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

[Matt Arsenault via llvm-commits]

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@@ -895,8 +895,14 @@ SDValue XtensaTargetLowering::LowerSTACKSAVE(SDValue Op,
 
 SDValue XtensaTargetLowering::LowerSTACKRESTORE(SDValue Op,
                                                 SelectionDAG &DAG) const {
-  return DAG.getCopyToReg(Op.getOperand(0), SDLoc(Op), Xtensa::SP,
-                          Op.getOperand(1));
+  if (Subtarget.isWindowedABI()) {
+    SDValue NewSP =
+        DAG.getNode(XtensaISD::MOVSP, SDLoc(Op), MVT::i32, Op.getOperand(1));
+    return DAG.getCopyToReg(Op.getOperand(0), SDLoc(Op), Xtensa::SP, NewSP);
+  } else {
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arsenm wrote:

No else after return 

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