[llvm-dev] Separate AA metadata for load/store portions of memcpy

Sanjoy Das via llvm-dev llvm-dev at lists.llvm.org
Wed Apr 19 16:32:42 PDT 2017


On Wed, Apr 19, 2017 at 11:21 AM, Hal Finkel via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>> Of course we currently don't allow this kind of thing in the IR at
>> all, so this would be a pretty major
>> change. I'd like to solicit some opinions on the best way to represent
>> this in the IR (in particular
>> whether it's worth introducing a way to annotate AA MD on function
>> arguments to avoid the uglyness of introducing 2N extra metadata
>> tags).
> Part of my motivation for suggesting this was that we already have a fair
> amount of duplication between attributes and metadata (e.g. we have a
> nonnull attribute and nonnull metadata). Does anyone else have an opinion
> here?

I would vote for generalizing metadata to work on arguments and
getting rid of the duplication we have today but, as you said, it is
going to be a major undertaking.  So count me in into the "cheering
from sidelines" camp (more seriously: I'd be happy to be a reviewer).

-- Sanjoy

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