llvm dev - Jan 2020 - Attribute for Function that does not write to memory that outlives itself

Hi all,

Is there a function attribute or otherwise way to query whether a function
could write to memory that outlives itself?

For example writing to a global or memory passed in via a function argument
would be writing to memory that outlives the function, but writing to a
stack variable or allocation that isn't returned would not.

Cheers,
Billy Moses
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Pure or const are similar to what you want but not exactly the same to what
you’re describing.

On Fri, Jan 3, 2020 at 2:12 PM William Moses via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi all,
>
> Is there a function attribute or otherwise way to query whether a function
> could write to memory that outlives itself?
>
> For example writing to a global or memory passed in via a function
> argument would be writing to memory that outlives the function, but writing
> to a stack variable or allocation that isn't returned would not.
>
> Cheers,
> Billy Moses
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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LLVM-IR: readnone/readonly/writeonly on functions is almost what you
want. They basically that from the perspective of the caller there is no
visible access/write/read.

On 01/03, Alex Brachet-Mialot via llvm-dev wrote:
> Pure or const are similar to what you want but not exactly the same to what
> you’re describing.
> 
> On Fri, Jan 3, 2020 at 2:12 PM William Moses via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> 
> > Hi all,
> >
> > Is there a function attribute or otherwise way to query whether a
function
> > could write to memory that outlives itself?
> >
> > For example writing to a global or memory passed in via a function
> > argument would be writing to memory that outlives the function, but
writing
> > to a stack variable or allocation that isn't returned would not.
> >
> > Cheers,
> > Billy Moses
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

-- 

Johannes Doerfert
Researcher

Argonne National Laboratory
Lemont, IL 60439, USA

jdoerfert at anl.gov
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