[llvm] [IRBuilder][GlobalISel] Add byte ptr cast support in IRBuilder (PR #222049)

[Anshil Gandhi via llvm-commits]

================
@@ -140,9 +146,7 @@ Value *IRBuilderBase::CreateBitPreservingCastChain(const DataLayout &DL,
   };
 
   // See if we need inttoptr for this type pair. May require additional bitcast.
-  bool OldIsIntLike =
-      OldTy->isIntOrIntVectorTy() || OldTy->isByteOrByteVectorTy();
-  if (OldIsIntLike && NewTy->isPtrOrPtrVectorTy()) {
+  if (OldTy->isIntOrIntVectorTy() && NewTy->isPtrOrPtrVectorTy()) {
----------------
gandhi56 wrote:

Yup, that's a contradiction in the langref. There was a discussion on implementing the `bytecast` instruction to cast byte -> other types (and I think the reverse as well). Based on the discussion on discourse, only the byte type can be casted to a ptr type via a bitcast. For ints, inttoptr would still be necessary.

https://github.com/llvm/llvm-project/pull/222049