onMatch = cond == Assembler::Equal ? label : &done;
+
+  // Load the object's shape pointer into shapeScratch, and prepare to compare
+  // it with the shapes in the list. On 64-bit, we box the shape. On 32-bit,
+  // we only have to compare the 32-bit payload.
+#ifdef JS_PUNBOX64
+  loadPtr(Address(obj, JSObject::offsetOfShape()), endScratch);
+  tagValue(JSVAL_TYPE_PRIVATE_GCTHING, endScratch, ValueOperand(shapeScratch));
+#else
+  loadPtr(Address(obj, JSObject::offsetOfShape()), shapeScratch);
+#endif
+
+  // Compute end pointer.
+  Address lengthAddr(shapeElements,
+                     ObjectElements::offsetOfInitializedLength());
+  load32(lengthAddr, endScratch);
+  BaseObjectElementIndex endPtrAddr(shapeElements, endScratch);
+  computeEffectiveAddress(endPtrAddr, endScratch);
+
+  Label loop;
+  bind(&loop);
+
+  // Compare the object's shape with a shape from the list. Note that on 64-bit
+  // this includes the tag bits, but on 32-bit we only compare the low word of
+  // the value. This is fine because the list of shapes is never exposed and the
+  // tag is guaranteed to be PrivateGCThing.
+  if (needSpectreMitigations) {
+    move32(Imm32(0), spectreScratch);
+  }
+  branchPtr(Assembler::Equal, Address(shapeElements, 0), shapeScratch, onMatch);
+  if (needSpectreMitigations) {
+    spectreMovePtr(Assembler::Equal, spectreScratch, obj);
+  }
+
+  // Advance to next shape and loop if not finished.
+  addPtr(Imm32(sizeof(Value)), shapeElements);
+  branchPtr(Assembler::Below, shapeElements, endScratch, &loop);
+
+  if (cond == Assembler::NotEqual) {
+    jump(label);
+    bind(&done);
+  }
+}
+
+void MacroAssembler::branchTestObjCompartment(Condition cond, Register obj,
+                                              const Address& compartment,
+                                              Register scratch, Label* label) {
+  MOZ_ASSERT(obj != scratch);
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch);
+  loadPtr(Address(scratch, Shape::offsetOfBaseShape()), scratch);
+  loadPtr(Address(scratch, BaseShape::offsetOfRealm()), scratch);
+  loadPtr(Address(scratch, Realm::offsetOfCompartment()), scratch);
+  branchPtr(cond, compartment, scratch, label);
+}
+
+void MacroAssembler::branchTestObjCompartment(
+    Condition cond, Register obj, const JS::Compartment* compartment,
+    Register scratch, Label* label) {
+  MOZ_ASSERT(obj != scratch);
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch);
+  loadPtr(Address(scratch, Shape::offsetOfBaseShape()), scratch);
+  loadPtr(Address(scratch, BaseShape::offsetOfRealm()), scratch);
+  loadPtr(Address(scratch, Realm::offsetOfCompartment()), scratch);
+  branchPtr(cond, scratch, ImmPtr(compartment), label);
+}
+
+void MacroAssembler::branchIfNonNativeObj(Register obj, Register scratch,
+                                          Label* label) {
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch);
+  branchTest32(Assembler::Zero,
+               Address(scratch, Shape::offsetOfImmutableFlags()),
+               Imm32(Shape::isNativeBit()), label);
+}
+
+void MacroAssembler::branchIfObjectNotExtensible(Register obj, Register scratch,
+                                                 Label* label) {
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch);
+
+  // Spectre-style checks are not needed here because we do not interpret data
+  // based on this check.
+  static_assert(sizeof(ObjectFlags) == sizeof(uint16_t));
+  load16ZeroExtend(Address(scratch, Shape::offsetOfObjectFlags()), scratch);
+  branchTest32(Assembler::NonZero, scratch,
+               Imm32(uint32_t(ObjectFlag::NotExtensible)), label);
+}
+
+void MacroAssembler::wasmTrap(wasm::Trap trap,
+                              wasm::BytecodeOffset bytecodeOffset) {
+  uint32_t trapOffset = wasmTrapInstruction().offset();
+  MOZ_ASSERT_IF(!oom(),
+                currentOffset() - trapOffset == WasmTrapInstructionLength);
+
+  append(trap, wasm::TrapSite(trapOffset, bytecodeOffset));
+}
+
+std::pair<CodeOffset, uint32_t> MacroAssembler::wasmReserveStackChecked(
+    uint32_t amount, wasm::BytecodeOffset trapOffset) {
+  if (amount > MAX_UNCHECKED_LEAF_FRAME_SIZE) {
+    // The frame is large.  Don't bump sp until after the stack limit check so
+    // that the trap handler isn't called with a wild sp.
+    Label ok;
+    Register scratch = ABINonArgReg0;
+    moveStackPtrTo(scratch);
+
+    Label trap;
+    branchPtr(Assembler::Below, scratch, Imm32(amount), &trap);
+    subPtr(Imm32(amount), scratch);
+    branchPtr(Assembler::Below,
+              Address(InstanceReg, wasm::Instance::offsetOfStackLimit()),
+              scratch, &ok);
+
+    bind(&trap);
+    wasmTrap(wasm::Trap::StackOverflow, trapOffset);
+    CodeOffset trapInsnOffset = CodeOffset(currentOffset());
+
+    bind(&ok);
+    reserveStack(amount);
+    return std::pair<CodeOffset, uint32_t>(trapInsnOffset, 0);
+  }
+
+  reserveStack(amount);
+  Label ok;
+  branchStackPtrRhs(Assembler::Below,
+                    Address(InstanceReg, wasm::Instance::offsetOfStackLimit()),
+                    &ok);
+  wasmTrap(wasm::Trap::StackOverflow, trapOffset);
+  CodeOffset trapInsnOffset = CodeOffset(currentOffset());
+  bind(&ok);
+  return std::pair<CodeOffset, uint32_t>(trapInsnOffset, amount);
+}
+
+void MacroAssembler::loadWasmGlobalPtr(uint32_t globalDataOffset,
+                                       Register dest) {
+  loadPtr(Address(InstanceReg,
+                  wasm::Instance::offsetOfGlobalArea() + globalDataOffset),
+          dest);
+}
+
+CodeOffset MacroAssembler::wasmCallImport(const wasm::CallSiteDesc& desc,
+                                          const wasm::CalleeDesc& callee) {
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCallerInstanceOffsetBeforeCall));
+
+  // Load the callee, before the caller's registers are clobbered.
+  uint32_t globalDataOffset = callee.importGlobalDataOffset();
+  loadWasmGlobalPtr(
+      globalDataOffset + offsetof(wasm::FuncImportInstanceData, code),
+      ABINonArgReg0);
+
+#if !defined(JS_CODEGEN_NONE) && !defined(JS_CODEGEN_WASM32)
+  static_assert(ABINonArgReg0 != InstanceReg, "by constraint");
+#endif
+
+  // Switch to the callee's realm.
+  loadWasmGlobalPtr(
+      globalDataOffset + offsetof(wasm::FuncImportInstanceData, realm),
+      ABINonArgReg1);
+  loadPtr(Address(InstanceReg, wasm::Instance::offsetOfCx()), ABINonArgReg2);
+  storePtr(ABINonArgReg1, Address(ABINonArgReg2, JSContext::offsetOfRealm()));
+
+  // Switch to the callee's instance and pinned registers and make the call.
+  loadWasmGlobalPtr(
+      globalDataOffset + offsetof(wasm::FuncImportInstanceData, instance),
+      InstanceReg);
+
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCalleeInstanceOffsetBeforeCall));
+  loadWasmPinnedRegsFromInstance();
+
+  return call(desc, ABINonArgReg0);
+}
+
+CodeOffset MacroAssembler::wasmCallBuiltinInstanceMethod(
+    const wasm::CallSiteDesc& desc, const ABIArg& instanceArg,
+    wasm::SymbolicAddress builtin, wasm::FailureMode failureMode) {
+  MOZ_ASSERT(instanceArg != ABIArg());
+
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCallerInstanceOffsetBeforeCall));
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCalleeInstanceOffsetBeforeCall));
+
+  if (instanceArg.kind() == ABIArg::GPR) {
+    movePtr(InstanceReg, instanceArg.gpr());
+  } else if (instanceArg.kind() == ABIArg::Stack) {
+    storePtr(InstanceReg,
+             Address(getStackPointer(), instanceArg.offsetFromArgBase()));
+  } else {
+    MOZ_CRASH("Unknown abi passing style for pointer");
+  }
+
+  CodeOffset ret = call(desc, builtin);
+
+  if (failureMode != wasm::FailureMode::Infallible) {
+    Label noTrap;
+    switch (failureMode) {
+      case wasm::FailureMode::Infallible:
+        MOZ_CRASH();
+      case wasm::FailureMode::FailOnNegI32:
+        branchTest32(Assembler::NotSigned, ReturnReg, ReturnReg, &noTrap);
+        break;
+      case wasm::FailureMode::FailOnNullPtr:
+        branchTestPtr(Assembler::NonZero, ReturnReg, ReturnReg, &noTrap);
+        break;
+      case wasm::FailureMode::FailOnInvalidRef:
+        branchPtr(Assembler::NotEqual, ReturnReg,
+                  ImmWord(uintptr_t(wasm::AnyRef::invalid().forCompiledCode())),
+                  &noTrap);
+        break;
+    }
+    wasmTrap(wasm::Trap::ThrowReported,
+             wasm::BytecodeOffset(desc.lineOrBytecode()));
+    bind(&noTrap);
+  }
+
+  return ret;
+}
+
+CodeOffset MacroAssembler::asmCallIndirect(const wasm::CallSiteDesc& desc,
+                                           const wasm::CalleeDesc& callee) {
+  MOZ_ASSERT(callee.which() == wasm::CalleeDesc::AsmJSTable);
+
+  const Register scratch = WasmTableCallScratchReg0;
+  const Register index = WasmTableCallIndexReg;
+
+  // Optimization opportunity: when offsetof(FunctionTableElem, code) == 0, as
+  // it is at present, we can probably generate better code here by folding
+  // the address computation into the load.
+
+  static_assert(sizeof(wasm::FunctionTableElem) == 8 ||
+                    sizeof(wasm::FunctionTableElem) == 16,
+                "elements of function tables are two words");
+
+  // asm.js tables require no signature check, and have had their index
+  // masked into range and thus need no bounds check.
+  loadWasmGlobalPtr(callee.tableFunctionBaseGlobalDataOffset(), scratch);
+  if (sizeof(wasm::FunctionTableElem) == 8) {
+    computeEffectiveAddress(BaseIndex(scratch, index, TimesEight), scratch);
+  } else {
+    lshift32(Imm32(4), index);
+    addPtr(index, scratch);
+  }
+  loadPtr(Address(scratch, offsetof(wasm::FunctionTableElem, code)), scratch);
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCallerInstanceOffsetBeforeCall));
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCalleeInstanceOffsetBeforeCall));
+  return call(desc, scratch);
+}
+
+// In principle, call_indirect requires an expensive context switch to the
+// callee's instance and realm before the call and an almost equally expensive
+// switch back to the caller's ditto after.  However, if the caller's instance
+// is the same as the callee's instance then no context switch is required, and
+// it only takes a compare-and-branch at run-time to test this - all values are
+// in registers already.  We therefore generate two call paths, one for the fast
+// call without the context switch (which additionally avoids a null check) and
+// one for the slow call with the context switch.
