/*
The classical use/def isnt quite enough here. There are two unusual
issues:
- the ref/non-ref issue.
An assignment to a var which is referenced doesnt end its
lifetime. In fact it could just be a "use" of the var. But it
also counts as a def.
- the destructor issue.
variables which might need to be destroyed later are technically
alive, but dont interfere with any other variables in the same state.
They /do/ interfere with any truly "live" variables, however.
These are "dying".
So we end up defining, use, kill, def and dying.
use : a read of the variable, an ordinary assignment if it could
be referenced
kill : an unset, a ref assignment, or, for non referenced vars, any assignment
def : ref or normal assignment
dying : a variable whose destructor is (partially/locally) anticipated.
*/
void LiveDict::updateAccess(ExpressionPtr e) {
int cls = e->getExprClass();
if (cls & Expression::Store) {
/*
Handled when we see the lhs
*/
return;
}
int eid = e->getCanonID();
int context = e->getContext();
bool unset = false;
bool store = false;
if (context & Expression::LValue && context & Expression::UnsetContext) {
unset = true;
} else if (context & Expression::AssignmentLHS) {
store = true;
}
if (e->is(Expression::KindOfSimpleVariable)) {
SimpleVariablePtr sv(static_pointer_cast<SimpleVariable>(e));
bool use = false, kill = false, def = false;
Symbol *sym = sv->getSymbol();
bool isReferenced =
e->isReferencedValid() ?
e->isReferenced() :
sym && sym->isReferenced();
bool isNeeded =
e->isNeededValid() ?
e->isNeeded() :
sym && sym->isNeeded();
if (unset) {
kill = true;
} else if (store) {
if (context & Expression::RefAssignmentLHS ||
(!m_am.hasWildRefs() && !isReferenced)) {
kill = true;
}
def = true;
} else if ((context & Expression::Declaration) == Expression::Declaration) {
// a global declaration
def = kill = true;
} else if (context & (Expression::LValue|
Expression::RefValue|
Expression::DeepReference|
Expression::UnsetContext|
Expression::OprLValue)) {
use = def = true;
} else {
use = true;
}
if (kill && (!sym || isNeeded || isReferenced) &&
!BitOps::get_bit(eid, m_altered) &&
!BitOps::get_bit(eid, m_available)) {
BitOps::set_bit(eid, m_dying, true);
}
if (use &&
!BitOps::get_bit(eid, m_altered) &&
!BitOps::get_bit(eid, m_available)) {
BitOps::set_bit(eid, m_anticipated, true);
e->setAnticipated();
}
if (kill) {
BitOps::set_bit(eid, m_altered, true);
BitOps::set_bit(eid, m_available, def);
} else if (def) {
BitOps::set_bit(eid, m_available, true);
}
if (!m_am.couldBeAliased(sv)) {
return;
}
} else if (!e->is(Expression::KindOfDynamicVariable) &&
(unset || (context & Expression::RefAssignmentLHS))) {
// An unset, or a reference assignment to anything other
// than a simple or dynamic variable can never affect a simple
// variable (outside of pseudoMain).
return;
}
if (store || cls & (Expression::Load|Expression::Call)) {
bool mod =
store ||
(cls & Expression::Load &&
e->getContext() & (Expression::LValue|
Expression::RefValue|
Expression::UnsetContext|
Expression::DeepReference|
Expression::OprLValue));
ExpressionPtr cur = m_refs, prev;
bool isLoad;
int depth = 0, effects = 0;
while (cur) {
ExpressionPtr next = cur->getCanonLVal();
int cid = cur->getCanonID();
if (cid != eid &&
m_am.checkAnyInterf(e, cur, isLoad, depth, effects) !=
AliasManager::DisjointAccess) {
if (mod) {
BitOps::set_bit(cid, m_available, true);
}
if (!BitOps::get_bit(cid, m_altered) &&
!BitOps::get_bit(cid, m_available)) {
BitOps::set_bit(cid, m_anticipated, true);
}
if (!prev) {
m_refs = next;
} else {
prev->setCanonPtr(next);
}
} else {
prev = cur;
}
cur = next;
}
}
}
void RefDict::updateAccess(ExpressionPtr e) {
always_assert(!e->getScope()->inPseudoMain());
int eid = e->getCanonID();
int context = e->getContext();
if (first_pass) {
if (!e->is(Expression::KindOfSimpleVariable) &&
!e->is(Expression::KindOfDynamicVariable)) return;
e->clearAvailable();
e->clearReferencedValid();
e->clearReferenced();
SimpleVariablePtr ptr(dynamic_pointer_cast<SimpleVariable>(e));
if (ptr && (ptr->isSuperGlobal() || ptr->isThis())) return;
if (e->is(Expression::KindOfSimpleVariable)) {
if (BitOps::get_bit(eid, m_referenced)) {
e->setReferenced();
} else if (!BitOps::get_bit(eid, m_killed)) {
// use as a temp place holder
e->setAvailable();
}
}
}
// let the first pass information propagate for both passes, since
// we need it in both contexts
if (context & Expression::RefAssignmentLHS ||
context & Expression::RefValue ||
context & Expression::RefParameter ||
((context & Expression::Declaration) == Expression::Declaration)) {
if (e->is(Expression::KindOfSimpleVariable)) {
BitOps::set_bit(eid, m_referenced, true);
BitOps::set_bit(eid, m_killed, false);
} else {
// for dynamic variables, we must assume the worst
BitOps::set(size(), m_referenced, -1);
BitOps::set(size(), m_killed, 0);
}
} else if (e->is(Expression::KindOfSimpleVariable) &&
context & Expression::LValue &&
context & Expression::UnsetContext) {
BitOps::set_bit(eid, m_referenced, false);
BitOps::set_bit(eid, m_killed, true);
}
if (first_pass) return;
// now we're on the second pass
if (context & Expression::AssignmentLHS ||
context & Expression::OprLValue) {
// we dealt with this node as a store expression
return;
}
int cls = e->getExprClass();
bool isRhsNeeded = false;
bool canKill = false;
ExpressionPtr lhs;
ExpressionPtr rhs;
if (cls & Expression::Store) {
// we care about two cases here
switch (e->getKindOf()) {
case Expression::KindOfAssignmentExpression:
// $x = ...
