[llvm-dev] Removing LLVM_ALWAYS_INLINE from ADT classes (original) (raw)

Mehdi AMINI via llvm-dev llvm-dev at lists.llvm.org
Mon Jan 7 13:47:46 PST 2019

On Mon, Jan 7, 2019 at 1:46 PM Jonas Devlieghere <jonas at devlieghere.com> wrote:

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 –DLLVMOPTIMIZETABLEGEN=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?

The way it is implemented is to create another build directory inside the build directory (called "native" IIRC) and call cmake into it and build llvm-tblgen there. However that means that a library like Support is built here before being rebuilt in the main build directory.

-- Mehdi

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 LLVMALWAYSINLINE 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 -DLLVMOPTIMIZETABLEGEN=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 > LLVMALWAYSINLINE 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 > LLVMALWYASINLINE 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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