void LinearScan::rematerializeAux(Trace* trace,
SSATmp* curSp,
SSATmp* curFp,
std::vector<SSATmp*> localValues) {
IRInstruction::List& instList = trace->getInstructionList();
for (IRInstruction::Iterator it = instList.begin();
it != instList.end();
++it) {
IRInstruction* inst = *it;
Opcode opc = inst->getOpcode();
SSATmp* dst = inst->getDst();
if (opc == DefFP || opc == FreeActRec) {
curFp = dst;
ASSERT(dst && dst->getReg() == rVmFp);
}
if (opc == Reload) {
// s = Spill t0
// t = Reload s
SSATmp* spilledTmp = getSpilledTmp(dst);
IRInstruction* spilledInst = spilledTmp->getInstruction();
IRInstruction* newInst = NULL;
if (spilledInst->isRematerializable() ||
(spilledInst->getOpcode() == LdStack &&
spilledInst->getSrc(0) == curSp)) {
// XXX: could change <newInst> to the non-check version.
// Rematerialize those rematerializable instructions (i.e.,
// isRematerializable returns true) and LdStack.
newInst = spilledInst->clone(m_irFactory);
// The new instruction needn't have an exit label, because it is always
// dominated by the original instruction.
newInst->setLabel(NULL);
} else {
// Rematerialize LdLoc.
std::vector<SSATmp*>::iterator pos =
std::find(localValues.begin(),
localValues.end(),
canonicalize(spilledTmp));
// Search for a local that stores the value of <spilledTmp>.
if (pos != localValues.end()) {
size_t locId = pos - localValues.begin();
ASSERT(curFp != NULL);
ConstInstruction constInst(curFp, Local(locId));
IRInstruction* ldHomeInst =
m_irFactory->cloneInstruction(&constInst);
newInst = m_irFactory->ldLoc(m_irFactory->getSSATmp(ldHomeInst),
dst->getType(),
NULL);
}
}
if (newInst) {
newInst->setDst(dst);
newInst->getDst()->setInstruction(newInst);
*it = newInst;
newInst->setParent(trace);
}
}
// Updating <curSp> and <localValues>.
if (dst && dst->getReg() == rVmSp) {
// <inst> modifies the stack pointer.
curSp = dst;
}
if (opc == LdLoc || opc == StLoc || opc == StLocNT) {
// dst = LdLoc home
// StLoc/StLocNT home, src
int locId = getLocalIdFromHomeOpnd(inst->getSrc(0));
SSATmp* localValue = (opc == LdLoc ? dst : inst->getSrc(1));
if (int(localValues.size()) < locId + 1) {
localValues.resize(locId + 1);
}
localValues[locId] = canonicalize(localValue);
}
if (inst->isControlFlowInstruction()) {
LabelInstruction* label = inst->getLabel();
if (label != NULL && label->getId() == inst->getId() + 1) {
rematerializeAux(label->getTrace(), curSp, curFp, localValues);
}
}
}
}
void LinearScan::rematerializeAux(Trace* trace,
SSATmp* curSp,
SSATmp* curFp,
std::vector<SSATmp*> localValues) {
IRInstruction::List& instList = trace->getInstructionList();
for (IRInstruction::Iterator it = instList.begin();
it != instList.end();
++it) {
IRInstruction* inst = *it;
Opcode opc = inst->getOpcode();
SSATmp* dst = inst->getDst();
if (opc == DefFP || opc == FreeActRec) {
curFp = dst;
assert(dst && dst->getReg() == rVmFp);
}
if (opc == Reload) {
// s = Spill t0
// t = Reload s
SSATmp* spilledTmp = getSpilledTmp(dst);
IRInstruction* spilledInst = spilledTmp->getInstruction();
IRInstruction* newInst = NULL;
if (spilledInst->isRematerializable() ||
(spilledInst->getOpcode() == LdStack &&
spilledInst->getSrc(0) == curSp)) {
// XXX: could change <newInst> to the non-check version.
// Rematerialize those rematerializable instructions (i.e.,
// isRematerializable returns true) and LdStack.
newInst = spilledInst->clone(m_irFactory);
// The new instruction needn't have an exit label, because it is always
// dominated by the original instruction.
newInst->setLabel(NULL);
} else {
// Rematerialize LdLoc.
std::vector<SSATmp*>::iterator pos =
std::find(localValues.begin(),
localValues.end(),
canonicalize(spilledTmp));
// Search for a local that stores the value of <spilledTmp>.
if (pos != localValues.end()) {
size_t locId = pos - localValues.begin();
assert(curFp != NULL);
ConstInstruction constInst(curFp, Local(locId));
IRInstruction* ldHomeInst =
m_irFactory->cloneInstruction(&constInst);
newInst = m_irFactory->gen(LdLoc,
dst->getType(),
m_irFactory->getSSATmp(ldHomeInst));
}
}
if (newInst) {
UNUSED Type::Tag oldType = dst->getType();
newInst->setDst(dst);
dst->setInstruction(newInst);
assert(outputType(newInst) == oldType);
*it = newInst;
newInst->setParent(trace);
}
}
// Updating <curSp> and <localValues>.
if (dst && dst->getReg() == rVmSp) {
// <inst> modifies the stack pointer.
curSp = dst;
}
if (opc == LdLoc || opc == StLoc || opc == StLocNT) {
// dst = LdLoc home
// StLoc/StLocNT home, src
int locId = getLocalIdFromHomeOpnd(inst->getSrc(0));
// Note that when we implement inlining, we will need to deal
// with the new local id space of the inlined function.
SSATmp* localValue = (opc == LdLoc ? dst : inst->getSrc(1));
if (int(localValues.size()) < locId + 1) {
localValues.resize(locId + 1);
}
localValues[locId] = canonicalize(localValue);
}
// Other instructions that may have side effects on locals must
// kill the local variable values.
else if (opc == IterInit) {
int valLocId = inst->getSrc(3)->getConstValAsInt();
localValues[valLocId] = NULL;
if (inst->getNumSrcs() == 5) {
int keyLocId = inst->getSrc(4)->getConstValAsInt();
localValues[keyLocId] = NULL;
}
} else if (opc == IterNext) {
int valLocId = inst->getSrc(2)->getConstValAsInt();
localValues[valLocId] = NULL;
if (inst->getNumSrcs() == 4) {
int keyLocId = inst->getSrc(3)->getConstValAsInt();
localValues[keyLocId] = NULL;
}
}
if (inst->isControlFlowInstruction()) {
LabelInstruction* label = inst->getLabel();
if (label != NULL && label->getId() == inst->getId() + 1) {
rematerializeAux(label->getParent(), curSp, curFp, localValues);
}
}
}
}