[llvm] [GVN] Combine visited and worklist in PropagateEquality (PR #216061)

[Antonio Frighetto via llvm-commits]

================
@@ -3107,8 +3106,9 @@ bool GVNPass::propagateEquality(
       DominatedBlocks.push_back(Node->getBlock());
   }
 
-  while (!Worklist.empty()) {
-    std::pair<Value*, Value*> Item = Worklist.pop_back_val();
+  unsigned WorklistIdx = 0;
+  while (WorklistIdx != Worklist.size()) {
+    std::pair<Value *, Value *> Item = Worklist[WorklistIdx++];
     LHS = Item.first; RHS = Item.second;
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antoniofrighetto wrote:

```suggestion
    std::tie(LHS, RHS) = Worklist[WorklistIdx++];
```

https://github.com/llvm/llvm-project/pull/216061