[llvm] [AArch64][SME] Rework VG CFI information for streaming-mode changes (PR #152283)

[Benjamin Maxwell via llvm-commits]

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@@ -338,9 +338,11 @@ static bool requiresSaveVG(const MachineFunction &MF);
 // Conservatively, returns true if the function is likely to have an SVE vectors
 // on the stack. This function is safe to be called before callee-saves or
 // object offsets have been determined.
-static bool isLikelyToHaveSVEStack(MachineFunction &MF) {
+static bool isLikelyToHaveSVEStack(const MachineFunction &MF) {
   auto *AFI = MF.getInfo<AArch64FunctionInfo>();
-  if (AFI->isSVECC())
+  if (MF.getFunction().getCallingConv() ==
+          CallingConv::AArch64_SVE_VectorCall ||
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MacDue wrote:

It's not the case right now (`IsSVECC` is only set if the function actually has SVE results/arguments). 

https://github.com/llvm/llvm-project/pull/152283