[llvm] [Xtensa] Implement Windowed Register Option. (PR #121118)

[Matt Arsenault via llvm-commits]

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@@ -39,6 +39,9 @@ class XtensaSubtarget : public XtensaGenSubtargetInfo {
   // Enabled Xtensa Density extension
   bool HasDensity;
 
+  // Enabled Xtensa Windowed Register Option
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arsenm wrote:

s/Option/Feature/?

https://github.com/llvm/llvm-project/pull/121118