================
@@ -221,18 +248,34 @@ static bool isZAorZTRegOp(const TargetRegisterInfo &TRI,
/// Returns the required ZA state needed before \p MI and an iterator pointing
/// to where any code required to change the ZA state should be inserted.
static std::pair<ZAState, MachineBasicBlock::iterator>
-getZAStateBeforeInst(const TargetRegisterInfo &TRI, MachineInstr &MI,
- bool ZAOffAtReturn) {
+getInstNeededZAState(const TargetRegisterInfo &TRI, MachineInstr &MI,
+ SMEAttrs SMEFnAttrs) {
MachineBasicBlock::iterator InsertPt(MI);
if (MI.getOpcode() == AArch64::InOutZAUsePseudo)
return {ZAState::ACTIVE, std::prev(InsertPt)};
+ // Note: If we need to save both ZA and ZT0 we use RequiresZASavePseudo.
if (MI.getOpcode() == AArch64::RequiresZASavePseudo)
return {ZAState::LOCAL_SAVED, std::prev(InsertPt)};
- if (MI.isReturn())
+ // If we only need to save ZT0 there's two cases to consider:
+ // 1. The function has ZA state (that we don't need to save).
+ // - In this case we switch to the "ACTIVE_ZT0_SAVED" state.
+ // This only saves ZT0.
+ // 2. The function does not have ZA state
+ // - In this case we switch to "LOCAL_COMMITTED" state.
+ // This saves ZT0 and turns ZA off.
+ if (MI.getOpcode() == AArch64::RequiresZT0SavePseudo) {
+ return {SMEFnAttrs.hasZAState() ? ZAState::ACTIVE_ZT0_SAVED
+ : ZAState::LOCAL_COMMITTED,
+ std::prev(InsertPt)};
----------------
MacDue wrote:
Added a comment to the top of this function.
https://github.com/llvm/llvm-project/pull/166362
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