[llvm] CFGPrinter: fix accidentally quadratic behavior (PR #125396)

[Nikita Popov via llvm-commits]

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@@ -208,3 +225,38 @@ bool DOTGraphTraits<DOTFuncInfo *>::isNodeHidden(const BasicBlock *Node,
   }
   return false;
 }
+
+std::string DOTGraphTraits<DOTFuncInfo *>::getCompleteNodeLabel(
+    const BasicBlock *Node, DOTFuncInfo *CFGInfo,
+    function_ref<void(raw_string_ostream &, const BasicBlock &)>
+        HandleBasicBlock,
+    function_ref<void(std::string &, unsigned &, unsigned)> HandleComment) {
+  if (HandleBasicBlock)
+    return CompleteNodeLabelString(Node, HandleBasicBlock, HandleComment);
+
+  // Default basic block printing
+  std::optional<ModuleSlotTracker> MSTStorage;
+  ModuleSlotTracker *MST = nullptr;
+
+  if (CFGInfo) {
+    MST = CFGInfo->getModuleSlotTracker();
+  } else {
+    MSTStorage.emplace(Node->getModule());
+    MST = &*MSTStorage;
+  }
+
+  return CompleteNodeLabelString(
+      Node,
+      function_ref<void(raw_string_ostream &, const BasicBlock &)>(
+          [MST](raw_string_ostream &OS, const BasicBlock &Node) -> void {
+            // Prepend label name
+            Node.printAsOperand(OS, false);
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nikic wrote:

Should pass MST here as well?

https://github.com/llvm/llvm-project/pull/125396