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Joseph Myers 63716ab270 Add build infrastructure for narrowing libm functions.
TS 18661-1 defines libm functions that carry out an operation (+ - * /
sqrt fma) on their arguments and return a result rounded to a
(usually) narrower type, as if the original result were computed to
infinite precision and then rounded directly to the result type
without any intermediate rounding to the argument type.  For example,
fadd, faddl and daddl for addition.  These are the last remaining TS
18661-1 functions left to be added to glibc.  TS 18661-3 extends this
to corresponding functions for _FloatN and _FloatNx types.

As functions parametrized by two rather than one varying
floating-point types, these functions require infrastructure in glibc
that was not required for previous libm functions.  This patch
provides such infrastructure - excluding test support, and actual
function implementations, which will be in subsequent patches.

Declaring the functions uses a header bits/mathcalls-narrow.h, which
is included many times, for each relevant pair of types.  This will
end up containing macro calls of the form

__MATHCALL_NARROW (__MATHCALL_NAME (add), __MATHCALL_REDIR_NAME (add), 2);

for each family of narrowing functions.  (The structure of this macro
call, with the calls to __MATHCALL_NAME and __MATHCALL_REDIR_NAME
there rather than in the definition of __MATHCALL_NARROW, arises from
the names such as "add" *not* themselves being reserved identifiers -
meaning it's necessary to avoid any indirection that would result in a
user-defined "add" macro being expanded.)  Whereas for existing
functions declaring long double functions is disabled if _LIBC in the
case where they alias double functions, to facilitate defining the
long double functions as aliases of the double ones, there is no such
logic for the narrowing functions in this patch.  Rather, the files
defining such functions are expected to use #define to hide the
original declarations of the alias names, to avoid errors about
defining aliases with incompatible types.

math/Makefile support is added for building the functions (listed in
libm-narrow-fns, currently empty) for all relevant pairs of types.  An
internal header math-narrow.h is added for macros shared between
multiple function implementations - currently a ROUND_TO_ODD macro to
facilitate writing functions using the round-to-odd implementation
approach, and alias macros to create all the required function
aliases.  libc_feholdexcept_setroundf128 and libc_feupdateenv_testf128
are added for use when required (only for x86_64).  float128_private.h
support is added for ldbl-128 narrowing functions to be used for
_Float128.

Certain things are specifically omitted from this patch and the
immediate followups.  tgmath.h support is deferred; there remain
unresolved questions about how the type-generic macros for these
functions are supposed to work, especially in the case of arguments of
integer type.  The math.h / bits/mathcalls-narrow.h logic, and the
logic for determining what functions / aliases to define, will need
some adjustments to support the sqrt and fma functions, where
e.g. f32xsqrtf64 can just be an alias for sqrt rather than a separate
function.  TS 18661-1 defines FP_FAST_* macros but no support is
included for defining them (they won't in general be true without
architecture-specific optimized function versions).

For each of the function groups (add sub mul div sqrt fma) there are
always six functions present (e.g. fadd, faddl, daddl, f32addf64,
f32addf32x, f32xaddf64).  When _Float64x and _Float128 are supported,
there are seven more (e.g. f32addf64x, f32addf128, f64addf64x,
f64addf128, f32xaddf64x, f32xaddf128, f64xaddf128).  In addition, in
the ldbl-opt case there are function names such as __nldbl_daddl (an
alias for f32xaddf64, which is not a reserved name in TS 18661-1, only
in TS 18661-3), for calls to daddl to be mapped to in the
-mlong-double-64 case.  (Calls to faddl just get mapped to fadd, and
for sqrt and fma there won't be __nldbl_* functions because dsqrtl and
dfmal can just be mapped to sqrt and fma with -mlong-double-64.)

While there are six or thirteen functions present in each group (plus
__nldbl_* names only as an ABI, not an API), not all are distinct;
they fall in various groups of aliases.  There are two distinct
versions built if long double has the same format as double; four if
they have distinct formats but there is no _Float64x or _Float128
support; five if long double has binary128 format; seven when
_Float128 is distinct from long double.

Architecture-specific optimized versions are possible, but not
included in my patches.  For example, IA64 generally supports
narrowing the result of most floating-point instructions; Power ISA
2.07 (POWER8) supports double values as arguments to float
instructions, with the results narrowed as expected; Power ISA 3
(POWER9) supports round-to-odd for float128 instructions, so meaning
that approach can be used without needing to set and restore the
rounding mode and test "inexact".  I intend to leave any such
optimized versions to the architecture maintainers.  Generally in such
cases it would also make sense for calls to these functions to be
expanded inline (given -fno-math-errno); I put a suggestion for TS
18661-1 built-in functions at <https://gcc.gnu.org/wiki/SummerOfCode>.

