[llvm] [MacroFusion] Support multiple predicators (PR #72219)

[Matt Arsenault via llvm-commits]

================
@@ -29,10 +29,10 @@ class SUnit;
 /// Check if the instr pair, FirstMI and SecondMI, should be fused
 /// together. Given SecondMI, when FirstMI is unspecified, then check if
 /// SecondMI may be part of a fused pair at all.
-using ShouldSchedulePredTy = std::function<bool(const TargetInstrInfo &TII,
-                                                const TargetSubtargetInfo &TSI,
-                                                const MachineInstr *FirstMI,
-                                                const MachineInstr &SecondMI)>;
+using MacroFusionPredTy = bool (*)(const TargetInstrInfo &TII,
----------------
arsenm wrote:

function_ref?

https://github.com/llvm/llvm-project/pull/72219