[llvm] [GlobalIsel] Combine freeze (PR #93239)

[Matt Arsenault via llvm-commits]

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In-Reply-To: <llvm.org/llvm/llvm-project/pull/93239 at github.com>


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@@ -265,11 +265,13 @@ bool CombinerHelper::matchFreezeOfSingleMaybePoisonOperand(
     }
   }
 
+  Observer.changingInstr(*OrigDef);
   cast<GenericMachineInstr>(OrigDef)->dropPoisonGeneratingFlags();
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arsenm wrote:

This seems like a problem, the match function should not be modifying the IR 

https://github.com/llvm/llvm-project/pull/93239