ExpressionPtr Expression::unneededHelper() {
ExpressionListPtr elist = ExpressionListPtr
(new ExpressionList(getScope(), getRange(),
ExpressionList::ListKindWrapped));
bool change = false;
for (int i=0, n = getKidCount(); i < n; i++) {
ExpressionPtr kid = getNthExpr(i);
if (kid && kid->getContainedEffects()) {
ExpressionPtr rep = kid->unneeded();
if (rep != kid) change = true;
if (rep->is(Expression::KindOfExpressionList)) {
for (int j=0, m = rep->getKidCount(); j < m; j++) {
elist->addElement(rep->getNthExpr(j));
}
} else {
elist->addElement(rep);
}
}
}
if (change) {
getScope()->addUpdates(BlockScope::UseKindCaller);
}
int n = elist->getCount();
assert(n);
if (n == 1) {
return elist->getNthExpr(0);
} else {
return elist;
}
}
void ExprDict::updateAccess(ExpressionPtr e) {
int cls = e->getExprClass();
int eid = e->getCanonID();
e->clearAnticipated();
e->clearAvailable();
// bail on non-canonical expressions
if (!isCanonicalStructure(eid)) {
// but record we saw a type assertion belonging to this block
m_avlTypeAsserts.push_back(eid);
return;
}
if (m_anticipated &&
(cls & Expression::Update ?
!BitOps::get_bit(eid, m_altered) : !e->getLocalEffects())) {
/*
Anticipated can be computed bottom up as we go. But note that we
only know altered for Load/Store expressions.
*/
int i = e->getKidCount();
while (true) {
if (!i--) {
e->setAnticipated();
if (!e->hasContext(Expression::AssignmentLHS)) {
setStructureOps(eid, m_anticipated, true);
}
break;
}
if (ExpressionPtr k = e->getNthExpr(i)) {
if (!isCanonicalStructure(k->getCanonID())) continue;
if (!k->isAnticipated()) {
break;
}
}
}
}
if (m_available) {
/*
Available has to be computed optimistically, because we dont yet
know what is going to be altered between here and the end of the block
So keep a list of the potentially-available accesses (avlAccess), and
for each id, the last potentially-available expression (avlExpr).
For each modifying expression that we process, we remove expressions
from avlAccess, and at the end, we build up the available expressions
bottom up.
*/
if ((cls & (Expression::Store|Expression::Call)) ||
(cls & Expression::Load &&
e->getContext() & (Expression::LValue|
Expression::RefValue|
Expression::UnsetContext|
Expression::DeepReference))) {
bool isLoad;
int depth = 0, effects = 0;
for (int i = 0, n = m_avlAccess.size(); i < n; ) {
ExpressionRawPtr a = m_avlAccess[i];
if (m_am.checkAnyInterf(e, a, isLoad, depth, effects) !=
AliasManager::DisjointAccess) {
int aid = a->getCanonID();
assert(isCanonicalStructure(aid));
if (eid != aid || cls == Expression::Load) {
BitOps::set_bit(aid, m_altered, true);
}
if (!(cls & Expression::Store) ||
a != e->getStoreVariable()) {
a->clearAvailable();
m_avlAccess[i] = m_avlAccess[--n];
m_avlAccess.resize(n);
continue;
}
}
i++;
}
}
if (cls & Expression::Update ||
!e->getContainedEffects()) {
int i = e->getKidCount();
while (true) {
if (!i--) {
e->setAvailable();
if (cls & Expression::Update) {
m_avlAccess.push_back(e);
}
m_avlExpr[eid] = e;
break;
}
if (ExpressionPtr k = e->getNthExpr(i)) {
if (!isCanonicalStructure(k->getCanonID())) continue;
if (!k->isAvailable()) {
break;
}
}
}
}
}
if ((cls & (Expression::Store|Expression::Call)) ||
(cls & Expression::Load &&
e->getContext() & (Expression::LValue|
Expression::RefValue|
Expression::UnsetContext|
Expression::DeepReference))) {
ExpressionPtr cur = m_active, prev;
bool isLoad;
int depth = 0, effects = 0;
while (cur) {
ExpressionPtr next = cur->getCanonLVal();
int cid = cur->getCanonID();
assert(isCanonicalStructure(cid));
if ((cid != eid || cls == Expression::Load) &&
(BitOps::get_bit(cid, m_altered) ||
m_am.checkAnyInterf(e, cur, isLoad, depth, effects) !=
AliasManager::DisjointAccess)) {
BitOps::set_bit(cid, m_altered, true);
if (!prev) {
m_active = next;
} else {
prev->setCanonPtr(next);
}
} else {
prev = cur;
}
cur = next;
}
}
}
