[clang-format] Quit analyzing solution space for large state count

[owenpan]

Summary

Fixes https://github.com/llvm/llvm-project/issues/56043.

When formatting compiler-rt/test/builtins/Unit/udivmodti4_test.c, which contains a nested braced init list with almost 2.5 million tokens, clang-format will run for hours and eventually be killed by the OS. Halving the size of the list would enable clang-format to format the file in a couple of minutes with Count being almost 25 million.

clang/lib/Format/UnwrappedLineFormatter.cpp

StateNode *RootNode =
         new (Allocator.Allocate()) StateNode(InitialState, false, nullptr);
     Queue.push(QueueItem(OrderedPenalty(0, Count), RootNode));
     ++Count;
 
     unsigned Penalty = 0;
 
     // While not empty, take first element and follow edges.
     while (!Queue.empty()) {
+      // Quit if we still haven't found a solution by now.
+      if (Count > 25000000)
+        return 0;
+
       Penalty = Queue.top().first.first;
       StateNode *Node = Queue.top().second;
       if (!Node->State.NextToken) {
         LLVM_DEBUG(llvm::dbgs()
                    << "\n---\nPenalty for line: " << Penalty << "\n");
         break;
       }
       Queue.pop();