how long to keep support for gcc on x86?

[Warner Losh]

On Jan 12, 2013, at 10:37 PM, John-Mark Gurney wrote:

> Adrian Chadd wrote this message on Sat, Jan 12, 2013 at 19:30 -0800:
>> IMHO gcc shuld be available until all of the platforms that we
>> currently ship FreeBSD on gets clang support.
> 
> Though, we have a very ancient version of gcc, a modern version would
> support the AES-NI intrinsicts that I am thinking of using...  It's
> more of a question of how long do we need to keep support for gcc
> 4.2.1, not another modern gcc/other compiler...

You have to support what's in the tree.

In the past when people have wanted to use newer instructions, which is more a binutils thing anyway, they have added support to them in our in-tree binutils.

>> This includes MIPS (which is there, but I don't think the default MIPS
>> build uses clang at the moment) and ia64, which Marcel has been
>> dutifully working on.
>> 
>> Please also note that people can and will compile FreeBSD on a
>> non-default-system compiler ; so deprecating gcc (either support or
>> framework) should be considered carefully.
> 
> Considering that the icc stuff was recently removed, unless the compiler
> has good gcc/clang emulation, I can't see how far another compiler would
> get compiling our code...

clang support isn't even complete yet. There are still numerous unresolved warnings on i386 and amd64 that gcc doesn't complain about. It is far too premature for desupporting gcc compiles of the kernel.

Warner

>> On 12 January 2013 17:42, Steve Kargl <sgk at troutmask.apl.washington.edu> wrote:
>>> On Sat, Jan 12, 2013 at 03:31:47PM -0800, John-Mark Gurney wrote:
>>>> So, now that -current x86 is defaulting to clang, how much longer do we
>>>> need to support gcc on platforms that default to clang?
>>> 
>>> IMHO, gcc should be available until after 10.0 is branched.
>>> 
>>>> I'm asking because clang support AES-NI, but gcc does not...
>>> 
>>> The last and only time I had for testing clang's handling
>>> of floating point revealed that clang had a few bugs and
>>> performance issues.
> 
> -- 
>  John-Mark Gurney				Voice: +1 415 225 5579
> 
>     "All that I will do, has been done, All that I have, has not."
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