All representations of floating-point numbers in types with IEC 60559
binary exchange format are canonical. On the other hand, types with IEC
60559 extended formats, such as those implemented under ldbl-96 and
ldbl-128ibm, contain representations that are not canonical.
TS 18661-1 introduced the type-generic macro iscanonical, which returns
whether a floating-point value is canonical or not. In Glibc, this
type-generic macro is implemented using the macro __MATH_TG, which, when
support for float128 is enabled, relies on __builtin_types_compatible_p
to select between floating-point types. However, this use of
iscanonical breaks C++ applications, because the builtin is only
available in C mode.
This patch provides a C++ implementation of iscanonical that relies on
function overloading, rather than builtins, to select between
floating-point types.
Unlike the C++ implementations for iszero and issignaling, this
implementation ignores __NO_LONG_DOUBLE_MATH. The double type always
matches IEC 60559 double format, which is always canonical. Thus, when
double and long double are the same (__NO_LONG_DOUBLE_MATH), iscanonical
always returns 1 and is not implemented with __MATH_TG.
Tested for powerpc64, powerpc64le and x86_64.
[BZ #22235]
* math/math.h: Trivial fix for unbalanced parentheses in comment.
* math/Makefile [CXX] (tests): Add test-math-iscanonical.cc.
(CFLAGS-test-math-iscanonical.cc): New variable.
* math/test-math-iscanonical.cc: New file.
* sysdeps/ieee754/ldbl-96/bits/iscanonical.h (iscanonical):
Provide a C++ implementation based on function overloading,
rather than using __MATH_TG, which uses C-only builtins.
* sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h (iscanonical):
Likewise.
* sysdeps/powerpc/powerpc64le/Makefile
(CFLAGS-test-math-iscanonical.cc): New variable.
On powerpc64le, not all files can have the flag -mfloat128 passed as an
option on the compile command, since that could conflict with other
flags, such as -mno-vsx. Each file that needs the flag, gets it through
a CFLAGS-filename variable on sysdeps/powerpc/powerpc64le/Makefile.
The test cases tst-strtod-nan-locale and tst-wcstod-nan-locale are
missing this flag.
Tested for powerpc64le.
* sysdeps/powerpc/powerpc64le/Makefile
(CFLAGS-tst-strtod-nan-locale.c): New variable.
(CFLAGS-tst-wcstod-nan-locale.c): New variable.
When signaling nans are enabled (with -fsignaling-nans), the C++ version
of iszero uses the fpclassify macro, which is defined with __MATH_TG.
However, when support for float128 is available, __MATH_TG uses the
builtin __builtin_types_compatible_p, which is only available in C mode.
This patch refactors the C++ version of iszero so that it uses function
overloading to select between the floating-point types, instead of
relying on fpclassify and __MATH_TG.
Tested for powerpc64le, s390x, x86_64, and with build-many-glibcs.py.
[BZ #21930]
* math/math.h [defined __cplusplus && defined __SUPPORT_SNAN__]
(iszero): New C++ implementation that does not use
fpclassify/__MATH_TG/__builtin_types_compatible_p, when
signaling nans are enabled, since __builtin_types_compatible_p
is a C-only feature.
* math/test-math-iszero.cc: When __HAVE_DISTINCT_FLOAT128 is
defined, include ieee754_float128.h for access to the union and
member ieee854_float128.ieee.
[__HAVE_DISTINCT_FLOAT128] (do_test): Call check_float128.
[__HAVE_DISTINCT_FLOAT128] (check_float128): New function.
* sysdeps/powerpc/powerpc64le/Makefile [subdir == math]
(CXXFLAGS-test-math-iszero.cc): Add -mfloat128 to the build
options of test-math-zero on powerpc64le.
The macro __MATH_TG contains the logic to select between long double and
_Float128, when these types are ABI-distinct. This logic relies on
__builtin_types_compatible_p, which is not available in C++ mode.
On the other hand, C++ function overloading provides the means to
distinguish between the floating-point types. The overloading
resolution will match the correct parameter regardless of type
qualifiers, i.e.: const and volatile.
Tested for powerpc64le, s390x, and x86_64.
