[PATCH] D12838: [GlobalsAA] Teach GlobalsAA about memory intrinsics

[James Molloy via llvm-commits]

Hi Sanjoy,

The lazy lambda idea is a good one, I'll implement that, thanks.

readonly/readnone: Yes, I think so. That'd be a simple addition.

Hal - I'm not certain I understand why having nocapture better supported is
a more general issue than this and not an orthogonal one. Nocapture can
tell us about the escapability of a pointer, sure, and what you suggest
seems a sensible addition to GMR (allows us to catch more cases of
non-escaping private globals). But this patch is really looking at mod/ref
behavior, and nocapture can't help us there.

Were you suggesting it as a general improvement or something you'd
specifically like to see in this patch?

Cheers,

James

On Mon, 14 Sep 2015 at 17:19 Sanjoy Das via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> sanjoy added a subscriber: sanjoy.
>
> ================
> Comment at: lib/Analysis/GlobalsModRef.cpp:771
> @@ +770,3 @@
> +  SmallVector<bool,4> Operands;
> +  for (auto &U : CS.args())
> +    Operands.push_back(GetUnderlyingObject(&*U, DL) == GV);
> ----------------
> I'd rather have this be a lambda that takes an argument index instead of
> an eagerly populated vector, given that for most intrinsics this isn't used.
>
> ================
> Comment at: lib/Analysis/GlobalsModRef.cpp:776
> @@ +775,3 @@
> +  default:
> +    return MRI_ModRef;
> +  case Intrinsic::memset:
> ----------------
> aadg wrote:
> > Shouldn't we also handle the isVolatile argument ? As anything could
> happen when this is a volatile operation, I think we should always return
> MRI_ModRef when it is set.
> Can we do something more precise here if the intrinsic is readonly or
> readnone?
>
>
> Repository:
>   rL LLVM
>
> http://reviews.llvm.org/D12838
>
>
>
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