+
+void MacroAssembler::wasmCallIndirect(const wasm::CallSiteDesc& desc,
+                                      const wasm::CalleeDesc& callee,
+                                      Label* boundsCheckFailedLabel,
+                                      Label* nullCheckFailedLabel,
+                                      mozilla::Maybe<uint32_t> tableSize,
+                                      CodeOffset* fastCallOffset,
+                                      CodeOffset* slowCallOffset) {
+  static_assert(sizeof(wasm::FunctionTableElem) == 2 * sizeof(void*),
+                "Exactly two pointers or index scaling won't work correctly");
+  MOZ_ASSERT(callee.which() == wasm::CalleeDesc::WasmTable);
+
+  const int shift = sizeof(wasm::FunctionTableElem) == 8 ? 3 : 4;
+  wasm::BytecodeOffset trapOffset(desc.lineOrBytecode());
+  const Register calleeScratch = WasmTableCallScratchReg0;
+  const Register index = WasmTableCallIndexReg;
+
+  // Check the table index and throw if out-of-bounds.
+  //
+  // Frequently the table size is known, so optimize for that.  Otherwise
+  // compare with a memory operand when that's possible.  (There's little sense
+  // in hoisting the load of the bound into a register at a higher level and
+  // reusing that register, because a hoisted value would either have to be
+  // spilled and re-loaded before the next call_indirect, or would be abandoned
+  // because we could not trust that a hoisted value would not have changed.)
+
+  if (boundsCheckFailedLabel) {
+    if (tableSize.isSome()) {
+      branch32(Assembler::Condition::AboveOrEqual, index, Imm32(*tableSize),
+               boundsCheckFailedLabel);
+    } else {
+      branch32(Assembler::Condition::BelowOrEqual,
+               Address(InstanceReg, wasm::Instance::offsetOfGlobalArea() +
+                                        callee.tableLengthGlobalDataOffset()),
+               index, boundsCheckFailedLabel);
+    }
+  }
+
+  // Write the functype-id into the ABI functype-id register.
+
+  const wasm::CallIndirectId callIndirectId = callee.wasmTableSigId();
+  switch (callIndirectId.kind()) {
+    case wasm::CallIndirectIdKind::Global:
+      loadWasmGlobalPtr(callIndirectId.globalDataOffset(), WasmTableCallSigReg);
+      break;
+    case wasm::CallIndirectIdKind::Immediate:
+      move32(Imm32(callIndirectId.immediate()), WasmTableCallSigReg);
+      break;
+    case wasm::CallIndirectIdKind::AsmJS:
+    case wasm::CallIndirectIdKind::None:
+      break;
+  }
+
+  // Load the base pointer of the table and compute the address of the callee in
+  // the table.
+
+  loadWasmGlobalPtr(callee.tableFunctionBaseGlobalDataOffset(), calleeScratch);
+  shiftIndex32AndAdd(index, shift, calleeScratch);
+
+  // Load the callee instance and decide whether to take the fast path or the
+  // slow path.
+
+  Label fastCall;
+  Label done;
+  const Register newInstanceTemp = WasmTableCallScratchReg1;
+  loadPtr(Address(calleeScratch, offsetof(wasm::FunctionTableElem, instance)),
+          newInstanceTemp);
+  branchPtr(Assembler::Equal, InstanceReg, newInstanceTemp, &fastCall);
+
+  // Slow path: Save context, check for null, setup new context, call, restore
+  // context.
+  //
+  // TODO: The slow path could usefully be out-of-line and the test above would
+  // just fall through to the fast path.  This keeps the fast-path code dense,
+  // and has correct static prediction for the branch (forward conditional
+  // branches predicted not taken, normally).
+
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCallerInstanceOffsetBeforeCall));
+  movePtr(newInstanceTemp, InstanceReg);
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCalleeInstanceOffsetBeforeCall));
+
+#ifdef WASM_HAS_HEAPREG
+  // Use the null pointer exception resulting from loading HeapReg from a null
+  // instance to handle a call to a null slot.
+  MOZ_ASSERT(nullCheckFailedLabel == nullptr);
+  loadWasmPinnedRegsFromInstance(mozilla::Some(trapOffset));
+#else
+  MOZ_ASSERT(nullCheckFailedLabel != nullptr);
+  branchTestPtr(Assembler::Zero, InstanceReg, InstanceReg,
+                nullCheckFailedLabel);
+
+  loadWasmPinnedRegsFromInstance();
+#endif
+  switchToWasmInstanceRealm(index, WasmTableCallScratchReg1);
+
+  loadPtr(Address(calleeScratch, offsetof(wasm::FunctionTableElem, code)),
+          calleeScratch);
+
+  *slowCallOffset = call(desc, calleeScratch);
+
+  // Restore registers and realm and join up with the fast path.
+
+  loadPtr(Address(getStackPointer(), WasmCallerInstanceOffsetBeforeCall),
+          InstanceReg);
+  loadWasmPinnedRegsFromInstance();
+  switchToWasmInstanceRealm(ABINonArgReturnReg0, ABINonArgReturnReg1);
+  jump(&done);
+
+  // Fast path: just load the code pointer and go.  The instance and heap
+  // register are the same as in the caller, and nothing will be null.
+  //
+  // (In particular, the code pointer will not be null: if it were, the instance
+  // would have been null, and then it would not have been equivalent to our
+  // current instance.  So no null check is needed on the fast path.)
+
+  bind(&fastCall);
+
+  loadPtr(Address(calleeScratch, offsetof(wasm::FunctionTableElem, code)),
+          calleeScratch);
+
+  // We use a different type of call site for the fast call since the instance
+  // slots in the frame do not have valid values.
+
+  wasm::CallSiteDesc newDesc(desc.lineOrBytecode(),
+                             wasm::CallSiteDesc::IndirectFast);
+  *fastCallOffset = call(newDesc, calleeScratch);
+
+  bind(&done);
+}
+
+void MacroAssembler::wasmCallRef(const wasm::CallSiteDesc& desc,
+                                 const wasm::CalleeDesc& callee,
+                                 CodeOffset* fastCallOffset,
+                                 CodeOffset* slowCallOffset) {
+  MOZ_ASSERT(callee.which() == wasm::CalleeDesc::FuncRef);
+  const Register calleeScratch = WasmCallRefCallScratchReg0;
+  const Register calleeFnObj = WasmCallRefReg;
+
+  // Load from the function's WASM_INSTANCE_SLOT extended slot, and decide
+  // whether to take the fast path or the slow path. Register this load
+  // instruction to be source of a trap -- null pointer check.
+
+  Label fastCall;
+  Label done;
+  const Register newInstanceTemp = WasmCallRefCallScratchReg1;
+  size_t instanceSlotOffset = FunctionExtended::offsetOfExtendedSlot(
+      FunctionExtended::WASM_INSTANCE_SLOT);
+  static_assert(FunctionExtended::WASM_INSTANCE_SLOT < wasm::NullPtrGuardSize);
+  wasm::BytecodeOffset trapOffset(desc.lineOrBytecode());
+  append(wasm::Trap::NullPointerDereference,
+         wasm::TrapSite(currentOffset(), trapOffset));
+  loadPtr(Address(calleeFnObj, instanceSlotOffset), newInstanceTemp);
+  branchPtr(Assembler::Equal, InstanceReg, newInstanceTemp, &fastCall);
+
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCallerInstanceOffsetBeforeCall));
+  movePtr(newInstanceTemp, InstanceReg);
+  storePtr(InstanceReg,
+           Address(getStackPointer(), WasmCalleeInstanceOffsetBeforeCall));
+
+  loadWasmPinnedRegsFromInstance();
+  switchToWasmInstanceRealm(WasmCallRefCallScratchReg0,
+                            WasmCallRefCallScratchReg1);
+
+  // Get funcUncheckedCallEntry() from the function's
+  // WASM_FUNC_UNCHECKED_ENTRY_SLOT extended slot.
+  size_t uncheckedEntrySlotOffset = FunctionExtended::offsetOfExtendedSlot(
+      FunctionExtended::WASM_FUNC_UNCHECKED_ENTRY_SLOT);
+  loadPtr(Address(calleeFnObj, uncheckedEntrySlotOffset), calleeScratch);
+
+  *slowCallOffset = call(desc, calleeScratch);
+
+  // Restore registers and realm and back to this caller's.
+  loadPtr(Address(getStackPointer(), WasmCallerInstanceOffsetBeforeCall),
+          InstanceReg);
+  loadWasmPinnedRegsFromInstance();
+  switchToWasmInstanceRealm(ABINonArgReturnReg0, ABINonArgReturnReg1);
+  jump(&done);
+
+  // Fast path: just load WASM_FUNC_UNCHECKED_ENTRY_SLOT value and go.
+  // The instance and pinned registers are the same as in the caller.
+
+  bind(&fastCall);
+
+  loadPtr(Address(calleeFnObj, uncheckedEntrySlotOffset), calleeScratch);
+
+  // We use a different type of call site for the fast call since the instance
+  // slots in the frame do not have valid values.
+
+  wasm::CallSiteDesc newDesc(desc.lineOrBytecode(),
+                             wasm::CallSiteDesc::FuncRefFast);
+  *fastCallOffset = call(newDesc, calleeScratch);
+
+  bind(&done);
+}
+
+void MacroAssembler::branchWasmTypeDefIsSubtype(Register subTypeDef,
+                                                Register superTypeDef,
+                                                Register scratch,
+                                                uint32_t subTypingDepth,
+                                                Label* label, bool onSuccess) {
+  MOZ_ASSERT_IF(subTypingDepth >= wasm::MinSuperTypeVectorLength,
+                scratch != Register::Invalid());
+
+  // We generate just different enough code for 'is' subtype vs 'is not'
+  // subtype that we handle them separately.
+  if (onSuccess) {
+    Label failed;
+
+    // Fast path for the type defs being equal.
+    branchPtr(Assembler::Equal, subTypeDef, superTypeDef, label);
+
+    // Slower path for checking the supertype vector of `subTypeDef`. We don't
+    // need `subTypeDef` at this point, so we use it as a scratch for storing
+    // the super type vector and entry from it.
+    loadPtr(Address(subTypeDef, wasm::TypeDef::offsetOfSuperTypeVector()),
+            subTypeDef);
+
+    // Emit a bounds check if the super type depth may be out-of-bounds.
