This PR fixes incorrect LCSSA PHI node generation when splitting critical edges with both `PreserveLCSSA` and `MergeIdenticalEdges` enabled. The bug caused PHI nodes in the split block to miss predecessors when multiple identical edges were merged.
DenseMap::insert_range
-i128:128
datalayout
llvm::StringTable
SwitchInst::defaultDestUnreachable
RecordKeeper::getDef()