src/third_party/mozjs/js/src/jit/arm/Lowering-arm.cpp - cobalt - Git at Google

 /* -*- 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/MIR.h"
 #include "jit/Lowering.h"
 #include "Assembler-arm.h"
 #include "jit/shared/Lowering-shared-inl.h"

 using namespace js;
 using namespace js::jit;

 bool
 LIRGeneratorARM::useBox(LInstruction *lir, size_t n, MDefinition *mir,
                         LUse::Policy policy, bool useAtStart)
 {
     JS_ASSERT(mir->type() == MIRType_Value);
     if (!ensureDefined(mir))
         return false;
     lir->setOperand(n, LUse(mir->virtualRegister(), policy, useAtStart));
     lir->setOperand(n + 1, LUse(VirtualRegisterOfPayload(mir), policy, useAtStart));
     return true;
 }

 bool
 LIRGeneratorARM::useBoxFixed(LInstruction *lir, size_t n, MDefinition *mir, Register reg1,
                              Register reg2)
 {
     JS_ASSERT(mir->type() == MIRType_Value);
     JS_ASSERT(reg1 != reg2);

     if (!ensureDefined(mir))
         return false;
     lir->setOperand(n, LUse(reg1, mir->virtualRegister()));
     lir->setOperand(n + 1, LUse(reg2, VirtualRegisterOfPayload(mir)));
     return true;
 }

 bool
 LIRGeneratorARM::lowerConstantDouble(double d, MInstruction *mir)
 {
     return define(new LDouble(d), mir);
 }

 bool
 LIRGeneratorARM::visitConstant(MConstant *ins)
 {
     if (ins->type() == MIRType_Double) {
         LDouble *lir = new LDouble(ins->value().toDouble());
         return define(lir, ins);
     }

     // Emit non-double constants at their uses.
     if (ins->canEmitAtUses())
         return emitAtUses(ins);

     return LIRGeneratorShared::visitConstant(ins);
 }

 bool
 LIRGeneratorARM::visitBox(MBox *box)
 {
     MDefinition *inner = box->getOperand(0);

     // If the box wrapped a double, it needs a new register.
     if (inner->type() == MIRType_Double)
         return defineBox(new LBoxDouble(useRegisterAtStart(inner), tempCopy(inner, 0)), box);

     if (box->canEmitAtUses())
         return emitAtUses(box);

     if (inner->isConstant())
         return defineBox(new LValue(inner->toConstant()->value()), box);

     LBox *lir = new LBox(use(inner), inner->type());

     // Otherwise, we should not define a new register for the payload portion
     // of the output, so bypass defineBox().
     uint32_t vreg = getVirtualRegister();
     if (vreg >= MAX_VIRTUAL_REGISTERS)
         return false;

     // Note that because we're using PASSTHROUGH, we do not change the type of
     // the definition. We also do not define the first output as "TYPE",
     // because it has no corresponding payload at (vreg + 1). Also note that
     // although we copy the input's original type for the payload half of the
     // definition, this is only for clarity. PASSTHROUGH definitions are
     // ignored.
     lir->setDef(0, LDefinition(vreg, LDefinition::GENERAL));
     lir->setDef(1, LDefinition(inner->virtualRegister(), LDefinition::TypeFrom(inner->type()),
                                LDefinition::PASSTHROUGH));
     box->setVirtualRegister(vreg);
     return add(lir);
 }

 bool
 LIRGeneratorARM::visitUnbox(MUnbox *unbox)
 {
     // An unbox on arm reads in a type tag (either in memory or a register) and
     // a payload. Unlike most instructions conusming a box, we ask for the type
     // second, so that the result can re-use the first input.
     MDefinition *inner = unbox->getOperand(0);

     if (!ensureDefined(inner))
         return false;

     if (unbox->type() == MIRType_Double) {
         LUnboxDouble *lir = new LUnboxDouble();
         if (unbox->fallible() && !assignSnapshot(lir, unbox->bailoutKind()))
             return false;
         if (!useBox(lir, LUnboxDouble::Input, inner))
             return false;
         return define(lir, unbox);
     }

     // Swap the order we use the box pieces so we can re-use the payload register.
     LUnbox *lir = new LUnbox;
     lir->setOperand(0, usePayloadInRegisterAtStart(inner));
     lir->setOperand(1, useType(inner, LUse::REGISTER));

     if (unbox->fallible() && !assignSnapshot(lir, unbox->bailoutKind()))
         return false;

