js/src/jit/MacroAssembler.cpp
author Hannes Verschore <hv1989@gmail.com>
Fri, 29 Jul 2016 16:53:44 +0200
changeset 347341 cb47a62a37a46a6081031a8d2fc78770ea4ba3e6
parent 347319 18af1ad335a52bc3852d195627757ceb0dad6836
child 347377 3424ab3ae5f7970a0ccd843db92ea6dd237b2c97
permissions -rw-r--r--
Bug 1279248 - Part 20: Implement the 64bit variant of WasmTruncate on x86, r=sunfish

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "jit/MacroAssembler-inl.h"

#include "jsfriendapi.h"
#include "jsprf.h"

#include "builtin/TypedObject.h"
#include "gc/GCTrace.h"
#include "jit/AtomicOp.h"
#include "jit/Bailouts.h"
#include "jit/BaselineFrame.h"
#include "jit/BaselineIC.h"
#include "jit/BaselineJIT.h"
#include "jit/Lowering.h"
#include "jit/MIR.h"
#include "js/Conversions.h"
#include "js/GCAPI.h"
#include "vm/TraceLogging.h"

#include "jsobjinlines.h"

#include "gc/Nursery-inl.h"
#include "jit/shared/Lowering-shared-inl.h"
#include "vm/Interpreter-inl.h"

using namespace js;
using namespace js::jit;

using JS::GenericNaN;
using JS::ToInt32;

template <typename Source> void
MacroAssembler::guardTypeSet(const Source& address, const TypeSet* types, BarrierKind kind,
                             Register scratch, Label* miss)
{
    MOZ_ASSERT(kind == BarrierKind::TypeTagOnly || kind == BarrierKind::TypeSet);
    MOZ_ASSERT(!types->unknown());

    Label matched;
    TypeSet::Type tests[8] = {
        TypeSet::Int32Type(),
        TypeSet::UndefinedType(),
        TypeSet::BooleanType(),
        TypeSet::StringType(),
        TypeSet::SymbolType(),
        TypeSet::NullType(),
        TypeSet::MagicArgType(),
        TypeSet::AnyObjectType()
    };

    // The double type also implies Int32.
    // So replace the int32 test with the double one.
    if (types->hasType(TypeSet::DoubleType())) {
        MOZ_ASSERT(types->hasType(TypeSet::Int32Type()));
        tests[0] = TypeSet::DoubleType();
    }

    Register tag = extractTag(address, scratch);

    // Emit all typed tests.
    BranchType lastBranch;
    for (size_t i = 0; i < mozilla::ArrayLength(tests); i++) {
        if (!types->hasType(tests[i]))
            continue;

        if (lastBranch.isInitialized())
            lastBranch.emit(*this);
        lastBranch = BranchType(Equal, tag, tests[i], &matched);
    }

    // If this is the last check, invert the last branch.
    if (types->hasType(TypeSet::AnyObjectType()) || !types->getObjectCount()) {
        if (!lastBranch.isInitialized()) {
            jump(miss);
            return;
        }

        lastBranch.invertCondition();
        lastBranch.relink(miss);
        lastBranch.emit(*this);

        bind(&matched);
        return;
    }

    if (lastBranch.isInitialized())
        lastBranch.emit(*this);

    // Test specific objects.
    MOZ_ASSERT(scratch != InvalidReg);
    branchTestObject(NotEqual, tag, miss);
    if (kind != BarrierKind::TypeTagOnly) {
        Register obj = extractObject(address, scratch);
        guardObjectType(obj, types, scratch, miss);
    } else {
#ifdef DEBUG
        Label fail;
        Register obj = extractObject(address, scratch);
        guardObjectType(obj, types, scratch, &fail);
        jump(&matched);
        bind(&fail);

        if (obj == scratch)
            extractObject(address, scratch);
        guardTypeSetMightBeIncomplete(types, obj, scratch, &matched);

        assumeUnreachable("Unexpected object type");
#endif
    }

    bind(&matched);
}

template <typename TypeSet>
void
MacroAssembler::guardTypeSetMightBeIncomplete(TypeSet* types, Register obj, Register scratch, Label* label)
{
    // Type set guards might miss when an object's group changes. In this case
    // either its old group's properties will become unknown, or it will change
    // to a native object with an original unboxed group. Jump to label if this
    // might have happened for the input object.

    if (types->unknownObject()) {
        jump(label);
        return;
    }

    loadPtr(Address(obj, JSObject::offsetOfGroup()), scratch);
    load32(Address(scratch, ObjectGroup::offsetOfFlags()), scratch);
    and32(Imm32(OBJECT_FLAG_ADDENDUM_MASK), scratch);
    branch32(Assembler::Equal,
             scratch, Imm32(ObjectGroup::addendumOriginalUnboxedGroupValue()), label);

    for (size_t i = 0; i < types->getObjectCount(); i++) {
        if (JSObject* singleton = types->getSingletonNoBarrier(i)) {
            movePtr(ImmGCPtr(singleton), scratch);
            loadPtr(Address(scratch, JSObject::offsetOfGroup()), scratch);
        } else if (ObjectGroup* group = types->getGroupNoBarrier(i)) {
            movePtr(ImmGCPtr(group), scratch);
        } else {
            continue;
        }
        branchTest32(Assembler::NonZero, Address(scratch, ObjectGroup::offsetOfFlags()),
                     Imm32(OBJECT_FLAG_UNKNOWN_PROPERTIES), label);
    }
}

void
MacroAssembler::guardObjectType(Register obj, const TypeSet* types,
                                Register scratch, Label* miss)
{
    MOZ_ASSERT(!types->unknown());
    MOZ_ASSERT(!types->hasType(TypeSet::AnyObjectType()));
    MOZ_ASSERT_IF(types->getObjectCount() > 0, scratch != InvalidReg);

    // Note: this method elides read barriers on values read from type sets, as
    // this may be called off the main thread during Ion compilation. This is
    // safe to do as the final JitCode object will be allocated during the
    // incremental GC (or the compilation canceled before we start sweeping),
    // see CodeGenerator::link. Other callers should use TypeSet::readBarrier
    // to trigger the barrier on the contents of type sets passed in here.
    Label matched;

    BranchGCPtr lastBranch;
    MOZ_ASSERT(!lastBranch.isInitialized());
    bool hasObjectGroups = false;
    unsigned count = types->getObjectCount();
    for (unsigned i = 0; i < count; i++) {
        if (!types->getSingletonNoBarrier(i)) {
            hasObjectGroups = hasObjectGroups || types->getGroupNoBarrier(i);
            continue;
        }

        if (lastBranch.isInitialized())
            lastBranch.emit(*this);

        JSObject* object = types->getSingletonNoBarrier(i);
        lastBranch = BranchGCPtr(Equal, obj, ImmGCPtr(object), &matched);
    }

    if (hasObjectGroups) {
        // We are possibly going to overwrite the obj register. So already
        // emit the branch, since branch depends on previous value of obj
        // register and there is definitely a branch following. So no need
        // to invert the condition.
        if (lastBranch.isInitialized())
            lastBranch.emit(*this);
        lastBranch = BranchGCPtr();

        // Note: Some platforms give the same register for obj and scratch.
        // Make sure when writing to scratch, the obj register isn't used anymore!
        loadPtr(Address(obj, JSObject::offsetOfGroup()), scratch);

        for (unsigned i = 0; i < count; i++) {
            if (!types->getGroupNoBarrier(i))
                continue;

            if (lastBranch.isInitialized())
                lastBranch.emit(*this);

            ObjectGroup* group = types->getGroupNoBarrier(i);
            lastBranch = BranchGCPtr(Equal, scratch, ImmGCPtr(group), &matched);
        }
    }

    if (!lastBranch.isInitialized()) {
        jump(miss);
        return;
    }

    lastBranch.invertCondition();
    lastBranch.relink(miss);
    lastBranch.emit(*this);

    bind(&matched);
}

template void MacroAssembler::guardTypeSet(const Address& address, const TypeSet* types,
                                           BarrierKind kind, Register scratch, Label* miss);
template void MacroAssembler::guardTypeSet(const ValueOperand& value, const TypeSet* types,
                                           BarrierKind kind, Register scratch, Label* miss);
template void MacroAssembler::guardTypeSet(const TypedOrValueRegister& value, const TypeSet* types,
                                           BarrierKind kind, Register scratch, Label* miss);

template void MacroAssembler::guardTypeSetMightBeIncomplete(const TemporaryTypeSet* types,
                                                            Register obj, Register scratch,
                                                            Label* label);

template<typename S, typename T>
static void
StoreToTypedFloatArray(MacroAssembler& masm, int arrayType, const S& value, const T& dest,
                       unsigned numElems)
{
    switch (arrayType) {
      case Scalar::Float32:
        masm.storeFloat32(value, dest);
        break;
      case Scalar::Float64:
        masm.storeDouble(value, dest);
        break;
      case Scalar::Float32x4:
        switch (numElems) {
          case 1:
            masm.storeFloat32(value, dest);
            break;
          case 2:
            masm.storeDouble(value, dest);
            break;
          case 3:
            masm.storeFloat32x3(value, dest);
            break;
          case 4:
            masm.storeUnalignedSimd128Float(value, dest);
            break;
          default: MOZ_CRASH("unexpected number of elements in simd write");
        }
        break;
      case Scalar::Int32x4:
        switch (numElems) {
          case 1:
            masm.storeInt32x1(value, dest);
            break;
          case 2:
            masm.storeInt32x2(value, dest);
            break;
          case 3:
            masm.storeInt32x3(value, dest);
            break;
          case 4:
            masm.storeUnalignedSimd128Int(value, dest);
            break;
          default: MOZ_CRASH("unexpected number of elements in simd write");
        }
        break;
      case Scalar::Int8x16:
        MOZ_ASSERT(numElems == 16, "unexpected partial store");
        masm.storeUnalignedSimd128Int(value, dest);
        break;
      case Scalar::Int16x8:
        MOZ_ASSERT(numElems == 8, "unexpected partial store");
        masm.storeUnalignedSimd128Int(value, dest);
        break;
      default:
        MOZ_CRASH("Invalid typed array type");
    }
}

