[llvm-branch-commits] [llvm] [AArch64][SME] Support Windows/stack probes in MachineSMEABIPass (PR #149063)

[Benjamin Maxwell via llvm-branch-commits]

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@@ -465,23 +473,25 @@ void MachineSMEABI::emitAllocateLazySaveBuffer(
   auto &Subtarget = MF.getSubtarget<AArch64Subtarget>();
   const TargetInstrInfo &TII = *Subtarget.getInstrInfo();
   MachineRegisterInfo &MRI = MF.getRegInfo();
+  auto *AFI = MF.getInfo<AArch64FunctionInfo>();
 
   DebugLoc DL = getDebugLoc(MBB, MBBI);
   Register SP = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
   Register SVL = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
-  Register Buffer = MRI.createVirtualRegister(&AArch64::GPR64RegClass);
+  Register Buffer = AFI->getEarlyAllocSMESaveBuffer();
 
   // Calculate SVL.
   BuildMI(MBB, MBBI, DL, TII.get(AArch64::RDSVLI_XI), SVL).addImm(1);
 
   // 1. Allocate the lazy save buffer.
-  {
+  if (Buffer == AArch64::NoRegister) {
     // TODO This function grows the stack with a subtraction, which doesn't work
     // on Windows. Some refactoring to share the functionality in
     // LowerWindowsDYNAMIC_STACKALLOC will be required once the Windows ABI
     // supports SME
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MacDue wrote:

I've rewritten this comment :+1: I think there's still a TODO to improve how this is handled. 

https://github.com/llvm/llvm-project/pull/149063