     // Note that PASSTHROUGH here is illegal, since types and payloads form two
     // separate intervals. If the type becomes dead before the payload, it
     // could be used as a Value without the type being recoverable. Unbox's
     // purpose is to eagerly kill the definition of a type tag, so keeping both
     // alive (for the purpose of gcmaps) is unappealing. Instead, we create a
     // new virtual register.
     return defineReuseInput(lir, unbox, 0);
 }

 bool
 LIRGeneratorARM::visitReturn(MReturn *ret)
 {
     MDefinition *opd = ret->getOperand(0);
     JS_ASSERT(opd->type() == MIRType_Value);

     LReturn *ins = new LReturn;
     ins->setOperand(0, LUse(JSReturnReg_Type));
     ins->setOperand(1, LUse(JSReturnReg_Data));
     return fillBoxUses(ins, 0, opd) && add(ins);
 }

 // x = !y
 bool
 LIRGeneratorARM::lowerForALU(LInstructionHelper<1, 1, 0> *ins, MDefinition *mir, MDefinition *input)
 {
     ins->setOperand(0, useRegister(input));
     return define(ins, mir,
                   LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));
 }

 // z = x+y
 bool
 LIRGeneratorARM::lowerForALU(LInstructionHelper<1, 2, 0> *ins, MDefinition *mir, MDefinition *lhs, MDefinition *rhs)
 {
     ins->setOperand(0, useRegister(lhs));
     ins->setOperand(1, useRegisterOrConstant(rhs));
     return define(ins, mir,
                   LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));
 }

 bool
 LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 1, 0> *ins, MDefinition *mir, MDefinition *input)
 {
     ins->setOperand(0, useRegister(input));
     return define(ins, mir,
                   LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));

 }

 bool
 LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 2, 0> *ins, MDefinition *mir, MDefinition *lhs, MDefinition *rhs)
 {
     ins->setOperand(0, useRegister(lhs));
     ins->setOperand(1, useRegister(rhs));
     return define(ins, mir,
                   LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));
 }

 bool
 LIRGeneratorARM::defineUntypedPhi(MPhi *phi, size_t lirIndex)
 {
     LPhi *type = current->getPhi(lirIndex + VREG_TYPE_OFFSET);
     LPhi *payload = current->getPhi(lirIndex + VREG_DATA_OFFSET);

     uint32_t typeVreg = getVirtualRegister();
     if (typeVreg >= MAX_VIRTUAL_REGISTERS)
         return false;

     phi->setVirtualRegister(typeVreg);

     uint32_t payloadVreg = getVirtualRegister();
     if (payloadVreg >= MAX_VIRTUAL_REGISTERS)
         return false;
     JS_ASSERT(typeVreg + 1 == payloadVreg);

     type->setDef(0, LDefinition(typeVreg, LDefinition::TYPE));
     payload->setDef(0, LDefinition(payloadVreg, LDefinition::PAYLOAD));
     annotate(type);
     annotate(payload);
     return true;
 }

 void
 LIRGeneratorARM::lowerUntypedPhiInput(MPhi *phi, uint32_t inputPosition, LBlock *block, size_t lirIndex)
 {
     // oh god, what is this code?
     MDefinition *operand = phi->getOperand(inputPosition);
     LPhi *type = block->getPhi(lirIndex + VREG_TYPE_OFFSET);
     LPhi *payload = block->getPhi(lirIndex + VREG_DATA_OFFSET);
     type->setOperand(inputPosition, LUse(operand->virtualRegister() + VREG_TYPE_OFFSET, LUse::ANY));
     payload->setOperand(inputPosition, LUse(VirtualRegisterOfPayload(operand), LUse::ANY));
 }

 bool
 LIRGeneratorARM::lowerForShift(LInstructionHelper<1, 2, 0> *ins, MDefinition *mir, MDefinition *lhs, MDefinition *rhs)
 {

     ins->setOperand(0, useRegister(lhs));
     ins->setOperand(1, useRegisterOrConstant(rhs));
     return define(ins, mir);
 }

 bool
 LIRGeneratorARM::lowerDivI(MDiv *div)
 {
     // Division instructions are slow. Division by constant denominators can be
     // rewritten to use other instructions.
     if (div->rhs()->isConstant()) {
         int32_t rhs = div->rhs()->toConstant()->value().toInt32();
         // Check for division by a positive power of two, which is an easy and
         // important case to optimize. Note that other optimizations are also
         // possible; division by negative powers of two can be optimized in a
         // similar manner as positive powers of two, and division by other
         // constants can be optimized by a reciprocal multiplication technique.
         int32_t shift;
         JS_FLOOR_LOG2(shift, rhs);
         if (rhs > 0 && 1 << shift == rhs) {
             LDivPowTwoI *lir = new LDivPowTwoI(useRegisterAtStart(div->lhs()), shift);
             if (div->fallible() && !assignSnapshot(lir))
                 return false;
             return define(lir, div);
         }
     }