void
MacroAssembler::storeToTypedFloatArray(Scalar::Type arrayType, FloatRegister value,
                                       const BaseIndex& dest, unsigned numElems)
{
    StoreToTypedFloatArray(*this, arrayType, value, dest, numElems);
}
void
MacroAssembler::storeToTypedFloatArray(Scalar::Type arrayType, FloatRegister value,
                                       const Address& dest, unsigned numElems)
{
    StoreToTypedFloatArray(*this, arrayType, value, dest, numElems);
}

template<typename T>
void
MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const T& src, AnyRegister dest, Register temp,
                                   Label* fail, bool canonicalizeDoubles, unsigned numElems)
{
    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());
        if (canonicalizeDoubles)
            canonicalizeDouble(dest.fpu());
        break;
      case Scalar::Int32x4:
        switch (numElems) {
          case 1:
            loadInt32x1(src, dest.fpu());
            break;
          case 2:
            loadInt32x2(src, dest.fpu());
            break;
          case 3:
            loadInt32x3(src, dest.fpu());
            break;
          case 4:
            loadUnalignedSimd128Int(src, dest.fpu());
            break;
          default: MOZ_CRASH("unexpected number of elements in SIMD load");
        }
        break;
      case Scalar::Float32x4:
        switch (numElems) {
          case 1:
            loadFloat32(src, dest.fpu());
            break;
          case 2:
            loadDouble(src, dest.fpu());
            break;
          case 3:
            loadFloat32x3(src, dest.fpu());
            break;
          case 4:
            loadUnalignedSimd128Float(src, dest.fpu());
            break;
          default: MOZ_CRASH("unexpected number of elements in SIMD load");
        }
        break;
      case Scalar::Int8x16:
        MOZ_ASSERT(numElems == 16, "unexpected partial load");
        loadUnalignedSimd128Int(src, dest.fpu());
        break;
      case Scalar::Int16x8:
        MOZ_ASSERT(numElems == 8, "unexpected partial load");
        loadUnalignedSimd128Int(src, dest.fpu());
        break;
      default:
        MOZ_CRASH("Invalid typed array type");
    }
}

template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const Address& src, AnyRegister dest,
                                                 Register temp, Label* fail, bool canonicalizeDoubles,
                                                 unsigned numElems);
template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const BaseIndex& src, AnyRegister dest,
                                                 Register temp, Label* fail, bool canonicalizeDoubles,
                                                 unsigned numElems);

template<typename T>
void
MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const T& src, const ValueOperand& dest,
                                   bool allowDouble, 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);
        if (allowDouble) {
            // If the value fits in an int32, store an int32 type tag.
            // Else, convert the value to double and box it.
            Label done, isDouble;
            branchTest32(Assembler::Signed, temp, temp, &isDouble);
            {
                tagValue(JSVAL_TYPE_INT32, temp, dest);
                jump(&done);
            }
            bind(&isDouble);
            {
                convertUInt32ToDouble(temp, ScratchDoubleReg);
                boxDouble(ScratchDoubleReg, dest);
            }
            bind(&done);
        } else {
            // Bailout if the value does not fit in an int32.
            branchTest32(Assembler::Signed, temp, temp, fail);
            tagValue(JSVAL_TYPE_INT32, temp, dest);
        }
        break;
      case Scalar::Float32:
        loadFromTypedArray(arrayType, src, AnyRegister(ScratchFloat32Reg), dest.scratchReg(),
                           nullptr);
        convertFloat32ToDouble(ScratchFloat32Reg, ScratchDoubleReg);
        boxDouble(ScratchDoubleReg, dest);
        break;
      case Scalar::Float64:
        loadFromTypedArray(arrayType, src, AnyRegister(ScratchDoubleReg), dest.scratchReg(),
                           nullptr);
        boxDouble(ScratchDoubleReg, dest);
        break;
      default:
        MOZ_CRASH("Invalid typed array type");
    }
}

template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const Address& src, const ValueOperand& dest,
                                                 bool allowDouble, Register temp, Label* fail);
template void MacroAssembler::loadFromTypedArray(Scalar::Type arrayType, const BaseIndex& src, const ValueOperand& dest,
                                                 bool allowDouble, Register temp, Label* fail);

template <typename T>
void
MacroAssembler::loadUnboxedProperty(T address, JSValueType type, TypedOrValueRegister output)
{
    switch (type) {
      case JSVAL_TYPE_INT32: {
          // Handle loading an int32 into a double reg.
          if (output.type() == MIRType::Double) {
              convertInt32ToDouble(address, output.typedReg().fpu());
              break;
          }
          MOZ_FALLTHROUGH;
      }

      case JSVAL_TYPE_BOOLEAN:
      case JSVAL_TYPE_STRING: {
        Register outReg;
        if (output.hasValue()) {
            outReg = output.valueReg().scratchReg();
        } else {
            MOZ_ASSERT(output.type() == MIRTypeFromValueType(type));
            outReg = output.typedReg().gpr();
        }

        switch (type) {
          case JSVAL_TYPE_BOOLEAN:
            load8ZeroExtend(address, outReg);
            break;
          case JSVAL_TYPE_INT32:
            load32(address, outReg);
            break;
          case JSVAL_TYPE_STRING:
            loadPtr(address, outReg);
            break;
          default:
            MOZ_CRASH();
        }

        if (output.hasValue())
            tagValue(type, outReg, output.valueReg());
        break;
      }

      case JSVAL_TYPE_OBJECT:
        if (output.hasValue()) {
            Register scratch = output.valueReg().scratchReg();
            loadPtr(address, scratch);

            Label notNull, done;
            branchPtr(Assembler::NotEqual, scratch, ImmWord(0), &notNull);

            moveValue(NullValue(), output.valueReg());
            jump(&done);

            bind(&notNull);
            tagValue(JSVAL_TYPE_OBJECT, scratch, output.valueReg());

            bind(&done);
        } else {
            // Reading null can't be possible here, as otherwise the result
            // would be a value (either because null has been read before or
            // because there is a barrier).
            Register reg = output.typedReg().gpr();
            loadPtr(address, reg);
#ifdef DEBUG
            Label ok;
            branchTestPtr(Assembler::NonZero, reg, reg, &ok);
            assumeUnreachable("Null not possible");
            bind(&ok);
#endif
        }
        break;

      case JSVAL_TYPE_DOUBLE:
        // Note: doubles in unboxed objects are not accessed through other
        // views and do not need canonicalization.
        if (output.hasValue())
            loadValue(address, output.valueReg());
        else
            loadDouble(address, output.typedReg().fpu());
        break;

      default:
        MOZ_CRASH();
    }
}

template void
MacroAssembler::loadUnboxedProperty(Address address, JSValueType type,
                                    TypedOrValueRegister output);

template void
MacroAssembler::loadUnboxedProperty(BaseIndex address, JSValueType type,
                                    TypedOrValueRegister output);

static void
StoreUnboxedFailure(MacroAssembler& masm, Label* failure)
{
    // Storing a value to an unboxed property is a fallible operation and
    // the caller must provide a failure label if a particular unboxed store
    // might fail. Sometimes, however, a store that cannot succeed (such as
    // storing a string to an int32 property) will be marked as infallible.
    // This can only happen if the code involved is unreachable.
    if (failure)
        masm.jump(failure);
    else
        masm.assumeUnreachable("Incompatible write to unboxed property");
}

template <typename T>
void
MacroAssembler::storeUnboxedProperty(T address, JSValueType type,
                                     ConstantOrRegister value, Label* failure)
{
    switch (type) {
      case JSVAL_TYPE_BOOLEAN:
        if (value.constant()) {
            if (value.value().isBoolean())
                store8(Imm32(value.value().toBoolean()), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else if (value.reg().hasTyped()) {
            if (value.reg().type() == MIRType::Boolean)
                store8(value.reg().typedReg().gpr(), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else {
            if (failure)
                branchTestBoolean(Assembler::NotEqual, value.reg().valueReg(), failure);
            storeUnboxedPayload(value.reg().valueReg(), address, /* width = */ 1);
        }
        break;

      case JSVAL_TYPE_INT32:
        if (value.constant()) {
            if (value.value().isInt32())
                store32(Imm32(value.value().toInt32()), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else if (value.reg().hasTyped()) {
            if (value.reg().type() == MIRType::Int32)
                store32(value.reg().typedReg().gpr(), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else {
            if (failure)
                branchTestInt32(Assembler::NotEqual, value.reg().valueReg(), failure);
            storeUnboxedPayload(value.reg().valueReg(), address, /* width = */ 4);
        }
        break;

      case JSVAL_TYPE_DOUBLE:
        if (value.constant()) {
            if (value.value().isNumber()) {
                loadConstantDouble(value.value().toNumber(), ScratchDoubleReg);
                storeDouble(ScratchDoubleReg, address);
            } else {
                StoreUnboxedFailure(*this, failure);
            }
        } else if (value.reg().hasTyped()) {
            if (value.reg().type() == MIRType::Int32) {
                convertInt32ToDouble(value.reg().typedReg().gpr(), ScratchDoubleReg);
                storeDouble(ScratchDoubleReg, address);
            } else if (value.reg().type() == MIRType::Double) {
                storeDouble(value.reg().typedReg().fpu(), address);
            } else {
                StoreUnboxedFailure(*this, failure);
            }
        } else {
            ValueOperand reg = value.reg().valueReg();
            Label notInt32, end;
            branchTestInt32(Assembler::NotEqual, reg, &notInt32);
            int32ValueToDouble(reg, ScratchDoubleReg);
            storeDouble(ScratchDoubleReg, address);
            jump(&end);
            bind(&notInt32);
            if (failure)
                branchTestDouble(Assembler::NotEqual, reg, failure);
            storeValue(reg, address);
            bind(&end);
        }
        break;

