llvm dev - Dec 2014 - [LLVMdev] RFC: Timeline for deprecating the autoconf build system?

Hi,

I would like to propose deprecating the autoconf build system at some
point in the future.  Maintaining two build systems is a hassle not
only for this project, but also for other projects that use LLVM
and have to deal with the slight differences in output between the two
build systems.

It seems like most people are using CMake at this point, so my questions
to the community are:

- Is there any technical reason why the remaining autoconf users can't
switch
  to CMake?

For example, I personally use automake, and the only reason I don't
use CMake is because it doesn't produce a single shared object
(e.g. libLLVM-3.6.0svn.so).

- What is a reasonable timeframe to allow the remaining autoconf users
  a chance to migrate to CMake?

Thanks,
Tom

On Fri Oct 31 2014 at 3:11:22 PM Tom Stellard <tom at stellard.net> wrote:
> Hi,
>
> I would like to propose deprecating the autoconf build system at some
> point in the future.  Maintaining two build systems is a hassle not
> only for this project, but also for other projects that use LLVM
> and have to deal with the slight differences in output between the two
> build systems.
>
> It seems like most people are using CMake at this point, so my questions
> to the community are:
>
> - Is there any technical reason why the remaining autoconf users can't
> switch
>   to CMake?
>
>
I think Bob was the lead on keeping the autoconf system last year when this
came up, there is a PR somewhere in the system about the blocking things
that need to work in cmake to get it to happen. I don't know where we are
on that list or what features people still need.

Personally I still use the autoconf system, but am willing to remove it if
we can get to a single system, but all of the requirements need to be
handled first.

-eric

> For example, I personally use automake, and the only reason I don't
> use CMake is because it doesn't produce a single shared object
> (e.g. libLLVM-3.6.0svn.so).
>
> - What is a reasonable timeframe to allow the remaining autoconf users
>   a chance to migrate to CMake?
>
> Thanks,
> Tom
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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> On Oct 31, 2014, at 4:19 PM, Eric Christopher <echristo at gmail.com>
wrote:
> 
> 
> 
> On Fri Oct 31 2014 at 3:11:22 PM Tom Stellard <tom at stellard.net
<mailto:tom at stellard.net>> wrote:
> Hi,
> 
> I would like to propose deprecating the autoconf build system at some
> point in the future.  Maintaining two build systems is a hassle not
> only for this project, but also for other projects that use LLVM
> and have to deal with the slight differences in output between the two
> build systems.
> 
> It seems like most people are using CMake at this point, so my questions
> to the community are:
> 
> - Is there any technical reason why the remaining autoconf users can't
switch
>   to CMake?
> 
> 
> I think Bob was the lead on keeping the autoconf system last year when this
came up, there is a PR somewhere in the system about the blocking things that
need to work in cmake to get it to happen. I don't know where we are on that
list or what features people still need.
I’ve come around to the point of accepting the inevitability of moving to cmake,
but I think there’s quite a bit of work to be done to get everything to work.
The compiler-rt build in particular is problematic.
> 
> Personally I still use the autoconf system, but am willing to remove it if
we can get to a single system, but all of the requirements need to be handled
first.
> 
> -eric
>  
> For example, I personally use automake, and the only reason I don't
> use CMake is because it doesn't produce a single shared object
> (e.g. libLLVM-3.6.0svn.so <http://libllvm-3.6.0svn.so/>).
> 
> - What is a reasonable timeframe to allow the remaining autoconf users
>   a chance to migrate to CMake?
I don’t know how to answer that. Someone will need to do the work to first
identify all the problems and then to get them fixed.

