[llvm] [ARM] R11 not pushed adjacent to link register with PAC-M and AAPCS frame chain fix (PR #82801)

[Eli Friedman via llvm-commits]

================
@@ -963,13 +976,18 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
   } else
     NumBytes = DPRCSOffset;
 
-  if (GPRCS2Size > 0 && STI.splitFramePointerPush(MF)) {
+  // Move past area 2 if following Win_AAPCS_CFGuard calling convention.
----------------
efriedma-quic wrote:

This comment doesn't look right?  Functions defined with the CFGuard_Check should be extremely rare, if they show up at all; it's used to model the behavior of runtime routines.

https://github.com/llvm/llvm-project/pull/82801