      case JSVAL_TYPE_OBJECT:
        if (value.constant()) {
            if (value.value().isObjectOrNull())
                storePtr(ImmGCPtr(value.value().toObjectOrNull()), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else if (value.reg().hasTyped()) {
            MOZ_ASSERT(value.reg().type() != MIRType::Null);
            if (value.reg().type() == MIRType::Object)
                storePtr(value.reg().typedReg().gpr(), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else {
            if (failure) {
                Label ok;
                branchTestNull(Assembler::Equal, value.reg().valueReg(), &ok);
                branchTestObject(Assembler::NotEqual, value.reg().valueReg(), failure);
                bind(&ok);
            }
            storeUnboxedPayload(value.reg().valueReg(), address, /* width = */ sizeof(uintptr_t));
        }
        break;

      case JSVAL_TYPE_STRING:
        if (value.constant()) {
            if (value.value().isString())
                storePtr(ImmGCPtr(value.value().toString()), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else if (value.reg().hasTyped()) {
            if (value.reg().type() == MIRType::String)
                storePtr(value.reg().typedReg().gpr(), address);
            else
                StoreUnboxedFailure(*this, failure);
        } else {
            if (failure)
                branchTestString(Assembler::NotEqual, value.reg().valueReg(), failure);
            storeUnboxedPayload(value.reg().valueReg(), address, /* width = */ sizeof(uintptr_t));
        }
        break;

      default:
        MOZ_CRASH();
    }
}

template void
MacroAssembler::storeUnboxedProperty(Address address, JSValueType type,
                                     ConstantOrRegister value, Label* failure);

template void
MacroAssembler::storeUnboxedProperty(BaseIndex address, JSValueType type,
                                     ConstantOrRegister value, Label* failure);

void
MacroAssembler::checkUnboxedArrayCapacity(Register obj, const RegisterOrInt32Constant& index,
                                          Register temp, Label* failure)
{
    Address initLengthAddr(obj, UnboxedArrayObject::offsetOfCapacityIndexAndInitializedLength());
    Address lengthAddr(obj, UnboxedArrayObject::offsetOfLength());

    Label capacityIsIndex, done;
    load32(initLengthAddr, temp);
    branchTest32(Assembler::NonZero, temp, Imm32(UnboxedArrayObject::CapacityMask), &capacityIsIndex);
    branch32(Assembler::BelowOrEqual, lengthAddr, index, failure);
    jump(&done);
    bind(&capacityIsIndex);

    // Do a partial shift so that we can get an absolute offset from the base
    // of CapacityArray to use.
    JS_STATIC_ASSERT(sizeof(UnboxedArrayObject::CapacityArray[0]) == 4);
    rshiftPtr(Imm32(UnboxedArrayObject::CapacityShift - 2), temp);
    and32(Imm32(~0x3), temp);

    addPtr(ImmPtr(&UnboxedArrayObject::CapacityArray), temp);
    branch32(Assembler::BelowOrEqual, Address(temp, 0), index, failure);
    bind(&done);
}

// 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 we are tracing allocations,
    // or when the memory profiler is enabled.
    if (js::gc::TraceEnabled() || MemProfiler::enabled())
        jump(fail);

#ifdef JS_GC_ZEAL
    // Don't execute the inline path if gc zeal or tracing are active.
    branch32(Assembler::NotEqual,
             AbsoluteAddress(GetJitContext()->runtime->addressOfGCZealModeBits()), Imm32(0),
             fail);
#endif

    // Don't execute the inline path if the compartment has an object metadata callback,
    // as the metadata to use for the object may vary between executions of the op.
    if (GetJitContext()->compartment->hasAllocationMetadataBuilder())
        jump(fail);
}

// Inline version of ShouldNurseryAllocate.
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::nurseryAllocate(Register result, Register temp, gc::AllocKind allocKind,
                                size_t nDynamicSlots, gc::InitialHeap initialHeap, Label* fail)
{
    MOZ_ASSERT(IsNurseryAllocable(allocKind));
    MOZ_ASSERT(initialHeap != gc::TenuredHeap);

    // 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;
    }

    // No explicit check for nursery.isEnabled() is needed, as the comparison
    // with the nursery's end will always fail in such cases.
    const Nursery& nursery = GetJitContext()->runtime->gcNursery();
    int thingSize = int(gc::Arena::thingSize(allocKind));
    int totalSize = thingSize + nDynamicSlots * sizeof(HeapSlot);
    loadPtr(AbsoluteAddress(nursery.addressOfPosition()), result);
    computeEffectiveAddress(Address(result, totalSize), temp);
    branchPtr(Assembler::Below, AbsoluteAddress(nursery.addressOfCurrentEnd()), temp, fail);
    storePtr(temp, AbsoluteAddress(nursery.addressOfPosition()));

    if (nDynamicSlots) {
        computeEffectiveAddress(Address(result, thingSize), 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 = GetJitContext()->compartment->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.
    loadPtr(AbsoluteAddress(zone->addressOfFreeList(allocKind)), 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(zone->addressOfFreeList(allocKind)), 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(zone->addressOfFreeList(allocKind)), 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);
}

void
MacroAssembler::callMallocStub(size_t nbytes, Register result, Label* fail)
{
    // This register must match the one in JitRuntime::generateMallocStub.
    const Register regNBytes = CallTempReg0;

    MOZ_ASSERT(nbytes > 0);
    MOZ_ASSERT(nbytes <= INT32_MAX);

    if (regNBytes != result)
        push(regNBytes);
    move32(Imm32(nbytes), regNBytes);
    call(GetJitContext()->runtime->jitRuntime()->mallocStub());
    if (regNBytes != result) {
        movePtr(regNBytes, result);
        pop(regNBytes);
    }
    branchTest32(Assembler::Zero, result, result, fail);
}

void
MacroAssembler::callFreeStub(Register slots)
{
    // This register must match the one in JitRuntime::generateFreeStub.
    const Register regSlots = CallTempReg0;

    push(regSlots);
    movePtr(slots, regSlots);
    call(GetJitContext()->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)
{
    MOZ_ASSERT(gc::IsObjectAllocKind(allocKind));

    checkAllocatorState(fail);

    if (shouldNurseryAllocate(allocKind, initialHeap))
        return nurseryAllocate(result, temp, allocKind, nDynamicSlots, initialHeap, fail);

    if (!nDynamicSlots)
        return freeListAllocate(result, temp, allocKind, fail);

    callMallocStub(nDynamicSlots * sizeof(GCPtrValue), temp, fail);

    Label failAlloc;
    Label success;

    push(temp);
    freeListAllocate(result, temp, allocKind, &failAlloc);

    pop(temp);
    storePtr(temp, Address(result, NativeObject::offsetOfSlots()));

    jump(&success);

    bind(&failAlloc);
    pop(temp);
    callFreeStub(temp);
    jump(fail);

    bind(&success);
}

void
MacroAssembler::createGCObject(Register obj, Register temp, JSObject* templateObj,
                               gc::InitialHeap initialHeap, Label* fail, bool initContents,
                               bool convertDoubleElements)
{
    gc::AllocKind allocKind = templateObj->asTenured().getAllocKind();
    MOZ_ASSERT(gc::IsObjectAllocKind(allocKind));

    uint32_t nDynamicSlots = 0;
    if (templateObj->isNative()) {
        nDynamicSlots = templateObj->as<NativeObject>().numDynamicSlots();

        // Arrays with copy on write elements do not need fixed space for an
        // elements header. The template object, which owns the original
        // elements, might have another allocation kind.
        if (templateObj->as<NativeObject>().denseElementsAreCopyOnWrite())
            allocKind = gc::AllocKind::OBJECT0_BACKGROUND;
    }

    allocateObject(obj, temp, allocKind, nDynamicSlots, initialHeap, fail);
    initGCThing(obj, temp, templateObj, initContents, convertDoubleElements);
}


// Inlined equivalent of gc::AllocateNonObject, without failure case handling.
// Non-object allocation does not need to worry about slots, so can take a
// simpler path.
void
MacroAssembler::allocateNonObject(Register result, Register temp, gc::AllocKind allocKind, Label* fail)
{
    checkAllocatorState(fail);
    freeListAllocate(result, temp, allocKind, fail);
}

void
MacroAssembler::newGCString(Register result, Register temp, Label* fail)
{
    allocateNonObject(result, temp, js::gc::AllocKind::STRING, fail);
}

void
MacroAssembler::newGCFatInlineString(Register result, Register temp, Label* fail)
{
    allocateNonObject(result, temp, js::gc::AllocKind::FAT_INLINE_STRING, fail);
}

void
MacroAssembler::copySlotsFromTemplate(Register obj, const NativeObject* templateObj,
                                      uint32_t start, uint32_t end)
{
    uint32_t nfixed = Min(templateObj->numFixedSlots(), end);
    for (unsigned i = start; i < nfixed; i++)
        storeValue(templateObj->getFixedSlot(i), 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.
    jsval_layout jv = JSVAL_TO_IMPL(v);

    Address addr = base;
    move32(Imm32(jv.s.payload.i32), temp);
    for (unsigned i = start; i < end; ++i, addr.offset += sizeof(GCPtrValue))
        store32(temp, ToPayload(addr));

    addr = base;
    move32(Imm32(jv.s.tag), temp);
    for (unsigned i = start; i < end; ++i, addr.offset += sizeof(GCPtrValue))
        store32(temp, ToType(addr));
#else
    moveValue(v, temp);
    for (uint32_t i = start; i < end; ++i, base.offset += sizeof(GCPtrValue))
        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 void
FindStartOfUndefinedAndUninitializedSlots(NativeObject* templateObj, uint32_t nslots,
                                          uint32_t* startOfUndefined, uint32_t* startOfUninitialized)
{
    MOZ_ASSERT(nslots == templateObj->lastProperty()->slotSpan(templateObj->getClass()));
    MOZ_ASSERT(nslots > 0);
    uint32_t first = nslots;
    for (; first != 0; --first) {
        if (!IsUninitializedLexical(templateObj->getSlot(first - 1)))
            break;
    }
    *startOfUninitialized = first;
    for (; first != 0; --first) {
        if (templateObj->getSlot(first - 1) != UndefinedValue()) {
            *startOfUndefined = first;
            return;
        }
    }
    *startOfUndefined = 0;
}

static void
AllocateObjectBufferWithInit(JSContext* cx, TypedArrayObject* obj, uint32_t count)
{
    JS::AutoCheckCannotGC nogc(cx);

    obj->initPrivate(nullptr);
    obj->setFixedSlot(TypedArrayObject::LENGTH_SLOT, Int32Value(count));

