[llvm] [CodeGen][NPM] Support generic regalloc-npm option (PR #172485)

[Akshat Oke via llvm-commits]

================
@@ -501,7 +506,17 @@ template <typename DerivedT, typename TargetMachineT> class CodeGenPassBuilder {
 
   /// addMachinePasses helper to create the target-selected or overriden
   /// regalloc pass.
-  void addRegAllocPass(PassManagerWrapper &PMW, bool Optimized) const;
+  Error addRegAllocPass(PassManagerWrapper &PMW, bool Optimized) const;
+  /// Read the --regalloc-npm-pipeline option to add the next pass in line.
----------------
optimisan wrote:

Conflicting opt names (`--regalloc-npm-pipeline` and `--regalloc-npm`)

https://github.com/llvm/llvm-project/pull/172485