[llvm] Add A Version Of `MachineModuleInfoWrapperPass` That Does Not Own Its Underlying `MachineModuleInfo` (PR #134554)

[Matt Arsenault via llvm-commits]

================
@@ -167,22 +163,51 @@ class MachineModuleInfo {
   /// \}
 }; // End class MachineModuleInfo
 
+/// \brief Interface for pass that provide access to \c MachineModuleInfo
+/// being worked on
 class MachineModuleInfoWrapperPass : public ImmutablePass {
-  MachineModuleInfo MMI;
 
 public:
   static char ID; // Pass identification, replacement for typeid
-  explicit MachineModuleInfoWrapperPass(const TargetMachine *TM = nullptr);
-
-  explicit MachineModuleInfoWrapperPass(const TargetMachine *TM,
-                                        MCContext *ExtContext);
+  MachineModuleInfoWrapperPass();
 
   // Initialization and Finalization
   bool doInitialization(Module &) override;
   bool doFinalization(Module &) override;
 
-  MachineModuleInfo &getMMI() { return MMI; }
-  const MachineModuleInfo &getMMI() const { return MMI; }
+  virtual MachineModuleInfo &getMMI() = 0;
+  virtual const MachineModuleInfo &getMMI() const = 0;
+};
+
+/// \brief a version of \c MachineModuleInfoWrapperPass that manages the
+/// lifetime of its \c MachineModuleInfo
+class OwningMachineModuleInfoWrapperPass : public MachineModuleInfoWrapperPass {
+  MachineModuleInfo MMI;
----------------
arsenm wrote:

I guess I don't understand what the use case is for this specific pass if you aren't using codegen. MachineModuleInfo, and by extension MachineModuleInfoWrapperPass are a fundamental part of codegen (it is after all just a map of MachineFunction). I would expect for only the owning version to exist, and it to not change the linking requirements of addPassesToEmitFile users 

https://github.com/llvm/llvm-project/pull/134554