    // Typed arrays with a non-compile-time known size that have a count of zero
    // eventually are essentially typed arrays with inline elements. The bounds
    // check will make sure that no elements are read or written to that memory.
    if (count == 0) {
        obj->setInlineElements();
        return;
    }

    size_t nbytes;

    switch (obj->type()) {
#define CREATE_TYPED_ARRAY(T, N) \
      case Scalar::N: \
        if (!js::CalculateAllocSize<T>(count, &nbytes)) \
            return; \
        break;
JS_FOR_EACH_TYPED_ARRAY(CREATE_TYPED_ARRAY)
#undef CREATE_TYPED_ARRAY
      default:
        MOZ_CRASH("Unsupported TypedArray type");
    }

    void* buf = AllocateObjectBuffer<char>(cx, obj, nbytes);
    if (buf) {
        obj->initPrivate(buf);
        memset(buf, 0, nbytes);
    }
}

void
MacroAssembler::initTypedArraySlots(Register obj, Register temp, Register lengthReg,
                                    LiveRegisterSet liveRegs, Label* fail,
                                    TypedArrayObject* templateObj)
{
    MOZ_ASSERT(templateObj->hasPrivate());
    MOZ_ASSERT(!templateObj->hasBuffer());

    size_t dataSlotOffset = TypedArrayObject::dataOffset();
    size_t dataOffset = TypedArrayObject::dataOffset() + sizeof(HeapSlot);

    static_assert(TypedArrayObject::FIXED_DATA_START == TypedArrayObject::DATA_SLOT + 1,
                    "fixed inline element data assumed to begin after the data slot");

    // Initialise data elements to zero.
    int32_t length = templateObj->length();
    size_t nbytes = length * templateObj->bytesPerElement();

    if (dataOffset + nbytes <= JSObject::MAX_BYTE_SIZE) {
        MOZ_ASSERT(dataOffset + nbytes <= templateObj->tenuredSizeOfThis());

        // Store data elements inside the remaining JSObject slots.
        computeEffectiveAddress(Address(obj, dataOffset), temp);
        storePtr(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 *)));
    } else {
        move32(Imm32(length), lengthReg);

        // Allocate a buffer on the heap to store the data elements.
        liveRegs.addUnchecked(temp);
        liveRegs.addUnchecked(obj);
        liveRegs.addUnchecked(lengthReg);
        PushRegsInMask(liveRegs);
        setupUnalignedABICall(temp);
        loadJSContext(temp);
        passABIArg(temp);
        passABIArg(obj);
        passABIArg(lengthReg);
        callWithABI(JS_FUNC_TO_DATA_PTR(void*, AllocateObjectBufferWithInit));
        PopRegsInMask(liveRegs);

        // Fail when data elements is set to NULL.
        branchPtr(Assembler::Equal, Address(obj, dataSlotOffset), ImmWord(0), fail);
    }
}

void
MacroAssembler::initGCSlots(Register obj, Register temp, NativeObject* templateObj,
                            bool initContents)
{
    // Slots of non-array objects are required to be initialized.
    // Use the values currently in the template object.
    uint32_t nslots = templateObj->lastProperty()->slotSpan(templateObj->getClass());
    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. Unitialized lexical slots always appear at the very end of
    // slots, after undefined.
    uint32_t startOfUndefined = nslots;
    uint32_t startOfUninitialized = nslots;
    FindStartOfUndefinedAndUninitializedSlots(templateObj, nslots,
                                              &startOfUndefined, &startOfUninitialized);
    MOZ_ASSERT(startOfUndefined <= nfixed); // Reserved slots must be fixed.
    MOZ_ASSERT_IF(startOfUndefined != nfixed, startOfUndefined <= startOfUninitialized);
    MOZ_ASSERT_IF(!templateObj->is<CallObject>(), startOfUninitialized == nslots);

    // Copy over any preserved reserved slots.
    copySlotsFromTemplate(obj, templateObj, 0, startOfUndefined);

    // Fill the rest of the fixed slots with undefined and uninitialized.
    if (initContents) {
        fillSlotsWithUndefined(Address(obj, NativeObject::getFixedSlotOffset(startOfUndefined)), temp,
                               startOfUndefined, Min(startOfUninitialized, nfixed));
        size_t offset = NativeObject::getFixedSlotOffset(startOfUninitialized);
        fillSlotsWithUninitialized(Address(obj, offset), temp, startOfUninitialized, 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);

        // Initially fill all dynamic slots with undefined.
        fillSlotsWithUndefined(Address(obj, 0), temp, 0, ndynamic);

        // Fill uninitialized slots if necessary.
        fillSlotsWithUninitialized(Address(obj, 0), temp, startOfUninitialized - nfixed,
                                   nslots - startOfUninitialized);

        pop(obj);
    }
}

void
MacroAssembler::initGCThing(Register obj, Register temp, JSObject* templateObj,
                            bool initContents, bool convertDoubleElements)
{
    // Fast initialization of an empty object returned by allocateObject().

    storePtr(ImmGCPtr(templateObj->group()), Address(obj, JSObject::offsetOfGroup()));

    if (Shape* shape = templateObj->maybeShape())
        storePtr(ImmGCPtr(shape), Address(obj, ShapedObject::offsetOfShape()));

    MOZ_ASSERT_IF(convertDoubleElements, templateObj->is<ArrayObject>());

    if (templateObj->isNative()) {
        NativeObject* ntemplate = &templateObj->as<NativeObject>();
        MOZ_ASSERT_IF(!ntemplate->denseElementsAreCopyOnWrite(), !ntemplate->hasDynamicElements());

        // If the object has dynamic slots, the slots member has already been
        // filled in.
        if (!ntemplate->hasDynamicSlots())
            storePtr(ImmPtr(nullptr), Address(obj, NativeObject::offsetOfSlots()));

        if (ntemplate->denseElementsAreCopyOnWrite()) {
            storePtr(ImmPtr((const Value*) ntemplate->getDenseElements()),
                     Address(obj, NativeObject::offsetOfElements()));
        } else if (ntemplate->is<ArrayObject>()) {
            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->as<ArrayObject>().length()),
                    Address(obj, elementsOffset + ObjectElements::offsetOfLength()));
            store32(Imm32(convertDoubleElements
                          ? ObjectElements::CONVERT_DOUBLE_ELEMENTS
                          : 0),
                    Address(obj, elementsOffset + ObjectElements::offsetOfFlags()));
            MOZ_ASSERT(!ntemplate->hasPrivate());
        } else if (ntemplate->is<ArgumentsObject>()) {
            // The caller will initialize the reserved slots.
            MOZ_ASSERT(!initContents);
            MOZ_ASSERT(!ntemplate->hasPrivate());
            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());

            storePtr(ImmPtr(emptyObjectElements), Address(obj, NativeObject::offsetOfElements()));

            initGCSlots(obj, temp, ntemplate, initContents);

            if (ntemplate->hasPrivate() && !ntemplate->is<TypedArrayObject>()) {
                uint32_t nfixed = ntemplate->numFixedSlots();
                storePtr(ImmPtr(ntemplate->getPrivate()),
                         Address(obj, NativeObject::getPrivateDataOffset(nfixed)));
            }
        }
    } else if (templateObj->is<InlineTypedObject>()) {
        size_t nbytes = templateObj->as<InlineTypedObject>().size();
        const uint8_t* memory = templateObj->as<InlineTypedObject>().inlineTypedMem();

        // Memcpy the contents of the template object to the new object.
        size_t offset = 0;
        while (nbytes) {
            uintptr_t value = *(uintptr_t*)(memory + offset);
            storePtr(ImmWord(value),
                     Address(obj, InlineTypedObject::offsetOfDataStart() + offset));
            nbytes = (nbytes < sizeof(uintptr_t)) ? 0 : nbytes - sizeof(uintptr_t);
            offset += sizeof(uintptr_t);
        }
    } else if (templateObj->is<UnboxedPlainObject>()) {
        storePtr(ImmWord(0), Address(obj, UnboxedPlainObject::offsetOfExpando()));
        if (initContents)
            initUnboxedObjectContents(obj, &templateObj->as<UnboxedPlainObject>());
    } else if (templateObj->is<UnboxedArrayObject>()) {
        MOZ_ASSERT(templateObj->as<UnboxedArrayObject>().hasInlineElements());
        int elementsOffset = UnboxedArrayObject::offsetOfInlineElements();
        computeEffectiveAddress(Address(obj, elementsOffset), temp);
        storePtr(temp, Address(obj, UnboxedArrayObject::offsetOfElements()));
        store32(Imm32(templateObj->as<UnboxedArrayObject>().length()),
                Address(obj, UnboxedArrayObject::offsetOfLength()));
        uint32_t capacityIndex = templateObj->as<UnboxedArrayObject>().capacityIndex();
        store32(Imm32(capacityIndex << UnboxedArrayObject::CapacityShift),
                Address(obj, UnboxedArrayObject::offsetOfCapacityIndexAndInitializedLength()));
    } else {
        MOZ_CRASH("Unknown object");
    }

#ifdef JS_GC_TRACE
    RegisterSet regs = RegisterSet::Volatile();
    PushRegsInMask(regs);
    regs.takeUnchecked(obj);
    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    passABIArg(obj);
    movePtr(ImmGCPtr(templateObj->type()), temp);
    passABIArg(temp);
    callWithABI(JS_FUNC_TO_DATA_PTR(void*, js::gc::TraceCreateObject));

    PopRegsInMask(RegisterSet::Volatile());
#endif
}

void
MacroAssembler::initUnboxedObjectContents(Register object, UnboxedPlainObject* templateObject)
{
    const UnboxedLayout& layout = templateObject->layoutDontCheckGeneration();