     LDivI *lir = new LDivI(useFixed(div->lhs(), r0), use(div->rhs(), r1),
                            tempFixed(r2), tempFixed(r3));
     if (div->fallible() && !assignSnapshot(lir))
         return false;
     return defineFixed(lir, div, LAllocation(AnyRegister(r0)));
 }

 bool
 LIRGeneratorARM::lowerMulI(MMul *mul, MDefinition *lhs, MDefinition *rhs)
 {
     LMulI *lir = new LMulI;
     if (mul->fallible() && !assignSnapshot(lir))
         return false;
     return lowerForALU(lir, mul, lhs, rhs);
 }

 bool
 LIRGeneratorARM::lowerModI(MMod *mod)
 {
     if (mod->rhs()->isConstant()) {
         int32_t rhs = mod->rhs()->toConstant()->value().toInt32();
         int32_t shift;
         JS_FLOOR_LOG2(shift, rhs);
         if (rhs > 0 && 1 << shift == rhs) {
             LModPowTwoI *lir = new LModPowTwoI(useRegister(mod->lhs()), shift);
             if (mod->fallible() && !assignSnapshot(lir))
                 return false;
             return define(lir, mod);
         } else if (shift < 31 && (1 << (shift+1)) - 1 == rhs) {
             LModMaskI *lir = new LModMaskI(useRegister(mod->lhs()), temp(LDefinition::GENERAL), shift+1);
             if (mod->fallible() && !assignSnapshot(lir))
                 return false;
             return define(lir, mod);
         }
     }
     LModI *lir = new LModI(useFixed(mod->lhs(), r0), use(mod->rhs(), r1),
                            tempFixed(r2), tempFixed(r3), temp(LDefinition::GENERAL));

     if (mod->fallible() && !assignSnapshot(lir))
         return false;
     return defineFixed(lir, mod, LAllocation(AnyRegister(r1)));
 }

 bool
 LIRGeneratorARM::visitPowHalf(MPowHalf *ins)
 {
     MDefinition *input = ins->input();
     JS_ASSERT(input->type() == MIRType_Double);
     LPowHalfD *lir = new LPowHalfD(useRegisterAtStart(input));
     return defineReuseInput(lir, ins, 0);
 }

 LTableSwitch *
 LIRGeneratorARM::newLTableSwitch(const LAllocation &in, const LDefinition &inputCopy,
                                        MTableSwitch *tableswitch)
 {
     return new LTableSwitch(in, inputCopy, tableswitch);
 }

 LTableSwitchV *
 LIRGeneratorARM::newLTableSwitchV(MTableSwitch *tableswitch)
 {
     return new LTableSwitchV(temp(), tempFloat(), tableswitch);
 }

 LGetPropertyCacheT *
 LIRGeneratorARM::newLGetPropertyCacheT(MGetPropertyCache *ins)
 {
     return new LGetPropertyCacheT(useRegister(ins->object()), LDefinition::BogusTemp());
 }

 bool
 LIRGeneratorARM::visitGuardShape(MGuardShape *ins)
 {
     JS_ASSERT(ins->obj()->type() == MIRType_Object);

     LDefinition tempObj = temp(LDefinition::OBJECT);
     LGuardShape *guard = new LGuardShape(useRegister(ins->obj()), tempObj);
     if (!assignSnapshot(guard, ins->bailoutKind()))
         return false;
     if (!add(guard, ins))
         return false;
     return redefine(ins, ins->obj());
 }

 bool
 LIRGeneratorARM::visitGuardObjectType(MGuardObjectType *ins)
 {
     JS_ASSERT(ins->obj()->type() == MIRType_Object);

     LDefinition tempObj = temp(LDefinition::OBJECT);
     LGuardObjectType *guard = new LGuardObjectType(useRegister(ins->obj()), tempObj);
     if (!assignSnapshot(guard))
         return false;
     if (!add(guard, ins))
         return false;
     return redefine(ins, ins->obj());
 }

 bool
 LIRGeneratorARM::visitStoreTypedArrayElement(MStoreTypedArrayElement *ins)
 {
     JS_ASSERT(ins->elements()->type() == MIRType_Elements);
     JS_ASSERT(ins->index()->type() == MIRType_Int32);

     if (ins->isFloatArray())
         JS_ASSERT(ins->value()->type() == MIRType_Double);
     else
         JS_ASSERT(ins->value()->type() == MIRType_Int32);

