-----Original Message----- From: kmx Sent: Monday, November 25, 2013 8:41 AM To: win32-vanilla@perl.org Subject: Re: FYI: quadmath.h's expq() crashes at runtime
Hi Rob,

On 5.10.2013 17:06, sisyph...@optusnet.com.au wrote:
> Hi,
>
> It's no big deal, but current Strawberry Perl 32-bit and 64-bit > compilers create executables that crash when expq() is called.
>
> Here's the minimalistic demo script:
>
> ####################
> #include <quadmath.h>
>
> int main (void) {
>  __float128 r;
>
>  r = expq(2.0Q);
>  r = sqrtq(2.0Q);
>  r = fabsq(2.0Q);
>  r = sinq(2.0Q);
>  r = logq(2.0Q);
>  r = cosq(2.0Q);
>
>  return 0;
> }
>
> ####################
>
> The resultant executable crashes when run, but remove the expq() call > and there's no problem. (Link to -lquadmath when building the above > program.)
>
> It's not just MinGW64's gcc-4.6.3 compilers that are affected. I find > the same with their 64-bit gcc-4.7.0, and 4.8.1 compilers. (I haven't > tested any other MinGW64 compilers.)
>
> I've also found that mingw.org's gcc-4.7.0 does *not* suffer this > problem; nor does Ubuntu's gcc-4.6.3 ... so I guess I probably should > report this to the mingw64 project.
>
> BTW, the perl relevance here is that, because of this bug, > Math::Float128 crashes its test suite when expq() gets called. But I > don't think that there's a high demand for this module, so I wouldn't be > too concerned about that aspect.


I am afraid I cannot do much about expq crash unless there is newer version of gcc and/or mingw-w64 runtime which does not suffer from this.


Yes - I subsequently reported the problem to the mingw64 mailing list, where it was confirmed as a bug in their compilers. I don't know when/if it will be fixed. I didn't actually file a bug report anywhere - mainly because I don't know offhand where to file such a report, and no-one replied when I asked about that on the mailing list.

In the meantime, I've changed the relevant XS code so that if __MINGW64_VERSION_MAJOR is defined, instead of doing expq(p), it does powq(e,p) - and that works fine.

>
> Also of slight relevance to Strawberry Perl is the fact that > c/lib/gcc/[whatever]-w64-mingw32/4.6.3 is not in $Config{libpth}. > As a consequence perl does not automatically find -lquadmath when the > Math::Float128 Makefile.PL is run, and perl therefore removes the link. > (The gcc linker can find -lquadmath without any help at all ... but it > won't look for that library if perl has removed the link.)

As for this part you mean using something like this:

libpth='C:\strawberry\c\lib C:\strawberry\c\x86_64-w64-mingw32\lib C:\strawberry\c\lib\gcc\x86_64-w64-mingw32\4.7.3'

right?

Yes - and similarly, for the 32-bit compiler, we want C:\strawberry\c\lib\gcc\i686-w64-mingw32\4.7.3 added to libpth. (Not sure if you're upgrading the compiler to "4.7.3" or whether you meant "4.6.3" ... I'll find out soon enough ;-)

Cheers,
Rob

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