+    if (subTypingDepth >= wasm::MinSuperTypeVectorLength) {
+      // Slowest path for having a bounds check of the super type vector
+      load32(Address(subTypeDef, wasm::SuperTypeVector::offsetOfLength()),
+             scratch);
+      branch32(Assembler::LessThanOrEqual, scratch, Imm32(subTypingDepth),
+               &failed);
+    }
+
+    // Load the `subTypingDepth` entry from subTypeDef's super type vector. This
+    // will be `superTypeDef` if `subTypeDef` is indeed a subtype.
+    loadPtr(Address(subTypeDef, wasm::SuperTypeVector::offsetOfTypeDefInVector(
+                                    subTypingDepth)),
+            subTypeDef);
+    branchPtr(Assembler::Equal, subTypeDef, superTypeDef, label);
+
+    // Fallthrough to the failed case
+    bind(&failed);
+    return;
+  }
+
+  // Load the super type vector from subTypeDef
+  loadPtr(Address(subTypeDef, wasm::TypeDef::offsetOfSuperTypeVector()),
+          subTypeDef);
+
+  // Emit a bounds check if the super type depth may be out-of-bounds.
+  if (subTypingDepth >= wasm::MinSuperTypeVectorLength) {
+    load32(Address(subTypeDef, wasm::SuperTypeVector::offsetOfLength()),
+           scratch);
+    branch32(Assembler::LessThanOrEqual, scratch, Imm32(subTypingDepth), label);
+  }
+
+  // Load the `subTypingDepth` entry from subTypeDef's super type vector. This
+  // will be `superTypeDef` if `subTypeDef` is indeed a subtype.
+  loadPtr(Address(subTypeDef, wasm::SuperTypeVector::offsetOfTypeDefInVector(
+                                  subTypingDepth)),
+          subTypeDef);
+  branchPtr(Assembler::NotEqual, subTypeDef, superTypeDef, label);
+  // Fallthrough to the success case
+}
+
+void MacroAssembler::nopPatchableToCall(const wasm::CallSiteDesc& desc) {
+  CodeOffset offset = nopPatchableToCall();
+  append(desc, offset);
+}
+
+void MacroAssembler::emitPreBarrierFastPath(JSRuntime* rt, MIRType type,
+                                            Register temp1, Register temp2,
+                                            Register temp3, Label* noBarrier) {
+  MOZ_ASSERT(temp1 != PreBarrierReg);
+  MOZ_ASSERT(temp2 != PreBarrierReg);
+  MOZ_ASSERT(temp3 != PreBarrierReg);
+
+  // Load the GC thing in temp1.
+  if (type == MIRType::Value) {
+    unboxGCThingForGCBarrier(Address(PreBarrierReg, 0), temp1);
+  } else {
+    MOZ_ASSERT(type == MIRType::Object || type == MIRType::String ||
+               type == MIRType::Shape);
+    loadPtr(Address(PreBarrierReg, 0), temp1);
+  }
+
+#ifdef DEBUG
+  // The caller should have checked for null pointers.
+  Label nonZero;
+  branchTestPtr(Assembler::NonZero, temp1, temp1, &nonZero);
+  assumeUnreachable("JIT pre-barrier: unexpected nullptr");
+  bind(&nonZero);
+#endif
+
+  // Load the chunk address in temp2.
+  movePtr(temp1, temp2);
+  andPtr(Imm32(int32_t(~gc::ChunkMask)), temp2);
+
+  // If the GC thing is in the nursery, we don't need to barrier it.
+  if (type == MIRType::Value || type == MIRType::Object ||
+      type == MIRType::String) {
+    branchPtr(Assembler::NotEqual, Address(temp2, gc::ChunkStoreBufferOffset),
+              ImmWord(0), noBarrier);
+  } else {
+#ifdef DEBUG
+    Label isTenured;
+    branchPtr(Assembler::Equal, Address(temp2, gc::ChunkStoreBufferOffset),
+              ImmWord(0), &isTenured);
+    assumeUnreachable("JIT pre-barrier: unexpected nursery pointer");
+    bind(&isTenured);
+#endif
+  }
+
+  // Determine the bit index and store in temp1.
+  //
+  // bit = (addr & js::gc::ChunkMask) / js::gc::CellBytesPerMarkBit +
+  //        static_cast<uint32_t>(colorBit);
+  static_assert(gc::CellBytesPerMarkBit == 8,
+                "Calculation below relies on this");
+  static_assert(size_t(gc::ColorBit::BlackBit) == 0,
+                "Calculation below relies on this");
+  andPtr(Imm32(gc::ChunkMask), temp1);
+  rshiftPtr(Imm32(3), temp1);
+
+  static_assert(gc::MarkBitmapWordBits == JS_BITS_PER_WORD,
+                "Calculation below relies on this");
+
+  // Load the bitmap word in temp2.
+  //
+  // word = chunk.bitmap[bit / MarkBitmapWordBits];
+
+  // Fold the adjustment for the fact that arenas don't start at the beginning
+  // of the chunk into the offset to the chunk bitmap.
+  const size_t firstArenaAdjustment = gc::FirstArenaAdjustmentBits / CHAR_BIT;
+  const intptr_t offset =
+      intptr_t(gc::ChunkMarkBitmapOffset) - intptr_t(firstArenaAdjustment);
+
+  movePtr(temp1, temp3);
+#if JS_BITS_PER_WORD == 64
+  rshiftPtr(Imm32(6), temp1);
+  loadPtr(BaseIndex(temp2, temp1, TimesEight, offset), temp2);
+#else
+  rshiftPtr(Imm32(5), temp1);
+  loadPtr(BaseIndex(temp2, temp1, TimesFour, offset), temp2);
+#endif
+
+  // Load the mask in temp1.
+  //
+  // mask = uintptr_t(1) << (bit % MarkBitmapWordBits);
+  andPtr(Imm32(gc::MarkBitmapWordBits - 1), temp3);
+  move32(Imm32(1), temp1);
+#ifdef JS_CODEGEN_X64
+  MOZ_ASSERT(temp3 == rcx);
+  shlq_cl(temp1);
+#elif JS_CODEGEN_X86
+  MOZ_ASSERT(temp3 == ecx);
+  shll_cl(temp1);
+#elif JS_CODEGEN_ARM
+  ma_lsl(temp3, temp1, temp1);
+#elif JS_CODEGEN_ARM64
+  Lsl(ARMRegister(temp1, 64), ARMRegister(temp1, 64), ARMRegister(temp3, 64));
+#elif JS_CODEGEN_MIPS32
+  ma_sll(temp1, temp1, temp3);
+#elif JS_CODEGEN_MIPS64
+  ma_dsll(temp1, temp1, temp3);
+#elif JS_CODEGEN_LOONG64
+  as_sll_d(temp1, temp1, temp3);
+#elif JS_CODEGEN_WASM32
+  MOZ_CRASH();
+#elif JS_CODEGEN_NONE
+  MOZ_CRASH();
+#else
+#  error "Unknown architecture"
+#endif
+
+  // No barrier is needed if the bit is set, |word & mask != 0|.
+  branchTestPtr(Assembler::NonZero, temp2, temp1, noBarrier);
+}
+
+// ========================================================================
+// JS atomic operations.
+
+void MacroAssembler::atomicIsLockFreeJS(Register value, Register output) {
+  // Keep this in sync with isLockfreeJS() in jit/AtomicOperations.h.
+  static_assert(AtomicOperations::isLockfreeJS(1));  // Implementation artifact
+  static_assert(AtomicOperations::isLockfreeJS(2));  // Implementation artifact
+  static_assert(AtomicOperations::isLockfreeJS(4));  // Spec requirement
+  static_assert(AtomicOperations::isLockfreeJS(8));  // Implementation artifact
+
+  Label done;
+  move32(Imm32(1), output);
+  branch32(Assembler::Equal, value, Imm32(8), &done);
+  branch32(Assembler::Equal, value, Imm32(4), &done);
+  branch32(Assembler::Equal, value, Imm32(2), &done);
+  branch32(Assembler::Equal, value, Imm32(1), &done);
+  move32(Imm32(0), output);
+  bind(&done);
+}
+
+// ========================================================================
+// Spectre Mitigations.
+
+void MacroAssembler::spectreMaskIndex32(Register index, Register length,
+                                        Register output) {
+  MOZ_ASSERT(JitOptions.spectreIndexMasking);
+  MOZ_ASSERT(length != output);
+  MOZ_ASSERT(index != output);
+
+  move32(Imm32(0), output);
+  cmp32Move32(Assembler::Below, index, length, index, output);
+}
+
+void MacroAssembler::spectreMaskIndex32(Register index, const Address& length,
+                                        Register output) {
+  MOZ_ASSERT(JitOptions.spectreIndexMasking);
+  MOZ_ASSERT(index != length.base);
+  MOZ_ASSERT(length.base != output);
+  MOZ_ASSERT(index != output);
+
+  move32(Imm32(0), output);
+  cmp32Move32(Assembler::Below, index, length, index, output);
+}
+
+void MacroAssembler::spectreMaskIndexPtr(Register index, Register length,
+                                         Register output) {
+  MOZ_ASSERT(JitOptions.spectreIndexMasking);
+  MOZ_ASSERT(length != output);
+  MOZ_ASSERT(index != output);
+
+  movePtr(ImmWord(0), output);
+  cmpPtrMovePtr(Assembler::Below, index, length, index, output);
+}
+
+void MacroAssembler::spectreMaskIndexPtr(Register index, const Address& length,
+                                         Register output) {
+  MOZ_ASSERT(JitOptions.spectreIndexMasking);
+  MOZ_ASSERT(index != length.base);
+  MOZ_ASSERT(length.base != output);
+  MOZ_ASSERT(index != output);
+
+  movePtr(ImmWord(0), output);
+  cmpPtrMovePtr(Assembler::Below, index, length, index, output);
+}
+
+void MacroAssembler::boundsCheck32PowerOfTwo(Register index, uint32_t length,
+                                             Label* failure) {
+  MOZ_ASSERT(mozilla::IsPowerOfTwo(length));
+  branch32(Assembler::AboveOrEqual, index, Imm32(length), failure);
+
+  // Note: it's fine to clobber the input register, as this is a no-op: it
+  // only affects speculative execution.
