[PATCH] D43349: [InstCombine] Make SimplifyDemandedUseBits handle PhiNode

[Rong Xu via llvm-commits]

Not sure how often this occurs. This is reduced from one of our internal Apps.
This app is highly optimized so this redundancy become quite expensive.


On Fri, Feb 16, 2018 at 11:04 AM, Daniel Berlin via Phabricator
<reviews at reviews.llvm.org> wrote:
> dberlin added a comment.
>
> Interesting. NewGVN can already figure this out if it's important.
> How often does stuff like this occur?
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>
> ================
> Comment at: test/Transforms/InstCombine/simplify-demanded-bits-across-phi.ll:35
> +  %11 = phi i64 [ %9, %6 ], [ %5, %3 ], [ 0, %2 ]
> +; ssCHECK: %{{[0-9]+}} = phi i64 [ %[[V3]], %[[L2]] ], [ %[[V1]], %[[L1]] ], [ 0, %{{[0-9]+}} ]
> +  %12 = lshr exact i64 %11, 32
> ----------------
> Remove the ss :)
>
>
> https://reviews.llvm.org/D43349
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