void Constraints::substIntoEquates(ConstraintMap& in) {
// Substitute the fixed types into the equates. This may generate more
// fixed types
ConstraintMap extra;
ConstraintMap cur = in;
while (cur.size()) {
extra.clear();
ConstraintMap::iterator kk;
for (kk = cur.begin(); kk != cur.end(); kk++) {
Exp* lhs = kk->first;
std::map<Exp*, LocationSet, lessExpStar>::iterator it = equates.find(lhs);
if (it != equates.end()) {
// Possibly new constraints that
// typeof(elements in it->second) == val
Exp* val = kk->second;
LocationSet& ls = it->second;
LocationSet::iterator ll;
for (ll = ls.begin(); ll != ls.end(); ll++) {
ConstraintMap::iterator ff;
ff = fixed.find(*ll);
if (ff != fixed.end()) {
if (!unify(val, ff->second, extra)) {
if (VERBOSE || DEBUG_TA)
LOG << "Constraint failure: " << *ll << " constrained to be " <<
((TypeVal*)val)->getType()->getCtype() << " and " <<
((TypeVal*)ff->second)->getType()->getCtype() << "\n";
return;
}
} else
extra[*ll] = val; // A new constant constraint
}
if (((TypeVal*)val)->getType()->isComplete()) {
// We have a complete type equal to one or more variables
// Remove the equate, and generate more fixed
// e.g. Ta = Tb,Tc and Ta = K => Tb=K, Tc=K
for (ll = ls.begin(); ll != ls.end(); ll++) {
Exp* newFixed = new Binary(opEquals,
*ll, // e.g. Tb
val); // e.g. K
extra.insert(newFixed);
}
equates.erase(it);
}
}
}
fixed.makeUnion(extra);
cur = extra; // Take care of any "ripple effect"
} // Repeat until no ripples
}
// Constraints up to but not including iterator it have been unified.
// The current solution is soln
// The set of all solutions is in solns
bool Constraints::doSolve(std::list<Exp*>::iterator it, ConstraintMap& soln, std::list<ConstraintMap>& solns) {
LOG << "Begin doSolve at level " << ++level << "\n";
LOG << "Soln now: " << soln.prints() << "\n";
if (it == disjunctions.end()) {
// We have gotten to the end with no unification failures
// Copy the current set of constraints as a solution
//if (soln.size() == 0)
// Awkward. There is a trivial solution, but we have no constraints
// So make a constraint of always-true
//soln.insert(new Terminal(opTrue));
// Copy the fixed constraints
soln.makeUnion(fixed);
solns.push_back(soln);
LOG << "Exiting doSolve at level " << level-- << " returning true\n";
return true;
}
Exp* dj = *it;
// Iterate through each disjunction d of dj
Exp* rem1 = dj; // Remainder
bool anyUnified = false;
Exp* d;
while ((d = nextDisjunct(rem1)) != NULL) {
LOG << " $$ d is " << d << ", rem1 is " << ((rem1==0)?"NULL":rem1->prints()) << " $$\n";
// Match disjunct d against the fixed types; it could be compatible,
// compatible and generate an additional constraint, or be
// incompatible
ConstraintMap extra; // Just for this disjunct
Exp* c;
Exp* rem2 = d;
bool unified = true;
while ((c = nextConjunct(rem2)) != NULL) {
LOG << " $$ c is " << c << ", rem2 is " << ((rem2==0)?"NULL":rem2->prints()) << " $$\n";
if (c->isFalse()) {
unified = false;
break;
}
assert(c->isEquality());
Exp* lhs = ((Binary*)c)->getSubExp1();
Exp* rhs = ((Binary*)c)->getSubExp2();
extra.insert(lhs, rhs);
ConstraintMap::iterator kk;
kk = fixed.find(lhs);
if (kk != fixed.end()) {
unified &= unify(rhs, kk->second, extra);
LOG << "Unified now " << unified << "; extra now " << extra.prints() << "\n";
if (!unified) break;
}
}
if (unified)
// True if any disjuncts had all the conjuncts satisfied
anyUnified = true;
if (!unified) continue;
// Use this disjunct
// We can't just difference out extra if this fails; it may remove
// elements from soln that should not be removed
// So need a copy of the old set in oldSoln
ConstraintMap oldSoln = soln;
soln.makeUnion(extra);
doSolve(++it, soln, solns);
// Revert to the previous soln (whether doSolve returned true or not)
// If this recursion did any good, it will have gotten to the end and
// added the resultant soln to solns
soln = oldSoln;
LOG << "After doSolve returned: soln back to: " << soln.prints() << "\n";
// Back to the current disjunction
it--;
// Continue for more disjuncts this disjunction
}
// We have run out of disjuncts. Return true if any disjuncts had no
// unification failures
LOG << "Exiting doSolve at level " << level-- << " returning " << anyUnified << "\n";
return anyUnified;
}
