[llvm] [RISCV] Use TableGen-based macro fusion (PR #72224)

[Wang Pengcheng via llvm-commits]

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@@ -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,
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wangpc-pp wrote:

My thought is that `std::function` objects need more memory spaces than function pointers.

https://github.com/llvm/llvm-project/pull/72224