[llvm] [AArch64][SME] Refactor MachineSMEABI pass state (NFCI) (PR #156674)

[Gaëtan Bossu via llvm-commits]

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@@ -110,6 +110,65 @@ struct PhysRegSave {
   Register X0Save = AArch64::NoRegister;
 };
 
+/// Contains the needed ZA state (and live registers) at an instruction.
+struct InstInfo {
+  ZAState NeededState{ZAState::ANY};
+  MachineBasicBlock::iterator InsertPt;
+  LiveRegs PhysLiveRegs = LiveRegs::None;
+};
+
+/// Contains the needed ZA state for each instruction in a block. Instructions
+/// that do not require a ZA state are not recorded.
+struct BlockInfo {
+  ZAState FixedEntryState{ZAState::ANY};
+  SmallVector<InstInfo> Insts;
+  LiveRegs PhysLiveRegsAtEntry = LiveRegs::None;
+  LiveRegs PhysLiveRegsAtExit = LiveRegs::None;
+};
+
+/// Contains the needed ZA state information for all blocks within a function.
+struct FunctionInfo {
+  SmallVector<BlockInfo> Blocks;
+  std::optional<MachineBasicBlock::iterator> AfterSMEProloguePt;
+  LiveRegs PhysLiveRegsAfterSMEPrologue = LiveRegs::None;
+};
+
+/// State/helpers that is only needed when emitting code to handle
+/// saving/restoring ZA.
+struct EmitContext {
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gbossu wrote:

Nit: Just make it a class?

https://github.com/llvm/llvm-project/pull/156674