    // Initialize reference fields of the object, per UnboxedPlainObject::create.
    if (const int32_t* list = layout.traceList()) {
        while (*list != -1) {
            storePtr(ImmGCPtr(GetJitContext()->runtime->names().empty),
                     Address(object, UnboxedPlainObject::offsetOfData() + *list));
            list++;
        }
        list++;
        while (*list != -1) {
            storePtr(ImmWord(0),
                     Address(object, UnboxedPlainObject::offsetOfData() + *list));
            list++;
        }
        // Unboxed objects don't have Values to initialize.
        MOZ_ASSERT(*(list + 1) == -1);
    }
}

void
MacroAssembler::compareStrings(JSOp op, Register left, Register right, Register result,
                               Label* fail)
{
    MOZ_ASSERT(IsEqualityOp(op));

    Label done;
    Label notPointerEqual;
    // Fast path for identical strings.
    branchPtr(Assembler::NotEqual, left, right, &notPointerEqual);
    move32(Imm32(op == JSOP_EQ || op == JSOP_STRICTEQ), result);
    jump(&done);

    bind(&notPointerEqual);

    Label notAtom;
    // Optimize the equality operation to a pointer compare for two atoms.
    Imm32 atomBit(JSString::ATOM_BIT);
    branchTest32(Assembler::Zero, Address(left, JSString::offsetOfFlags()), atomBit, &notAtom);
    branchTest32(Assembler::Zero, Address(right, JSString::offsetOfFlags()), atomBit, &notAtom);

    cmpPtrSet(JSOpToCondition(MCompare::Compare_String, op), left, right, result);
    jump(&done);

    bind(&notAtom);
    // Strings of different length can never be equal.
    loadStringLength(left, result);
    branch32(Assembler::Equal, Address(right, JSString::offsetOfLength()), result, fail);
    move32(Imm32(op == JSOP_NE || op == JSOP_STRICTNE), result);

    bind(&done);
}

void
MacroAssembler::loadStringChars(Register str, Register dest)
{
    Label isInline, done;
    branchTest32(Assembler::NonZero, Address(str, JSString::offsetOfFlags()),
                 Imm32(JSString::INLINE_CHARS_BIT), &isInline);

    loadPtr(Address(str, JSString::offsetOfNonInlineChars()), dest);
    jump(&done);

    bind(&isInline);
    computeEffectiveAddress(Address(str, JSInlineString::offsetOfInlineStorage()), dest);

    bind(&done);
}

void
MacroAssembler::loadStringChar(Register str, Register index, Register output)
{
    MOZ_ASSERT(str != output);
    MOZ_ASSERT(index != output);

    loadStringChars(str, output);

    Label isLatin1, done;
    branchLatin1String(str, &isLatin1);
    load16ZeroExtend(BaseIndex(output, index, TimesTwo), output);
    jump(&done);

    bind(&isLatin1);
    load8ZeroExtend(BaseIndex(output, index, TimesOne), output);

    bind(&done);
}

static void
BailoutReportOverRecursed(JSContext* cx)
{
    ReportOverRecursed(cx);
}

void
MacroAssembler::generateBailoutTail(Register scratch, Register bailoutInfo)
{
    enterExitFrame();

    Label baseline;

    // The return value from Bailout is tagged as:
    // - 0x0: done (enter baseline)
    // - 0x1: error (handle exception)
    // - 0x2: overrecursed
    JS_STATIC_ASSERT(BAILOUT_RETURN_OK == 0);
    JS_STATIC_ASSERT(BAILOUT_RETURN_FATAL_ERROR == 1);
    JS_STATIC_ASSERT(BAILOUT_RETURN_OVERRECURSED == 2);

    branch32(Equal, ReturnReg, Imm32(BAILOUT_RETURN_OK), &baseline);
    branch32(Equal, ReturnReg, Imm32(BAILOUT_RETURN_FATAL_ERROR), exceptionLabel());

    // Fall-through: overrecursed.
    {
        loadJSContext(ReturnReg);
        setupUnalignedABICall(scratch);
        passABIArg(ReturnReg);
        callWithABI(JS_FUNC_TO_DATA_PTR(void*, BailoutReportOverRecursed));
        jump(exceptionLabel());
    }

    bind(&baseline);
    {
        // Prepare a register set for use in this case.
        AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
        MOZ_ASSERT(!regs.has(getStackPointer()));
        regs.take(bailoutInfo);

        // Reset SP to the point where clobbering starts.
        loadStackPtr(Address(bailoutInfo, offsetof(BaselineBailoutInfo, incomingStack)));

        Register copyCur = regs.takeAny();
        Register copyEnd = regs.takeAny();
        Register temp = 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(4), copyCur);
            subFromStackPtr(Imm32(4));
            load32(Address(copyCur, 0), temp);
            store32(temp, Address(getStackPointer(), 0));
            jump(&copyLoop);
            bind(&endOfCopy);
        }

        // Enter exit frame for the FinishBailoutToBaseline call.
        loadPtr(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeFramePtr)), temp);
        load32(Address(temp, BaselineFrame::reverseOffsetOfFrameSize()), temp);
        makeFrameDescriptor(temp, JitFrame_BaselineJS, ExitFrameLayout::Size());
        push(temp);
        push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeAddr)));
        // No GC things to mark on the stack, push a bare token.
        enterFakeExitFrame(ExitFrameLayoutBareToken);

        // If monitorStub is non-null, handle resumeAddr appropriately.
        Label noMonitor;
        Label done;
        branchPtr(Assembler::Equal,
                  Address(bailoutInfo, offsetof(BaselineBailoutInfo, monitorStub)),
                  ImmPtr(nullptr),
                  &noMonitor);

        //
        // Resuming into a monitoring stub chain.
        //
        {
            // Save needed values onto stack temporarily.
            pushValue(Address(bailoutInfo, offsetof(BaselineBailoutInfo, valueR0)));
            push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeFramePtr)));
            push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeAddr)));
            push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, monitorStub)));

            // Call a stub to free allocated memory and create arguments objects.
            setupUnalignedABICall(temp);
            passABIArg(bailoutInfo);
            callWithABI(JS_FUNC_TO_DATA_PTR(void*, FinishBailoutToBaseline));
            branchTest32(Zero, ReturnReg, ReturnReg, exceptionLabel());

            // Restore values where they need to be and resume execution.
            AllocatableGeneralRegisterSet enterMonRegs(GeneralRegisterSet::All());
            enterMonRegs.take(R0);
            enterMonRegs.take(ICStubReg);
            enterMonRegs.take(BaselineFrameReg);
            enterMonRegs.takeUnchecked(ICTailCallReg);

            pop(ICStubReg);
            pop(ICTailCallReg);
            pop(BaselineFrameReg);
            popValue(R0);

            // Discard exit frame.
            addToStackPtr(Imm32(ExitFrameLayout::SizeWithFooter()));

#if defined(JS_CODEGEN_X86) || defined(JS_CODEGEN_X64)
            push(ICTailCallReg);
#endif
            jump(Address(ICStubReg, ICStub::offsetOfStubCode()));
        }

        //
        // Resuming into main jitcode.
        //
        bind(&noMonitor);
        {
            // Save needed values onto stack temporarily.
            pushValue(Address(bailoutInfo, offsetof(BaselineBailoutInfo, valueR0)));
            pushValue(Address(bailoutInfo, offsetof(BaselineBailoutInfo, valueR1)));
            push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeFramePtr)));
            push(Address(bailoutInfo, offsetof(BaselineBailoutInfo, resumeAddr)));

            // Call a stub to free allocated memory and create arguments objects.
            setupUnalignedABICall(temp);
            passABIArg(bailoutInfo);
            callWithABI(JS_FUNC_TO_DATA_PTR(void*, FinishBailoutToBaseline));
            branchTest32(Zero, ReturnReg, ReturnReg, exceptionLabel());

            // Restore values where they need to be and resume execution.
            AllocatableGeneralRegisterSet enterRegs(GeneralRegisterSet::All());
            enterRegs.take(R0);
            enterRegs.take(R1);
            enterRegs.take(BaselineFrameReg);
            Register jitcodeReg = enterRegs.takeAny();

            pop(jitcodeReg);
            pop(BaselineFrameReg);
            popValue(R1);
            popValue(R0);

            // Discard exit frame.
            addToStackPtr(Imm32(ExitFrameLayout::SizeWithFooter()));

            jump(jitcodeReg);
        }
    }
}

void
MacroAssembler::loadBaselineOrIonRaw(Register script, Register dest, Label* failure)
{
    loadPtr(Address(script, JSScript::offsetOfBaselineOrIonRaw()), dest);
    if (failure)
        branchTestPtr(Assembler::Zero, dest, dest, failure);
}

void
MacroAssembler::loadBaselineOrIonNoArgCheck(Register script, Register dest, Label* failure)
{
    loadPtr(Address(script, JSScript::offsetOfBaselineOrIonSkipArgCheck()), dest);
    if (failure)
        branchTestPtr(Assembler::Zero, dest, dest, failure);
}

void
MacroAssembler::loadBaselineFramePtr(Register framePtr, Register dest)
{
    if (framePtr != dest)
        movePtr(framePtr, dest);
    subPtr(Imm32(BaselineFrame::Size()), dest);
}

void
MacroAssembler::handleFailure()
{
    // Re-entry code is irrelevant because the exception will leave the
    // running function and never come back
    JitCode* excTail = GetJitContext()->runtime->jitRuntime()->getExceptionTail();
    jump(excTail);
}

#ifdef DEBUG
static void
AssumeUnreachable_(const char* output) {
    MOZ_ReportAssertionFailure(output, __FILE__, __LINE__);
}
#endif

void
MacroAssembler::assumeUnreachable(const char* output)
{
#ifdef DEBUG
    if (!IsCompilingAsmJS()) {
        AllocatableRegisterSet regs(RegisterSet::Volatile());
        LiveRegisterSet save(regs.asLiveSet());
        PushRegsInMask(save);
        Register temp = regs.takeAnyGeneral();

        setupUnalignedABICall(temp);
        movePtr(ImmPtr(output), temp);
        passABIArg(temp);
        callWithABI(JS_FUNC_TO_DATA_PTR(void*, AssumeUnreachable_));

