// Inputs to the terminator of the region are converted to return values of
// the function. If `extern_values_passthrough` is true, all the extern values
// are also added as return values from the function
StringRef ExtractSingleBlockRegion(
    SymbolTableCollection& symbol_table, Region& region, StringRef name,
    llvm::SmallVectorImpl<Value>& extern_values,
    llvm::SmallVectorImpl<func::FuncOp>& worklist,