[PATCH] D113289: LICM: Hoist LOAD without STORE

[Djordje Todorovic via Phabricator via llvm-commits]

djtodoro added a comment.

In D113289#3147618 <https://reviews.llvm.org/D113289#3147618>, @reames wrote:

> Ok, let me describe back to you what you're trying to do.  Give a case like:
>
>   loop {
>     a = *g;
>     if (a) break;
>     *g = a + 1
>   }
>
> Where g is some loop invariant address, you want to produce a form which looks like this:
>
>   a0 = *g
>   loop {
>     a1 = phi (a0, a2)
>     if (a1) break;
>     a2 = a1 + 1
>     *g = a2;
>   }

Yep, that's it!

> Assuming I've correctly described that, I agree this is valuable.  I'm honestly a bit shocked we didn't already handle it.  However, this should absolutely not be target dependent.  It should simply be always enabled.

Thanks! I totally agree, so I removed the flag and abandoned the second patch from the stack that was target-dependent.


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