bool RegionInfo::isRegion(BasicBlock *entry, BasicBlock *exit) const {
assert(entry && exit && "entry and exit must not be null!");
typedef DominanceFrontier::DomSetType DST;
DST *entrySuccs = &DF->find(entry)->second;
// Exit is the header of a loop that contains the entry. In this case,
// the dominance frontier must only contain the exit.
if (!DT->dominates(entry, exit)) {
for (DST::iterator SI = entrySuccs->begin(), SE = entrySuccs->end();
SI != SE; ++SI)
if (*SI != exit && *SI != entry)
return false;
return true;
}
DST *exitSuccs = &DF->find(exit)->second;
// Do not allow edges leaving the region.
for (DST::iterator SI = entrySuccs->begin(), SE = entrySuccs->end();
SI != SE; ++SI) {
if (*SI == exit || *SI == entry)
continue;
if (exitSuccs->find(*SI) == exitSuccs->end())
return false;
if (!isCommonDomFrontier(*SI, entry, exit))
return false;
}
// Do not allow edges pointing into the region.
for (DST::iterator SI = exitSuccs->begin(), SE = exitSuccs->end();
SI != SE; ++SI)
if (DT->properlyDominates(entry, *SI) && *SI != exit)
return false;
return true;
}
