[llvm] Xtensa] Implement windowed call ABI. (PR #130001)

[Matt Arsenault via llvm-commits]

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@@ -34,13 +34,19 @@ XtensaRegisterInfo::XtensaRegisterInfo(const XtensaSubtarget &STI)
 
 const uint16_t *
 XtensaRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
-  return CSR_Xtensa_SaveList;
+  if (Subtarget.isWinABI())
+    return CSRW8_Xtensa_SaveList;
+  else
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arsenm wrote:

No else after return. Return ternary operator? 

https://github.com/llvm/llvm-project/pull/130001