Re: [PATCH] libstdc++: Add C++ runtime support for new 128-bit long double format

[Tulio Magno Quites Machado Filho <tuliom@ascii.art.br>]

Jonathan Wakely via Libstdc++ <libstdc++@gcc.gnu.org> writes:

> diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
> index cbfdf4c6bad..d25842fef35 100644
> --- a/libstdc++-v3/configure.ac
> +++ b/libstdc++-v3/configure.ac
> @@ -421,12 +425,43 @@ case "$target" in
>      port_specific_symbol_files="\$(top_srcdir)/config/os/gnu-linux/ldbl-extra.ver"
>      case "$target" in
>        powerpc*-*-linux*)
> -	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute" ;;
> +	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute"
> +        # Check for IEEE128 support in libm:
> +        AC_CHECK_LIB(m, frexpf128,

I suggest to replace frexpf128 with __frexpieee128.

The former is available on a glibc that support _Float128 (since glibc 2.26).
The later is available on a glibc that supports binary128 long double (since
glibc 2.32)

Without this modification, the build fails on glibc between 2.26 and 2.31.

I'm also running a couple of tests here.
I believe this is showing a couple of glitches in glibc which I'm already
investigating.

Thanks!

-- 
Tulio Magno