     LUse elements = useRegister(ins->elements());
     LAllocation index = useRegisterOrConstant(ins->index());
     LAllocation value = useRegisterOrNonDoubleConstant(ins->value());
     return add(new LStoreTypedArrayElement(elements, index, value), ins);
 }

 bool
 LIRGeneratorARM::visitStoreTypedArrayElementHole(MStoreTypedArrayElementHole *ins)
 {
     JS_ASSERT(ins->elements()->type() == MIRType_Elements);
     JS_ASSERT(ins->index()->type() == MIRType_Int32);
     JS_ASSERT(ins->length()->type() == MIRType_Int32);

     if (ins->isFloatArray())
         JS_ASSERT(ins->value()->type() == MIRType_Double);
     else
         JS_ASSERT(ins->value()->type() == MIRType_Int32);

     LUse elements = useRegister(ins->elements());
     LAllocation length = useRegisterOrConstant(ins->length());
     LAllocation index = useRegisterOrConstant(ins->index());
     LAllocation value = useRegisterOrNonDoubleConstant(ins->value());
     return add(new LStoreTypedArrayElementHole(elements, length, index, value), ins);
 }

 bool
 LIRGeneratorARM::visitInterruptCheck(MInterruptCheck *ins)
 {
     LInterruptCheck *lir = new LInterruptCheck();
     if (!add(lir))
         return false;
     if (!assignSafepoint(lir, ins))
         return false;
     return true;
 }

 bool
 LIRGeneratorARM::lowerUrshD(MUrsh *mir)
 {
     MDefinition *lhs = mir->lhs();
     MDefinition *rhs = mir->rhs();

     JS_ASSERT(lhs->type() == MIRType_Int32);
     JS_ASSERT(rhs->type() == MIRType_Int32);

     LUrshD *lir = new LUrshD(useRegister(lhs), useRegisterOrConstant(rhs), temp());
     return define(lir, mir);
 }

 bool
 LIRGeneratorARM::visitAsmJSNeg(MAsmJSNeg *ins)
 {
     if (ins->type() == MIRType_Int32)
         return define(new LNegI(useRegisterAtStart(ins->input())), ins);

     JS_ASSERT(ins->type() == MIRType_Double);
     return define(new LNegD(useRegisterAtStart(ins->input())), ins);
 }
 bool
 LIRGeneratorARM::visitAsmJSUDiv(MAsmJSUDiv *div)
 {
     LAsmJSDivOrMod *lir = new LAsmJSDivOrMod(useFixed(div->lhs(), r0),
                                          useFixed(div->rhs(), r1),
                                          tempFixed(r2), tempFixed(r3));
     return defineFixed(lir, div, LAllocation(AnyRegister(r0)));
 }

 bool
 LIRGeneratorARM::visitAsmJSUMod(MAsmJSUMod *mod)
 {
     LAsmJSDivOrMod *lir = new LAsmJSDivOrMod(useFixed(mod->lhs(), r0),
                                          useFixed(mod->rhs(), r1),
                                          tempFixed(r2), tempFixed(r3));
     return defineFixed(lir, mod, LAllocation(AnyRegister(r1)));
 }

 bool
 LIRGeneratorARM::visitAsmJSUnsignedToDouble(MAsmJSUnsignedToDouble *ins)
 {
     JS_ASSERT(ins->input()->type() == MIRType_Int32);
     LUInt32ToDouble *lir = new LUInt32ToDouble(useRegisterAtStart(ins->input()));
     return define(lir, ins);
 }

 bool
 LIRGeneratorARM::visitAsmJSStoreHeap(MAsmJSStoreHeap *ins)
 {
     LAsmJSStoreHeap *lir;
     switch (ins->viewType()) {
       case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
       case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
       case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
         lir = new LAsmJSStoreHeap(useRegisterAtStart(ins->ptr()),
                                   useRegisterAtStart(ins->value()));
         break;
       case ArrayBufferView::TYPE_FLOAT32:
       case ArrayBufferView::TYPE_FLOAT64:
         lir = new LAsmJSStoreHeap(useRegisterAtStart(ins->ptr()),
                                   useRegisterAtStart(ins->value()));
         break;
       default: JS_NOT_REACHED("unexpected array type");
     }

     return add(lir, ins);
 }

 bool
 LIRGeneratorARM::visitAsmJSLoadFuncPtr(MAsmJSLoadFuncPtr *ins)
 {
     return define(new LAsmJSLoadFuncPtr(useRegister(ins->index()), temp()), ins);
 }

 bool
 LIRGeneratorARM::lowerTruncateDToInt32(MTruncateToInt32 *ins)
 {
     MDefinition *opd = ins->input();
     JS_ASSERT(opd->type() == MIRType_Double);

     return define(new LTruncateDToInt32(useRegister(opd), LDefinition::BogusTemp()), ins);
 }

 bool
 LIRGeneratorARM::visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic *ins)
 {
     JS_NOT_REACHED("NYI");
     return true;
 }

