[llvm] [DirectX] Legalize i8 allocas (PR #137399)

[Farzon Lotfi via llvm-commits]

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@@ -81,16 +108,29 @@ static void fixI8TruncUseChain(Instruction &I,
     Value *NewInst =
         Builder.CreateBinOp(BO->getOpcode(), NewOperands[0], NewOperands[1]);
     if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(&I)) {
-      if (OBO->hasNoSignedWrap())
-        cast<BinaryOperator>(NewInst)->setHasNoSignedWrap();
-      if (OBO->hasNoUnsignedWrap())
-        cast<BinaryOperator>(NewInst)->setHasNoUnsignedWrap();
+      auto *NewBO = dyn_cast<BinaryOperator>(NewInst);
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farzonl wrote:

We are see line 110.  But since we can't cast to BinaryOperator we can't set `setHasNoSignedWrap` or `setHasNoUnsignedWrap` so the cast to OverflowingBinaryOperator is not used.

https://github.com/llvm/llvm-project/pull/137399