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Re: [PATCH] PR middle-end/30250: Evaluate lgamma/gamma at compile-time using MPFR
On Wed, 9 May 2007, Andrew Pinski wrote:
> On 5/9/07, Richard Guenther <richard.guenther@gmail.com> wrote:
> >
> > I agree, we need to get rid of all langhooks for LTO. Looking at the
> > C99 standard
> > I fail to see that a thing like signgam is set for lgamma (looking at
> > 7.12.8.3) - it's
> > in the linux manpage I have, but it doesn't seem to be in the
> > standard. Can anyone
> > confirm this part is part of C99?
>
> And it is not part of C99, only POSIX/Single UNIX. See
> http://std.dkuug.dk/JTC1/SC22/WG14/www/C99RationaleV5.10.pdf which
> talks about this feature and C99 standard.
Not being part of C99 also means it would be incorrect to set this
variable for -std=c99 - the user could have their own variable with that
name - so it can only be set for -std=gnu99.
Abstractly, I think you want a built-in signgam which is a variable rather
than a function (and is DEF_EXT_LIB_BUILTIN whereas lgamma is
DEF_C99_BUILTIN) and only set the variable if both built-ins are enabled,
but I don't know if built-ins being variables rather than functions will
work at all at present.
--
Joseph S. Myers
joseph@codesourcery.com