[PATCH] D95141: [InstCombine] Remove unused llvm.experimental.noalias.scope.decl

Jeroen Dobbelaere via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Sat Jan 23 14:27:27 PST 2021


jeroen.dobbelaere added a comment.

In D95141#2517801 <https://reviews.llvm.org/D95141#2517801>, @nikic wrote:

> In D95141#2517795 <https://reviews.llvm.org/D95141#2517795>, @nikic wrote:
>
>>> During the analysis of !alias.scope and !nolias : when a 'list of scopes' was already analysed we do not need to go over it again.
>>
>> I would expect that analysing scope list multiple times isn't really what's causing the compile-time hit here. It's probably the fact that you're looking up two kinds of metadata for each instruction, and metadata lookup is pretty expensive. You might want to check what the impact is if you only analyze mayReadOrWriteMemory() instructions.
>
> Though possibly that won't help, as it's exactly loads, stores and calls that typically carry metadata anyway. Maybe just skipping DbgInfoIntrinsic would help to avoid a larger hit for `-g` builds...

Thanks for the feedback ! I'll check some variants tomorrow (Sunday). First getting some sleep ;)


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