[llvm] [AArch64][SME] Propagate desired ZA states in the MachineSMEABIPass (PR #149510)

[Sander de Smalen via llvm-commits]

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@@ -918,6 +987,43 @@ bool MachineSMEABI::runOnMachineFunction(MachineFunction &MF) {
       getAnalysis<EdgeBundlesWrapperLegacy>().getEdgeBundles();
 
   FunctionInfo FnInfo = collectNeededZAStates(SMEFnAttrs);
+
+  if (OptLevel != CodeGenOptLevel::None) {
+    // Propagate desired states forwards then backwards. We propagate forwards
+    // first as this propagates desired states from inner to outer loops.
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sdesmalen-arm wrote:

Perhaps I'm getting this backwards, but if it would be propagating forwards first then I'd expect that it would first propagate states from the outer to the inner loop? (it would start at BB0, then BB1/BB3, then BB2)

https://github.com/llvm/llvm-project/pull/149510