Converting everything to cmake will take quite a lot of work. In comparison, the
minor hassle of keeping the makefiles working for a bit longer seems pretty
insignificant.
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On 1.11.2014 0:08, Tom Stellard wrote:
> Hi,
>
> I would like to propose deprecating the autoconf build system at some
> point in the future.  Maintaining two build systems is a hassle not
> only for this project, but also for other projects that use LLVM
> and have to deal with the slight differences in output between the two
> build systems.
Because of these differences between build systems, I decided to start 
my personal project recently to bring up each build system to equal 
grounds for a platform which I care (which is FreeBSD). Motivation for 
this has been to have identical test results (and builds) from each 
other, in the case autoconf build system is retired.
> It seems like most people are using CMake at this point, so my questions
> to the community are:
>
> - Is there any technical reason why the remaining autoconf users can't
switch
>    to CMake?
At least better job could be done for canonicalization of architectures 
within cmake configurations. For example at the moment some LLVM tests 
does not run with cmake builds for x86_64 FreeBSD, since it identifies 
itself as "amd64" for cmake, which cascades down to lit testing 
infrastructure. That's an easy example what I have faced at least so far.

Pasi
> For example, I personally use automake, and the only reason I don't
> use CMake is because it doesn't produce a single shared object
> (e.g. libLLVM-3.6.0svn.so).
>
> - What is a reasonable timeframe to allow the remaining autoconf users
>    a chance to migrate to CMake?
>
> Thanks,
> Tom
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

On Fri, Oct 31, 2014 at 3:08 PM, Tom Stellard <tom at stellard.net>
wrote:
> - Is there any technical reason why the remaining autoconf users can't
switch
>   to CMake?
Last time I tried, the CMake build was missing some pieces required
for the Gold plugin.  Specifically, the --with-binutils-include
option.

> Last time I tried, the CMake build was missing some pieces required
> for the Gold plugin.  Specifically, the --with-binutils-include
> option.
Pretty sure that's been fixed (actually, I don't think it finds
binutils without it now): LLVM_BINUTILS_INCDIR.

Cheers.

Tim.

On Fri, Oct 31, 2014 at 8:40 PM, Steve King <steve at metrokings.com>
wrote:
>
> On Fri, Oct 31, 2014 at 3:08 PM, Tom Stellard <tom at stellard.net>
wrote:
> > - Is there any technical reason why the remaining autoconf users
can't switch
> >   to CMake?
>
> Last time I tried, the CMake build was missing some pieces required
> for the Gold plugin.  Specifically, the --with-binutils-include
> option.
Must've been fixed. I regularly build with -DLLVM_BINUTILS_INCDIR=...
to build the gold plugin.


Diego.

Sent from my iPhone
> On Oct 31, 2014, at 17:40, Steve King <steve at metrokings.com>
wrote:
> 
>> On Fri, Oct 31, 2014 at 3:08 PM, Tom Stellard <tom at
stellard.net> wrote:
>> - Is there any technical reason why the remaining autoconf users
can't switch
>>  to CMake?
> 
> Last time I tried, the CMake build was missing some pieces required
> for the Gold plugin.  Specifically, the --with-binutils-include
> option.
It is there. I build the plugin and haven't used autoconf in years.
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On Fri, Oct 31, 2014 at 03:08:21PM -0700, Tom Stellard
wrote:
> - Is there any technical reason why the remaining autoconf users can't
switch
>   to CMake?
Requiring cmake for NetBSD is not acceptable as it is almost as heavy as
a C++ compiler itself. That said, I don't really care about the
Makefiles, just about configure and the associated loggic to craete
Config.h and friends. I would expect FreeBSD to have similar concerns.

Joerg

> Requiring cmake for NetBSD is not acceptable as it is almost as heavy as
> a C++ compiler itself. That said, I don't really care about the
> Makefiles, just about configure and the associated loggic to craete
> Config.h and friends. I would expect FreeBSD to have similar concerns.
I don't think the extra dependency is a compelling enough reason to
hold back everyone else.

Tim.

On 2 Nov 2014, at 14:17, Joerg Sonnenberger <joerg at britannica.bec.de>
wrote:
> Requiring cmake for NetBSD is not acceptable as it is almost as heavy as
> a C++ compiler itself. That said, I don't really care about the
> Makefiles, just about configure and the associated loggic to craete
> Config.h and friends. I would expect FreeBSD to have similar concerns.
For the FreeBSD base system, we use a bmake-based build system for LLVM, but
that is based on the Makefiles generated by CMake.  I believe that we're now
using CMake for the version of LLVM in ports.

