https://gcc.gnu.org/g:3696abc890a0e9acbd4e93c688d0e238c011ee76
commit 3696abc890a0e9acbd4e93c688d0e238c011ee76
Author: Michael Meissner <meiss...@linux.ibm.com>
Date: Wed Sep 4 11:31:56 2024 -0400
Do not build IEEE 128-bit libstdc++ support if VSX is not available.
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 libstdc++-v3
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 libgfortran 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?
2024-09-04 Michael Meissner <meiss...@linux.ibm.com>
libstdc++-v3/
PR target/115800
* configure.ac (powerpc*-*-linux*): Don't enable IEEE 128-bit on
PowerPC
systems without VSX.
* configure: Regenerate.
* numeric_traits.h: Don't enable IEEE 128-bit on PowerPC systems
without
VSX.
Diff:
---
libgcc/config.host | 12 ++++++------
libgcc/config/rs6000/t-float128 | 8 +++++++-
libgcc/config/rs6000/t-float128-hw | 3 +--
libgcc/config/rs6000/t-float128-p10-hw | 3 +--
libgcc/configure | 8 +++++++-
libgcc/configure.ac | 8 +++++++-
6 files changed, 29 insertions(+), 13 deletions(-)
diff --git a/libgcc/config.host b/libgcc/config.host
index 9fae51d4ce7..261b08859a4 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -1292,14 +1292,14 @@ powerpc*-*-linux*)
if test $libgcc_cv_powerpc_float128 = yes; then
tmake_file="${tmake_file} rs6000/t-float128"
- fi
- if test $libgcc_cv_powerpc_float128_hw = yes; then
- tmake_file="${tmake_file} rs6000/t-float128-hw"
- fi
+ if test $libgcc_cv_powerpc_float128_hw = yes; then
+ tmake_file="${tmake_file} rs6000/t-float128-hw"
- if test $libgcc_cv_powerpc_3_1_float128_hw = yes; then
- tmake_file="${tmake_file} rs6000/t-float128-p10-hw"
+ if test $libgcc_cv_powerpc_3_1_float128_hw = yes; then
+ tmake_file="${tmake_file}
rs6000/t-float128-p10-hw"
+ fi
+ fi
fi
extra_parts="$extra_parts ecrti.o ecrtn.o ncrti.o ncrtn.o"
diff --git a/libgcc/config/rs6000/t-float128 b/libgcc/config/rs6000/t-float128
index b09b5664af0..93e78adcd62 100644
--- a/libgcc/config/rs6000/t-float128
+++ b/libgcc/config/rs6000/t-float128
@@ -74,7 +74,13 @@ fp128_includes = $(srcdir)/soft-fp/double.h \
$(srcdir)/soft-fp/soft-fp.h
# Build the emulator without ISA 3.0 hardware support.
-FP128_CFLAGS_SW = -Wno-type-limits -mvsx -mfloat128 \
+#
+# In the past we added -mvsx to build the float128 specific libraries with the
+# VSX instruction set. This allowed the big endian GCC on server platforms to
+# build the float128 support. However, is causes problems when other default
+# cpu targets are used such as the 7450.
+
+FP128_CFLAGS_SW = -Wno-type-limits -mfloat128 \
-mno-float128-hardware -mno-gnu-attribute \
-I$(srcdir)/soft-fp \
-I$(srcdir)/config/rs6000 \
diff --git a/libgcc/config/rs6000/t-float128-hw
b/libgcc/config/rs6000/t-float128-hw
index ed67b572580..82726c98b98 100644
--- a/libgcc/config/rs6000/t-float128-hw
+++ b/libgcc/config/rs6000/t-float128-hw
@@ -23,8 +23,7 @@ fp128_ifunc_obj = $(fp128_ifunc_static_obj)
$(fp128_ifunc_shared_obj)
fp128_sed_hw = -hw
# Build the hardware support functions with appropriate hardware support
-FP128_CFLAGS_HW = -Wno-type-limits -mvsx -mfloat128 \
- -mcpu=power9 \
+FP128_CFLAGS_HW = -Wno-type-limits -mfloat128 -mcpu=power9 \
-mfloat128-hardware -mno-gnu-attribute \
-I$(srcdir)/soft-fp \
-I$(srcdir)/config/rs6000 \
diff --git a/libgcc/config/rs6000/t-float128-p10-hw
b/libgcc/config/rs6000/t-float128-p10-hw
index edaaee0e478..ee50d248ca1 100644
--- a/libgcc/config/rs6000/t-float128-p10-hw
+++ b/libgcc/config/rs6000/t-float128-p10-hw
@@ -13,8 +13,7 @@ fp128_3_1_hw_shared_obj = $(addsuffix
_s$(objext),$(fp128_3_1_hw_funcs))
fp128_3_1_hw_obj = $(fp128_3_1_hw_static_obj) $(fp128_3_1_hw_shared_obj)
# Build the hardware support functions with appropriate hardware support
-FP128_3_1_CFLAGS_HW = -Wno-type-limits -mvsx -mfloat128 \
- -mcpu=power10 \
+FP128_3_1_CFLAGS_HW = -Wno-type-limits -mfloat128 -mcpu=power10 \
-mfloat128-hardware -mno-gnu-attribute \
-I$(srcdir)/soft-fp \
-I$(srcdir)/config/rs6000 \
diff --git a/libgcc/configure b/libgcc/configure
index a69d314374a..635237a06c8 100755
--- a/libgcc/configure
+++ b/libgcc/configure
@@ -5184,9 +5184,15 @@ case ${host} in
# check if we have VSX (ISA 2.06) support to build the software libraries, and
# whether the assembler can handle xsaddqp for hardware support. Also check if
# a new glibc is being used so that __builtin_cpu_supports can be used.
+#
+# with the VSX instruction set. This allowed the big endian GCC on server
+# platforms to build the float128 support. However, is causes problems when
+# other default cpu targets are used such as the 7450. Now
+# libgcc_cv_powerpc_float128 will fail if the default cpu cannot build the
+# float128 support.
powerpc*-*-linux*)
saved_CFLAGS="$CFLAGS"
- CFLAGS="$CFLAGS -mabi=altivec -mvsx -mfloat128"
+ CFLAGS="$CFLAGS -mfloat128"
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for PowerPC ISA 2.06 to
build __float128 libraries" >&5
$as_echo_n "checking for PowerPC ISA 2.06 to build __float128 libraries... "
>&6; }
if ${libgcc_cv_powerpc_float128+:} false; then :
diff --git a/libgcc/configure.ac b/libgcc/configure.ac
index c2749fe0958..2a725a6f662 100644
--- a/libgcc/configure.ac
+++ b/libgcc/configure.ac
@@ -407,9 +407,15 @@ case ${host} in
# check if we have VSX (ISA 2.06) support to build the software libraries, and
# whether the assembler can handle xsaddqp for hardware support. Also check if
# a new glibc is being used so that __builtin_cpu_supports can be used.
+#
+# with the VSX instruction set. This allowed the big endian GCC on server
+# platforms to build the float128 support. However, is causes problems when
+# other default cpu targets are used such as the 7450. Now
+# libgcc_cv_powerpc_float128 will fail if the default cpu cannot build the
+# float128 support.
powerpc*-*-linux*)
saved_CFLAGS="$CFLAGS"
- CFLAGS="$CFLAGS -mabi=altivec -mvsx -mfloat128"
+ CFLAGS="$CFLAGS -mfloat128"
AC_CACHE_CHECK([for PowerPC ISA 2.06 to build __float128 libraries],
[libgcc_cv_powerpc_float128],
[AC_COMPILE_IFELSE(
