Factor some code out of SimplifyCFG, forming a new
DeleteBlockIfDead method.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60463 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 9ba7550..7077436 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1681,27 +1681,7 @@
// as a predecessor. These are unreachable.
if (pred_begin(BB) == pred_end(BB) || BB->getSinglePredecessor() == BB) {
DOUT << "Removing BB: \n" << *BB;
-
- // Loop through all of our successors and make sure they know that one
- // of their predecessors is going away.
- for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
- SI->removePredecessor(BB);
-
- while (!BB->empty()) {
- Instruction &I = BB->back();
- // If this instruction is used, replace uses with an arbitrary
- // value. Because control flow can't get here, we don't care
- // what we replace the value with. Note that since this block is
- // unreachable, and all values contained within it must dominate their
- // uses, that all uses will eventually be removed.
- if (!I.use_empty())
- // Make all users of this instruction use undef instead
- I.replaceAllUsesWith(UndefValue::get(I.getType()));
-
- // Remove the instruction from the basic block
- BB->getInstList().pop_back();
- }
- BB->eraseFromParent();
+ DeleteBlockIfDead(BB);
return true;
}