r195676 - Make the integrated assembler the default for cygwin/mingw too.

[NAKAMURA Takumi]

Rafael,
I see. I don't object to switch -integrated-as by default. It's good
and what I'd like to do.
To give an error to -no-integrated-as, could you file bugzilla for
this issue, "incompatibilities to gnu as"?
(llc is already affected.)

Bill,
At least, release_34/r195823 (master/r195798) should be reverted.

2013/12/1 Rafael Espíndola <rafael.espindola at gmail.com>:
> On 30 November 2013 08:10, NAKAMURA Takumi <geek4civic at gmail.com> wrote:
>> Rafael,
>>
>> Since llvm's r195798, clang -no-integrated-as has been broken, at
>> least on cygming gnu as.
>> Would you like to hide incompatibility to gnu as?
>>
>> FYI, release_34 has been broken due to lack of this, r195676, on
>> cygwin selfhosting.
>> http://bb.pgr.jp/builders/clang-3stage-cygwin/builds/1348
>
> How come 34 has r195798 but not r195676?
>
> The short answer is that gnu as has the fundamental limitation of not
> supporting two sections with the same name on COFF (it does support it
> on ELF). Defining the same sections as gcc is pretty much impossible
> given that it can't agree with itself in different optimization levels
> (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59236).
>
> If we really need to support gnu as on COFF, we can do some arbitrary
> section name uniquing behind a flag. The best course I think is to not
> have r195798 on 3.4 and produce an error for -no-integrated-as on
> trunk (as we already do for -win32 triples).
>
> Cheers,
> Rafael