 //__aeabi_uidiv
	/* -- 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/MIR.h"
	#include "jit/Lowering.h"
	#include "Assembler-arm.h"
	#include "jit/shared/Lowering-shared-inl.h"

	using namespace js;
	using namespace js::jit;

	bool
	LIRGeneratorARM::useBox(LInstruction lir, size_t n, MDefinition mir,
	LUse::Policy policy, bool useAtStart)
	{
	JS_ASSERT(mir->type() == MIRType_Value);
	if (!ensureDefined(mir))
	return false;
	lir->setOperand(n, LUse(mir->virtualRegister(), policy, useAtStart));
	lir->setOperand(n + 1, LUse(VirtualRegisterOfPayload(mir), policy, useAtStart));
	return true;
	}

	bool
	LIRGeneratorARM::useBoxFixed(LInstruction lir, size_t n, MDefinition mir, Register reg1,
	Register reg2)
	{
	JS_ASSERT(mir->type() == MIRType_Value);
	JS_ASSERT(reg1 != reg2);

	if (!ensureDefined(mir))
	return false;
	lir->setOperand(n, LUse(reg1, mir->virtualRegister()));
	lir->setOperand(n + 1, LUse(reg2, VirtualRegisterOfPayload(mir)));
	return true;
	}

	bool
	LIRGeneratorARM::lowerConstantDouble(double d, MInstruction *mir)
	{
	return define(new LDouble(d), mir);
	}

	bool
	LIRGeneratorARM::visitConstant(MConstant *ins)
	{
	if (ins->type() == MIRType_Double) {
	LDouble *lir = new LDouble(ins->value().toDouble());
	return define(lir, ins);
	}

	// Emit non-double constants at their uses.
	if (ins->canEmitAtUses())
	return emitAtUses(ins);

	return LIRGeneratorShared::visitConstant(ins);
	}

	bool
	LIRGeneratorARM::visitBox(MBox *box)
	{
	MDefinition *inner = box->getOperand(0);

	// If the box wrapped a double, it needs a new register.
	if (inner->type() == MIRType_Double)
	return defineBox(new LBoxDouble(useRegisterAtStart(inner), tempCopy(inner, 0)), box);

	if (box->canEmitAtUses())
	return emitAtUses(box);

	if (inner->isConstant())
	return defineBox(new LValue(inner->toConstant()->value()), box);

	LBox *lir = new LBox(use(inner), inner->type());

	// Otherwise, we should not define a new register for the payload portion
	// of the output, so bypass defineBox().
	uint32_t vreg = getVirtualRegister();
	if (vreg >= MAX_VIRTUAL_REGISTERS)
	return false;

	// Note that because we're using PASSTHROUGH, we do not change the type of
	// the definition. We also do not define the first output as "TYPE",
	// because it has no corresponding payload at (vreg + 1). Also note that
	// although we copy the input's original type for the payload half of the
	// definition, this is only for clarity. PASSTHROUGH definitions are
	// ignored.
	lir->setDef(0, LDefinition(vreg, LDefinition::GENERAL));
	lir->setDef(1, LDefinition(inner->virtualRegister(), LDefinition::TypeFrom(inner->type()),
	LDefinition::PASSTHROUGH));
	box->setVirtualRegister(vreg);
	return add(lir);
	}

	bool
	LIRGeneratorARM::visitUnbox(MUnbox *unbox)
	{
	// An unbox on arm reads in a type tag (either in memory or a register) and
	// a payload. Unlike most instructions conusming a box, we ask for the type
	// second, so that the result can re-use the first input.
	MDefinition *inner = unbox->getOperand(0);

	if (!ensureDefined(inner))
	return false;

	if (unbox->type() == MIRType_Double) {
	LUnboxDouble *lir = new LUnboxDouble();
	if (unbox->fallible() && !assignSnapshot(lir, unbox->bailoutKind()))
	return false;
	if (!useBox(lir, LUnboxDouble::Input, inner))
	return false;
	return define(lir, unbox);
	}

	// Swap the order we use the box pieces so we can re-use the payload register.
	LUnbox *lir = new LUnbox;
	lir->setOperand(0, usePayloadInRegisterAtStart(inner));
	lir->setOperand(1, useType(inner, LUse::REGISTER));

	if (unbox->fallible() && !assignSnapshot(lir, unbox->bailoutKind()))
	return false;

