llvm dev - Jul 2020 - Removing IPConstantPropagation.cpp

Hi,

As far as I know, the ipconstprop  pass has not been actively used in years and
ipsccp has been used instead. This has the potential for confusion and sometimes
leads people to spend time finding & reporting bugs as well as updating it
to work with the latest API changes.

If there are people actively using it, I would love to hear.

If no-ones using it, I’d propose to remove the dead code:
https://reviews.llvm.org/D84447

Cheers,
Florian

On 7/27/20 5:40 AM, Florian Hahn via llvm-dev wrote:
> Hi,
>
> As far as I know, the ipconstprop  pass has not been actively used in years
and ipsccp has been used instead. This has the potential for confusion and
sometimes leads people to spend time finding & reporting bugs as well as
updating it to work with the latest API changes.
>
> If there are people actively using it, I would love to hear.
>
> If no-ones using it, I’d propose to remove the dead code:
https://reviews.llvm.org/D84447
+1 for removal


> Cheers,
> Florian
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

I don't know this pass very well, but may I ask, why isn't it used? I
mean,
is this transformation already implemented as part of another (used)?

On Mon, 27 Jul 2020 at 16:30 Johannes Doerfert via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
>
> On 7/27/20 5:40 AM, Florian Hahn via llvm-dev wrote:
> > Hi,
> >
> > As far as I know, the ipconstprop  pass has not been actively used in
> years and ipsccp has been used instead. This has the potential for
> confusion and sometimes leads people to spend time finding & reporting
bugs
> as well as updating it to work with the latest API changes.
> >
> > If there are people actively using it, I would love to hear.
> >
> > If no-ones using it, I’d propose to remove the dead code:
> https://reviews.llvm.org/D84447
>
> +1 for removal
>
>
>
> > Cheers,
> > Florian
> > _______________________________________________
> > 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
>
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I’m ok removing it.  The only utility I can see is as a simple interprocedural
pass for teaching people.  I’m not sure that it is the best thing to use for
that.

-Chris
> On Jul 27, 2020, at 3:40 AM, Florian Hahn via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi,
> 
> As far as I know, the ipconstprop  pass has not been actively used in years
and ipsccp has been used instead. This has the potential for confusion and
sometimes leads people to spend time finding & reporting bugs as well as
updating it to work with the latest API changes.
> 
> If there are people actively using it, I would love to hear.
> 
> If no-ones using it, I’d propose to remove the dead code:
https://reviews.llvm.org/D84447
> 
> Cheers,
> Florian
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Should ConstantProp.cpp also be removed? It doesn't look like it's been
worked on in over 10 years, and aside from check-llvm lit tests, the only
use is in llvm/unittests/ExecutionEngine/MCJIT/MCJITAPITest.cpp
via LLVMAddConstantPropagationPass.
(it hasn't been ported to the new pass manager which is why I'm asking)

On Mon, Jul 27, 2020 at 6:01 PM Chris Lattner via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> I’m ok removing it.  The only utility I can see is as a simple
> interprocedural pass for teaching people.  I’m not sure that it is the best
> thing to use for that.
>
> -Chris
>
> > On Jul 27, 2020, at 3:40 AM, Florian Hahn via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Hi,
> >
> > As far as I know, the ipconstprop  pass has not been actively used in
> years and ipsccp has been used instead. This has the potential for
> confusion and sometimes leads people to spend time finding & reporting
bugs
> as well as updating it to work with the latest API changes.
> >
> > If there are people actively using it, I would love to hear.
> >
> > If no-ones using it, I’d propose to remove the dead code:
> https://reviews.llvm.org/D84447
> >
> > Cheers,
> > Florian
> > _______________________________________________
> > 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
>
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> On Jul 28, 2020, at 02:01, Chris Lattner <clattner at nondot.org>
wrote:
> 
> I’m ok removing it.  The only utility I can see is as a simple
interprocedural pass for teaching people.  I’m not sure that it is the best
thing to use for that.
Agreed, it has the potential for a relatively simple IPO example pass. I think
it would need some accompanying material and if anyone is interested in using it
as an example, it should be easy enough to restore the code and move it to
llvm/examples.

Cheers,
Florian