[llvm] [DirectX] Move memset and memcpy handling to a new pass. NFC (PR #172921)

[Justin Bogner via llvm-commits]

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@@ -269,8 +269,8 @@ static bool upcastI8AllocasAndUses(Instruction &I,
       if (CastInst *Cast = dyn_cast<CastInst>(LU))
         Ty = Cast->getType();
       else if (CallInst *CI = dyn_cast<CallInst>(LU)) {
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bogner wrote:

Good point. Follow up here: https://github.com/llvm/llvm-project/pull/173040

https://github.com/llvm/llvm-project/pull/172921