[llvm] [AArch64] Initial compiler support for SVE unwind on Windows. (PR #138609)

[Benjamin Maxwell via llvm-commits]

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@@ -2303,10 +2371,16 @@ void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
     assert(AfterCSRPopSize == 0);
     return;
   }
+
+  bool FPAfterSVECalleeSaves =
+      Subtarget.isTargetWindows() && AFI->getSVECalleeSavedStackSize();
+
   bool CombineSPBump = shouldCombineCSRLocalStackBumpInEpilogue(MBB, NumBytes);
   // Assume we can't combine the last pop with the sp restore.
   bool CombineAfterCSRBump = false;
-  if (!CombineSPBump && PrologueSaveSize != 0) {
+  if (FPAfterSVECalleeSaves) {
+    AfterCSRPopSize = FixedObject;
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MacDue wrote:

Does the previous value of `AfterCSRPopSize` (`ArgumentStackToRestore`) not matter? Note: Changing this to `AfterCSRPopSize += FixedObject` also does not change any tests.

https://github.com/llvm/llvm-project/pull/138609