[llvm-dev] [RFC] Deprecating the legacy pass manager for the optimization pipeline

[Arthur Eubanks via llvm-dev]

If nobody is setting -DLLVM_ENABLE_NEW_PASS_MANAGER=off then I'm not sure
that we need to go through the whole deprecation dance. Is there anybody
doing that?

But if we do the deprecation dance, should it be a CMake warning or a clang
warning? I'm not sure people will notice a CMake warning.
And would putting that in the 13.x branch be good enough to start removing
after 14.x?

On Tue, Aug 24, 2021 at 12:26 PM Fāng-ruì Sòng <maskray at google.com> wrote:

> On Tue, Aug 24, 2021 at 12:21 PM Chris Tetreault <ctetreau at quicinc.com>
> wrote:
> >
> > Since deprecating something is giving warning that it’s going to be
> removed, I don’t think it’s fair to deprecate and remove in one step. If
> legacy pass manager isn’t currently formally deprecated (as in, loudly
> complains when you try to use it), then I’d personally like to see it
> deprecated for a release before any steps to completely remove it are taken.
>
> I just wanted to say the same thing:)
>
> I don't mind that we install a warning for
> -DLLVM_ENABLE_NEW_PASS_MANAGER=off
> in the release/13.x branch so that the signal is clearer to downstream
> users.
>
> > From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of Arthur
> Eubanks via llvm-dev
> > Sent: Tuesday, August 24, 2021 12:10 PM
> > To: Fangrui Song <maskray at google.com>
> > Cc: llvm-dev <llvm-dev at lists.llvm.org>
> > Subject: Re: [llvm-dev] [RFC] Deprecating the legacy pass manager for
> the optimization pipeline
> >
> >
> >
> > WARNING: This email originated from outside of Qualcomm. Please be wary
> of any links or attachments, and do not enable macros.
> >
> > I probably should have said "deprecating and removing".
> >
> >
> >
> > My intention was to remove it completely. -DLLVM_ENABLE_NEW_PASS_MANAGER
> wouldn't do anything and we'd remove the
> -flegacy-pass-manaager/-fexperimental-new-pass-manager flags, as well as
> the corresponding lld flags.
> >
> >
> >
> > On Tue, Aug 24, 2021 at 12:02 PM Fangrui Song <maskray at google.com>
> wrote:
> >
> > On 2021-08-24, Arthur Eubanks via llvm-dev wrote:
> > >The new pass manager has been on by default since the 13 branch. Now
> that
> > >we've branched for 14, I'd like to start the process of deprecating and
> > >removing legacy pass manager support for the optimization pipeline. This
> > >includes clang, opt, and lld LTO support.
> > >
> > >Note that this doesn't apply to the codegen pipeline since there's no
> new
> > >pass manager support for that yet.
> > >
> > >Are there any objections?
> >
> > "deprecating" and 'removing" are different.
> >
> > For 14.0.0, do you plan that -DLLVM_ENABLE_NEW_PASS_MANAGER=off will
> > give a warning or will be completely unsupported?
>
>
>
> --
> 宋方睿
>
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