On Thu, Mar 24, 2022 at 9:27 AM David Seifert via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Mon, 2022-03-14 at 18:38 +0100, David Seifert wrote:
> > Use AC_CACHE_CHECK to store the result of the header check for
> > systemtap's "sys/sdt.h", which is similar in spirit to libstdc++'s
> > AC_CACHE_CHECK(..., glibcxx_cv_sys_sdt_h).
> >
> > gcc/
> > * configure.ac: Add AC_CACHE_CHECK(..., gcc_cv_sys_sdt_h).
> > * configure: Regenerate.
> > ---
> > gcc/configure | 20 +++++++++++++++-----
> > gcc/configure.ac | 16 +++++++++-------
> > 2 files changed, 24 insertions(+), 12 deletions(-)
> >
> > diff --git a/gcc/configure b/gcc/configure
> > index 14b19c8fe0c..1dfc5cc7344 100755
> > --- a/gcc/configure
> > +++ b/gcc/configure
> > @@ -31389,15 +31389,25 @@ fi
> >
> > { $as_echo "$as_me:${as_lineno-$LINENO}: checking sys/sdt.h in the
> > target C library" >&5
> > $as_echo_n "checking sys/sdt.h in the target C library... " >&6; }
> > -have_sys_sdt_h=no
> > -if test -f $target_header_dir/sys/sdt.h; then
> > - have_sys_sdt_h=yes
> > +if ${gcc_cv_sys_sdt_h+:} false; then :
> > + $as_echo_n "(cached) " >&6
> > +else
> > +
> > + gcc_cv_sys_sdt_h=no
> > + if test -f $target_header_dir/sys/sdt.h; then
> > + gcc_cv_sys_sdt_h=yes
> > + fi
> > +
> > +fi
> > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_sys_sdt_h"
> > >&5
> > +$as_echo "$gcc_cv_sys_sdt_h" >&6; }
> > +if test x$gcc_cv_sys_sdt_h = xyes; then :
> > +
> >
> > $as_echo "#define HAVE_SYS_SDT_H 1" >>confdefs.h
> >
> > +
> > fi
> > -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_sys_sdt_h" >&5
> > -$as_echo "$have_sys_sdt_h" >&6; }
> >
> > # Check if TFmode long double should be used by default or not.
> > # Some glibc targets used DFmode long double, but with glibc 2.4
> > diff --git a/gcc/configure.ac b/gcc/configure.ac
> > index 90cad309762..c86ce5e0a9b 100644
> > --- a/gcc/configure.ac
> > +++ b/gcc/configure.ac
> > @@ -6904,14 +6904,16 @@ AC_SUBST([enable_default_ssp])
> >
> > # Test for <sys/sdt.h> on the target.
> > GCC_TARGET_TEMPLATE([HAVE_SYS_SDT_H])
> > -AC_MSG_CHECKING(sys/sdt.h in the target C library)
> > -have_sys_sdt_h=no
> > -if test -f $target_header_dir/sys/sdt.h; then
> > - have_sys_sdt_h=yes
> > - AC_DEFINE(HAVE_SYS_SDT_H, 1,
> > +AC_CACHE_CHECK([sys/sdt.h in the target C library],
> > [gcc_cv_sys_sdt_h], [
> > + gcc_cv_sys_sdt_h=no
> > + if test -f $target_header_dir/sys/sdt.h; then
> > + gcc_cv_sys_sdt_h=yes
> > + fi
> > +])
> > +AS_IF([test x$gcc_cv_sys_sdt_h = xyes], [
> > + AC_DEFINE([HAVE_SYS_SDT_H], [1],
> > [Define if your target C library provides sys/sdt.h])
> > -fi
> > -AC_MSG_RESULT($have_sys_sdt_h)
> > +])
> >
> > # Check if TFmode long double should be used by default or not.
> > # Some glibc targets used DFmode long double, but with glibc 2.4
>
> Ping, I think we agreed making this a cache variable is fine (which is
> how libstdc++ also does it).
>
So wait does this supersede the one adding a configure flag for it?
i.e.: https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591704.html