+  if (JitOptions.spectreIndexMasking) {
+    and32(Imm32(length - 1), index);
+  }
+}
+
+void MacroAssembler::loadWasmPinnedRegsFromInstance(
+    mozilla::Maybe<wasm::BytecodeOffset> trapOffset) {
+#ifdef WASM_HAS_HEAPREG
+  static_assert(wasm::Instance::offsetOfMemoryBase() < 4096,
+                "We count only on the low page being inaccessible");
+  if (trapOffset) {
+    append(wasm::Trap::IndirectCallToNull,
+           wasm::TrapSite(currentOffset(), *trapOffset));
+  }
+  loadPtr(Address(InstanceReg, wasm::Instance::offsetOfMemoryBase()), HeapReg);
+#else
+  MOZ_ASSERT(!trapOffset);
+#endif
+}
+
+//}}} check_macroassembler_style
+
+#ifdef JS_64BIT
+void MacroAssembler::debugAssertCanonicalInt32(Register r) {
+#  ifdef DEBUG
+  if (!js::jit::JitOptions.lessDebugCode) {
+#    if defined(JS_CODEGEN_X64) || defined(JS_CODEGEN_ARM64)
+    Label ok;
+    branchPtr(Assembler::BelowOrEqual, r, ImmWord(UINT32_MAX), &ok);
+    breakpoint();
+    bind(&ok);
+#    elif defined(JS_CODEGEN_MIPS64) || defined(JS_CODEGEN_LOONG64)
+    Label ok;
+    ScratchRegisterScope scratch(asMasm());
+    move32SignExtendToPtr(r, scratch);
+    branchPtr(Assembler::Equal, r, scratch, &ok);
+    breakpoint();
+    bind(&ok);
+#    else
+    MOZ_CRASH("IMPLEMENT ME");
+#    endif
+  }
+#  endif
+}
+#endif
+
+void MacroAssembler::memoryBarrierBefore(const Synchronization& sync) {
+  memoryBarrier(sync.barrierBefore);
+}
+
+void MacroAssembler::memoryBarrierAfter(const Synchronization& sync) {
+  memoryBarrier(sync.barrierAfter);
+}
+
+void MacroAssembler::debugAssertIsObject(const ValueOperand& val) {
+#ifdef DEBUG
+  Label ok;
+  branchTestObject(Assembler::Equal, val, &ok);
+  assumeUnreachable("Expected an object!");
+  bind(&ok);
+#endif
+}
+
+void MacroAssembler::debugAssertObjHasFixedSlots(Register obj,
+                                                 Register scratch) {
+#ifdef DEBUG
+  Label hasFixedSlots;
+  loadPtr(Address(obj, JSObject::offsetOfShape()), scratch);
+  branchTest32(Assembler::NonZero,
+               Address(scratch, Shape::offsetOfImmutableFlags()),
+               Imm32(NativeShape::fixedSlotsMask()), &hasFixedSlots);
+  assumeUnreachable("Expected a fixed slot");
+  bind(&hasFixedSlots);
+#endif
+}
+
+void MacroAssembler::debugAssertObjectHasClass(Register obj, Register scratch,
+                                               const JSClass* clasp) {
+#ifdef DEBUG
+  Label done;
+  branchTestObjClassNoSpectreMitigations(Assembler::Equal, obj, clasp, scratch,
+                                         &done);
+  assumeUnreachable("Class check failed");
+  bind(&done);
+#endif
+}
+
+void MacroAssembler::branchArrayIsNotPacked(Register array, Register temp1,
+                                            Register temp2, Label* label) {
+  loadPtr(Address(array, NativeObject::offsetOfElements()), temp1);
+
+  // Test length == initializedLength.
+  Address initLength(temp1, ObjectElements::offsetOfInitializedLength());
+  load32(Address(temp1, ObjectElements::offsetOfLength()), temp2);
+  branch32(Assembler::NotEqual, initLength, temp2, label);
+
+  // Test the NON_PACKED flag.
+  Address flags(temp1, ObjectElements::offsetOfFlags());
+  branchTest32(Assembler::NonZero, flags, Imm32(ObjectElements::NON_PACKED),
+               label);
+}
+
+void MacroAssembler::setIsPackedArray(Register obj, Register output,
+                                      Register temp) {
+  // Ensure it's an ArrayObject.
+  Label notPackedArray;
+  branchTestObjClass(Assembler::NotEqual, obj, &ArrayObject::class_, temp, obj,
+                     &notPackedArray);
+
+  branchArrayIsNotPacked(obj, temp, output, &notPackedArray);
+
+  Label done;
+  move32(Imm32(1), output);
+  jump(&done);
+
+  bind(&notPackedArray);
+  move32(Imm32(0), output);
+
+  bind(&done);
+}
+
+void MacroAssembler::packedArrayPop(Register array, ValueOperand output,
+                                    Register temp1, Register temp2,
+                                    Label* fail) {
+  // Load obj->elements in temp1.
+  loadPtr(Address(array, NativeObject::offsetOfElements()), temp1);
+
+  // Check flags.
+  static constexpr uint32_t UnhandledFlags =
+      ObjectElements::Flags::NON_PACKED |
+      ObjectElements::Flags::NONWRITABLE_ARRAY_LENGTH |
+      ObjectElements::Flags::NOT_EXTENSIBLE |
+      ObjectElements::Flags::MAYBE_IN_ITERATION;
+  Address flags(temp1, ObjectElements::offsetOfFlags());
+  branchTest32(Assembler::NonZero, flags, Imm32(UnhandledFlags), fail);
+
+  // Load length in temp2. Ensure length == initializedLength.
+  Address lengthAddr(temp1, ObjectElements::offsetOfLength());
+  Address initLengthAddr(temp1, ObjectElements::offsetOfInitializedLength());
+  load32(lengthAddr, temp2);
+  branch32(Assembler::NotEqual, initLengthAddr, temp2, fail);
+
+  // Result is |undefined| if length == 0.
+  Label notEmpty, done;
+  branchTest32(Assembler::NonZero, temp2, temp2, &notEmpty);
+  {
+    moveValue(UndefinedValue(), output);
+    jump(&done);
+  }
+
+  bind(&notEmpty);
+
+  // Load the last element.
+  sub32(Imm32(1), temp2);
+  BaseObjectElementIndex elementAddr(temp1, temp2);
+  loadValue(elementAddr, output);
+
+  // Pre-barrier the element because we're removing it from the array.
+  EmitPreBarrier(*this, elementAddr, MIRType::Value);
+
+  // Update length and initializedLength.
+  store32(temp2, lengthAddr);
+  store32(temp2, initLengthAddr);
+
+  bind(&done);
+}
+
+void MacroAssembler::packedArrayShift(Register array, ValueOperand output,
+                                      Register temp1, Register temp2,
+                                      LiveRegisterSet volatileRegs,
+                                      Label* fail) {
+  // Load obj->elements in temp1.
+  loadPtr(Address(array, NativeObject::offsetOfElements()), temp1);
+
+  // Check flags.
+  static constexpr uint32_t UnhandledFlags =
+      ObjectElements::Flags::NON_PACKED |
+      ObjectElements::Flags::NONWRITABLE_ARRAY_LENGTH |
+      ObjectElements::Flags::NOT_EXTENSIBLE |
+      ObjectElements::Flags::MAYBE_IN_ITERATION;
+  Address flags(temp1, ObjectElements::offsetOfFlags());
+  branchTest32(Assembler::NonZero, flags, Imm32(UnhandledFlags), fail);
+
+  // Load length in temp2. Ensure length == initializedLength.
+  Address lengthAddr(temp1, ObjectElements::offsetOfLength());
+  Address initLengthAddr(temp1, ObjectElements::offsetOfInitializedLength());
+  load32(lengthAddr, temp2);
+  branch32(Assembler::NotEqual, initLengthAddr, temp2, fail);
+
+  // Result is |undefined| if length == 0.
+  Label notEmpty, done;
+  branchTest32(Assembler::NonZero, temp2, temp2, &notEmpty);
+  {
+    moveValue(UndefinedValue(), output);
+    jump(&done);
+  }
+
+  bind(&notEmpty);
+
+  // Load the first element.
+  Address elementAddr(temp1, 0);
+  loadValue(elementAddr, output);
+
+  // Move the other elements and update the initializedLength/length. This will
+  // also trigger pre-barriers.
+  {
+    // Ensure output is in volatileRegs. Don't preserve temp1 and temp2.
+    volatileRegs.takeUnchecked(temp1);
+    volatileRegs.takeUnchecked(temp2);
+    if (output.hasVolatileReg()) {
+      volatileRegs.addUnchecked(output);
+    }
+
+    PushRegsInMask(volatileRegs);
+
+    using Fn = void (*)(ArrayObject * arr);
+    setupUnalignedABICall(temp1);
+    passABIArg(array);
+    callWithABI<Fn, ArrayShiftMoveElements>();
+
+    PopRegsInMask(volatileRegs);
+  }
+
+  bind(&done);
+}
+
+void MacroAssembler::loadArgumentsObjectElement(Register obj, Register index,
+                                                ValueOperand output,
+                                                Register temp, Label* fail) {
+  Register temp2 = output.scratchReg();
+
+  // Get initial length value.
+  unboxInt32(Address(obj, ArgumentsObject::getInitialLengthSlotOffset()), temp);
+
+  // Ensure no overridden elements.
+  branchTest32(Assembler::NonZero, temp,
+               Imm32(ArgumentsObject::ELEMENT_OVERRIDDEN_BIT), fail);
+
+  // Bounds check.
+  rshift32(Imm32(ArgumentsObject::PACKED_BITS_COUNT), temp);
+  spectreBoundsCheck32(index, temp, temp2, fail);
+
+  // Load ArgumentsData.
+  loadPrivate(Address(obj, ArgumentsObject::getDataSlotOffset()), temp);
+
+  // Guard the argument is not a FORWARD_TO_CALL_SLOT MagicValue.
+  BaseValueIndex argValue(temp, index, ArgumentsData::offsetOfArgs());
+  branchTestMagic(Assembler::Equal, argValue, fail);
+  loadValue(argValue, output);
+}
+
+void MacroAssembler::loadArgumentsObjectElementHole(Register obj,
+                                                    Register index,
+                                                    ValueOperand output,
+                                                    Register temp,
+                                                    Label* fail) {
+  Register temp2 = output.scratchReg();
+
+  // Get initial length value.
+  unboxInt32(Address(obj, ArgumentsObject::getInitialLengthSlotOffset()), temp);
+
+  // Ensure no overridden elements.
+  branchTest32(Assembler::NonZero, temp,
+               Imm32(ArgumentsObject::ELEMENT_OVERRIDDEN_BIT), fail);
+
+  // Bounds check.
+  Label outOfBounds, done;
+  rshift32(Imm32(ArgumentsObject::PACKED_BITS_COUNT), temp);
+  spectreBoundsCheck32(index, temp, temp2, &outOfBounds);
+
+  // Load ArgumentsData.
+  loadPrivate(Address(obj, ArgumentsObject::getDataSlotOffset()), temp);
+
+  // Guard the argument is not a FORWARD_TO_CALL_SLOT MagicValue.
+  BaseValueIndex argValue(temp, index, ArgumentsData::offsetOfArgs());
+  branchTestMagic(Assembler::Equal, argValue, fail);
+  loadValue(argValue, output);
+  jump(&done);
+
+  bind(&outOfBounds);
+  branch32(Assembler::LessThan, index, Imm32(0), fail);
+  moveValue(UndefinedValue(), output);
+
+  bind(&done);
+}
+
+void MacroAssembler::loadArgumentsObjectElementExists(
+    Register obj, Register index, Register output, Register temp, Label* fail) {
+  // Ensure the index is non-negative.
+  branch32(Assembler::LessThan, index, Imm32(0), fail);
+
+  // Get initial length value.
+  unboxInt32(Address(obj, ArgumentsObject::getInitialLengthSlotOffset()), temp);
+
+  // Ensure no overridden or deleted elements.
