src/third_party/mozjs/js/src/jit/x86/Lowering-x86.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 "Lowering-x86.h"

 #include "jit/MIR.h"
 #include "Assembler-x86.h"
 #include "jit/shared/Lowering-shared-inl.h"

 using namespace js;
 using namespace js::jit;

 bool
 LIRGeneratorX86::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
 LIRGeneratorX86::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
 LIRGeneratorX86::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
 LIRGeneratorX86::visitUnbox(MUnbox *unbox)
 {
     // An unbox on x86 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::ANY));

     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
 LIRGeneratorX86::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);
 }

 bool
 LIRGeneratorX86::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
 LIRGeneratorX86::lowerUntypedPhiInput(MPhi *phi, uint32_t inputPosition, LBlock *block, size_t lirIndex)
 {
     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
 LIRGeneratorX86::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;

     // For byte arrays, the value has to be in a byte register on x86.
     if (ins->isByteArray())
         value = useFixed(ins->value(), eax);
     else
         value = useRegisterOrNonDoubleConstant(ins->value());
     return add(new LStoreTypedArrayElement(elements, index, value), ins);
 }

 bool
 LIRGeneratorX86::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 = useAnyOrConstant(ins->length());
     LAllocation index = useRegisterOrConstant(ins->index());
     LAllocation value;

     // For byte arrays, the value has to be in a byte register on x86.
     if (ins->isByteArray())
         value = useFixed(ins->value(), eax);
     else
         value = useRegisterOrNonDoubleConstant(ins->value());
     return add(new LStoreTypedArrayElementHole(elements, length, index, value), ins);
 }

 bool
 LIRGeneratorX86::visitAsmJSUnsignedToDouble(MAsmJSUnsignedToDouble *ins)
 {
     JS_ASSERT(ins->input()->type() == MIRType_Int32);
     LUInt32ToDouble *lir = new LUInt32ToDouble(useRegisterAtStart(ins->input()), temp());
     return define(lir, ins);
 }

 bool
 LIRGeneratorX86::visitAsmJSStoreHeap(MAsmJSStoreHeap *ins)
 {
     LAsmJSStoreHeap *lir;
     switch (ins->viewType()) {
       case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
         // It's a trap! On x86, the 1-byte store can only use one of
         // {al,bl,cl,dl,ah,bh,ch,dh}. That means if the register allocator
         // gives us one of {edi,esi,ebp,esp}, we're out of luck. (The formatter
         // will assert on us.) Ideally, we'd just ask the register allocator to
         // give us one of {al,bl,cl,dl}. For now, just useFixed(al).
         lir = new LAsmJSStoreHeap(useRegister(ins->ptr()),
                                   useFixed(ins->value(), eax));
         break;
       case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
       case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
       case ArrayBufferView::TYPE_FLOAT32: case ArrayBufferView::TYPE_FLOAT64:
         // For now, don't allow constants. The immediate operand affects
         // instruction layout which affects patching.
         lir = new LAsmJSStoreHeap(useRegisterAtStart(ins->ptr()),
                                   useRegisterAtStart(ins->value()));
         break;
       default: JS_NOT_REACHED("unexpected array type");
     }

     return add(lir, ins);
 }

 bool
 LIRGeneratorX86::visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic *ins)
 {
     // The code generated for StoreTypedArrayElementStatic is identical to that
     // for AsmJSStoreHeap, and the same concerns apply.
     LStoreTypedArrayElementStatic *lir;
     switch (ins->viewType()) {
       case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
       case ArrayBufferView::TYPE_UINT8_CLAMPED:
         lir = new LStoreTypedArrayElementStatic(useRegister(ins->ptr()),
                                                 useFixed(ins->value(), eax));
         break;
       case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
       case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
       case ArrayBufferView::TYPE_FLOAT32: case ArrayBufferView::TYPE_FLOAT64:
         lir = new LStoreTypedArrayElementStatic(useRegisterAtStart(ins->ptr()),
                                                 useRegisterAtStart(ins->value()));
         break;
       default: JS_NOT_REACHED("unexpected array type");
     }

     return add(lir, ins);
 }

 bool
 LIRGeneratorX86::visitAsmJSLoadFuncPtr(MAsmJSLoadFuncPtr *ins)
 {
     return define(new LAsmJSLoadFuncPtr(useRegisterAtStart(ins->index())), ins);
 }

 LGetPropertyCacheT *
 LIRGeneratorX86::newLGetPropertyCacheT(MGetPropertyCache *ins)
 {
     // Since x86 doesn't have a scratch register and we need one for the
     // indirect jump for dispatch-style ICs, we need a temporary in the case
     // of a double output type as we can't get a scratch from the output.
     LDefinition scratch;
     if (ins->type() == MIRType_Double)
         scratch = temp();
     else
         scratch = LDefinition::BogusTemp();
     return new LGetPropertyCacheT(useRegister(ins->object()), scratch);
 }
	/* -- 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 "Lowering-x86.h"

