[llvm] [llubi] Add support for byval pointer arguments (PR #201852)

[Nikita Popov via llvm-commits]

nikic wrote:

> The hidden copy is implemented as load-store forwarding in the byval type argument. See llvm/test/tools/llubi/byval_padding.ll for example. IMO if we want to interpret it as a memcpy, the argument should be an integer size :-)

It would be good to submit a LangRef PR to clarify this. I do think the typed copy interpretation makes sense, even if I don't particularly like it... (it would be an argument to keep the type argument around long-term instead of making it just a size...)

https://github.com/llvm/llvm-project/pull/201852