From 2f7f63243fbc7e4341e8b2825472d1980bc91235 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20B=C3=B6ving?= <hargonix@gmail.com>
Date: Wed, 14 Jan 2026 21:05:02 +0100
Subject: [PATCH] perf: fast path for SCC decomposition (#12009)

---
 src/Lean/Compiler/LCNF/SplitSCC.lean | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/Lean/Compiler/LCNF/SplitSCC.lean b/src/Lean/Compiler/LCNF/SplitSCC.lean
index bcc222ab49..7b06e8a5a5 100644
--- a/src/Lean/Compiler/LCNF/SplitSCC.lean
+++ b/src/Lean/Compiler/LCNF/SplitSCC.lean
@@ -36,6 +36,8 @@ where
 end SplitScc
 
 public def splitScc (scc : Array Decl) : CompilerM (Array (Array Decl)) := do
+  if scc.size == 1 then
+    return #[scc]
   let declMap := Std.HashMap.ofArray <| scc.map fun decl => (decl.name, decl)
   let callers := Std.HashMap.ofArray <| ← scc.mapM fun decl => do
     let calls ← SplitScc.findSccCalls declMap decl