[llvm] [MemCpyOpt] Avoid infinite loops in `MemCpyOptPass::processMemCpyMemCpyDependence` (PR #103218)

[via llvm-commits]

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@@ -1198,6 +1198,10 @@ bool MemCpyOptPass::processMemCpyMemCpyDependence(MemCpyInst *M,
       CopySourceAlign = commonAlignment(*CopySourceAlign, MForwardOffset);
   }
 
+  // Avoid infinite loops
+  if (BAA.isMustAlias(M->getSource(), CopySource))
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dianqk wrote:

> I tried to change this check into `BAA.isMustAlias(M->getSource(), MDep->getSource())`. But it doesn't work.

This appears to should be `BAA.isMustAlias(MDep->getDest(), MDep->getSource())` #140376.

https://github.com/llvm/llvm-project/pull/103218