[cfe-dev] MinGW problem with GSL

[Ruben Van Boxem]

2011/7/7 Eric Christopher <echristo at apple.com>:
>>>
>>>
>>> a) try passing -no-integrated-as to see if it's a problem with passing down arguments
>>
>> Same problem. I have also verified all the commands being run against
>> a matching GCC install.
>
> Good to know.
>
>>
>>> b) try to get a testcase of the failing instructions
>>
>> Heh, well, yeah. Euhm... My assembly isn't that... good, and that's
>> being optimistic. As in, I know *nothing* about it, except that it
>> exists. So here I go:
>>
>> The bits of assembly causing the problem are these:
>>
>> .Ltmp224:
>>       .loc    4 129 5
>>       movsd   %xmm6, -616(%rbp)
>>       fldl    -616(%rbp)
>>       fstpt   -772(%rbp)
>>       fld     %ss
>>       #APP
>>       fabs;
>>       #NO_APP
>>       fstpl   -624(%rbp)
>>       movsd   .LCPI3_10(%rip), %xmm0
>> ...
>> .Ltmp521:
>>       fstpt   -656(%rbp)
>>       fld     %ss
>>       #APP
>>       fabs;
>>       #NO_APP
>>
>> I can't find these or even similar bits in GCC's output, which
>> probably isn't surprising.
>>
>> The source file this comes from is pretty big, with a lot of GSL
>> specific functionality being used (kind of expected). I do know GCC
>> does not have a "fld" instruction anywhere in its version of the
>> assembler output.
>>
>> Would this have anything to do with the <ieeefp.h> header? This is
>> used when Clang is used, but a mingw-w64 (which provides the header)
>> dev told me it includes ansidecl.h which is a GCC internal header. It
>> defines (among a *lot* of other things) some va_args things, but
>> there's no error when clang parses this file, so it probably is not
>> causing the issue. Plus, the only place where it's being used is GSL's
>> sys/infnan.c (grep -r , which couldn't possibly be included in the
>> file causing the error.
>>
>> I also tried a i686-w64-mingw32 built Clang with matching mingw-w64
>> CRT and GCC. It hits the same problem.
>>
>> Any tips on what simple testcase couldd produce an fld instruction?
>> GCC doesn't in this case, which only adds to the oddity.
>
> Not sure that's really important at the moment, it might be nice to get
> you to file a bug report with a preprocessed source file testcase
> and the command line that'll get this to show.

Sorry for the delay in getting these files to you, but since then the
problem has gone away. GSL compiles fine, although the first test
fails (keeps running endlessly). But I will investigate the cause
here.

Ruben