* Linux and LLVM
@ 2009-05-08 19:28 Grozdan
2009-05-08 19:41 ` Jeff Garzik
0 siblings, 1 reply; 4+ messages in thread
From: Grozdan @ 2009-05-08 19:28 UTC (permalink / raw)
To: linux-kernel
Hi,
First, I'd like to say that I'm not interested in any holy wars,
trolling, ego-boosters, or whatever, and basically want to ask a
simple question and get the views of the Linux developers on it, at
least from those who are interested in answering it or have time to do
so as I know that most kernel devs are very busy :)
Recently, FreeBSD has reported that it's slowly switching from GCC to
LLVM/CLANG for compilers. What are the thoughts of the Linux kernel
devs about this and do they things that it's a good idea to go in the
same direction as FreeBSD (switching over to LLVM)?
Please CC me as I'm not subscribed to this specific mailing list
Thanks :)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Linux and LLVM
2009-05-08 19:28 Linux and LLVM Grozdan
@ 2009-05-08 19:41 ` Jeff Garzik
2009-05-08 19:50 ` Grozdan
0 siblings, 1 reply; 4+ messages in thread
From: Jeff Garzik @ 2009-05-08 19:41 UTC (permalink / raw)
To: Grozdan; +Cc: linux-kernel
Grozdan wrote:
> Hi,
>
> First, I'd like to say that I'm not interested in any holy wars,
> trolling, ego-boosters, or whatever, and basically want to ask a
> simple question and get the views of the Linux developers on it, at
> least from those who are interested in answering it or have time to do
> so as I know that most kernel devs are very busy :)
>
> Recently, FreeBSD has reported that it's slowly switching from GCC to
> LLVM/CLANG for compilers. What are the thoughts of the Linux kernel
> devs about this and do they things that it's a good idea to go in the
> same direction as FreeBSD (switching over to LLVM)?
It is highly unlikely we will switch compilers away from gcc -- we have
enough problems just supporting multiple gcc versions.
That said, you could join the effort to get LLVM to compile under the
kernel. Here is a meta-bug for that:
http://llvm.org/bugs/show_bug.cgi?id=4068
It is a moot question until LLVM can actually build a bootable kernel :)
Regards,
Jeff
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Linux and LLVM
2009-05-08 19:41 ` Jeff Garzik
@ 2009-05-08 19:50 ` Grozdan
2009-05-09 9:13 ` Theodore Tso
0 siblings, 1 reply; 4+ messages in thread
From: Grozdan @ 2009-05-08 19:50 UTC (permalink / raw)
To: Jeff Garzik; +Cc: linux-kernel
2009/5/8 Jeff Garzik <jeff@garzik.org>:
> Grozdan wrote:
>>
>> Hi,
>>
>> First, I'd like to say that I'm not interested in any holy wars,
>> trolling, ego-boosters, or whatever, and basically want to ask a
>> simple question and get the views of the Linux developers on it, at
>> least from those who are interested in answering it or have time to do
>> so as I know that most kernel devs are very busy :)
>>
>> Recently, FreeBSD has reported that it's slowly switching from GCC to
>> LLVM/CLANG for compilers. What are the thoughts of the Linux kernel
>> devs about this and do they things that it's a good idea to go in the
>> same direction as FreeBSD (switching over to LLVM)?
>
> It is highly unlikely we will switch compilers away from gcc -- we have
> enough problems just supporting multiple gcc versions.
>
> That said, you could join the effort to get LLVM to compile under the
> kernel. Here is a meta-bug for that:
> http://llvm.org/bugs/show_bug.cgi?id=4068
>
> It is a moot question until LLVM can actually build a bootable kernel :)
Thanks for the quick answer! I was not aware that currently there's
lots of work until CLANG can compile a bootable Linux kernel. Thanks
for the link too. I'll dig through it
>
> Regards,
>
> Jeff
>
>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Linux and LLVM
2009-05-08 19:50 ` Grozdan
@ 2009-05-09 9:13 ` Theodore Tso
0 siblings, 0 replies; 4+ messages in thread
From: Theodore Tso @ 2009-05-09 9:13 UTC (permalink / raw)
To: Grozdan; +Cc: Jeff Garzik, linux-kernel
On Fri, May 08, 2009 at 09:50:04PM +0200, Grozdan wrote:
> 2009/5/8 Jeff Garzik <jeff@garzik.org>:
> > Grozdan wrote:
> >>
> > It is highly unlikely we will switch compilers away from gcc -- we have
> > enough problems just supporting multiple gcc versions.
> >
> > That said, you could join the effort to get LLVM to compile under the
> > kernel. Here is a meta-bug for that:
> > http://llvm.org/bugs/show_bug.cgi?id=4068
> >
> > It is a moot question until LLVM can actually build a bootable kernel :)
>
> Thanks for the quick answer! I was not aware that currently there's
> lots of work until CLANG can compile a bootable Linux kernel. Thanks
> for the link too. I'll dig through it
Note also that the list of architectures currently supported by Linux:
http://en.wikipedia.org/wiki/Linux_kernel_portability_and_supported_architectures
Seems to be a superset of the architectures supported by LLVM, and the
CLANG web page states that it is production quality only on the x86
and x86_64 architectures. So "switch away from" seems to be a rather
ambitious goal.
As Jeff has suggested, getting CLANG to at least be able to compile a
single Linux kernel, on one architecture is clearly the first step.
The next step will be to work on fixing regressions on a wide variety
of different kernel configurations such that in people's mind, that
when a kernel bug is submitted, the probability that it is a compiler
bug must be roughly the same as in GCC --- in other words, that for
any give bug report submitted, P(LLVM/CLANG compiler bug) must be less
than P(GCC compiler bug). At that point, assuming there is a large
enough community of users who prefer to use LLVM/CLANG (presumably
because its code generator is proving itself superior to gcc), it
would be possible to call LLVM/CLANG "supported" under Linux.
I suspect we have quite a ways to go before we get to that point, and
even then there is the issue of the architectures which aren't yet
supported by LLVM.
Regards,
- Ted
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2009-05-09 9:13 UTC | newest]
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2009-05-08 19:28 Linux and LLVM Grozdan
2009-05-08 19:41 ` Jeff Garzik
2009-05-08 19:50 ` Grozdan
2009-05-09 9:13 ` Theodore Tso
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