Hi Mike,
I guess you should CC fortran@gcc.gnu.org as well.
on 2024/7/11 01:25, Michael Meissner wrote:
> If you build a little endian compiler and select a default CPU of power5
> (i.e. --with-cpu=power5), GCC cannot be built. The reason is that both the
> libgfortran and libstdc++-v3 libraries assume that all little endian powerpc
> builds support IEEE 128-bit floating point.
>
> However, if the default cpu does not support the VSX instruction set, then we
> cannot build the IEEE 128-bit libraries. This patch fixes the libgfortran
> library so if the GCC compiler does not support IEEE 128-bit floating point,
> the
> IEEE 128-bit floating point libraries are not built. A companion patch will
> fix
> the libstdc++-v3 library.
>
> I have built these patches on a little endian system, doing both normal
> builds,
> and making a build with a power5 default. There was no regression in the
> normal
> builds. I have also built a big endian GCC compiler and there was no
> regression
> there. Can I check this patch into the trunk?
>
> 2024-07-10 Michael Meissner <meiss...@linux.ibm.com>
>
> libgfortran/
>
> PR target/115800
> * configure.ac (powerpc64le*-linux*): Check to see that the compiler
> uses VSX before enabling IEEE 128-bit support.
> * configure: Regenerate.
> * kinds-override.h (GFC_REAL_17): Add check for __VSX__.
> * libgfortran.h (POWER_IEEE128): Likewise.
>
> ---
> libgfortran/configure | 7 +++++--
> libgfortran/configure.ac | 3 +++
> libgfortran/kinds-override.h | 2 +-
> libgfortran/libgfortran.h | 2 +-
> 4 files changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/libgfortran/configure b/libgfortran/configure
> index 11a1bc5f070..2708e5c7eca 100755
> --- a/libgfortran/configure
> +++ b/libgfortran/configure
> @@ -5981,6 +5981,9 @@ if test "x$GCC" = "xyes"; then
> #if __SIZEOF_LONG_DOUBLE__ != 16
> #error long double is double
> #endif
> + #if !defined(__VSX__)
> + #error VSX is not available
> + #endif
All the touched code cares about type _Float128 which is available only if
TARGET_FLOAT128_TYPE is set (TARGET_FLOAT128_TYPE depends on VSX). I think
we should check for macro __FLOAT128_TYPE__ instead (we define this macro
when TARGET_FLOAT128_TYPE is set), IMHO it looks more meaningful, this is
similar for libstdc++ sub-patch.
BR,
Kewen
> int
> main ()
> {
> @@ -12847,7 +12850,7 @@ else
> lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
> lt_status=$lt_dlunknown
> cat > conftest.$ac_ext <<_LT_EOF
> -#line 12850 "configure"
> +#line 12853 "configure"
> #include "confdefs.h"
>
> #if HAVE_DLFCN_H
> @@ -12953,7 +12956,7 @@ else
> lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
> lt_status=$lt_dlunknown
> cat > conftest.$ac_ext <<_LT_EOF
> -#line 12956 "configure"
> +#line 12959 "configure"
> #include "confdefs.h"
>
> #if HAVE_DLFCN_H
> diff --git a/libgfortran/configure.ac b/libgfortran/configure.ac
> index cca1ea0ea97..cfaeb9717ab 100644
> --- a/libgfortran/configure.ac
> +++ b/libgfortran/configure.ac
> @@ -148,6 +148,9 @@ if test "x$GCC" = "xyes"; then
> AC_PREPROC_IFELSE(
> [AC_LANG_PROGRAM([[#if __SIZEOF_LONG_DOUBLE__ != 16
> #error long double is double
> + #endif
> + #if !defined(__VSX__)
> + #error VSX is not available
> #endif]],
> [[(void) 0;]])],
> [AM_FCFLAGS="$AM_FCFLAGS -mabi=ibmlongdouble -mno-gnu-attribute";
> diff --git a/libgfortran/kinds-override.h b/libgfortran/kinds-override.h
> index f6b4956c5ca..51f440e5323 100644
> --- a/libgfortran/kinds-override.h
> +++ b/libgfortran/kinds-override.h
> @@ -30,7 +30,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.
> If not, see
> #endif
>
> /* Keep these conditions on one line so grep can filter it out. */
> -#if defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ &&
> __SIZEOF_LONG_DOUBLE__ == 16
> +#if defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ &&
> __SIZEOF_LONG_DOUBLE__ == 16 && defined(__VSX__)
> typedef _Float128 GFC_REAL_17;
> typedef _Complex _Float128 GFC_COMPLEX_17;
> #define HAVE_GFC_REAL_17
> diff --git a/libgfortran/libgfortran.h b/libgfortran/libgfortran.h
> index 5c59ec26e16..23660335243 100644
> --- a/libgfortran/libgfortran.h
> +++ b/libgfortran/libgfortran.h
> @@ -104,7 +104,7 @@ typedef off_t gfc_offset;
> #endif
>
> #if defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ \
> - && defined __GLIBC_PREREQ
> + && defined __GLIBC_PREREQ && defined(__VSX__)
> #if __GLIBC_PREREQ (2, 32)
> #define POWER_IEEE128 1
> #endif