David

On Fri, Oct 31, 2014 at 11:19:22PM +0000, Eric Christopher
wrote:
> On Fri Oct 31 2014 at 3:11:22 PM Tom Stellard <tom at stellard.net>
wrote:
> 
> > Hi,
> >
> > I would like to propose deprecating the autoconf build system at some
> > point in the future.  Maintaining two build systems is a hassle not
> > only for this project, but also for other projects that use LLVM
> > and have to deal with the slight differences in output between the two
> > build systems.
> >
> > It seems like most people are using CMake at this point, so my
questions
> > to the community are:
> >
> > - Is there any technical reason why the remaining autoconf users
can't
> > switch
> >   to CMake?
> >
> >
> I think Bob was the lead on keeping the autoconf system last year when this
> came up, there is a PR somewhere in the system about the blocking things
> that need to work in cmake to get it to happen. I don't know where we
are
> on that list or what features people still need.
Was this the PR: http://www.llvm.org/bugs/show_bug.cgi?id=15732 ?

-Tom
> 
> Personally I still use the autoconf system, but am willing to remove it if
> we can get to a single system, but all of the requirements need to be
> handled first.
> 
> -eric
> 
> 
> > For example, I personally use automake, and the only reason I
don't
> > use CMake is because it doesn't produce a single shared object
> > (e.g. libLLVM-3.6.0svn.so).
> >
> > - What is a reasonable timeframe to allow the remaining autoconf users
> >   a chance to migrate to CMake?
> >
> > Thanks,
> > Tom
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >

On Sat, Nov 01, 2014 at 02:26:08AM +0200, Pasi Parviainen
wrote:
> On 1.11.2014 0:08, Tom Stellard wrote:
> > Hi,
> >
> > I would like to propose deprecating the autoconf build system at some
> > point in the future.  Maintaining two build systems is a hassle not
> > only for this project, but also for other projects that use LLVM
> > and have to deal with the slight differences in output between the two
> > build systems.
> 
> Because of these differences between build systems, I decided to start 
> my personal project recently to bring up each build system to equal 
> grounds for a platform which I care (which is FreeBSD). Motivation for 
> this has been to have identical test results (and builds) from each 
> other, in the case autoconf build system is retired.
> 
This sounds like a good project, do you have a list of remaining
differences?

-Tom
> > It seems like most people are using CMake at this point, so my
questions
> > to the community are:
> >
> > - Is there any technical reason why the remaining autoconf users
can't switch
> >    to CMake?
> 
> At least better job could be done for canonicalization of architectures 
> within cmake configurations. For example at the moment some LLVM tests 
> does not run with cmake builds for x86_64 FreeBSD, since it identifies 
> itself as "amd64" for cmake, which cascades down to lit testing 
> infrastructure. That's an easy example what I have faced at least so
far.
> 
> Pasi
> 
> > For example, I personally use automake, and the only reason I
don't
> > use CMake is because it doesn't produce a single shared object
> > (e.g. libLLVM-3.6.0svn.so).
> >
> > - What is a reasonable timeframe to allow the remaining autoconf users
> >    a chance to migrate to CMake?
> >
> > Thanks,
> > Tom
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>

On 31 October 2014 22:08, Tom Stellard <tom at stellard.net>
wrote:
> - Is there any technical reason why the remaining autoconf users can't
switch
>   to CMake?
Hi Tom,

One reason that wasn't mentioned is the buildbot infrastructure. Many
bots still build on autoconf and they all need to be moved into a
CMake builder. I have moved some ARM bots to my new ClangCMakeBuilder
but that's far from enough. Compiler-RT and libc++ (and I believe lld)
do use CMake, but the test suite is still dependent on autoconf and
the Windows build uses a different CMake builder. We were trying to
merge both, but didn't go very far.

> - What is a reasonable timeframe to allow the remaining autoconf users
>   a chance to migrate to CMake?
I'd say a few months and many engineer-hours from all over the place.
We'd need a task force like we did for the C++11 move: someone with
the will (you :) and representatives from the major groups (Linux,
BSD, Darwin / ARM, Intel, MIPS, PPC, etc) moving the bots, fixing the
issues, etc.

