[llvm-commits] [cfe-commits] [PATCH][Review Request] EarlyCSE stack overflow - bugzilla 11794

[Jakob Stoklund Olesen]

On Jan 30, 2012, at 1:11 PM, Lenny Maiorani wrote:
> 
> Ok, I understand the algorithm difference, but I don't know what to do to store the hash table scopes on the stack. They are not copy-constructable or assignable so they don't work with STL containers. I could use a shared pointer, but that is just reference counting again.

Oh, how annoying. I think you should just do what MachineCSE does and store pointers:

void MachineCSE::EnterScope(MachineBasicBlock *MBB) {
  DEBUG(dbgs() << "Entering: " << MBB->getName() << '\n');
  ScopeType *Scope = new ScopeType(VNT);
  ScopeMap[MBB] = Scope;
}

void MachineCSE::ExitScope(MachineBasicBlock *MBB) {
  DEBUG(dbgs() << "Exiting: " << MBB->getName() << '\n');
  DenseMap<MachineBasicBlock*, ScopeType*>::iterator SI = ScopeMap.find(MBB);
  assert(SI != ScopeMap.end());
  ScopeMap.erase(SI);
  delete SI->second;
}

(But please don't dereference iterators after erasing them).

/jakob