[PATCH] D79636: [LangRef] Clarify the semantics of the `byval` attribute

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> Do you object to say that the call site argument and the argument point to distinct memory locations or something else?

Like I said, my issue is with the "Attributes on the call site argument and function argument are associated with the original and copied memory respectively".  I assume this means "attributes other than byval".  If I'm understanding this correctly, this means it isn't legal to copy attributes from the caller to the callee.  If an argument is marked "readnone byval" on a function, it's illegal to copy that "readnone" to the callsite, because the readnone would then be associated with the original memory, not the copied memory.  Or, a more silly example, say you had "byval returned" on the called function, and that got copied to the callsite: that clearly can't mean the original pointer is returned by the function.


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https://reviews.llvm.org/D79636