	// Note that PASSTHROUGH here is illegal, since types and payloads form two
	// separate intervals. If the type becomes dead before the payload, it
	// could be used as a Value without the type being recoverable. Unbox's
	// purpose is to eagerly kill the definition of a type tag, so keeping both
	// alive (for the purpose of gcmaps) is unappealing. Instead, we create a
	// new virtual register.
	return defineReuseInput(lir, unbox, 0);
	}

	bool
	LIRGeneratorARM::visitReturn(MReturn *ret)
	{
	MDefinition *opd = ret->getOperand(0);
	JS_ASSERT(opd->type() == MIRType_Value);

	LReturn *ins = new LReturn;
	ins->setOperand(0, LUse(JSReturnReg_Type));
	ins->setOperand(1, LUse(JSReturnReg_Data));
	return fillBoxUses(ins, 0, opd) && add(ins);
	}

	// x = !y
	bool
	LIRGeneratorARM::lowerForALU(LInstructionHelper<1, 1, 0> ins, MDefinition mir, MDefinition *input)
	{
	ins->setOperand(0, useRegister(input));
	return define(ins, mir,
	LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));
	}

	// z = x+y
	bool
	LIRGeneratorARM::lowerForALU(LInstructionHelper<1, 2, 0> ins, MDefinition mir, MDefinition lhs, MDefinition rhs)
	{
	ins->setOperand(0, useRegister(lhs));
	ins->setOperand(1, useRegisterOrConstant(rhs));
	return define(ins, mir,
	LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));
	}

	bool
	LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 1, 0> ins, MDefinition mir, MDefinition *input)
	{
	ins->setOperand(0, useRegister(input));
	return define(ins, mir,
	LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));

	}

	bool
	LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 2, 0> ins, MDefinition mir, MDefinition lhs, MDefinition rhs)
	{
	ins->setOperand(0, useRegister(lhs));
	ins->setOperand(1, useRegister(rhs));
	return define(ins, mir,
	LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::DEFAULT));
	}

	bool
	LIRGeneratorARM::defineUntypedPhi(MPhi *phi, size_t lirIndex)
	{
	LPhi *type = current->getPhi(lirIndex + VREG_TYPE_OFFSET);
	LPhi *payload = current->getPhi(lirIndex + VREG_DATA_OFFSET);

	uint32_t typeVreg = getVirtualRegister();
	if (typeVreg >= MAX_VIRTUAL_REGISTERS)
	return false;

	phi->setVirtualRegister(typeVreg);

	uint32_t payloadVreg = getVirtualRegister();
	if (payloadVreg >= MAX_VIRTUAL_REGISTERS)
	return false;
	JS_ASSERT(typeVreg + 1 == payloadVreg);

	type->setDef(0, LDefinition(typeVreg, LDefinition::TYPE));
	payload->setDef(0, LDefinition(payloadVreg, LDefinition::PAYLOAD));
	annotate(type);
	annotate(payload);
	return true;
	}

	void
	LIRGeneratorARM::lowerUntypedPhiInput(MPhi phi, uint32_t inputPosition, LBlock block, size_t lirIndex)
	{
	// oh god, what is this code?
	MDefinition *operand = phi->getOperand(inputPosition);
	LPhi *type = block->getPhi(lirIndex + VREG_TYPE_OFFSET);
	LPhi *payload = block->getPhi(lirIndex + VREG_DATA_OFFSET);
	type->setOperand(inputPosition, LUse(operand->virtualRegister() + VREG_TYPE_OFFSET, LUse::ANY));
	payload->setOperand(inputPosition, LUse(VirtualRegisterOfPayload(operand), LUse::ANY));
	}

	bool
	LIRGeneratorARM::lowerForShift(LInstructionHelper<1, 2, 0> ins, MDefinition mir, MDefinition lhs, MDefinition rhs)
	{

	ins->setOperand(0, useRegister(lhs));
	ins->setOperand(1, useRegisterOrConstant(rhs));
	return define(ins, mir);
	}

	bool
	LIRGeneratorARM::lowerDivI(MDiv *div)
	{
	// Division instructions are slow. Division by constant denominators can be
	// rewritten to use other instructions.
	if (div->rhs()->isConstant()) {
	int32_t rhs = div->rhs()->toConstant()->value().toInt32();
	// Check for division by a positive power of two, which is an easy and
	// important case to optimize. Note that other optimizations are also
	// possible; division by negative powers of two can be optimized in a
	// similar manner as positive powers of two, and division by other
	// constants can be optimized by a reciprocal multiplication technique.
	int32_t shift;
	JS_FLOOR_LOG2(shift, rhs);
	if (rhs > 0 && 1 << shift == rhs) {
	LDivPowTwoI *lir = new LDivPowTwoI(useRegisterAtStart(div->lhs()), shift);
	if (div->fallible() && !assignSnapshot(lir))
	return false;
	return define(lir, div);
	}
	}

