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

[Matt Arsenault via llvm-commits]

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@@ -293,6 +294,38 @@ bool AVRExpandPseudo::expand<AVR::ADCWRdRr>(Block &MBB, BlockIt MBBI) {
   return expandArith(AVR::ADCRdRr, AVR::ADCRdRr, MBB, MBBI);
 }
 
+template <>
+bool AVRExpandPseudo::expand<AVR::ADIWRdKP>(Block &MBB, BlockIt MBBI) {
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arsenm wrote:

I don't understand why this is a template 

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