perf: better detection of repeated branching on same value

Author: hargoniX

src/Lean/Compiler/LCNF/Simp/DiscrM.lean

@@ -61,8 +61,7 @@ def findCtor? (fvarId : FVarId) : DiscrM (Option CtorInfo) := do
   | some { value := .const declName _ args, .. } =>
     let some (.ctorInfo val) := (← getEnv).find? declName | return none
     return some <| .ctor val args
-  | some _ => return none
-  | none => return (← read).discrCtorMap.get? fvarId
+  | _ => return (← read).discrCtorMap.get? fvarId
 
 def findCtorName? (fvarId : FVarId) : DiscrM (Option Name) := do
   let some ctorInfo ← findCtor? fvarId | return none