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

[Matt Arsenault via llvm-commits]

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@@ -339,7 +348,18 @@ SDValue XtensaTargetLowering::LowerFormalArguments(
 
       // Transform the arguments stored on
       // physical registers into virtual ones
-      Register Reg = MF.addLiveIn(VA.getLocReg(), &Xtensa::ARRegClass);
+      Register Reg = 0;
+      unsigned FrameReg = Subtarget.getRegisterInfo()->getFrameRegister(MF);
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arsenm wrote:

MCegister 

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