[llvm] [Tablegen] Support Operand in morphing patterns (PR #99645)

[Matt Arsenault via llvm-commits]

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@@ -294,6 +294,12 @@ void MatcherGen::EmitLeafMatchCode(const TreePatternNode &N) {
     return;
   }
 
+  if (LeafRec->isSubClassOf("Operand")) {
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arsenm wrote:

An Operand is more of a construct of the output instruction, and less so the pattern it's matching. I'm not sure it makes sense to just let any Operand pass through as an unchecked input. I would expect such a pattern to be matching timm 

https://github.com/llvm/llvm-project/pull/99645