[llvm] [SLP]Represent SLP graph as a tree (PR #126771)

[Simon Pilgrim via llvm-commits]

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@@ -3559,9 +3572,9 @@ class BoUpSLP {
       for (unsigned ReorderIdx : ReorderIndices)
         dbgs() << ReorderIdx << ", ";
       dbgs() << "\n";
-      dbgs() << "UserTreeIndices: ";
-      for (const auto &EInfo : UserTreeIndices)
-        dbgs() << EInfo << ", ";
+      dbgs() << "UserTreeIndex: ";
+      if (UserTreeIndex)
+        dbgs() << UserTreeIndex;
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RKSimon wrote:

write `"<invalid>"` if !UserTreeIndex?

https://github.com/llvm/llvm-project/pull/126771