        PopRegsInMask(save);
    }
#endif

    breakpoint();
}

template<typename T>
void
MacroAssembler::assertTestInt32(Condition cond, const T& value, const char* output)
{
#ifdef DEBUG
    Label ok;
    branchTestInt32(cond, value, &ok);
    assumeUnreachable(output);
    bind(&ok);
#endif
}

template void MacroAssembler::assertTestInt32(Condition, const Address&, const char*);

static void
Printf0_(const char* output) {
    // Use stderr instead of stdout because this is only used for debug
    // output. stderr is less likely to interfere with the program's normal
    // output, and it's always unbuffered.
    fprintf(stderr, "%s", output);
}

void
MacroAssembler::printf(const char* output)
{
    AllocatableRegisterSet regs(RegisterSet::Volatile());
    LiveRegisterSet save(regs.asLiveSet());
    PushRegsInMask(save);

    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    movePtr(ImmPtr(output), temp);
    passABIArg(temp);
    callWithABI(JS_FUNC_TO_DATA_PTR(void*, Printf0_));

    PopRegsInMask(save);
}

static void
Printf1_(const char* output, uintptr_t value) {
    AutoEnterOOMUnsafeRegion oomUnsafe;
    char* line = JS_sprintf_append(nullptr, output, value);
    if (!line)
        oomUnsafe.crash("OOM at masm.printf");
    fprintf(stderr, "%s", line);
    js_free(line);
}

void
MacroAssembler::printf(const char* output, Register value)
{
    AllocatableRegisterSet regs(RegisterSet::Volatile());
    LiveRegisterSet save(regs.asLiveSet());
    PushRegsInMask(save);

    regs.takeUnchecked(value);

    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    movePtr(ImmPtr(output), temp);
    passABIArg(temp);
    passABIArg(value);
    callWithABI(JS_FUNC_TO_DATA_PTR(void*, Printf1_));

    PopRegsInMask(save);
}

#ifdef JS_TRACE_LOGGING
void
MacroAssembler::tracelogStartId(Register logger, uint32_t textId, bool force)
{
    if (!force && !TraceLogTextIdEnabled(textId))
        return;

    AllocatableRegisterSet regs(RegisterSet::Volatile());
    LiveRegisterSet save(regs.asLiveSet());
    PushRegsInMask(save);
    regs.takeUnchecked(logger);

    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    passABIArg(logger);
    move32(Imm32(textId), temp);
    passABIArg(temp);
    callWithABI(JS_FUNC_TO_DATA_PTR(void*, TraceLogStartEventPrivate));

    PopRegsInMask(save);
}

void
MacroAssembler::tracelogStartId(Register logger, Register textId)
{
    AllocatableRegisterSet regs(RegisterSet::Volatile());
    LiveRegisterSet save(regs.asLiveSet());
    PushRegsInMask(save);
    regs.takeUnchecked(logger);
    regs.takeUnchecked(textId);

    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    passABIArg(logger);
    passABIArg(textId);
    callWithABI(JS_FUNC_TO_DATA_PTR(void*, TraceLogStartEventPrivate));

    PopRegsInMask(save);
}

void
MacroAssembler::tracelogStartEvent(Register logger, Register event)
{
    void (&TraceLogFunc)(TraceLoggerThread*, const TraceLoggerEvent&) = TraceLogStartEvent;

    AllocatableRegisterSet regs(RegisterSet::Volatile());
    LiveRegisterSet save(regs.asLiveSet());
    PushRegsInMask(save);
    regs.takeUnchecked(logger);
    regs.takeUnchecked(event);

    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    passABIArg(logger);
    passABIArg(event);
    callWithABI(JS_FUNC_TO_DATA_PTR(void*, TraceLogFunc));

    PopRegsInMask(save);
}

void
MacroAssembler::tracelogStopId(Register logger, uint32_t textId, bool force)
{
    if (!force && !TraceLogTextIdEnabled(textId))
        return;

    AllocatableRegisterSet regs(RegisterSet::Volatile());
    LiveRegisterSet save(regs.asLiveSet());
    PushRegsInMask(save);
    regs.takeUnchecked(logger);

    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    passABIArg(logger);
    move32(Imm32(textId), temp);
    passABIArg(temp);

    callWithABI(JS_FUNC_TO_DATA_PTR(void*, TraceLogStopEventPrivate));

    PopRegsInMask(save);
}

void
MacroAssembler::tracelogStopId(Register logger, Register textId)
{
    AllocatableRegisterSet regs(RegisterSet::Volatile());
    LiveRegisterSet save(regs.asLiveSet());
    PushRegsInMask(save);
    regs.takeUnchecked(logger);
    regs.takeUnchecked(textId);

    Register temp = regs.takeAnyGeneral();

    setupUnalignedABICall(temp);
    passABIArg(logger);
    passABIArg(textId);
    callWithABI(JS_FUNC_TO_DATA_PTR(void*, TraceLogStopEventPrivate));

    PopRegsInMask(save);
}
#endif

void
MacroAssembler::convertInt32ValueToDouble(const Address& address, Register scratch, Label* done)
{
    branchTestInt32(Assembler::NotEqual, address, done);
    unboxInt32(address, scratch);
    convertInt32ToDouble(scratch, ScratchDoubleReg);
    storeDouble(ScratchDoubleReg, address);
}

void
MacroAssembler::convertValueToFloatingPoint(ValueOperand value, FloatRegister output,
                                            Label* fail, MIRType outputType)
{
    Register tag = splitTagForTest(value);

    Label isDouble, isInt32, isBool, isNull, done;

    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);

    bind(&isDouble);
    FloatRegister tmp = output;
    if (outputType == MIRType::Float32 && hasMultiAlias())
        tmp = ScratchDoubleReg;

    unboxDouble(value, tmp);
    if (outputType == MIRType::Float32)
        convertDoubleToFloat32(tmp, output);

    bind(&done);
}

bool
MacroAssembler::convertValueToFloatingPoint(JSContext* cx, const Value& v, FloatRegister output,
                                            Label* fail, MIRType outputType)
{
    if (v.isNumber() || v.isString()) {
        double d;
        if (v.isNumber())
            d = v.toNumber();
        else if (!StringToNumber(cx, v.toString(), &d))
            return false;

        loadConstantFloatingPoint(d, (float)d, output, outputType);
        return true;
    }

    if (v.isBoolean()) {
        if (v.toBoolean())
            loadConstantFloatingPoint(1.0, 1.0f, output, outputType);
        else
            loadConstantFloatingPoint(0.0, 0.0f, output, outputType);
        return true;
    }

    if (v.isNull()) {
        loadConstantFloatingPoint(0.0, 0.0f, output, outputType);
        return true;
    }

    if (v.isUndefined()) {
        loadConstantFloatingPoint(GenericNaN(), float(GenericNaN()), output, outputType);
        return true;
    }

    MOZ_ASSERT(v.isObject() || v.isSymbol());
    jump(fail);
    return true;
}

bool
MacroAssembler::convertConstantOrRegisterToFloatingPoint(JSContext* cx, ConstantOrRegister src,
                                                         FloatRegister output, Label* fail,
                                                         MIRType outputType)
{
    if (src.constant())
        return convertValueToFloatingPoint(cx, src.value(), output, fail, outputType);

    convertTypedOrValueToFloatingPoint(src.reg(), output, fail, outputType);
    return true;
}

void
MacroAssembler::convertTypedOrValueToFloatingPoint(TypedOrValueRegister src, FloatRegister output,
                                                   Label* fail, MIRType outputType)
{
    MOZ_ASSERT(IsFloatingPointType(outputType));

    if (src.hasValue()) {
        convertValueToFloatingPoint(src.valueReg(), output, fail, outputType);
        return;
    }

    bool outputIsDouble = outputType == MIRType::Double;
    switch (src.type()) {
      case MIRType::Null:
        loadConstantFloatingPoint(0.0, 0.0f, output, outputType);
        break;
      case MIRType::Boolean:
      case MIRType::Int32:
        convertInt32ToFloatingPoint(src.typedReg().gpr(), output, outputType);
        break;
      case MIRType::Float32:
        if (outputIsDouble) {
            convertFloat32ToDouble(src.typedReg().fpu(), output);
        } else {
            if (src.typedReg().fpu() != output)
                moveFloat32(src.typedReg().fpu(), output);
        }
        break;
      case MIRType::Double:
        if (outputIsDouble) {
            if (src.typedReg().fpu() != output)
                moveDouble(src.typedReg().fpu(), output);
        } else {
            convertDoubleToFloat32(src.typedReg().fpu(), output);
        }
        break;
      case MIRType::Object:
      case MIRType::String:
      case MIRType::Symbol:
        jump(fail);
        break;
      case MIRType::Undefined:
        loadConstantFloatingPoint(GenericNaN(), float(GenericNaN()), output, outputType);
        break;
      default:
        MOZ_CRASH("Bad MIRType");
    }
}

void
MacroAssembler::outOfLineTruncateSlow(FloatRegister src, Register dest, bool widenFloatToDouble,
                                      bool compilingWasm)
{
#if defined(JS_CODEGEN_ARM) || defined(JS_CODEGEN_ARM64) || \
    defined(JS_CODEGEN_MIPS32) || defined(JS_CODEGEN_MIPS64)
    if (widenFloatToDouble) {
        convertFloat32ToDouble(src, ScratchDoubleReg);
        src = ScratchDoubleReg;
    }
#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());

    setupUnalignedABICall(dest);
    passABIArg(src, MoveOp::DOUBLE);
    if (compilingWasm)
        callWithABI(wasm::SymbolicAddress::ToInt32);
    else
        callWithABI(mozilla::BitwiseCast<void*, int32_t(*)(double)>(JS::ToInt32));
    storeCallResult(dest);

