Re: [Tinycc-devel] The inline assembly clobber for floating point register stack `%st' not implemented?

[KHMan]

On 1/20/2015 7:39 PM, YX Hao wrote:
> This serial of functions in 'math.h' all use "st":
> http://en.cppreference.com/w/c/numeric/math/rint
> and
> http://blogs.msdn.com/b/vcblog/archive/2013/07/19/c99-library-support-in-visual-studio-2013.aspx
>
> ----- Original Message ----- From: "Sergey Korshunoff"
> Sent: Tuesday, January 20, 2015 4:41 PM
>
> I'm assumed that "st" register can be considered  by tcc as "memory"
> specification. This assumption allowed me to build a nimrod compiler
> for windows. Not tested if it works.

fistpl pops the stack, so the entire 8087 stack (st) is clobbered.

> 2015-01-19 14:37 GMT+03:00, YX Hao
> > Hi,
> >
> > From: "Sergey Korshunoff"
> > Sent: Monday, January 19, 2015 1:14 AM
> >
> >
> > > Hi! Another question:  Compiling a nimrod compiler by
> > > i386-win-tcc I
> > > got  the following error:
> > > /usr/local/lib/win32/include/math.h:541: error: invalid clobber
> > > register
> > > 'st'
> >
> > Go into include/math.h:541:
> >
> >   __CRT_INLINE long __cdecl lrint (double x)
> >   {
> >     long retval;
> >     __asm__ __volatile__             \
> >       ("fistpl %0"  : "=m" (retval) : "t" (x) : "st");          \
> >       return retval;
> >   }
> >
> > __asm__　__volatile__("Instruction List" : Output : Input :
> > Clobber/Modify);
> >
> > Guide to Inline Assembly:
> > http://www.delorie.com/djgpp/doc/brennan/brennan_att_inline_djgpp.html
> >
> > Clobber List:
> > http://www.ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html#ss5.3
> >
> > st:
> > http://sourceware.org/binutils/docs-2.25/as/i386_002dRegs.html#i386_002dRegs
> >
> >
> > Anyone know more abount it?

--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia