+/// removeDeadUsersOfConstant - If the specified constantexpr is dead, remove
+/// it. This involves recursively eliminating any dead users of the
+/// constantexpr.
+static bool removeDeadUsersOfConstant(const Constant *C) {
+ if (isa<GlobalValue>(C)) return false; // Cannot remove this
+
+ while (!C->use_empty()) {
+ const Constant *User = dyn_cast<Constant>(C->use_back());
+ if (!User) return false; // Non-constant usage;
+ if (!removeDeadUsersOfConstant(User))
+ return false; // Constant wasn't dead
+ }
+
+ const_cast<Constant*>(C)->destroyConstant();
+ return true;
+}
+
+
+/// removeDeadConstantUsers - If there are any dead constant users dangling
+/// off of this constant, remove them. This method is useful for clients
+/// that want to check to see if a global is unused, but don't want to deal
+/// with potentially dead constants hanging off of the globals.
+void Constant::removeDeadConstantUsers() const {
+ Value::const_use_iterator I = use_begin(), E = use_end();
+ Value::const_use_iterator LastNonDeadUser = E;
+ while (I != E) {
+ const Constant *User = dyn_cast<Constant>(*I);
+ if (User == 0) {
+ LastNonDeadUser = I;
+ ++I;
+ continue;
+ }
+
+ if (!removeDeadUsersOfConstant(User)) {
+ // If the constant wasn't dead, remember that this was the last live use
+ // and move on to the next constant.
+ LastNonDeadUser = I;
+ ++I;
+ continue;
+ }
+
+ // If the constant was dead, then the iterator is invalidated.
+ if (LastNonDeadUser == E) {
+ I = use_begin();
+ if (I == E) break;
+ } else {
+ I = LastNonDeadUser;
+ ++I;
+ }
+ }
+}
+
+