+  branchTest32(Assembler::NonZero, temp,
+               Imm32(ArgumentsObject::ELEMENT_OVERRIDDEN_BIT), fail);
+
+  // Compare index against the length.
+  rshift32(Imm32(ArgumentsObject::PACKED_BITS_COUNT), temp);
+  cmp32Set(Assembler::LessThan, index, temp, output);
+}
+
+void MacroAssembler::loadArgumentsObjectLength(Register obj, Register output,
+                                               Label* fail) {
+  // Get initial length value.
+  unboxInt32(Address(obj, ArgumentsObject::getInitialLengthSlotOffset()),
+             output);
+
+  // Test if length has been overridden.
+  branchTest32(Assembler::NonZero, output,
+               Imm32(ArgumentsObject::LENGTH_OVERRIDDEN_BIT), fail);
+
+  // Shift out arguments length and return it.
+  rshift32(Imm32(ArgumentsObject::PACKED_BITS_COUNT), output);
+}
+
+void MacroAssembler::branchTestArgumentsObjectFlags(Register obj, Register temp,
+                                                    uint32_t flags,
+                                                    Condition cond,
+                                                    Label* label) {
+  MOZ_ASSERT((flags & ~ArgumentsObject::PACKED_BITS_MASK) == 0);
+
+  // Get initial length value.
+  unboxInt32(Address(obj, ArgumentsObject::getInitialLengthSlotOffset()), temp);
+
+  // Test flags.
+  branchTest32(cond, temp, Imm32(flags), label);
+}
+
+static constexpr bool ValidateSizeRange(Scalar::Type from, Scalar::Type to) {
+  for (Scalar::Type type = from; type < to; type = Scalar::Type(type + 1)) {
+    if (TypedArrayElemSize(type) != TypedArrayElemSize(from)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+void MacroAssembler::typedArrayElementSize(Register obj, Register output) {
+  static_assert(Scalar::Int8 == 0, "Int8 is the first typed array class");
+  static_assert(
+      (Scalar::BigUint64 - Scalar::Int8) == Scalar::MaxTypedArrayViewType - 1,
+      "BigUint64 is the last typed array class");
+
+  Label one, two, four, eight, done;
+
+  loadObjClassUnsafe(obj, output);
+
+  static_assert(ValidateSizeRange(Scalar::Int8, Scalar::Int16),
+                "element size is one in [Int8, Int16)");
+  branchPtr(Assembler::Below, output,
+            ImmPtr(TypedArrayObject::classForType(Scalar::Int16)), &one);
+
+  static_assert(ValidateSizeRange(Scalar::Int16, Scalar::Int32),
+                "element size is two in [Int16, Int32)");
+  branchPtr(Assembler::Below, output,
+            ImmPtr(TypedArrayObject::classForType(Scalar::Int32)), &two);
+
+  static_assert(ValidateSizeRange(Scalar::Int32, Scalar::Float64),
+                "element size is four in [Int32, Float64)");
+  branchPtr(Assembler::Below, output,
+            ImmPtr(TypedArrayObject::classForType(Scalar::Float64)), &four);
+
+  static_assert(ValidateSizeRange(Scalar::Float64, Scalar::Uint8Clamped),
+                "element size is eight in [Float64, Uint8Clamped)");
+  branchPtr(Assembler::Below, output,
+            ImmPtr(TypedArrayObject::classForType(Scalar::Uint8Clamped)),
+            &eight);
+
+  static_assert(ValidateSizeRange(Scalar::Uint8Clamped, Scalar::BigInt64),
+                "element size is one in [Uint8Clamped, BigInt64)");
+  branchPtr(Assembler::Below, output,
+            ImmPtr(TypedArrayObject::classForType(Scalar::BigInt64)), &one);
+
+  static_assert(
+      ValidateSizeRange(Scalar::BigInt64, Scalar::MaxTypedArrayViewType),
+      "element size is eight in [BigInt64, MaxTypedArrayViewType)");
+  // Fall through for BigInt64 and BigUint64
+
+  bind(&eight);
+  move32(Imm32(8), output);
+  jump(&done);
+
+  bind(&four);
+  move32(Imm32(4), output);
+  jump(&done);
+
+  bind(&two);
+  move32(Imm32(2), output);
+  jump(&done);
+
+  bind(&one);
+  move32(Imm32(1), output);
+
+  bind(&done);
+}
+
+void MacroAssembler::branchIfClassIsNotTypedArray(Register clasp,
+                                                  Label* notTypedArray) {
+  static_assert(Scalar::Int8 == 0, "Int8 is the first typed array class");
+  const JSClass* firstTypedArrayClass =
+      TypedArrayObject::classForType(Scalar::Int8);
+
+  static_assert(
+      (Scalar::BigUint64 - Scalar::Int8) == Scalar::MaxTypedArrayViewType - 1,
+      "BigUint64 is the last typed array class");
+  const JSClass* lastTypedArrayClass =
+      TypedArrayObject::classForType(Scalar::BigUint64);
+
+  branchPtr(Assembler::Below, clasp, ImmPtr(firstTypedArrayClass),
+            notTypedArray);
+  branchPtr(Assembler::Above, clasp, ImmPtr(lastTypedArrayClass),
+            notTypedArray);
+}
+
+void MacroAssembler::branchIfHasDetachedArrayBuffer(Register obj, Register temp,
+                                                    Label* label) {
+  // Inline implementation of ArrayBufferViewObject::hasDetachedBuffer().
+
+  // Load obj->elements in temp.
+  loadPtr(Address(obj, NativeObject::offsetOfElements()), temp);
+
+  // Shared buffers can't be detached.
+  Label done;
+  branchTest32(Assembler::NonZero,
+               Address(temp, ObjectElements::offsetOfFlags()),
+               Imm32(ObjectElements::SHARED_MEMORY), &done);
+
+  // An ArrayBufferView with a null buffer has never had its buffer exposed to
+  // become detached.
+  fallibleUnboxObject(Address(obj, ArrayBufferViewObject::bufferOffset()), temp,
+                      &done);
+
+  // Load the ArrayBuffer flags and branch if the detached flag is set.
+  unboxInt32(Address(temp, ArrayBufferObject::offsetOfFlagsSlot()), temp);
+  branchTest32(Assembler::NonZero, temp, Imm32(ArrayBufferObject::DETACHED),
+               label);
+
+  bind(&done);
+}
+
+void MacroAssembler::branchIfNativeIteratorNotReusable(Register ni,
+                                                       Label* notReusable) {
+  // See NativeIterator::isReusable.
+  Address flagsAddr(ni, NativeIterator::offsetOfFlagsAndCount());
+
+#ifdef DEBUG
+  Label niIsInitialized;
+  branchTest32(Assembler::NonZero, flagsAddr,
+               Imm32(NativeIterator::Flags::Initialized), &niIsInitialized);
+  assumeUnreachable(
+      "Expected a NativeIterator that's been completely "
+      "initialized");
+  bind(&niIsInitialized);
+#endif
+
+  branchTest32(Assembler::NonZero, flagsAddr,
+               Imm32(NativeIterator::Flags::NotReusable), notReusable);
+}
+
+static void LoadNativeIterator(MacroAssembler& masm, Register obj,
+                               Register dest) {
+  MOZ_ASSERT(obj != dest);
+
+#ifdef DEBUG
+  // Assert we have a PropertyIteratorObject.
+  Label ok;
+  masm.branchTestObjClass(Assembler::Equal, obj,
+                          &PropertyIteratorObject::class_, dest, obj, &ok);
+  masm.assumeUnreachable("Expected PropertyIteratorObject!");
+  masm.bind(&ok);
+#endif
+
+  // Load NativeIterator object.
+  Address slotAddr(obj, PropertyIteratorObject::offsetOfIteratorSlot());
+  masm.loadPrivate(slotAddr, dest);
+}
+
+// The ShapeCachePtr may be used to cache an iterator for for-in. Return that
+// iterator in |dest| if:
+// - the shape cache pointer exists and stores a native iterator
+// - the iterator is reusable
+// - the iterated object has no dense elements
+// - the shapes of each object on the proto chain of |obj| match the cached
+//   shapes
+// - the proto chain has no dense elements
+// Otherwise, jump to |failure|.
+void MacroAssembler::maybeLoadIteratorFromShape(Register obj, Register dest,
+                                                Register temp, Register temp2,
+                                                Register temp3,
+                                                Label* failure) {
+  // Register usage:
+  // obj: always contains the input object
+  // temp: walks the obj->shape->baseshape->proto->shape->... chain
+  // temp2: points to the native iterator. Incremented to walk the shapes array.
+  // temp3: scratch space
+  // dest: stores the resulting PropertyIteratorObject on success
+
+  Label success;
+  Register shapeAndProto = temp;
+  Register nativeIterator = temp2;
+
+  // Load ShapeCache from shape.
+  loadPtr(Address(obj, JSObject::offsetOfShape()), shapeAndProto);
+  loadPtr(Address(shapeAndProto, Shape::offsetOfCachePtr()), dest);
+
+  // Check if it's an iterator.
+  movePtr(dest, temp3);
+  andPtr(Imm32(ShapeCachePtr::MASK), temp3);
+  branch32(Assembler::NotEqual, temp3, Imm32(ShapeCachePtr::ITERATOR), failure);
+
+  // If we've cached an iterator, |obj| must be a native object.
+#ifdef DEBUG
+  Label nonNative;
+  branchIfNonNativeObj(obj, temp3, &nonNative);
+#endif
+
+  // Verify that |obj| has no dense elements.
+  loadPtr(Address(obj, NativeObject::offsetOfElements()), temp3);
+  branch32(Assembler::NotEqual,
+           Address(temp3, ObjectElements::offsetOfInitializedLength()),
+           Imm32(0), failure);
+
+  // Clear tag bits from iterator object. |dest| is now valid.
+  // Load the native iterator and verify that it's reusable.
+  andPtr(Imm32(~ShapeCachePtr::MASK), dest);
+  LoadNativeIterator(*this, dest, nativeIterator);
+  branchIfNativeIteratorNotReusable(nativeIterator, failure);
+
+  // We have to compare the shapes in the native iterator with the shapes on the
+  // proto chain to ensure the cached iterator is still valid. The shape array
+  // always starts at a fixed offset from the base of the NativeIterator, so
+  // instead of using an instruction outside the loop to initialize a pointer to
+  // the shapes array, we can bake it into the offset and reuse the pointer to
+  // the NativeIterator. We add |sizeof(Shape*)| to start at the second shape.
+  // (The first shape corresponds to the object itself. We don't have to check
+  // it, because we got the iterator via the shape.)
+  size_t nativeIteratorProtoShapeOffset =
+      NativeIterator::offsetOfFirstShape() + sizeof(Shape*);
+
+  // Loop over the proto chain. At the head of the loop, |shape| is the shape of
+  // the current object, and |iteratorShapes| points to the expected shape of
+  // its proto.