* math/math.h [defined __cplusplus] (issignaling): Provide a C++
definition for issignaling that does not rely on __MATH_TG,
since __MATH_TG uses __builtin_types_compatible_p, which is only
available in C mode.
(CFLAGS-test-math-issignaling.cc): New variable.
* math/Makefile [CXX] (tests): Add test-math-issignaling.
* math/test-math-issignaling.cc: New test for C++ implementation
of type-generic issignaling.
* sysdeps/powerpc/powerpc64le/Makefile [subdir == math]
(CXXFLAGS-test-math-issignaling.cc): Add -mfloat128 to the build
options of test-math-issignaling on powerpc64le.
The patch proposed by Peter Bergner [1] to libgcc in order to fix
[BZ #21707] adds a dependency on a symbol provided by the loader,
forcing the loader to be linked to tests after libgcc was linked.
It also requires to read the thread pointer during IRELA relocations.
Tested on powerpc, powerpc64, powerpc64le, s390x and x86_64.
[1] https://sourceware.org/ml/libc-alpha/2017-06/msg01383.html
[BZ #21707]
* csu/libc-start.c (LIBC_START_MAIN): Perform IREL{,A}
relocations before or after initializing the TCB on statically
linked executables. That's a per-architecture definition.
* elf/rtld.c (dl_main): Add a comment about thread-local
variables initialization.
* sysdeps/generic/libc-start.h: New file. Define
ARCH_APPLY_IREL and ARCH_SETUP_IREL.
* sysdeps/powerpc/Makefile:
[$(subdir) = elf && $(multi-arch) != no] (tests-static-internal): Add tst-tlsifunc-static.
[$(subdir) = elf && $(multi-arch) != no && $(build-shared) == yes]
(tests-internal): Add tst-tlsifunc.
* sysdeps/powerpc/tst-tlsifunc.c: New file.
* sysdeps/powerpc/tst-tlsifunc-static.c: Likewise.
* sysdeps/powerpc/powerpc64le/Makefile (f128-loader-link): New
variable.
[$(subdir) = math] (test-float128% test-ifloat128%): Force
linking to the loader after linking to libgcc.
[$(subdir) = wcsmbs || $(subdir) = stdlib] (bug-strtod bug-strtod2)
(bug-strtod2 tst-strtod-round tst-wcstod-round tst-strtod6 tst-strrom)
(tst-strfrom-locale strfrom-skeleton): Likewise.
* sysdeps/unix/sysv/linux/powerpc/libc-start.h: New file. Define
ARCH_APPLY_IREL and ARCH_SETUP_IREL.
On powerpc64le, the compilation of the files related to float128 support
requires the option -mfloat128 to be passed to gcc. However, not all
possible object suffixes were covered in the Makefile. This patch uses
$(all-object-suffixes) in all remaining rules.
Tested for powerpc64le.
* sysdeps/powerpc/powerpc64le/Makefile: Use $(all-object-suffixes)
to iterate over all possible object suffixes. Add a comment
explaining the use of sysdep-CFLAGS instead of CFLAGS.
This patch adds ULPs for the float128 type, updates the abilist for libc
and libm, and adds the files bits/floatn.h and float128-abi.h, in order to
enable the new type for powerpc64le.
This patch also adds the implementation of sqrtf128 for powerpc64le, since
it is not implemented in libgcc. The sfp-machine.h header is taken from
libgcc.
Tested for powerpc64le (GCC 6.2 and GCC 7.1), powerpc64 and s390x.
* manual/math.texi (Mathematics): Mention the enabling of float128
for powerpc64le.
* sysdeps/powerpc/bits/floatn.h: New file.
* sysdeps/powerpc/fpu/libm-test-ulps: Regenerated.
* sysdeps/powerpc/fpu/math_private.h:
(__ieee754_sqrtf128): New inline override.
* sysdeps/powerpc/powerpc64le/Implies-before: New file.
* sysdeps/powerpc/powerpc64le/Makefile: New file.
* sysdeps/powerpc/powerpc64le/fpu/e_sqrtf128.c: New file.
* sysdeps/powerpc/powerpc64le/fpu/sfp-machine.h: New file.
* sysdeps/powerpc/powerpc64le/power9/fpu/e_sqrtf128.c: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist:
Updated.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64le/float128-abi.h:
New file.
