In math/math.h, __MATH_TG will expand signbit to __builtin_signbit*,
e.g.: __builtin_signbitf128, before GCC 6. However, there has never
been a __builtin_signbitf128 in GCC and the type-generic builtin is
only available since GCC 6. For older GCC, this patch defines
__builtin_signbitf128 to __signbitf128, so that the internal function
is used instead of the non-existent builtin.
This patch also changes the implementation of __signbitf128, because
it was reusing the implementation of __signbitl from ldbl-128, which
calls __builtin_signbitl. Using the long double version of the
builtin is not correct on machines where _Float128 is ABI-distinct
from long double (i.e.: ia64, powerpc64le, x86, x86_84). The new
implementation does not rely on builtins when being built with GCC
versions older than 6.0.
The new code does not currently affect powerpc64le builds, because
only GCC 6.2 fulfills the requirements from configure. It might
affect powerpc64le builds if those requirements are backported to
older versions of the compiler. The new code affects x86_64 builds,
since glibc is supposed to build correctly with older versions of GCC.
Tested for powerpc64le and x86_64.
* include/math.h (__signbitf128): Define as hidden.
* sysdeps/ieee754/float128/s_signbitf128.c (__signbitf128):
Reimplement without builtins.
* sysdeps/ia64/bits/floatn.h [!__GNUC_PREREQ (6, 0)]
(__builtin_signbitf128): Define to __signbitf128.
* sysdeps/powerpc/bits/floatn.h: Likewise.
* sysdeps/x86/bits/floatn.h: Likewise.
This patch enables float128 support for ia64, so that all the
configurations where GCC supports _Float128 / __float128 as an
ABI-distinct type now have glibc support as well. bits/floatn.h
declares the support to be available for GCC 4.4 and later, which is
when the libgcc support was added. The removal of
sysdeps/ia64/fpu/k_rem_pio2.c is because the generic k_rem_pio2.c
defines a function required by the float128 code.
Tested (compilation only) with build-many-glibcs.py for ia64 (GCC 6
and GCC 7).
Given how long it is since libm-test-ulps has been updated for ia64, I
think truncating the file and regenerating it from scratch would be a
good idea when doing a regeneration to add float128 ulps. I expect
various ia64 libm issues (at least some already filed in Bugzilla) to
result in test failures even after ulps regeneration, but hopefully
the float128 code will pass tests as it's the same as used on other
architectures.
* sysdeps/ia64/Implies: Add ieee754/float128.
* sysdeps/ia64/bits/floatn.h: New file.
* sysdeps/ia64/float128-abi.h: Likewise.
* manual/math.texi (Mathematics): Document support for _Float128
on ia64.
* sysdeps/ia64/Makefile [$(subdir) = math] (CPPFLAGS): Append to
Makefile variable.
* sysdeps/ia64/fpu/e_sqrtf128.c: New file.
* sysdeps/ia64/fpu/k_rem_pio2.c: Remove file.
* sysdeps/ia64/fpu/sfp-machine.h: New file. Based on libgcc.
* sysdeps/ia64/math-tests.h: New file.
* math/libm-test-support.h (XFAIL_FLOAT128_PAYLOAD): Also define
based on TEST_COND_binary128 for [__ia64__].
* sysdeps/unix/sysv/linux/ia64/libc.abilist: Update.
* sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise,