	LDivI *lir = new LDivI(useFixed(div->lhs(), r0), use(div->rhs(), r1),
	tempFixed(r2), tempFixed(r3));
	if (div->fallible() && !assignSnapshot(lir))
	return false;
	return defineFixed(lir, div, LAllocation(AnyRegister(r0)));
	}

	bool
	LIRGeneratorARM::lowerMulI(MMul mul, MDefinition lhs, MDefinition *rhs)
	{
	LMulI *lir = new LMulI;
	if (mul->fallible() && !assignSnapshot(lir))
	return false;
	return lowerForALU(lir, mul, lhs, rhs);
	}

	bool
	LIRGeneratorARM::lowerModI(MMod *mod)
	{
	if (mod->rhs()->isConstant()) {
	int32_t rhs = mod->rhs()->toConstant()->value().toInt32();
	int32_t shift;
	JS_FLOOR_LOG2(shift, rhs);
	if (rhs > 0 && 1 << shift == rhs) {
	LModPowTwoI *lir = new LModPowTwoI(useRegister(mod->lhs()), shift);
	if (mod->fallible() && !assignSnapshot(lir))
	return false;
	return define(lir, mod);
	} else if (shift < 31 && (1 << (shift+1)) - 1 == rhs) {
	LModMaskI *lir = new LModMaskI(useRegister(mod->lhs()), temp(LDefinition::GENERAL), shift+1);
	if (mod->fallible() && !assignSnapshot(lir))
	return false;
	return define(lir, mod);
	}
	}
	LModI *lir = new LModI(useFixed(mod->lhs(), r0), use(mod->rhs(), r1),
	tempFixed(r2), tempFixed(r3), temp(LDefinition::GENERAL));

	if (mod->fallible() && !assignSnapshot(lir))
	return false;
	return defineFixed(lir, mod, LAllocation(AnyRegister(r1)));
	}

	bool
	LIRGeneratorARM::visitPowHalf(MPowHalf *ins)
	{
	MDefinition *input = ins->input();
	JS_ASSERT(input->type() == MIRType_Double);
	LPowHalfD *lir = new LPowHalfD(useRegisterAtStart(input));
	return defineReuseInput(lir, ins, 0);
	}

	LTableSwitch *
	LIRGeneratorARM::newLTableSwitch(const LAllocation &in, const LDefinition &inputCopy,
	MTableSwitch *tableswitch)
	{
	return new LTableSwitch(in, inputCopy, tableswitch);
	}

	LTableSwitchV *
	LIRGeneratorARM::newLTableSwitchV(MTableSwitch *tableswitch)
	{
	return new LTableSwitchV(temp(), tempFloat(), tableswitch);
	}

	LGetPropertyCacheT *
	LIRGeneratorARM::newLGetPropertyCacheT(MGetPropertyCache *ins)
	{
	return new LGetPropertyCacheT(useRegister(ins->object()), LDefinition::BogusTemp());
	}

	bool
	LIRGeneratorARM::visitGuardShape(MGuardShape *ins)
	{
	JS_ASSERT(ins->obj()->type() == MIRType_Object);

	LDefinition tempObj = temp(LDefinition::OBJECT);
	LGuardShape *guard = new LGuardShape(useRegister(ins->obj()), tempObj);
	if (!assignSnapshot(guard, ins->bailoutKind()))
	return false;
	if (!add(guard, ins))
	return false;
	return redefine(ins, ins->obj());
	}

	bool
	LIRGeneratorARM::visitGuardObjectType(MGuardObjectType *ins)
	{
	JS_ASSERT(ins->obj()->type() == MIRType_Object);

	LDefinition tempObj = temp(LDefinition::OBJECT);
	LGuardObjectType *guard = new LGuardObjectType(useRegister(ins->obj()), tempObj);
	if (!assignSnapshot(guard))
	return false;
	if (!add(guard, ins))
	return false;
	return redefine(ins, ins->obj());
	}

	bool
	LIRGeneratorARM::visitStoreTypedArrayElement(MStoreTypedArrayElement *ins)
	{
	JS_ASSERT(ins->elements()->type() == MIRType_Elements);
	JS_ASSERT(ins->index()->type() == MIRType_Int32);

	if (ins->isFloatArray())
	JS_ASSERT(ins->value()->type() == MIRType_Double);
	else
	JS_ASSERT(ins->value()->type() == MIRType_Int32);