{
AssignmentExpressionPtr assign(
static_pointer_cast<AssignmentExpression>(e));
lhs = assign->getVariable();
rhs = assign->getValue();
isRhsNeeded = Expression::CheckNeededRHS(rhs);
canKill = true;
}
break;
case Expression::KindOfBinaryOpExpression:
// $x += ...
{
BinaryOpExpressionPtr binop(
static_pointer_cast<BinaryOpExpression>(e));
if (binop->getOp() == T_PLUS_EQUAL) {
lhs = binop->getExp1();
rhs = binop->getExp2();
isRhsNeeded = Expression::CheckNeededRHS(rhs);
}
}
break;
default:
break;
}
}
bool isLhsSimpleVar = false;
bool isLhsDynamic = false;
bool isRefd = false;
if (lhs) {
isLhsSimpleVar = lhs->is(Expression::KindOfSimpleVariable);
// TODO: can a variable only be simple or dynamic?
// If so, this is un-necessary
isLhsDynamic = lhs->is(Expression::KindOfDynamicVariable);
if (isLhsSimpleVar) {
// clean up the LHS AST
lhs->clearAvailable();
lhs->clearNeeded();
lhs->clearNeededValid();
if (BitOps::get_bit(lhs->getCanonID(), m_obj)) {
lhs->setNeeded();
lhs->setNeededValid();
} else if (!BitOps::get_bit(lhs->getCanonID(), m_noobj)) {
lhs->setAvailable();
}
}
if (lhs->isReferencedValid() && lhs->isReferenced() && isRhsNeeded) {
// could we possibly have modified another referenced variable?
isRefd = true;
}
if (isLhsSimpleVar && isRhsNeeded) {
// we see this case:
// $x = new ...
// so we mark $x as being needed
BitOps::set_bit(lhs->getCanonID(), m_obj, true);
BitOps::set_bit(lhs->getCanonID(), m_noobj, false);
} else if (isLhsSimpleVar && canKill && !isRhsNeeded) {
// we saw an assignment that was of the form
// $x = <primitive>
// we can now set $x to be not an object
BitOps::set_bit(lhs->getCanonID(), m_obj, false);
BitOps::set_bit(lhs->getCanonID(), m_noobj, true);
}
}
if (isLhsDynamic && isRhsNeeded) {
// in this case, we must set EVERY variable to contain an object
BitOps::set(size(), m_obj, -1 /* true for each bit */);
BitOps::set(size(), m_noobj, 0 /* false for each bit */);
// we're done, since it can be no worse (no more conservative) than this
return;
}
// do we see a load which could cause the value of this expr to be changed?
// for example:
// function foo(&$x) { $x = 10; }
// $x = 30;
// foo($x); /* <-- this is what we care about */
if ((cls & (Expression::Load|Expression::Call)) &&
(context & (Expression::RefValue|Expression::DeepReference))) {
isRefd = true;
}
// we want to propagate this information to other simple vars we see
if (e->is(Expression::KindOfSimpleVariable)) {
// clean up the AST
e->clearAvailable();
e->clearNeeded();
e->clearNeededValid();
SimpleVariablePtr svp(static_pointer_cast<SimpleVariable>(e));
if (svp->isSuperGlobal() || svp->isThis()) return;
// update the AST to *before* the modification
if (BitOps::get_bit(eid, m_obj)) {
e->setNeeded();
e->setNeededValid();
} else if (!BitOps::get_bit(eid, m_noobj)) {
// use as a temp place holder
e->setAvailable();
}
if (context & Expression::LValue &&
context & Expression::UnsetContext) {
always_assert(!isRefd);
// unset($x);
BitOps::set_bit(eid, m_obj, false);
BitOps::set_bit(eid, m_noobj, true);
} else if (isRefd ||
((context & Expression::Declaration) == Expression::Declaration)) {
// if a simple variable has isRefd, then we need to mark it
// as potentially containing an object.
// also, if the simple variable is in global context
// then we also mark it as potentially containing an object
BitOps::set_bit(eid, m_obj, true);
BitOps::set_bit(eid, m_noobj, false);
}
}
if (isRefd) {
// do a scan for every simple variable referenced value
// in the dictionary and mark it as potentially
// containing an object (in the bit vector)
for (int i = size(); i--; ) {
if (ExpressionPtr e = get(i)) {
always_assert(e->is(Expression::KindOfSimpleVariable));
always_assert(((unsigned int)i) == e->getCanonID());
if (BitOps::get_bit(i, m_referenced)) {
BitOps::set_bit(i, m_obj, true);
BitOps::set_bit(i, m_noobj, false);
}
}
}
}
}