[llvm] [IR] PossiblyExactOperator -> PossiblyExactInst (NFC) (PR #72501)

[Philip Reames via llvm-commits]

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@@ -314,7 +314,9 @@ void Instruction::setHasNoSignedWrap(bool b) {
 }
 
 void Instruction::setIsExact(bool b) {
-  cast<PossiblyExactOperator>(this)->setIsExact(b);
+  assert(isa<PossiblyExactInst>(this) && "Instruction must support exact flag");
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preames wrote:

The idiomatic structure for these accessors appears to be to implement them on the subclass, and then dispatch via a cast to that subclass.  The way you implemented this is perfectly valid, but I think it'd be better to follow the convention just to keep the code structure analogous.  

https://github.com/llvm/llvm-project/pull/72501