[clang] [CIR] Upstream GotoOp (PR #153701)

[Andy Kaylor via cfe-commits]

================
@@ -1649,7 +1649,27 @@ void cir::FuncOp::print(OpAsmPrinter &p) {
 
 // TODO(CIR): The properties of functions that require verification haven't
 // been implemented yet.
-mlir::LogicalResult cir::FuncOp::verify() { return success(); }
+mlir::LogicalResult cir::FuncOp::verify() {
+
+  std::set<llvm::StringRef> labels;
+  std::set<llvm::StringRef> gotos;
+
+  getOperation()->walk([&](mlir::Operation *op) {
+    if (auto lab = dyn_cast<cir::LabelOp>(op)) {
+      labels.emplace(lab.getLabel());
+    } else if (auto goTo = dyn_cast<cir::GotoOp>(op)) {
+      gotos.emplace(goTo.getLabel());
+    }
+  });
+
+  std::vector<llvm::StringRef> mismatched;
+  std::set_difference(gotos.begin(), gotos.end(), labels.begin(), labels.end(),
----------------
andykaylor wrote:

If you use SmallSet this becomes
```suggestion
  SmallSet<llvm::StringRef, 16> mismatched = llvm::set_difference(gotos, labels));
```

https://github.com/llvm/llvm-project/pull/153701