[PATCH] D24517: GVN-hoist: fix store past load dependence analysis (PR30216)

[Sebastian Pop via llvm-commits]

>> liveOnEntry uses cannot be reached by walking through the MSSA.
> These will both be uses of the live on entry access.
> It's a real access, it has real uses :)

I see, now it makes sense.
I was under the impression that one cannot walk through the uses of liveOnEntry.

> Given how we determine aliasing, and we use optimize, an aliased load must
> be attached to *either* live on entry, *or* a store that clobbers your store

Agreed.

> Note: I don't claim this is efficient or sensible. I'm simply refuting the
> claim that they literally cannot be extracted.
>
> They can.
> It's just inefficient as hell :)

I'll send a patch implementing your algorithm.
I think it still could be more efficient than the patch I sent,
as it would ask the alias question only for the liveOnEntry loads.