The big unknown is what to do with bots to which no one has access to,
or to which cannot be built with CMake. For example an old
architecture that hasn't been migrated to CMake. Do we deprecate the
bot? The architecture? Strongly encourage someone to migrate it? What
are the costs of this unknown migration, if that's even possible?

We may try to aim for the next release and see how far do we get...

cheers,
-renato

On Sat, Nov 01, 2014 at 02:26:08AM +0200, Pasi Parviainen
wrote:
> On 1.11.2014 0:08, Tom Stellard wrote:
> >Hi,
> >
> >I would like to propose deprecating the autoconf build system at some
> >point in the future.  Maintaining two build systems is a hassle not
> >only for this project, but also for other projects that use LLVM
> >and have to deal with the slight differences in output between the two
> >build systems.
> 
> Because of these differences between build systems, I decided to
> start my personal project recently to bring up each build system to
> equal grounds for a platform which I care (which is FreeBSD).
> Motivation for this has been to have identical test results (and
> builds) from each other, in the case autoconf build system is
> retired.
> 
> >It seems like most people are using CMake at this point, so my
questions
> >to the community are:
> >
> >- Is there any technical reason why the remaining autoconf users
can't switch
> >   to CMake?
> 
> At least better job could be done for canonicalization of
> architectures within cmake configurations. For example at the moment
> some LLVM tests does not run with cmake builds for x86_64 FreeBSD,
> since it identifies itself as "amd64" for cmake, which cascades
down
> to lit testing infrastructure. That's an easy example what I have
> faced at least so far.
> 
Hi,

I've filed a bug for this: http://www.llvm.org/bugs/show_bug.cgi?id=21559
Feel free to add additional information if needed.

If your run into any more issues, it would be great if you could file bugs
and mark them as blocking the meta cmake bug:  15732 so we can track it.

Thanks,
Tom
> Pasi
> 
> >For example, I personally use automake, and the only reason I don't
> >use CMake is because it doesn't produce a single shared object
> >(e.g. libLLVM-3.6.0svn.so).
> >
> >- What is a reasonable timeframe to allow the remaining autoconf users
> >   a chance to migrate to CMake?
> >
> >Thanks,
> >Tom
> >_______________________________________________
> >LLVM Developers mailing list
> >LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> >http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>

> - Is there any technical reason why the remaining autoconf users can't
switch
>   to CMake?
I can't see how to do 'configure --disable-assertions
--disable-optimized', using CMake in LLVM. This is useful for example to
build for coverage testing.

(Also, it seems like CMake still don't take the CPPFLAGS environment
variable (for example, for passing a custom -I path) :
http://www.cmake.org/Bug/view.php?id=12928. It is inconvenient to set both
CFLAGS and CXXFLAGS for this.)

/Patrik Hägglund

-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Tom Stellard
Sent: den 31 oktober 2014 23:08
To: llvmdev at cs.uiuc.edu
Subject: [LLVMdev] RFC: Timeline for deprecating the autoconf build system?

Hi,

I would like to propose deprecating the autoconf build system at some
point in the future.  Maintaining two build systems is a hassle not
only for this project, but also for other projects that use LLVM
and have to deal with the slight differences in output between the two
build systems.

It seems like most people are using CMake at this point, so my questions
to the community are:

- Is there any technical reason why the remaining autoconf users can't
switch
  to CMake?

For example, I personally use automake, and the only reason I don't
use CMake is because it doesn't produce a single shared object
(e.g. libLLVM-3.6.0svn.so).

- What is a reasonable timeframe to allow the remaining autoconf users
  a chance to migrate to CMake?

Thanks,
Tom
_______________________________________________
LLVM Developers mailing list
LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On Wed, Dec 3, 2014 at 11:08 AM, Patrik Hägglund H <
patrik.h.hagglund at ericsson.com> wrote:
> > - Is there any technical reason why the remaining autoconf users
can't
> switch
> >   to CMake?
>
> I can't see how to do 'configure --disable-assertions
> --disable-optimized', using CMake in LLVM. This is useful for example
to
> build for coverage testing.
>
Use cmake -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_ASSERTIONS=OFF
For more flags see http://llvm.org/docs/CMake.html

Regards,
ismail
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