+  Label protoLoop;
+  bind(&protoLoop);
+
+  // Load the proto. If the proto is null, then we're done.
+  loadPtr(Address(shapeAndProto, Shape::offsetOfBaseShape()), shapeAndProto);
+  loadPtr(Address(shapeAndProto, BaseShape::offsetOfProto()), shapeAndProto);
+  branchPtr(Assembler::Equal, shapeAndProto, ImmPtr(nullptr), &success);
+
+#ifdef DEBUG
+  // We have guarded every shape up until this point, so we know that the proto
+  // is a native object.
+  branchIfNonNativeObj(shapeAndProto, temp3, &nonNative);
+#endif
+
+  // Verify that the proto has no dense elements.
+  loadPtr(Address(shapeAndProto, NativeObject::offsetOfElements()), temp3);
+  branch32(Assembler::NotEqual,
+           Address(temp3, ObjectElements::offsetOfInitializedLength()),
+           Imm32(0), failure);
+
+  // Compare the shape of the proto to the expected shape.
+  loadPtr(Address(shapeAndProto, JSObject::offsetOfShape()), shapeAndProto);
+  loadPtr(Address(nativeIterator, nativeIteratorProtoShapeOffset), temp3);
+  branchPtr(Assembler::NotEqual, shapeAndProto, temp3, failure);
+
+  // Increment |iteratorShapes| and jump back to the top of the loop.
+  addPtr(Imm32(sizeof(Shape*)), nativeIterator);
+  jump(&protoLoop);
+
+#ifdef DEBUG
+  bind(&nonNative);
+  assumeUnreachable("Expected NativeObject in maybeLoadIteratorFromShape");
+#endif
+
+  bind(&success);
+}
+
+void MacroAssembler::iteratorMore(Register obj, ValueOperand output,
+                                  Register temp) {
+  Label done;
+  Register outputScratch = output.scratchReg();
+  LoadNativeIterator(*this, obj, outputScratch);
+
+  // If propertyCursor_ < propertiesEnd_, load the next string and advance
+  // the cursor.  Otherwise return MagicValue(JS_NO_ITER_VALUE).
+  Label iterDone;
+  Address cursorAddr(outputScratch, NativeIterator::offsetOfPropertyCursor());
+  Address cursorEndAddr(outputScratch, NativeIterator::offsetOfPropertiesEnd());
+  loadPtr(cursorAddr, temp);
+  branchPtr(Assembler::BelowOrEqual, cursorEndAddr, temp, &iterDone);
+
+  // Get next string.
+  loadPtr(Address(temp, 0), temp);
+
+  // Increase the cursor.
+  addPtr(Imm32(sizeof(GCPtr<JSLinearString*>)), cursorAddr);
+
+  tagValue(JSVAL_TYPE_STRING, temp, output);
+  jump(&done);
+
+  bind(&iterDone);
+  moveValue(MagicValue(JS_NO_ITER_VALUE), output);
+
+  bind(&done);
+}
+
+void MacroAssembler::iteratorClose(Register obj, Register temp1, Register temp2,
+                                   Register temp3) {
+  LoadNativeIterator(*this, obj, temp1);
+
+  // The shared iterator used for for-in with null/undefined is immutable and
+  // unlinked. See NativeIterator::isEmptyIteratorSingleton.
+  Label done;
+  branchTest32(Assembler::NonZero,
+               Address(temp1, NativeIterator::offsetOfFlagsAndCount()),
+               Imm32(NativeIterator::Flags::IsEmptyIteratorSingleton), &done);
+
+  // Clear active bit.
+  and32(Imm32(~NativeIterator::Flags::Active),
+        Address(temp1, NativeIterator::offsetOfFlagsAndCount()));
+
+  // Clear objectBeingIterated.
+  Address iterObjAddr(temp1, NativeIterator::offsetOfObjectBeingIterated());
+  guardedCallPreBarrierAnyZone(iterObjAddr, MIRType::Object, temp2);
+  storePtr(ImmPtr(nullptr), iterObjAddr);
+
+  // Reset property cursor.
+  loadPtr(Address(temp1, NativeIterator::offsetOfShapesEnd()), temp2);
+  storePtr(temp2, Address(temp1, NativeIterator::offsetOfPropertyCursor()));
+
+  // Unlink from the iterator list.
+  const Register next = temp2;
+  const Register prev = temp3;
+  loadPtr(Address(temp1, NativeIterator::offsetOfNext()), next);
+  loadPtr(Address(temp1, NativeIterator::offsetOfPrev()), prev);
+  storePtr(prev, Address(next, NativeIterator::offsetOfPrev()));
+  storePtr(next, Address(prev, NativeIterator::offsetOfNext()));
+#ifdef DEBUG
+  storePtr(ImmPtr(nullptr), Address(temp1, NativeIterator::offsetOfNext()));
+  storePtr(ImmPtr(nullptr), Address(temp1, NativeIterator::offsetOfPrev()));
+#endif
+
+  bind(&done);
+}
+
+void MacroAssembler::registerIterator(Register enumeratorsList, Register iter,
+                                      Register temp) {
+  // iter->next = list
+  storePtr(enumeratorsList, Address(iter, NativeIterator::offsetOfNext()));
+
+  // iter->prev = list->prev
+  loadPtr(Address(enumeratorsList, NativeIterator::offsetOfPrev()), temp);
+  storePtr(temp, Address(iter, NativeIterator::offsetOfPrev()));
+
+  // list->prev->next = iter
+  storePtr(iter, Address(temp, NativeIterator::offsetOfNext()));
+
+  // list->prev = iter
+  storePtr(iter, Address(enumeratorsList, NativeIterator::offsetOfPrev()));
+}
+
+void MacroAssembler::toHashableNonGCThing(ValueOperand value,
+                                          ValueOperand result,
+                                          FloatRegister tempFloat) {
+  // Inline implementation of |HashableValue::setValue()|.
+
+#ifdef DEBUG
+  Label ok;
+  branchTestGCThing(Assembler::NotEqual, value, &ok);
+  assumeUnreachable("Unexpected GC thing");
+  bind(&ok);
+#endif
+
+  Label useInput, done;
+  branchTestDouble(Assembler::NotEqual, value, &useInput);
+  {
+    Register int32 = result.scratchReg();
+    unboxDouble(value, tempFloat);
+
+    // Normalize int32-valued doubles to int32 and negative zero to +0.
+    Label canonicalize;
+    convertDoubleToInt32(tempFloat, int32, &canonicalize, false);
+    {
+      tagValue(JSVAL_TYPE_INT32, int32, result);
+      jump(&done);
+    }
+    bind(&canonicalize);
+    {
+      // Normalize the sign bit of a NaN.
+      branchDouble(Assembler::DoubleOrdered, tempFloat, tempFloat, &useInput);
+      moveValue(JS::NaNValue(), result);
+      jump(&done);
+    }
+  }
+
+  bind(&useInput);
+  moveValue(value, result);
+
+  bind(&done);
+}
+
+void MacroAssembler::toHashableValue(ValueOperand value, ValueOperand result,
+                                     FloatRegister tempFloat,
+                                     Label* atomizeString, Label* tagString) {
+  // Inline implementation of |HashableValue::setValue()|.
+
+  ScratchTagScope tag(*this, value);
+  splitTagForTest(value, tag);
+
+  Label notString, useInput, done;
+  branchTestString(Assembler::NotEqual, tag, &notString);
+  {
+    ScratchTagScopeRelease _(&tag);
+
+    Register str = result.scratchReg();
+    unboxString(value, str);
+
+    branchTest32(Assembler::NonZero, Address(str, JSString::offsetOfFlags()),
+                 Imm32(JSString::ATOM_BIT), &useInput);
+
+    jump(atomizeString);
+    bind(tagString);
+
+    tagValue(JSVAL_TYPE_STRING, str, result);
+    jump(&done);
+  }
+  bind(&notString);
+  branchTestDouble(Assembler::NotEqual, tag, &useInput);
+  {
+    ScratchTagScopeRelease _(&tag);
+
+    Register int32 = result.scratchReg();
+    unboxDouble(value, tempFloat);
+
+    Label canonicalize;
+    convertDoubleToInt32(tempFloat, int32, &canonicalize, false);
+    {
+      tagValue(JSVAL_TYPE_INT32, int32, result);
+      jump(&done);
+    }
+    bind(&canonicalize);
+    {
+      branchDouble(Assembler::DoubleOrdered, tempFloat, tempFloat, &useInput);
+      moveValue(JS::NaNValue(), result);
+      jump(&done);
+    }
+  }
+
+  bind(&useInput);
+  moveValue(value, result);
+
+  bind(&done);
+}
+
+void MacroAssembler::scrambleHashCode(Register result) {
+  // Inline implementation of |mozilla::ScrambleHashCode()|.
+
+  mul32(Imm32(mozilla::kGoldenRatioU32), result);
+}
+
+void MacroAssembler::prepareHashNonGCThing(ValueOperand value, Register result,
+                                           Register temp) {
+  // Inline implementation of |OrderedHashTable::prepareHash()| and
+  // |mozilla::HashGeneric(v.asRawBits())|.
+
+#ifdef DEBUG
+  Label ok;
+  branchTestGCThing(Assembler::NotEqual, value, &ok);
+  assumeUnreachable("Unexpected GC thing");
+  bind(&ok);
+#endif
+
+  // uint32_t v1 = static_cast<uint32_t>(aValue);
+#ifdef JS_PUNBOX64
+  move64To32(value.toRegister64(), result);
+#else
+  move32(value.payloadReg(), result);
+#endif
+
+  // uint32_t v2 = static_cast<uint32_t>(static_cast<uint64_t>(aValue) >> 32);
+#ifdef JS_PUNBOX64
+  auto r64 = Register64(temp);
+  move64(value.toRegister64(), r64);
+  rshift64Arithmetic(Imm32(32), r64);
+#else
+  // TODO: This seems like a bug in mozilla::detail::AddUintptrToHash().
+  // The uint64_t input is first converted to uintptr_t and then back to
+  // uint64_t. But |uint64_t(uintptr_t(bits))| actually only clears the high
+  // bits, so this computation:
+  //
+  // aValue = uintptr_t(bits)
+  // v2 = static_cast<uint32_t>(static_cast<uint64_t>(aValue) >> 32)
+  //
+  // really just sets |v2 = 0|. And that means the xor-operation in AddU32ToHash
+  // can be optimized away, because |x ^ 0 = x|.
+  //
+  // Filed as bug 1718516.
+#endif
+
+  // mozilla::WrappingMultiply(kGoldenRatioU32, RotateLeft5(aHash) ^ aValue);
+  // with |aHash = 0| and |aValue = v1|.
+  mul32(Imm32(mozilla::kGoldenRatioU32), result);
+
+  // mozilla::WrappingMultiply(kGoldenRatioU32, RotateLeft5(aHash) ^ aValue);
+  // with |aHash = <above hash>| and |aValue = v2|.
