[llvm] [IRBuilder] Handle byte types in CreateBitPreservingCastChain (PR #209557)

[Steffen Larsen via llvm-commits]

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@@ -139,8 +139,18 @@ Value *IRBuilderBase::CreateBitPreservingCastChain(const DataLayout &DL,
     return CreateBitCast(In, Ty);
   };
 
+  // Byte (and byte-vector) types are not integers, but like integers they can
+  // be reinterpreted as a pointer-sized integer before/after an inttoptr or
+  // ptrtoint step.  Treat them the same as integers here so we never attempt a
+  // direct (and invalid) bitcast between a byte/integer aggregate and a
+  // pointer.
+  bool OldIsIntLike =
+      OldTy->isIntOrIntVectorTy() || OldTy->isByteOrByteVectorTy();
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steffenlarsen wrote:

Since it is a common property of these two type-categories (ints and bytes) I lean towards having a new member in `Type`, like @vporpo suggests.

https://github.com/llvm/llvm-project/pull/209557