GCC 7.5.0 (PR94200) will refuse to compile if both -mabi=% and
-mlong-double-128 are passed on the command line. Surprisingly,
it will work happily if the latter is not. For the sake of
maintaining status quo, test for and blacklist such compilers.
Tested with a GCC 8.3.1 and GCC 7.5.0 compiler for ppc64le.
---
INSTALL | 8 +++---
manual/install.texi | 10 ++++++--
sysdeps/ieee754/ldbl-128ibm-compat/Makefile | 12 ---------
sysdeps/powerpc/powerpc64/le/configure | 27 +++++++++++++++++++++
sysdeps/powerpc/powerpc64/le/configure.ac | 15 ++++++++++++
5 files changed, 55 insertions(+), 17 deletions(-)
@@ -469,9 +469,11 @@ build the GNU C Library:
For PowerPC 64-bits little-endian (powerpc64le), a GCC version with
support for '-mno-gnu-attribute', '-mabi=ieeelongdouble', and
- '-mabi=ibmlondouble' is required. These additional features are
- required for building the GNU C Library with support for IEEE long
- double.
+ '-mabi=ibmlondouble' is required. Likewise, the compiler must also
+ support passing '-mlong-double-128' with the preceding options. As
+ of release, this implies GCC 7.4 and newer (excepting GCC 7.5.0,
+ see GCC PR94200). These additional features are required for
+ building the GNU C Library with support for IEEE long double.
For multi-arch support it is recommended to use a GCC which has
been built with support for GNU indirect functions. This ensures
@@ -509,8 +509,14 @@ release time, GCC 9.2.1 is the newest compiler verified to work to build
For PowerPC 64-bits little-endian (powerpc64le), a GCC version with support
for @option{-mno-gnu-attribute}, @option{-mabi=ieeelongdouble}, and
-@option{-mabi=ibmlondouble} is required. These additional features are
-required for building the GNU C Library with support for IEEE long double.
+@option{-mabi=ibmlondouble} is required. Likewise, the compiler must also
+support passing @option{-mlong-double-128} with the preceding options. As
+of release, this implies GCC 7.4 and newer (excepting GCC 7.5.0, see GCC
+PR94200). These additional features are required for building the GNU C
+Library with support for IEEE long double.
+
+@c powerpc64le performs an autoconf test to verify the compiler compiles with
+@c commands like "$CC -c foo.c -mabi=ibmlongdouble -mlong-double-128".
For multi-arch support it is recommended to use a GCC which has been built with
support for GNU indirect functions. This ensures that correct debugging
@@ -249,13 +249,6 @@ ldbl-extra-routines += err \
CFLAGS-ieee128-qefgcvt.c += -mabi=ieeelongdouble -Wno-psabi -mno-gnu-attribute
CFLAGS-ieee128-qefgcvt_r.c += -mabi=ieeelongdouble -Wno-psabi -mno-gnu-attribute
-# Remove -mlong-double-128 because it does not work correctly with
-# -mabi=ibmlongdoule in some GCC versions, e.g. GCC 7.
-$(foreach o,$(all-object-suffixes),$(objpfx)ieee128-qefgcvt$(o)): \
- sysdep-CFLAGS := $(filter-out -mlong-double-128, $(sysdep-CFLAGS))
-$(foreach o,$(all-object-suffixes),$(objpfx)ieee128-qefgcvt_r$(o)): \
- sysdep-CFLAGS := $(filter-out -mlong-double-128, $(sysdep-CFLAGS))
-
tests-internal += tst-ibm128-warn tst-ieee128-warn
tests-internal += tst-ibm128-error tst-ieee128-error
tests-internal += tst-ibm128-efgcvt tst-ieee128-efgcvt
@@ -348,11 +341,6 @@ ldbl-ibm128-files := $(objpfx)test-%-ibm128^ \
$(foreach r,$(ldbl-extra-routines),$(objpfx)$(r)-internal^)
obj-suf-foreach = $(foreach suf,$(all-object-suffixes),$(subst ^,$(suf),$(1)))
-# Remove -mlong-double-128 because it does not work correctly with
-# -mabi=ibmlongdoule in some GCC versions, e.g. GCC 7.
-$(call obj-suf-foreach,$(ldbl-ibm128-files)): \
- sysdep-CFLAGS := $(filter-out -mlong-double-128, $(sysdep-CFLAGS))
-
# Explicitly add -mabi=ibm-long-double to required files.
$(call obj-suf-foreach,$(ldbl-ibm128-files)): \
sysdep-CFLAGS += -mabi=ibmlongdouble
@@ -90,6 +90,33 @@ if test "$libc_cv_compiler_powerpc64le_ice" != "yes"; then :
critic_missing="$critic_missing __builtin_signbit is broken. GCC 7.4 or newer is required to resolve (PR83862)."
fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if $CC compiles with -mabi=ieeelongdouble and -mlong-double-128" >&5
+$as_echo_n "checking if $CC compiles with -mabi=ieeelongdouble and -mlong-double-128... " >&6; }
+if ${libc_cv_compiler_powerpc64le_ldbl128_mabi+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -mabi=ieeelongdouble -mlong-double-128"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+long double x;
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+ libc_cv_compiler_powerpc64le_ldbl128_mabi=yes
+else
+ libc_cv_compiler_powerpc64le_ldbl128_mabi=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+CFLAGS="$save_CFLAGS"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_compiler_powerpc64le_ldbl128_mabi" >&5
+$as_echo "$libc_cv_compiler_powerpc64le_ldbl128_mabi" >&6; }
+if test "$libc_cv_compiler_powerpc64le_ldbl128_mabi" == "no"; then :
+ critic_missing="$critic_missing The compiler must support -mabi=ieeelongdouble and -mlongdouble simultaneously."
+fi
+
for ac_prog in $OBJCOPY
do
# Extract the first word of "$ac_prog", so it can be a program name with args.
@@ -51,6 +51,21 @@ CFLAGS="$save_CFLAGS"])
AS_IF([test "$libc_cv_compiler_powerpc64le_ice" != "yes"],
[critic_missing="$critic_missing __builtin_signbit is broken. GCC 7.4 or newer is required to resolve (PR83862)."])
+dnl Some old compiler versions give out error messages when combining
+dnl -mabi=% and -mlong-double-128. i.e GCC 7.5.0 (PR94200)
+AC_CACHE_CHECK([if $CC compiles with -mabi=ieeelongdouble and -mlong-double-128],
+ libc_cv_compiler_powerpc64le_ldbl128_mabi, [dnl
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -mabi=ieeelongdouble -mlong-double-128"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+long double x;
+]])],
+ [libc_cv_compiler_powerpc64le_ldbl128_mabi=yes],
+ [libc_cv_compiler_powerpc64le_ldbl128_mabi=no])
+CFLAGS="$save_CFLAGS"])
+AS_IF([test "$libc_cv_compiler_powerpc64le_ldbl128_mabi" == "no"],
+ [critic_missing="$critic_missing The compiler must support -mabi=ieeelongdouble and -mlongdouble simultaneously."])
+
dnl objcopy (binutils) 2.26 or newer required to support the --update-section
dnl feature for fixing up .gnu.attribute section with IEEE ldbl.
AC_CHECK_PROG_VER(OBJCOPY, $OBJCOPY, --version,