[llvm-dev] Removing LLVM_ALWAYS_INLINE from ADT classes

[Jonas Devlieghere via llvm-dev]

On Mon, Jan 7, 2019 at 8:33 AM via llvm-dev <llvm-dev at lists.llvm.org> wrote:

> IIRC the issues with defaulting to –DLLVM_OPTIMIZE_TABLEGEN=ON came up in
> two places:
>
> First, if it's not a Debug build, this actually slows down the build. The
> defaulting has to be for Debug config only.  This is arguably bad UI,
> because it makes the default modal, but there's a clear benefit in build
> time so I think we can live with that.
>
> Second, if it's a multi-config builder (e.g. MSBuild) then it gets a
> little weird, I don't remember exactly how.
>
> --paulr
>

Out of curiosity, why does it slow down a non-debug build?


>
>
> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] *On Behalf Of *Mehdi
> AMINI via llvm-dev
> *Sent:* Saturday, January 05, 2019 7:42 PM
> *To:* Paweł Bylica; Chris Bieneman
> *Cc:* LLVM Dev
> *Subject:* Re: [llvm-dev] Removing LLVM_ALWAYS_INLINE from ADT classes
>
>
>
>
>
>
>
> On Fri, Jan 4, 2019 at 3:52 PM Paweł Bylica via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> On Sat, Jan 5, 2019 at 12:38 AM Duncan P. N. Exon Smith via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> This makes sense to me.
>
> One concern is that this in itself will slow down the build, since
> tablegen will get even slower.  Ideally, there would be some (perhaps
> default?) configuration where we build the tablegen binaries with
> optimizations on and then use them in the build, as if we were
> cross-compiling.
>
>
>
> Maybe something simple like -DLLVM_OPTIMIZE_TABLEGEN=ON (enabled by
> default for Debug builds). You would need to set it to off only if you want
> to debug tablegen.
>
>
>
> I proposed this a while back, but it think there were some problems with
> it, I don't remember what exactly but maybe related to bootstrapping /
> 2-stages builds?
>
>
>
> + Chris, maybe he remembers something?
>
>
>
> --
>
> Mehdi
>
>
>
>
>
>
>
>
>
>
> > On Jan 4, 2019, at 15:14, Davide Italiano via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Hi,
> > I would like to propose, based on a previous discussion on llvm-dev,
> > the following change.
> > https://reviews.llvm.org/D56337
> >
> > The main motivation for annotating member functions of ADT clases with
> > LLVM_ALWAYS_INLINE  was that of speeding up `check-llvm` at `-O0`.
> > Turns out this significantly degrades the debuggability of fundamental
> > classes in llvm itself, e.g. StringRef or SmallVector.
> >
> > After discussing we agreed that it's reasonable to drop
> > LLVM_ALWYAS_INLINE from ADT classes  member functions and add a note
> > in the developer's manual.
> >
> > If you have any feedbacks or concerns, please speak up.
> > If nothing major arises, I'm going to commit this patch in a week (or
> such).
> >
> > Thanks for your time,
> >
> > --
> > Davide
> >
> > "There are no solved problems; there are only problems that are more
> > or less solved" -- Henri Poincare
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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