	LUse elements = useRegister(ins->elements());
	LAllocation index = useRegisterOrConstant(ins->index());
	LAllocation value = useRegisterOrNonDoubleConstant(ins->value());
	return add(new LStoreTypedArrayElement(elements, index, value), ins);
	}

	bool
	LIRGeneratorARM::visitStoreTypedArrayElementHole(MStoreTypedArrayElementHole *ins)
	{
	JS_ASSERT(ins->elements()->type() == MIRType_Elements);
	JS_ASSERT(ins->index()->type() == MIRType_Int32);
	JS_ASSERT(ins->length()->type() == MIRType_Int32);

	if (ins->isFloatArray())
	JS_ASSERT(ins->value()->type() == MIRType_Double);
	else
	JS_ASSERT(ins->value()->type() == MIRType_Int32);

	LUse elements = useRegister(ins->elements());
	LAllocation length = useRegisterOrConstant(ins->length());
	LAllocation index = useRegisterOrConstant(ins->index());
	LAllocation value = useRegisterOrNonDoubleConstant(ins->value());
	return add(new LStoreTypedArrayElementHole(elements, length, index, value), ins);
	}

	bool
	LIRGeneratorARM::visitInterruptCheck(MInterruptCheck *ins)
	{
	LInterruptCheck *lir = new LInterruptCheck();
	if (!add(lir))
	return false;
	if (!assignSafepoint(lir, ins))
	return false;
	return true;
	}

	bool
	LIRGeneratorARM::lowerUrshD(MUrsh *mir)
	{
	MDefinition *lhs = mir->lhs();
	MDefinition *rhs = mir->rhs();

	JS_ASSERT(lhs->type() == MIRType_Int32);
	JS_ASSERT(rhs->type() == MIRType_Int32);

	LUrshD *lir = new LUrshD(useRegister(lhs), useRegisterOrConstant(rhs), temp());
	return define(lir, mir);
	}

	bool
	LIRGeneratorARM::visitAsmJSNeg(MAsmJSNeg *ins)
	{
	if (ins->type() == MIRType_Int32)
	return define(new LNegI(useRegisterAtStart(ins->input())), ins);

	JS_ASSERT(ins->type() == MIRType_Double);
	return define(new LNegD(useRegisterAtStart(ins->input())), ins);
	}
	bool
	LIRGeneratorARM::visitAsmJSUDiv(MAsmJSUDiv *div)
	{
	LAsmJSDivOrMod *lir = new LAsmJSDivOrMod(useFixed(div->lhs(), r0),
	useFixed(div->rhs(), r1),
	tempFixed(r2), tempFixed(r3));
	return defineFixed(lir, div, LAllocation(AnyRegister(r0)));
	}

	bool
	LIRGeneratorARM::visitAsmJSUMod(MAsmJSUMod *mod)
	{
	LAsmJSDivOrMod *lir = new LAsmJSDivOrMod(useFixed(mod->lhs(), r0),
	useFixed(mod->rhs(), r1),
	tempFixed(r2), tempFixed(r3));
	return defineFixed(lir, mod, LAllocation(AnyRegister(r1)));
	}

	bool
	LIRGeneratorARM::visitAsmJSUnsignedToDouble(MAsmJSUnsignedToDouble *ins)
	{
	JS_ASSERT(ins->input()->type() == MIRType_Int32);
	LUInt32ToDouble *lir = new LUInt32ToDouble(useRegisterAtStart(ins->input()));
	return define(lir, ins);
	}

	bool
	LIRGeneratorARM::visitAsmJSStoreHeap(MAsmJSStoreHeap *ins)
	{
	LAsmJSStoreHeap *lir;
	switch (ins->viewType()) {
	case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
	case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
	case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
	lir = new LAsmJSStoreHeap(useRegisterAtStart(ins->ptr()),
	useRegisterAtStart(ins->value()));
	break;
	case ArrayBufferView::TYPE_FLOAT32:
	case ArrayBufferView::TYPE_FLOAT64:
	lir = new LAsmJSStoreHeap(useRegisterAtStart(ins->ptr()),
	useRegisterAtStart(ins->value()));
	break;
	default: JS_NOT_REACHED("unexpected array type");
	}

	return add(lir, ins);
	}

	bool
	LIRGeneratorARM::visitAsmJSLoadFuncPtr(MAsmJSLoadFuncPtr *ins)
	{
	return define(new LAsmJSLoadFuncPtr(useRegister(ins->index()), temp()), ins);
	}

	bool
	LIRGeneratorARM::lowerTruncateDToInt32(MTruncateToInt32 *ins)
	{
	MDefinition *opd = ins->input();
	JS_ASSERT(opd->type() == MIRType_Double);

	return define(new LTruncateDToInt32(useRegister(opd), LDefinition::BogusTemp()), ins);
	}

	bool
	LIRGeneratorARM::visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic *ins)
	{
	JS_NOT_REACHED("NYI");
	return true;
	}

	//__aeabi_uidiv