[llvm] [CodeLayout] Faster basic block reordering, ext-tsp (PR #68617)

[Fangrui Song via llvm-commits]

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@@ -741,12 +750,23 @@ class ExtTSPImpl {
         // Get candidates for merging with the current chain.
         for (const auto &[ChainSucc, Edge] : ChainPred->Edges) {
           // Ignore loop edges.
-          if (ChainPred == ChainSucc)
+          if (Edge->isSelfEdge())
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MaskRay wrote:

Nit: This is often called self-loop or loop. If you think fine, I'll push a NFC commit renaming isSelfEdge to isSelfLoop...

https://github.com/llvm/llvm-project/pull/68617