// sweep over the program can safely delete dead instructions without
// other dead instructions still refering to them.
//
- for (BasicBlock::iterator I = BB->begin(), E = --BB->end(); I != E; ++I)
- if (!LiveSet.count(I)) // Is this instruction alive?
+ for (BasicBlock::iterator I = BB->begin(), E = --BB->end(); I != E; )
+ if (!LiveSet.count(I)) { // Is this instruction alive?
I->dropAllReferences(); // Nope, drop references...
+ if (PHINode *PN = dyn_cast<PHINode>(&*I)) {
+ // We don't want to leave PHI nodes in the program that have
+ // #arguments != #predecessors, so we remove them now.
+ //
+ PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
+
+ // Delete the instruction...
+ I = BB->getInstList().erase(I);
+ } else {
+ ++I;
+ }
+ } else {
+ ++I;
+ }
}
}