[PATCH] Implement __readeflags and __writeeflags intrinsics

[Reid Kleckner]

I can see value in making it cross-platform to allow easier porting of
code.  The only thing I don't like about it is that we'd be vending these
interfaces under the name <Intrin.h> without the user explicitly requesting
compatibility with a flag like -fms-extensions.


On Mon, Dec 30, 2013 at 8:12 AM, Eric Christopher <echristo at gmail.com>wrote:

> So why are you wanting to make Intrin.h non-windows? Is there a
> version of Intrin.h that's cross platform?
>
> -eric
>
> On Mon, Dec 30, 2013 at 5:35 AM, Alexey Volkov <avolkov.intel at gmail.com>
> wrote:
> >   I moved intrinsics to Intrin.h into non-Windows section since Windows
> part of header cannot be compiled on Linux.
> >   I also removed include_next directive for Linux.
> >
> > http://llvm-reviews.chandlerc.com/D2468
> >
> > CHANGE SINCE LAST DIFF
> >   http://llvm-reviews.chandlerc.com/D2468?vs=6263&id=6313#toc
> >
> > Files:
> >   lib/Headers/Intrin.h
> >
> > Index: lib/Headers/Intrin.h
> > ===================================================================
> > --- lib/Headers/Intrin.h
> > +++ lib/Headers/Intrin.h
> > @@ -21,17 +21,65 @@
> >
> *===-----------------------------------------------------------------------===
> >   */
> >
> > -/* Only include this if we're compiling for the windows platform. */
> > -#ifndef _MSC_VER
> > -#include_next <Intrin.h>
> > -#else
> > -
> >  #ifndef __INTRIN_H
> >  #define __INTRIN_H
> >
> >  /* First include the standard intrinsics. */
> >  #include <x86intrin.h>
> >
> > +#ifndef _MSC_VER
> > +#ifdef __x86_64__
> > +static __inline__ unsigned long long __attribute__((__always_inline__,
> __nodebug__))
> > +__readeflags(void)
> > +{
> > +  unsigned long long res = 0;
> > +  __asm__ __volatile__ ("pushf\n\t"
> > +                        "popq %0\n"
> > +                        :"=r"(res)
> > +                        :
> > +                        :
> > +                       );
> > +  return res;
> > +}
> > +
> > +static __inline__ void __attribute__((__always_inline__, __nodebug__))
> > +__writeeflags(unsigned long long __f)
> > +{
> > +  __asm__ __volatile__ ("pushq %0\n\t"
> > +                        "popf\n"
> > +                        :
> > +                        :"r"(__f)
> > +                        :"flags"
> > +                       );
> > +}
> > +
> > +#else
> > +static __inline__ unsigned int __attribute__((__always_inline__,
> __nodebug__))
> > +__readeflags(void)
> > +{
> > +  unsigned int res = 0;
> > +  __asm__ __volatile__ ("pushf\n\t"
> > +                        "popl %0\n"
> > +                        :"=r"(res)
> > +                        :
> > +                        :
> > +                       );
> > +  return res;
> > +}
> > +
> > +static __inline__ void __attribute__((__always_inline__, __nodebug__))
> > +__writeeflags(unsigned int __f)
> > +{
> > +  __asm__ __volatile__ ("pushl %0\n\t"
> > +                        "popf\n"
> > +                        :
> > +                        :"r"(__f)
> > +                        :"flags"
> > +                       );
> > +}
> > +#endif
> > +#else
> > +
> >  #ifdef __cplusplus
> >  extern "C" {
> >  #endif
> > @@ -780,5 +828,5 @@
> >  }
> >  #endif
> >
> > -#endif /* __INTRIN_H */
> >  #endif /* _MSC_VER */
> > +#endif /* __INTRIN_H */
>
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