[PATCH] D28388: Add ArgumentCopyElision MI pass

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

I haven't measured either yet.

Build time effect should be below the noise because it is O(entry block instructions) if there are no address taken parameters, which seems to be the common case given that this doesn't have much impact on overall size. If there are address-taken parameters, it iterates all instructions once to replace frame indices. I don't think it's common practice to measure for compile time regressions when adding one more linear pass every function.

The runtime effects will definitely be positive, since we're eliding copies, but given how low the size impact was, I don't expect it will be measurable either :(. Maybe we should chat about different ways we could measure it.


https://reviews.llvm.org/D28388