[llvm] [AVR] Support stack realignment (PR #187129)

[Matt Arsenault via llvm-commits]

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@@ -623,11 +623,13 @@ class MachineFrameInfo {
   /// Set the correction for frame offsets.
   void setOffsetAdjustment(int64_t Adj) { OffsetAdjustment = Adj; }
 
-  /// Return the alignment in bytes that this function must be aligned to,
-  /// which is greater than the default stack alignment provided by the target.
+  /// Return alignment of this function's frame.
   Align getMaxAlign() const { return MaxAlignment; }
 
-  /// Make sure the function is at least Align bytes aligned.
+  /// Overwrite alignment of this function's frame.
+  void setMaxAlign(Align Alignment) { MaxAlignment = Alignment; }
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arsenm wrote:

I still don't think this should be addd 

https://github.com/llvm/llvm-project/pull/187129