void MemMap::optimizeMemoryAccesses(Trace* trace) {
StoreList tracking;
for (IRInstruction* inst : trace->getInstructionList()) {
// initialize each instruction as live
inst->setId(LIVE);
int offset = -1;
Opcode op = inst->getOpcode();
if (isLoad(op)) {
if (op == LdProp) {
offset = inst->getSrc(1)->getConstValAsInt();
}
optimizeLoad(inst, offset);
} else if (isStore(op)) {
if (op == StProp || op == StPropNT) {
offset = inst->getSrc(1)->getConstValAsInt();
}
// if we see a store, first check if its last available access is a store
// if it is, then the last access is a dead store
IRInstruction* access = getLastAccess(inst->getSrc(0), offset);
if (access != NULL && isStore(access->getOpcode())) {
// if a dead St* is followed by a St*NT, then the second store needs to
// now write in the type because the first store will be removed
if (access->getOpcode() == StProp && op == StPropNT) {
inst->setOpcode(StProp);
} else if (access->getOpcode() == StLoc && op == StLocNT) {
inst->setOpcode(StLoc);
} else if (access->getOpcode() == StRef && op == StRefNT) {
inst->setOpcode(StRef);
}
access->setId(DEAD);
}
// start tracking the current store
tracking.push_back(std::make_pair(inst, std::vector<IRInstruction*>()));
} else if (inst->mayRaiseError()) {
// if the function has an exit edge that we don't know anything about
// (raising an error), then all stores we're currently tracking need to
// be erased. all stores already declared dead are untouched
StoreList::iterator it, end;
for (it = tracking.begin(), end = tracking.end(); it != end; ) {
StoreList::iterator copy = it;
++it;
if (copy->first->getId() != DEAD) {
// XXX: t1779667
tracking.erase(copy);
}
}
}
// if the current instruction is guarded, make sure all of our stores that
// are not yet dead know about it
if (inst->getLabel() != NULL) {
for (auto& entry : tracking) {
if (entry.first->getId() != DEAD) {
entry.second.push_back(inst);
}
}
}
Simplifier::copyProp(inst);
processInstruction(inst);
}
sinkStores(tracking);
// kill the dead stores
removeDeadInstructions(trace);
}
void MemMap::optimizeMemoryAccesses(Trace* trace) {
if (hasInternalFlow(trace)) {
// This algorithm only works with linear traces.
// TODO t2066994: reset state after each block, at least.
return;
}
StoreList tracking;
const Func* curFunc = nullptr;
for (Block* block : trace->getBlocks()) {
for (IRInstruction& inst : *block) {
if (inst.getOpcode() == Marker) {
curFunc = inst.getExtra<Marker>()->func;
}
// initialize each instruction as live
setLive(inst, true);
int offset = -1;
Opcode op = inst.getOpcode();
if (isLoad(op)) {
if (op == LdProp) {
offset = inst.getSrc(1)->getValInt();
}
// initialize each instruction as live
setLive(inst, true);
optimizeLoad(&inst, offset);
} else if (isStore(op)) {
if (op == StProp || op == StPropNT) {
offset = inst.getSrc(1)->getValInt();
}
// if we see a store, first check if its last available access is a store
// if it is, then the last access is a dead store
auto access = inst.getOpcode() == StLoc || inst.getOpcode() == StLocNT
? lastLocalAccess(inst.getExtra<LocalId>()->locId)
: getLastAccess(inst.getSrc(0), offset);
if (access && isStore(access->getOpcode())) {
// if a dead St* is followed by a St*NT, then the second store needs to
// now write in the type because the first store will be removed
if (access->getOpcode() == StProp && op == StPropNT) {
inst.setOpcode(StProp);
} else if (access->getOpcode() == StLoc && op == StLocNT) {
inst.setOpcode(StLoc);
} else if (access->getOpcode() == StRef && op == StRefNT) {
inst.setOpcode(StRef);
}
setLive(*access, false);
}
// start tracking the current store
tracking.push_back(std::make_pair(&inst, std::vector<IRInstruction*>()));
} else if (inst.mayRaiseError()) {
// if the function has an exit edge that we don't know anything about
// (raising an error), then all stores we're currently tracking need to
// be erased. all stores already declared dead are untouched
StoreList::iterator it, end;
for (it = tracking.begin(), end = tracking.end(); it != end; ) {
StoreList::iterator copy = it;
++it;
if (isLive(copy->first)) {
// XXX: t1779667
tracking.erase(copy);
}
}
}
// if the current instruction is guarded, make sure all of our stores that
// are not yet dead know about it
if (inst.getTaken()) {
for (auto& entry : tracking) {
if (isLive(entry.first)) {
entry.second.push_back(&inst);
}
}
}
Simplifier::copyProp(&inst);
processInstruction(&inst, curFunc && curFunc->isPseudoMain());
}
}
sinkStores(tracking);
// kill the dead stores
removeDeadInstructions(trace, m_liveInsts);
}