[llvm-dev] Status of llvm.invariant.{start|end}

[Yichao Yu via llvm-dev]

> Just to clarify: If g can modify %a in some way, the front end needs to
> identify it and avoid adding
> invariant.start.

OK cool, that's what I thought too.

>
> Once the invariant.start has been added by the front end,this is a perfectly
> legal transform to do
> based on the LLVM spec.
>
> In fact we should be implementing this in LLVM, patches welcome :)

Which is kind of what I was asking about in the original post. The
issue suggests that something needs rework and I'm not sure what
exactly it is referring to.....

I am pretty interested in this optimization so I would have submitted
a patch if I know how... I'm not really sure where this should be
implemented so that all optimization passes can make use of it (AA?)
and how the information should be translated (I wasn't able to find
anything similar to this in AA)