#if defined(JS_CODEGEN_ARM) || defined(JS_CODEGEN_ARM64) || \
    defined(JS_CODEGEN_MIPS32) || defined(JS_CODEGEN_MIPS64)
    // Nothing
#elif defined(JS_CODEGEN_X86) || defined(JS_CODEGEN_X64)
    if (widenFloatToDouble)
        pop(srcSingle);
#else
    MOZ_CRASH("MacroAssembler platform hook: outOfLineTruncateSlow");
#endif
}

void
MacroAssembler::convertDoubleToInt(FloatRegister src, Register output, FloatRegister temp,
                                   Label* truncateFail, Label* fail,
                                   IntConversionBehavior behavior)
{
    switch (behavior) {
      case IntConversion_Normal:
      case IntConversion_NegativeZeroCheck:
        convertDoubleToInt32(src, output, fail, behavior == IntConversion_NegativeZeroCheck);
        break;
      case IntConversion_Truncate:
        branchTruncateDoubleMaybeModUint32(src, output, truncateFail ? truncateFail : fail);
        break;
      case IntConversion_ClampToUint8:
        // Clamping clobbers the input register, so use a temp.
        moveDouble(src, temp);
        clampDoubleToUint8(temp, output);
        break;
    }
}

void
MacroAssembler::convertValueToInt(ValueOperand value, MDefinition* maybeInput,
                                  Label* handleStringEntry, Label* handleStringRejoin,
                                  Label* truncateDoubleSlow,
                                  Register stringReg, FloatRegister temp, Register output,
                                  Label* fail, IntConversionBehavior behavior,
                                  IntConversionInputKind conversion)
{
    Register tag = splitTagForTest(value);
    bool handleStrings = (behavior == IntConversion_Truncate ||
                          behavior == IntConversion_ClampToUint8) &&
                         handleStringEntry &&
                         handleStringRejoin;

    MOZ_ASSERT_IF(handleStrings, conversion == IntConversion_Any);

    Label done, isInt32, isBool, isDouble, isNull, isString;

    maybeBranchTestType(MIRType::Int32, maybeInput, tag, &isInt32);
    if (conversion == IntConversion_Any || conversion == IntConversion_NumbersOrBoolsOnly)
        maybeBranchTestType(MIRType::Boolean, maybeInput, tag, &isBool);
    maybeBranchTestType(MIRType::Double, maybeInput, tag, &isDouble);

    if (conversion == IntConversion_Any) {
        // If we are not truncating, we fail for anything that's not
        // null. Otherwise we might be able to handle strings and objects.
        switch (behavior) {
          case IntConversion_Normal:
          case IntConversion_NegativeZeroCheck:
            branchTestNull(Assembler::NotEqual, tag, fail);
            break;

          case IntConversion_Truncate:
          case IntConversion_ClampToUint8:
            maybeBranchTestType(MIRType::Null, maybeInput, tag, &isNull);
            if (handleStrings)
                maybeBranchTestType(MIRType::String, maybeInput, tag, &isString);
            maybeBranchTestType(MIRType::Object, maybeInput, tag, fail);
            branchTestUndefined(Assembler::NotEqual, tag, fail);
            break;
        }
    } else {
        jump(fail);
    }

    // The value is null or undefined in truncation contexts - just emit 0.
    if (isNull.used())
        bind(&isNull);
    mov(ImmWord(0), output);
    jump(&done);

    // Try converting a string into a double, then jump to the double case.
    if (handleStrings) {
        bind(&isString);
        unboxString(value, stringReg);
        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()) {
        bind(&isInt32);
        unboxInt32(value, output);
        if (behavior == IntConversion_ClampToUint8)
            clampIntToUint8(output);
    }

    bind(&done);
}

bool
MacroAssembler::convertValueToInt(JSContext* cx, const Value& v, Register output, Label* fail,
                                  IntConversionBehavior behavior)
{
    bool handleStrings = (behavior == IntConversion_Truncate ||
                          behavior == IntConversion_ClampToUint8);

    if (v.isNumber() || (handleStrings && v.isString())) {
        double d;
        if (v.isNumber())
            d = v.toNumber();
        else if (!StringToNumber(cx, v.toString(), &d))
            return false;

        switch (behavior) {
          case IntConversion_Normal:
          case IntConversion_NegativeZeroCheck: {
            // -0 is checked anyways if we have a constant value.
            int i;
            if (mozilla::NumberIsInt32(d, &i))
                move32(Imm32(i), output);
            else
                jump(fail);
            break;
          }
          case IntConversion_Truncate:
            move32(Imm32(ToInt32(d)), output);
            break;
          case IntConversion_ClampToUint8:
            move32(Imm32(ClampDoubleToUint8(d)), output);
            break;
        }

        return true;
    }

    if (v.isBoolean()) {
        move32(Imm32(v.toBoolean() ? 1 : 0), output);
        return true;
    }

    if (v.isNull() || v.isUndefined()) {
        move32(Imm32(0), output);
        return true;
    }

    MOZ_ASSERT(v.isObject() || v.isSymbol());

    jump(fail);
    return true;
}

bool
MacroAssembler::convertConstantOrRegisterToInt(JSContext* cx, ConstantOrRegister src,
                                               FloatRegister temp, Register output,
                                               Label* fail, IntConversionBehavior behavior)
{
    if (src.constant())
        return convertValueToInt(cx, src.value(), output, fail, behavior);

    convertTypedOrValueToInt(src.reg(), temp, output, fail, behavior);
    return true;
}

void
MacroAssembler::convertTypedOrValueToInt(TypedOrValueRegister src, FloatRegister temp,
                                         Register output, Label* fail,
                                         IntConversionBehavior behavior)
{
    if (src.hasValue()) {
        convertValueToInt(src.valueReg(), temp, output, fail, behavior);
        return;
    }

    switch (src.type()) {
      case MIRType::Undefined:
      case MIRType::Null:
        move32(Imm32(0), output);
        break;
      case MIRType::Boolean:
      case MIRType::Int32:
        if (src.typedReg().gpr() != output)
            move32(src.typedReg().gpr(), output);
        if (src.type() == MIRType::Int32 && behavior == IntConversion_ClampToUint8)
            clampIntToUint8(output);
        break;
      case MIRType::Double:
        convertDoubleToInt(src.typedReg().fpu(), output, temp, nullptr, fail, behavior);
        break;
      case MIRType::Float32:
        // Conversion to Double simplifies implementation at the expense of performance.
        convertFloat32ToDouble(src.typedReg().fpu(), temp);
        convertDoubleToInt(temp, output, temp, nullptr, fail, behavior);
        break;
      case MIRType::String:
      case MIRType::Symbol:
      case MIRType::Object:
        jump(fail);
        break;
      default:
        MOZ_CRASH("Bad MIRType");
    }
}

void
MacroAssembler::finish()
{
    if (failureLabel_.used()) {
        bind(&failureLabel_);
        handleFailure();
    }

    MacroAssemblerSpecific::finish();
}

void
MacroAssembler::link(JitCode* code)
{
    MOZ_ASSERT(!oom());
    linkSelfReference(code);
    linkProfilerCallSites(code);
}

MacroAssembler::AutoProfilerCallInstrumentation::AutoProfilerCallInstrumentation(
    MacroAssembler& masm
    MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
{
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    if (!masm.emitProfilingInstrumentation_)
        return;

    Register reg = CallTempReg0;
    Register reg2 = CallTempReg1;
    masm.push(reg);
    masm.push(reg2);

    JitContext* icx = GetJitContext();
    AbsoluteAddress profilingActivation(icx->runtime->addressOfProfilingActivation());

    CodeOffset label = masm.movWithPatch(ImmWord(uintptr_t(-1)), reg);
    masm.loadPtr(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)
{
    if (JitStackValueAlignment == 1)
        return;

    // A JitFrameLayout is composed of the following:
    // [padding?] [argN] .. [arg1] [this] [[argc] [callee] [descr] [raddr]]
    //
    // We want to ensure that the |raddr| address is aligned.
    // Which implies that we want to ensure that |this| is aligned.
    static_assert(sizeof(JitFrameLayout) % JitStackAlignment == 0,
      "No need to consider the JitFrameLayout for aligning the stack");

    // Which implies that |argN| is aligned if |nargs| is even, and offset by
    // |sizeof(Value)| if |nargs| is odd.
    MOZ_ASSERT(JitStackValueAlignment == 2);

    // Thus the |padding| is offset by |sizeof(Value)| if |nargs| is even, and
    // aligned if |nargs| is odd.

    // if (nargs % 2 == 0) {
    //     if (sp % JitStackAlignment == 0)
    //         sp -= sizeof(Value);
    //     MOZ_ASSERT(sp % JitStackAlignment == JitStackAlignment - sizeof(Value));
    // } else {
    //     sp = sp & ~(JitStackAlignment - 1);
    // }
    Label odd, end;
    Label* maybeAssert = &end;
#ifdef DEBUG
    Label assert;
    maybeAssert = &assert;
#endif
    assertStackAlignment(sizeof(Value), 0);
    branchTestPtr(Assembler::NonZero, nargs, Imm32(1), &odd);
    branchTestStackPtr(Assembler::NonZero, Imm32(JitStackAlignment - 1), maybeAssert);
    subFromStackPtr(Imm32(sizeof(Value)));
#ifdef DEBUG
    bind(&assert);
#endif
    assertStackAlignment(JitStackAlignment, sizeof(Value));
    jump(&end);
    bind(&odd);
    andToStackPtr(Imm32(~(JitStackAlignment - 1)));
    bind(&end);
}

void
MacroAssembler::alignJitStackBasedOnNArgs(uint32_t nargs)
{
    if (JitStackValueAlignment == 1)
        return;

    // A JitFrameLayout is composed of the following:
    // [padding?] [argN] .. [arg1] [this] [[argc] [callee] [descr] [raddr]]
    //
    // We want to ensure that the |raddr| address is aligned.
    // Which implies that we want to ensure that |this| is aligned.
    static_assert(sizeof(JitFrameLayout) % JitStackAlignment == 0,
      "No need to consider the JitFrameLayout for aligning the stack");

    // Which implies that |argN| is aligned if |nargs| is even, and offset by
    // |sizeof(Value)| if |nargs| is odd.
    MOZ_ASSERT(JitStackValueAlignment == 2);

    // Thus the |padding| is offset by |sizeof(Value)| if |nargs| is even, and
    // aligned if |nargs| is odd.