+  rotateLeft(Imm32(5), result, result);
+#ifdef JS_PUNBOX64
+  xor32(temp, result);
+#endif
+
+  // Combine |mul32| and |scrambleHashCode| by directly multiplying with
+  // |kGoldenRatioU32 * kGoldenRatioU32|.
+  //
+  // mul32(Imm32(mozilla::kGoldenRatioU32), result);
+  //
+  // scrambleHashCode(result);
+  mul32(Imm32(mozilla::kGoldenRatioU32 * mozilla::kGoldenRatioU32), result);
+}
+
+void MacroAssembler::prepareHashString(Register str, Register result,
+                                       Register temp) {
+  // Inline implementation of |OrderedHashTable::prepareHash()| and
+  // |JSAtom::hash()|.
+
+#ifdef DEBUG
+  Label ok;
+  branchTest32(Assembler::NonZero, Address(str, JSString::offsetOfFlags()),
+               Imm32(JSString::ATOM_BIT), &ok);
+  assumeUnreachable("Unexpected non-atom string");
+  bind(&ok);
+#endif
+
+  move32(Imm32(JSString::FAT_INLINE_MASK), temp);
+  and32(Address(str, JSString::offsetOfFlags()), temp);
+
+  // Set |result| to 1 for FatInlineAtoms.
+  move32(Imm32(0), result);
+  cmp32Set(Assembler::Equal, temp, Imm32(JSString::FAT_INLINE_MASK), result);
+
+  // Use a computed load for branch-free code.
+
+  static_assert(FatInlineAtom::offsetOfHash() > NormalAtom::offsetOfHash());
+
+  constexpr size_t offsetDiff =
+      FatInlineAtom::offsetOfHash() - NormalAtom::offsetOfHash();
+  static_assert(mozilla::IsPowerOfTwo(offsetDiff));
+
+  uint8_t shift = mozilla::FloorLog2Size(offsetDiff);
+  if (IsShiftInScaleRange(shift)) {
+    load32(
+        BaseIndex(str, result, ShiftToScale(shift), NormalAtom::offsetOfHash()),
+        result);
+  } else {
+    lshift32(Imm32(shift), result);
+    load32(BaseIndex(str, result, TimesOne, NormalAtom::offsetOfHash()),
+           result);
+  }
+
+  scrambleHashCode(result);
+}
+
+void MacroAssembler::prepareHashSymbol(Register sym, Register result) {
+  // Inline implementation of |OrderedHashTable::prepareHash()| and
+  // |Symbol::hash()|.
+
+  load32(Address(sym, JS::Symbol::offsetOfHash()), result);
+
+  scrambleHashCode(result);
+}
+
+void MacroAssembler::prepareHashBigInt(Register bigInt, Register result,
+                                       Register temp1, Register temp2,
+                                       Register temp3) {
+  // Inline implementation of |OrderedHashTable::prepareHash()| and
+  // |BigInt::hash()|.
+
+  // Inline implementation of |mozilla::AddU32ToHash()|.
+  auto addU32ToHash = [&](auto toAdd) {
+    rotateLeft(Imm32(5), result, result);
+    xor32(toAdd, result);
+    mul32(Imm32(mozilla::kGoldenRatioU32), result);
+  };
+
+  move32(Imm32(0), result);
+
+  // Inline |mozilla::HashBytes()|.
+
+  load32(Address(bigInt, BigInt::offsetOfLength()), temp1);
+  loadBigIntDigits(bigInt, temp2);
+
+  Label start, loop;
+  jump(&start);
+  bind(&loop);
+
+  {
+    // Compute |AddToHash(AddToHash(hash, data), sizeof(Digit))|.
+#if defined(JS_CODEGEN_MIPS64)
+    // Hash the lower 32-bits.
+    addU32ToHash(Address(temp2, 0));
+
+    // Hash the upper 32-bits.
+    addU32ToHash(Address(temp2, sizeof(int32_t)));
+#elif JS_PUNBOX64
+    // Use a single 64-bit load on non-MIPS64 platforms.
+    loadPtr(Address(temp2, 0), temp3);
+
+    // Hash the lower 32-bits.
+    addU32ToHash(temp3);
+
+    // Hash the upper 32-bits.
+    rshiftPtr(Imm32(32), temp3);
+    addU32ToHash(temp3);
+#else
+    addU32ToHash(Address(temp2, 0));
+#endif
+  }
+  addPtr(Imm32(sizeof(BigInt::Digit)), temp2);
+
+  bind(&start);
+  branchSub32(Assembler::NotSigned, Imm32(1), temp1, &loop);
+
+  // Compute |mozilla::AddToHash(h, isNegative())|.
+  {
+    static_assert(mozilla::IsPowerOfTwo(BigInt::signBitMask()));
+
+    load32(Address(bigInt, BigInt::offsetOfFlags()), temp1);
+    and32(Imm32(BigInt::signBitMask()), temp1);
+    rshift32(Imm32(mozilla::FloorLog2(BigInt::signBitMask())), temp1);
+
+    addU32ToHash(temp1);
+  }
+
+  scrambleHashCode(result);
+}
+
+void MacroAssembler::prepareHashObject(Register setObj, ValueOperand value,
+                                       Register result, Register temp1,
+                                       Register temp2, Register temp3,
+                                       Register temp4) {
+#ifdef JS_PUNBOX64
+  // Inline implementation of |OrderedHashTable::prepareHash()| and
+  // |HashCodeScrambler::scramble(v.asRawBits())|.
+
+  // Load the |ValueSet| or |ValueMap|.
+  static_assert(SetObject::getDataSlotOffset() ==
+                MapObject::getDataSlotOffset());
+  loadPrivate(Address(setObj, SetObject::getDataSlotOffset()), temp1);
+
+  // Load |HashCodeScrambler::mK0| and |HashCodeScrambler::mK0|.
+  static_assert(ValueSet::offsetOfImplHcsK0() == ValueMap::offsetOfImplHcsK0());
+  static_assert(ValueSet::offsetOfImplHcsK1() == ValueMap::offsetOfImplHcsK1());
+  auto k0 = Register64(temp1);
+  auto k1 = Register64(temp2);
+  load64(Address(temp1, ValueSet::offsetOfImplHcsK1()), k1);
+  load64(Address(temp1, ValueSet::offsetOfImplHcsK0()), k0);
+
+  // Hash numbers are 32-bit values, so only hash the lower double-word.
+  static_assert(sizeof(mozilla::HashNumber) == 4);
+  move32To64ZeroExtend(value.valueReg(), Register64(result));
+
+  // Inline implementation of |SipHasher::sipHash()|.
+  auto m = Register64(result);
+  auto v0 = Register64(temp3);
+  auto v1 = Register64(temp4);
+  auto v2 = k0;
+  auto v3 = k1;
+
+  auto sipRound = [&]() {
+    // mV0 = WrappingAdd(mV0, mV1);
+    add64(v1, v0);
+
+    // mV1 = RotateLeft(mV1, 13);
+    rotateLeft64(Imm32(13), v1, v1, InvalidReg);
+
+    // mV1 ^= mV0;
+    xor64(v0, v1);
+
+    // mV0 = RotateLeft(mV0, 32);
+    rotateLeft64(Imm32(32), v0, v0, InvalidReg);
+
+    // mV2 = WrappingAdd(mV2, mV3);
+    add64(v3, v2);
+
+    // mV3 = RotateLeft(mV3, 16);
+    rotateLeft64(Imm32(16), v3, v3, InvalidReg);
+
+    // mV3 ^= mV2;
+    xor64(v2, v3);
+
+    // mV0 = WrappingAdd(mV0, mV3);
+    add64(v3, v0);
+
+    // mV3 = RotateLeft(mV3, 21);
+    rotateLeft64(Imm32(21), v3, v3, InvalidReg);
+
+    // mV3 ^= mV0;
+    xor64(v0, v3);
+
+    // mV2 = WrappingAdd(mV2, mV1);
+    add64(v1, v2);
+
+    // mV1 = RotateLeft(mV1, 17);
+    rotateLeft64(Imm32(17), v1, v1, InvalidReg);
+
+    // mV1 ^= mV2;
+    xor64(v2, v1);
+
+    // mV2 = RotateLeft(mV2, 32);
+    rotateLeft64(Imm32(32), v2, v2, InvalidReg);
+  };
+
+  // 1. Initialization.
+  // mV0 = aK0 ^ UINT64_C(0x736f6d6570736575);
+  move64(Imm64(0x736f6d6570736575), v0);
+  xor64(k0, v0);
+
+  // mV1 = aK1 ^ UINT64_C(0x646f72616e646f6d);
+  move64(Imm64(0x646f72616e646f6d), v1);
+  xor64(k1, v1);
+
+  // mV2 = aK0 ^ UINT64_C(0x6c7967656e657261);
+  MOZ_ASSERT(v2 == k0);
+  xor64(Imm64(0x6c7967656e657261), v2);
+
+  // mV3 = aK1 ^ UINT64_C(0x7465646279746573);
+  MOZ_ASSERT(v3 == k1);
+  xor64(Imm64(0x7465646279746573), v3);
+
+  // 2. Compression.
+  // mV3 ^= aM;
+  xor64(m, v3);
+
+  // sipRound();
+  sipRound();
+
+  // mV0 ^= aM;
+  xor64(m, v0);
+
+  // 3. Finalization.
+  // mV2 ^= 0xff;
+  xor64(Imm64(0xff), v2);
+
+  // for (int i = 0; i < 3; i++) sipRound();
+  for (int i = 0; i < 3; i++) {
+    sipRound();
+  }
+
+  // return mV0 ^ mV1 ^ mV2 ^ mV3;
+  xor64(v1, v0);
+  xor64(v2, v3);
+  xor64(v3, v0);
+
+  move64To32(v0, result);
+
+  scrambleHashCode(result);
+#else
+  MOZ_CRASH("Not implemented");
+#endif
+}
+
+void MacroAssembler::prepareHashValue(Register setObj, ValueOperand value,
+                                      Register result, Register temp1,
+                                      Register temp2, Register temp3,
+                                      Register temp4) {
+  Label isString, isObject, isSymbol, isBigInt;
+  {
+    ScratchTagScope tag(*this, value);
+    splitTagForTest(value, tag);
+
+    branchTestString(Assembler::Equal, tag, &isString);
+    branchTestObject(Assembler::Equal, tag, &isObject);
+    branchTestSymbol(Assembler::Equal, tag, &isSymbol);
+    branchTestBigInt(Assembler::Equal, tag, &isBigInt);
+  }
+
+  Label done;
+  {
+    prepareHashNonGCThing(value, result, temp1);
+    jump(&done);
+  }
+  bind(&isString);
+  {
+    unboxString(value, temp1);
+    prepareHashString(temp1, result, temp2);
+    jump(&done);
+  }
+  bind(&isObject);
+  {
+    prepareHashObject(setObj, value, result, temp1, temp2, temp3, temp4);
+    jump(&done);
+  }
+  bind(&isSymbol);
+  {
+    unboxSymbol(value, temp1);
+    prepareHashSymbol(temp1, result);
+    jump(&done);
+  }
+  bind(&isBigInt);
+  {
+    unboxBigInt(value, temp1);
+    prepareHashBigInt(temp1, result, temp2, temp3, temp4);
+
+    // Fallthrough to |done|.
