[llvm] [DFAJumpThreading][NFC] Clear cleanPhiNodes and phi-related code (PR #162423)

[Nikita Popov via llvm-commits]

================
@@ -1313,27 +1301,19 @@ struct TransformDFA {
   void cleanPhiNodes(BasicBlock *BB) {
     // If BB is no longer reachable, remove any remaining phi nodes
     if (pred_empty(BB)) {
-      std::vector<PHINode *> PhiToRemove;
-      for (auto II = BB->begin(); PHINode *Phi = dyn_cast<PHINode>(II); ++II) {
-        PhiToRemove.push_back(Phi);
-      }
-      for (PHINode *PN : PhiToRemove) {
-        PN->replaceAllUsesWith(PoisonValue::get(PN->getType()));
-        PN->eraseFromParent();
+      for (PHINode &PN : make_early_inc_range(BB->phis())) {
+        PN.replaceAllUsesWith(PoisonValue::get(PN.getType()));
+        PN.eraseFromParent();
       }
       return;
     }
 
     // Remove any incoming values that come from an invalid predecessor
-    for (auto II = BB->begin(); PHINode *Phi = dyn_cast<PHINode>(II); ++II) {
-      std::vector<BasicBlock *> BlocksToRemove;
-      for (BasicBlock *IncomingBB : Phi->blocks()) {
-        if (!isPredecessor(BB, IncomingBB))
-          BlocksToRemove.push_back(IncomingBB);
-      }
-      for (BasicBlock *BB : BlocksToRemove)
-        Phi->removeIncomingValue(BB);
-    }
+    for (PHINode &Phi : BB->phis())
+      Phi.removeIncomingValueIf([&](uint Index) {
----------------
nikic wrote:

```suggestion
      Phi.removeIncomingValueIf([&](unsigned Index) {
```

https://github.com/llvm/llvm-project/pull/162423