[PassBuilder] Add a pass to LTO postlink step

Author: gulfemsavrun

llvm/lib/Passes/PassBuilderPipelines.cpp

@@ -2121,6 +2121,8 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
   if (PTO.MergeFunctions)
     MPM.addPass(MergeFunctionsPass());
 
+  MPM.addPass(RelLookupTableConverterPass());
+
   if (PTO.CallGraphProfile)
     MPM.addPass(CGProfilePass(/*InLTOPostLink=*/true));