================
@@ -969,17 +1047,63 @@ void MachineSMEABI::emitStateChange(EmitContext &Context,
From = ZAState::ACTIVE;
}
- if (From == ZAState::ACTIVE && To == ZAState::LOCAL_SAVED)
- emitZASave(Context, MBB, InsertPt, PhysLiveRegs);
- else if (From == ZAState::LOCAL_SAVED && To == ZAState::ACTIVE)
- emitZARestore(Context, MBB, InsertPt, PhysLiveRegs);
- else if (To == ZAState::OFF) {
- assert(From != ZAState::ENTRY &&
- "ENTRY to OFF should have already been handled");
- assert(!SMEFnAttrs.hasAgnosticZAInterface() &&
- "Should not turn ZA off in agnostic ZA function");
- emitZAOff(MBB, InsertPt, /*ClearTPIDR2=*/From == ZAState::LOCAL_SAVED);
- } else {
+ bool IsAgnosticZA = SMEFnAttrs.hasAgnosticZAInterface();
+ bool HasZT0State = SMEFnAttrs.hasZT0State();
+ bool HasZAState = IsAgnosticZA || SMEFnAttrs.hasZAState();
+
+ switch (transitionFrom(From).to(To)) {
+ // This section handles: ACTIVE <-> ACTIVE_ZT0_SAVED
+ case transitionFrom(ZAState::ACTIVE).to(ZAState::ACTIVE_ZT0_SAVED):
+ emitZT0SaveRestore(Context, MBB, InsertPt, /*IsSave=*/true);
+ break;
+ case transitionFrom(ZAState::ACTIVE_ZT0_SAVED).to(ZAState::ACTIVE):
+ emitZT0SaveRestore(Context, MBB, InsertPt, /*IsSave=*/false);
+ break;
+
+ // This section handles: ACTIVE -> LOCAL_SAVED
+ case transitionFrom(ZAState::ACTIVE).to(ZAState::LOCAL_SAVED):
+ if (HasZT0State)
+ emitZT0SaveRestore(Context, MBB, InsertPt, /*IsSave=*/true);
+ if (HasZAState)
+ emitZASave(Context, MBB, InsertPt, PhysLiveRegs);
+ break;
+
+ // This section handles: ACTIVE -> LOCAL_COMMITTED
+ case transitionFrom(ZAState::ACTIVE).to(ZAState::LOCAL_COMMITTED):
+ // Note: We could support ZA state here, but this transition is currently
+ // only possible when we _don't_ have ZA state.
+ assert(HasZT0State && !HasZAState && "Expect to only have ZT0 state.");
+ emitZT0SaveRestore(Context, MBB, InsertPt, /*IsSave=*/true);
+ emitZAMode(MBB, InsertPt, /*ClearTPIDR2=*/false, /*On=*/false);
+ break;
+
+ // This section handles: LOCAL_COMMITTED -> (OFF|LOCAL_SAVED)
+ case transitionFrom(ZAState::LOCAL_COMMITTED).to(ZAState::OFF):
+ case transitionFrom(ZAState::LOCAL_COMMITTED).to(ZAState::LOCAL_SAVED):
----------------
sdesmalen-arm wrote:
Can this case (local_committed -> local_saved) ever happen in practice? If so,
when does it happen?
https://github.com/llvm/llvm-project/pull/166362
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