+  }
+
+  bind(&done);
+}
+
+template <typename OrderedHashTable>
+void MacroAssembler::orderedHashTableLookup(Register setOrMapObj,
+                                            ValueOperand value, Register hash,
+                                            Register entryTemp, Register temp1,
+                                            Register temp2, Register temp3,
+                                            Register temp4, Label* found,
+                                            IsBigInt isBigInt) {
+  // Inline implementation of |OrderedHashTable::lookup()|.
+
+  MOZ_ASSERT_IF(isBigInt == IsBigInt::No, temp3 == InvalidReg);
+  MOZ_ASSERT_IF(isBigInt == IsBigInt::No, temp4 == InvalidReg);
+
+#ifdef DEBUG
+  Label ok;
+  if (isBigInt == IsBigInt::No) {
+    branchTestBigInt(Assembler::NotEqual, value, &ok);
+    assumeUnreachable("Unexpected BigInt");
+  } else if (isBigInt == IsBigInt::Yes) {
+    branchTestBigInt(Assembler::Equal, value, &ok);
+    assumeUnreachable("Unexpected non-BigInt");
+  }
+  bind(&ok);
+#endif
+
+#ifdef DEBUG
+  PushRegsInMask(LiveRegisterSet(RegisterSet::Volatile()));
+
+  pushValue(value);
+  moveStackPtrTo(temp2);
+
+  setupUnalignedABICall(temp1);
+  loadJSContext(temp1);
+  passABIArg(temp1);
+  passABIArg(setOrMapObj);
+  passABIArg(temp2);
+  passABIArg(hash);
+
+  if constexpr (std::is_same_v<OrderedHashTable, ValueSet>) {
+    using Fn =
+        void (*)(JSContext*, SetObject*, const Value*, mozilla::HashNumber);
+    callWithABI<Fn, jit::AssertSetObjectHash>();
+  } else {
+    using Fn =
+        void (*)(JSContext*, MapObject*, const Value*, mozilla::HashNumber);
+    callWithABI<Fn, jit::AssertMapObjectHash>();
+  }
+
+  popValue(value);
+  PopRegsInMask(LiveRegisterSet(RegisterSet::Volatile()));
+#endif
+
+  // Load the |ValueSet| or |ValueMap|.
+  static_assert(SetObject::getDataSlotOffset() ==
+                MapObject::getDataSlotOffset());
+  loadPrivate(Address(setOrMapObj, SetObject::getDataSlotOffset()), temp1);
+
+  // Load the bucket.
+  move32(hash, entryTemp);
+  load32(Address(temp1, OrderedHashTable::offsetOfImplHashShift()), temp2);
+  flexibleRshift32(temp2, entryTemp);
+
+  loadPtr(Address(temp1, OrderedHashTable::offsetOfImplHashTable()), temp2);
+  loadPtr(BaseIndex(temp2, entryTemp, ScalePointer), entryTemp);
+
+  // Search for a match in this bucket.
+  Label start, loop;
+  jump(&start);
+  bind(&loop);
+  {
+    // Inline implementation of |HashableValue::operator==|.
+
+    static_assert(OrderedHashTable::offsetOfImplDataElement() == 0,
+                  "offsetof(Data, element) is 0");
+    auto keyAddr = Address(entryTemp, OrderedHashTable::offsetOfEntryKey());
+
+    if (isBigInt == IsBigInt::No) {
+      // Two HashableValues are equal if they have equal bits.
+      branch64(Assembler::Equal, keyAddr, value.toRegister64(), found);
+    } else {
+#ifdef JS_PUNBOX64
+      auto key = ValueOperand(temp1);
+#else
+      auto key = ValueOperand(temp1, temp2);
+#endif
+
+      loadValue(keyAddr, key);
+
+      // Two HashableValues are equal if they have equal bits.
+      branch64(Assembler::Equal, key.toRegister64(), value.toRegister64(),
+               found);
+
+      // BigInt values are considered equal if they represent the same
+      // mathematical value.
+      Label next;
+      fallibleUnboxBigInt(key, temp2, &next);
+      if (isBigInt == IsBigInt::Yes) {
+        unboxBigInt(value, temp1);
+      } else {
+        fallibleUnboxBigInt(value, temp1, &next);
+      }
+      equalBigInts(temp1, temp2, temp3, temp4, temp1, temp2, &next, &next,
+                   &next);
+      jump(found);
+      bind(&next);
+    }
+  }
+  loadPtr(Address(entryTemp, OrderedHashTable::offsetOfImplDataChain()),
+          entryTemp);
+  bind(&start);
+  branchTestPtr(Assembler::NonZero, entryTemp, entryTemp, &loop);
+}
+
+void MacroAssembler::setObjectHas(Register setObj, ValueOperand value,
+                                  Register hash, Register result,
+                                  Register temp1, Register temp2,
+                                  Register temp3, Register temp4,
+                                  IsBigInt isBigInt) {
+  Label found;
+  orderedHashTableLookup<ValueSet>(setObj, value, hash, result, temp1, temp2,
+                                   temp3, temp4, &found, isBigInt);
+
+  Label done;
+  move32(Imm32(0), result);
+  jump(&done);
+
+  bind(&found);
+  move32(Imm32(1), result);
+  bind(&done);
+}
+
+void MacroAssembler::mapObjectHas(Register mapObj, ValueOperand value,
+                                  Register hash, Register result,
+                                  Register temp1, Register temp2,
+                                  Register temp3, Register temp4,
+                                  IsBigInt isBigInt) {
+  Label found;
+  orderedHashTableLookup<ValueMap>(mapObj, value, hash, result, temp1, temp2,
+                                   temp3, temp4, &found, isBigInt);
+
+  Label done;
+  move32(Imm32(0), result);
+  jump(&done);
+
+  bind(&found);
+  move32(Imm32(1), result);
+  bind(&done);
+}
+
+void MacroAssembler::mapObjectGet(Register mapObj, ValueOperand value,
+                                  Register hash, ValueOperand result,
+                                  Register temp1, Register temp2,
+                                  Register temp3, Register temp4,
+                                  Register temp5, IsBigInt isBigInt) {
+  Label found;
+  orderedHashTableLookup<ValueMap>(mapObj, value, hash, temp1, temp2, temp3,
+                                   temp4, temp5, &found, isBigInt);
+
+  Label done;
+  moveValue(UndefinedValue(), result);
+  jump(&done);
+
+  // |temp1| holds the found entry.
+  bind(&found);
+  loadValue(Address(temp1, ValueMap::Entry::offsetOfValue()), result);
+
+  bind(&done);
+}
+
+template <typename OrderedHashTable>
+void MacroAssembler::loadOrderedHashTableCount(Register setOrMapObj,
+                                               Register result) {
+  // Inline implementation of |OrderedHashTable::count()|.
+
+  // Load the |ValueSet| or |ValueMap|.
+  static_assert(SetObject::getDataSlotOffset() ==
+                MapObject::getDataSlotOffset());
+  loadPrivate(Address(setOrMapObj, SetObject::getDataSlotOffset()), result);
+
+  // Load the live count.
+  load32(Address(result, OrderedHashTable::offsetOfImplLiveCount()), result);
+}
+
+void MacroAssembler::loadSetObjectSize(Register setObj, Register result) {
+  loadOrderedHashTableCount<ValueSet>(setObj, result);
+}
+
+void MacroAssembler::loadMapObjectSize(Register mapObj, Register result) {
+  loadOrderedHashTableCount<ValueMap>(mapObj, result);
+}
+
+// Can't push large frames blindly on windows, so we must touch frame memory
+// incrementally, with no more than 4096 - 1 bytes between touches.
+//
+// This is used across all platforms for simplicity.
+void MacroAssembler::touchFrameValues(Register numStackValues,
+                                      Register scratch1, Register scratch2) {
+  const size_t FRAME_TOUCH_INCREMENT = 2048;
+  static_assert(FRAME_TOUCH_INCREMENT < 4096 - 1,
+                "Frame increment is too large");
+
+  moveStackPtrTo(scratch2);
+  mov(numStackValues, scratch1);
+  lshiftPtr(Imm32(3), scratch1);
+  subPtr(scratch1, scratch2);
+  {
+    moveStackPtrTo(scratch1);
+    subPtr(Imm32(FRAME_TOUCH_INCREMENT), scratch1);
+
+    Label touchFrameLoop;
+    Label touchFrameLoopEnd;
+    bind(&touchFrameLoop);
+    branchPtr(Assembler::Below, scratch1, scratch2, &touchFrameLoopEnd);
+    store32(Imm32(0), Address(scratch1, 0));
+    subPtr(Imm32(FRAME_TOUCH_INCREMENT), scratch1);
+    jump(&touchFrameLoop);
+    bind(&touchFrameLoopEnd);
+  }
+}
+
+namespace js {
+namespace jit {
+
+#ifdef DEBUG
+template <class RegisterType>
+AutoGenericRegisterScope<RegisterType>::AutoGenericRegisterScope(
+    MacroAssembler& masm, RegisterType reg)
+    : RegisterType(reg), masm_(masm), released_(false) {
+  masm.debugTrackedRegisters_.add(reg);
+}
+
+template AutoGenericRegisterScope<Register>::AutoGenericRegisterScope(
+    MacroAssembler& masm, Register reg);
+template AutoGenericRegisterScope<FloatRegister>::AutoGenericRegisterScope(
+    MacroAssembler& masm, FloatRegister reg);
+#endif  // DEBUG
+
+#ifdef DEBUG
+template <class RegisterType>
+AutoGenericRegisterScope<RegisterType>::~AutoGenericRegisterScope() {
+  if (!released_) {
+    release();
+  }
+}
+
+template AutoGenericRegisterScope<Register>::~AutoGenericRegisterScope();
+template AutoGenericRegisterScope<FloatRegister>::~AutoGenericRegisterScope();
+
+template <class RegisterType>
+void AutoGenericRegisterScope<RegisterType>::release() {
+  MOZ_ASSERT(!released_);
+  released_ = true;
+  const RegisterType& reg = *dynamic_cast<RegisterType*>(this);
+  masm_.debugTrackedRegisters_.take(reg);
+}
+
+template void AutoGenericRegisterScope<Register>::release();
+template void AutoGenericRegisterScope<FloatRegister>::release();
+
+template <class RegisterType>
+void AutoGenericRegisterScope<RegisterType>::reacquire() {
+  MOZ_ASSERT(released_);
+  released_ = false;
+  const RegisterType& reg = *dynamic_cast<RegisterType*>(this);
+  masm_.debugTrackedRegisters_.add(reg);
+}
+
+template void AutoGenericRegisterScope<Register>::reacquire();
+template void AutoGenericRegisterScope<FloatRegister>::reacquire();
+
+#endif  // DEBUG
+
+}  // namespace jit
+
+}  // namespace js