[PATCH] D22203: Update the LangRef description of the 'returned' attribute

[Dan Gohman via llvm-commits]

sunfish added a subscriber: sunfish.
sunfish added a comment.

The referenced WebAssembly optimization is a caller-side optimization, not a callee-side optimization, so it itself isn't actually a motivation for this LangRef change.

Also, it's not clear what the optimization purpose of `returned` would be in the callee. If some IR producer or transformer knows that one of the argument values is returned, it should just set the return operand(s) to use the argument value, or a bitcast thereof, and let SSA form to describe the property naturally.


http://reviews.llvm.org/D22203