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From: Jonathan Wakely <jwakely.gcc@gmail.com>
Date: Fri, 6 May 2022 18:05:31 +0100
Message-ID: <CAH6eHdR2b95X62R4adOJAjLNN=g9dbsOarLv0tGF9nm7XiOOaQ@mail.gmail.com>
Subject: Re: [PATCH v2] libstdc++: ppc: conditionalize vsx-only simd intrinsics
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Alexandre Oliva <oliva@adacore.com>, "libstdc++" <libstdc++@gcc.gnu.org>, 
 gcc-patches <gcc-patches@gcc.gnu.org>, David Edelsohn <dje.gcc@gmail.com>
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On Fri, 6 May 2022 at 17:17, Segher Boessenkool wrote:
> > +#if defined __VSX__ || __LONG_WIDTH__ == 32
> >  _GLIBCXX_SIMD_PPC_INTRIN(signed long);
> >  _GLIBCXX_SIMD_PPC_INTRIN(unsigned long);
> > +#endif
>
> Is __LONG_WIDTH__ the right macro to use here?  Nothing else in
> libstdc++v3 uses it.  "__CHAR_BIT__ * __SIZEOF_LONG__" is the usual
> thing to do.  Is __LONG_WIDTH__ always defined anyway?

Presumably it could be simply __SIZEOF_LONG__ == 4 if this is
PowerPC-specific code where CHAR_BIT==8 is always true?

We don't need to consider hypothetical targets where CHAR_BIT!=8 if we
already know the target is some version of PowerPC.