	#include "jit/MIR.h"
	#include "Assembler-x86.h"
	#include "jit/shared/Lowering-shared-inl.h"

	using namespace js;
	using namespace js::jit;

	bool
	LIRGeneratorX86::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
	LIRGeneratorX86::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
	LIRGeneratorX86::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
	LIRGeneratorX86::visitUnbox(MUnbox *unbox)
	{
	// An unbox on x86 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::ANY));

	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
	LIRGeneratorX86::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);
	}

	bool
	LIRGeneratorX86::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
	LIRGeneratorX86::lowerUntypedPhiInput(MPhi phi, uint32_t inputPosition, LBlock block, size_t lirIndex)
	{
	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
	LIRGeneratorX86::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;

	// For byte arrays, the value has to be in a byte register on x86.
	if (ins->isByteArray())
	value = useFixed(ins->value(), eax);
	else
	value = useRegisterOrNonDoubleConstant(ins->value());
	return add(new LStoreTypedArrayElement(elements, index, value), ins);
	}

	bool
	LIRGeneratorX86::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 = useAnyOrConstant(ins->length());
	LAllocation index = useRegisterOrConstant(ins->index());
	LAllocation value;

	// For byte arrays, the value has to be in a byte register on x86.
	if (ins->isByteArray())
	value = useFixed(ins->value(), eax);
	else
	value = useRegisterOrNonDoubleConstant(ins->value());
	return add(new LStoreTypedArrayElementHole(elements, length, index, value), ins);
	}

	bool
	LIRGeneratorX86::visitAsmJSUnsignedToDouble(MAsmJSUnsignedToDouble *ins)
	{
	JS_ASSERT(ins->input()->type() == MIRType_Int32);
	LUInt32ToDouble *lir = new LUInt32ToDouble(useRegisterAtStart(ins->input()), temp());
	return define(lir, ins);
	}

	bool
	LIRGeneratorX86::visitAsmJSStoreHeap(MAsmJSStoreHeap *ins)
	{
	LAsmJSStoreHeap *lir;
	switch (ins->viewType()) {
	case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
	// It's a trap! On x86, the 1-byte store can only use one of
	// {al,bl,cl,dl,ah,bh,ch,dh}. That means if the register allocator
	// gives us one of {edi,esi,ebp,esp}, we're out of luck. (The formatter
	// will assert on us.) Ideally, we'd just ask the register allocator to
	// give us one of {al,bl,cl,dl}. For now, just useFixed(al).
	lir = new LAsmJSStoreHeap(useRegister(ins->ptr()),
	useFixed(ins->value(), eax));
	break;
	case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
	case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
	case ArrayBufferView::TYPE_FLOAT32: case ArrayBufferView::TYPE_FLOAT64:
	// For now, don't allow constants. The immediate operand affects
	// instruction layout which affects patching.
	lir = new LAsmJSStoreHeap(useRegisterAtStart(ins->ptr()),
	useRegisterAtStart(ins->value()));
	break;
	default: JS_NOT_REACHED("unexpected array type");
	}

	return add(lir, ins);
	}

	bool
	LIRGeneratorX86::visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic *ins)
	{
	// The code generated for StoreTypedArrayElementStatic is identical to that
	// for AsmJSStoreHeap, and the same concerns apply.
	LStoreTypedArrayElementStatic *lir;
	switch (ins->viewType()) {
	case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
	case ArrayBufferView::TYPE_UINT8_CLAMPED:
	lir = new LStoreTypedArrayElementStatic(useRegister(ins->ptr()),
	useFixed(ins->value(), eax));
	break;
	case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
	case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
	case ArrayBufferView::TYPE_FLOAT32: case ArrayBufferView::TYPE_FLOAT64:
	lir = new LStoreTypedArrayElementStatic(useRegisterAtStart(ins->ptr()),
	useRegisterAtStart(ins->value()));
	break;
	default: JS_NOT_REACHED("unexpected array type");
	}

	return add(lir, ins);
	}

	bool
	LIRGeneratorX86::visitAsmJSLoadFuncPtr(MAsmJSLoadFuncPtr *ins)
	{
	return define(new LAsmJSLoadFuncPtr(useRegisterAtStart(ins->index())), ins);
	}

	LGetPropertyCacheT *
	LIRGeneratorX86::newLGetPropertyCacheT(MGetPropertyCache *ins)
	{
	// Since x86 doesn't have a scratch register and we need one for the
	// indirect jump for dispatch-style ICs, we need a temporary in the case
	// of a double output type as we can't get a scratch from the output.
	LDefinition scratch;
	if (ins->type() == MIRType_Double)
	scratch = temp();
	else
	scratch = LDefinition::BogusTemp();
	return new LGetPropertyCacheT(useRegister(ins->object()), scratch);
	}