    assertStackAlignment(sizeof(Value), 0);
    if (nargs % 2 == 0) {
        Label end;
        branchTestStackPtr(Assembler::NonZero, Imm32(JitStackAlignment - 1), &end);
        subFromStackPtr(Imm32(sizeof(Value)));
        bind(&end);
        assertStackAlignment(JitStackAlignment, sizeof(Value));
    } else {
        andToStackPtr(Imm32(~(JitStackAlignment - 1)));
    }
}

// ===============================================================

MacroAssembler::MacroAssembler(JSContext* cx, IonScript* ion,
                               JSScript* script, jsbytecode* pc)
  : framePushed_(0),
#ifdef DEBUG
    inCall_(false),
#endif
    emitProfilingInstrumentation_(false)
{
    constructRoot(cx);
    jitContext_.emplace(cx, (js::jit::TempAllocator*)nullptr);
    alloc_.emplace(cx);
    moveResolver_.setAllocator(*jitContext_->temp);
#if defined(JS_CODEGEN_ARM)
    initWithAllocator();
    m_buffer.id = GetJitContext()->getNextAssemblerId();
#elif defined(JS_CODEGEN_ARM64)
    initWithAllocator();
    armbuffer_.id = GetJitContext()->getNextAssemblerId();
#endif
    if (ion) {
        setFramePushed(ion->frameSize());
        if (pc && cx->runtime()->spsProfiler.enabled())
            enableProfilingInstrumentation();
    }
}

MacroAssembler::AfterICSaveLive
MacroAssembler::icSaveLive(LiveRegisterSet& liveRegs)
{
    PushRegsInMask(liveRegs);
    AfterICSaveLive aic(framePushed());
    alignFrameForICArguments(aic);
    return aic;
}

bool
MacroAssembler::icBuildOOLFakeExitFrame(void* fakeReturnAddr, AfterICSaveLive& aic)
{
    return buildOOLFakeExitFrame(fakeReturnAddr);
}

void
MacroAssembler::icRestoreLive(LiveRegisterSet& liveRegs, AfterICSaveLive& aic)
{
    restoreFrameAlignmentForICArguments(aic);
    MOZ_ASSERT(framePushed() == aic.initialStack);
    PopRegsInMask(liveRegs);
}

//{{{ 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(jsid id, Register scratchReg)
{
    if (JSID_IS_GCTHING(id)) {
        // If we're pushing a gcthing, then we can't just push the tagged jsid
        // 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 id at runtime.

        if (JSID_IS_STRING(id)) {
            JSString* str = JSID_TO_STRING(id);
            MOZ_ASSERT(((size_t)str & JSID_TYPE_MASK) == 0);
            MOZ_ASSERT(JSID_TYPE_STRING == 0x0);
            Push(ImmGCPtr(str));
        } else {
            MOZ_ASSERT(JSID_IS_SYMBOL(id));
            JS::Symbol* sym = JSID_TO_SYMBOL(id);
            movePtr(ImmGCPtr(sym), scratchReg);
            orPtr(Imm32(JSID_TYPE_SYMBOL), scratchReg);
            Push(scratchReg);
        }
    } else {
        Push(ImmWord(JSID_BITS(id)));
    }
}

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) {
            convertFloat32ToDouble(reg, ScratchDoubleReg);
            reg = ScratchDoubleReg;
        }
        Push(reg);
    } else {
        Push(ValueTypeFromMIRType(v.type()), v.typedReg().gpr());
    }
}

void
MacroAssembler::Push(ConstantOrRegister v)
{
    if (v.constant())
        Push(v.value());
    else
        Push(v.reg());
}

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::PushValue(const Address& addr)
{
    MOZ_ASSERT(addr.base != getStackPointer());
    pushValue(addr);
    framePushed_ += sizeof(Value);
}

void
MacroAssembler::PushEmptyRooted(VMFunction::RootType rootType)
{
    switch (rootType) {
      case VMFunction::RootNone:
        MOZ_CRASH("Handle must have root type");
      case VMFunction::RootObject:
      case VMFunction::RootString:
      case VMFunction::RootPropertyName:
      case VMFunction::RootFunction:
      case VMFunction::RootCell:
        Push(ImmPtr(nullptr));
        break;
      case VMFunction::RootValue:
        Push(UndefinedValue());
        break;
    }
}

void
MacroAssembler::popRooted(VMFunction::RootType rootType, Register cellReg,
                          const ValueOperand& valueReg)
{
    switch (rootType) {
      case VMFunction::RootNone:
        MOZ_CRASH("Handle must have root type");
      case VMFunction::RootObject:
      case VMFunction::RootString:
      case VMFunction::RootPropertyName:
      case VMFunction::RootFunction:
      case VMFunction::RootCell:
        Pop(cellReg);
        break;
      case VMFunction::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.

void
MacroAssembler::setupABICall()
{
#ifdef DEBUG
    MOZ_ASSERT(!inCall_);
    inCall_ = true;
#endif

#ifdef JS_SIMULATOR
    signature_ = 0;
#endif

    // Reinitialize the ABIArg generator.
    abiArgs_ = ABIArgGenerator();

#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::setupAlignedABICall()
{
    setupABICall();
    dynamicAlignment_ = false;
    assertStackAlignment(ABIStackAlignment);

#if defined(JS_CODEGEN_ARM64)
    MOZ_CRASH("Not supported on arm64");
#endif
}

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)
{
    appendSignatureType(result);
#ifdef JS_SIMULATOR
    fun = Simulator::RedirectNativeFunction(fun, signature());
#endif

    uint32_t stackAdjust;
    callWithABIPre(&stackAdjust);
    call(ImmPtr(fun));
    callWithABIPost(stackAdjust, result);
}

void
MacroAssembler::callWithABINoProfiler(wasm::SymbolicAddress imm, MoveOp::Type result)
{
    uint32_t stackAdjust;
    callWithABIPre(&stackAdjust, /* callFromAsmJS = */ true);
    call(imm);
    callWithABIPost(stackAdjust, result);
}

// ===============================================================
// Exit frame footer.

void
MacroAssembler::linkExitFrame()
{
    AbsoluteAddress jitTop(GetJitContext()->runtime->addressOfJitTop());
    storeStackPtr(jitTop);
}

void
MacroAssembler::linkSelfReference(JitCode* code)
{
    // If this code can transition to C++ code and witness a GC, then we need to store
    // the JitCode onto the stack in order to GC it correctly.  exitCodePatch should
    // be unset if the code never needed to push its JitCode*.
    if (hasSelfReference()) {
        PatchDataWithValueCheck(CodeLocationLabel(code, selfReferencePatch_),
                                ImmPtr(code),
                                ImmPtr((void*)-1));
    }
}

// ===============================================================
// Branch functions

void
MacroAssembler::branchIfNotInterpretedConstructor(Register fun, Register scratch, Label* label)
{
    // 16-bit loads are slow and unaligned 32-bit loads may be too so
    // perform an aligned 32-bit load and adjust the bitmask accordingly.
    MOZ_ASSERT(JSFunction::offsetOfNargs() % sizeof(uint32_t) == 0);
    MOZ_ASSERT(JSFunction::offsetOfFlags() == JSFunction::offsetOfNargs() + 2);

    // First, ensure it's a scripted function.
    load32(Address(fun, JSFunction::offsetOfNargs()), scratch);
    int32_t bits = IMM32_16ADJ(JSFunction::INTERPRETED);
    branchTest32(Assembler::Zero, scratch, Imm32(bits), label);

    // Check if the CONSTRUCTOR bit is set.
    bits = IMM32_16ADJ(JSFunction::CONSTRUCTOR);
    branchTest32(Assembler::Zero, scratch, Imm32(bits), label);
}

void
MacroAssembler::maybeBranchTestType(MIRType type, MDefinition* maybeDef, Register tag, Label* label)
{
    if (!maybeDef || maybeDef->mightBeType(type)) {
        switch (type) {
          case MIRType::Null:
            branchTestNull(Equal, tag, label);
            break;
          case MIRType::Boolean:
            branchTestBoolean(Equal, tag, label);
            break;
          case MIRType::Int32:
            branchTestInt32(Equal, tag, label);
            break;
          case MIRType::Double:
            branchTestDouble(Equal, tag, label);
            break;
          case MIRType::String:
            branchTestString(Equal, tag, label);
            break;
          case MIRType::Symbol:
            branchTestSymbol(Equal, tag, label);
            break;
          case MIRType::Object:
            branchTestObject(Equal, tag, label);
            break;
          default:
            MOZ_CRASH("Unsupported type");
        }
    }
}

//}}} check_macroassembler_style

void
MacroAssembler::BranchType::emit(MacroAssembler& masm)
{
    MOZ_ASSERT(isInitialized());
    MIRType mirType = MIRType::None;

    if (type_.isPrimitive()) {
        if (type_.isMagicArguments())
            mirType = MIRType::MagicOptimizedArguments;
        else
            mirType = MIRTypeFromValueType(type_.primitive());
    } else if (type_.isAnyObject()) {
        mirType = MIRType::Object;
    } else {
        MOZ_CRASH("Unknown conversion to mirtype");
    }

    if (mirType == MIRType::Double)
        masm.branchTestNumber(cond(), reg(), jump());
    else
        masm.branchTestMIRType(cond(), reg(), mirType, jump());
}

void
MacroAssembler::BranchGCPtr::emit(MacroAssembler& masm)
{
    MOZ_ASSERT(isInitialized());
    masm.branchPtr(cond(), reg(), ptr_, jump());
}

namespace js {
namespace jit {

#ifdef DEBUG
template <class RegisterType>
AutoGenericRegisterScope<RegisterType>::AutoGenericRegisterScope(MacroAssembler& masm, RegisterType reg)
  : RegisterType(reg), masm_(masm)
{
    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()
{
    const RegisterType& reg = *dynamic_cast<RegisterType*>(this);
    masm_.debugTrackedRegisters_.take(reg);
}

template AutoGenericRegisterScope<Register>::~AutoGenericRegisterScope();
template AutoGenericRegisterScope<FloatRegister>::~AutoGenericRegisterScope();
#endif // DEBUG

} // namespace jit
} // namespace js