Tested for x86_64 (this patch in isolation, as well as testing for
various configurations in conjunction with further patches).

	* math/bits/mathcalls-narrow.h: New file.
	* include/bits/mathcalls-narrow.h: Likewise.
	* math/math-narrow.h: Likewise.
	* math/math.h (__MATHCALL_NARROW_ARGS_1): New macro.
	(__MATHCALL_NARROW_ARGS_2): Likewise.
	(__MATHCALL_NARROW_ARGS_3): Likewise.
	(__MATHCALL_NARROW_NORMAL): Likewise.
	(__MATHCALL_NARROW_REDIR): Likewise.
	(__MATHCALL_NARROW): Likewise.
	[__GLIBC_USE (IEC_60559_BFP_EXT)]: Repeatedly include
	<bits/mathcalls-narrow.h> with _Mret_, _Marg_ and __MATHCALL_NAME
	defined.
	[__GLIBC_USE (IEC_60559_TYPES_EXT)]: Likewise.
	* math/Makefile (headers): Add bits/mathcalls-narrow.h.
	(libm-narrow-fns): New variable.
	(libm-narrow-types-basic): Likewise.
	(libm-narrow-types-ldouble-yes): Likewise.
	(libm-narrow-types-float128-yes): Likewise.
	(libm-narrow-types-float128-alias-yes): Likewise.
	(libm-narrow-types): Likewise.
	(libm-routines): Add narrowing functions.
	* sysdeps/i386/fpu/fenv_private.h [__x86_64__]
	(libc_feholdexcept_setroundf128): New macro.
	[__x86_64__] (libc_feupdateenv_testf128): Likewise.
	* sysdeps/ieee754/float128/float128_private.h: Include
	<math/math-narrow.h>.
	[libc_feholdexcept_setroundf128] (libc_feholdexcept_setroundl):
	Undefine and redefine.
	[libc_feupdateenv_testf128] (libc_feupdateenv_testl): Likewise.
	(libm_alias_float_ldouble): Undefine and redefine.
	(libm_alias_double_ldouble): Likewise.
2018-02-09 21:18:52 +00:00
argp Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
assert Fix uninitialized variable in assert_perror (bug 22761) 2018-02-05 11:06:15 +01:00
benchtests benchtests: Make bench-memcmp print json 2018-02-02 09:56:47 +05:30
bits Post-cleanup 2: minimize _G_config.h. 2018-02-07 10:10:32 -05:00
catgets Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
ChangeLog.old Add missing reference to bug 21654 2017-10-07 13:14:36 +02:00
conform Don't install libio.h or _G_config.h. 2018-02-07 10:07:31 -05:00
crypt crypt: Fix badsalttest test (Bug 22765) 2018-02-01 00:02:49 -08:00
csu Post-cleanup 2: minimize _G_config.h. 2018-02-07 10:10:32 -05:00
ctype Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
debug Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
dirent Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
dlfcn Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
elf Add elf.h NT_* macros from Linux 4.15 (bug 14890). 2018-02-06 00:37:17 +00:00
gmon Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
gnulib Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
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gshadow Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
hesiod Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
hurd hurd: Fix preprocessor indentation 2018-01-29 23:00:17 +01:00
iconv Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
iconvdata Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
include Add build infrastructure for narrowing libm functions. 2018-02-09 21:18:52 +00:00
inet Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
intl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
io Revert "hurd: Fix building io/tst-fchownat.c" 2018-01-28 19:13:20 +01:00
libidn Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
libio Post-cleanup 2: minimize _G_config.h. 2018-02-07 10:10:32 -05:00
locale Fix -Os strcoll, wcscoll, build (bug 21313). 2018-02-07 13:36:14 +00:00
localedata hr_HR: Add alternative month names (bug 10871). 2018-01-30 12:48:17 +01:00
login Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
mach hurd: Add expected ABI lists 2018-01-29 22:07:44 +01:00
malloc malloc: Use assert.h's assert macro 2018-01-29 23:00:17 +01:00
manual manual: Fix Texinfo warnings about improper node names. 2018-02-09 04:40:48 -08:00
math Add build infrastructure for narrowing libm functions. 2018-02-09 21:18:52 +00:00
mathvec Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
misc Fix -Os gnu_dev_* linknamespace, localplt issues (bug 15105, bug 19463). 2018-02-07 14:57:31 +00:00
nis libnsl: Turn remaining symbols into compat symbols [BZ #22701] 2018-01-29 17:42:30 +01:00
nptl Revert Intel CET changes to __jmp_buf_tag (Bug 22743) 2018-01-25 23:43:46 -08:00
nptl_db Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
nscd hurd: Fix getifaddrs / freeifaddrs exposition 2018-01-28 19:06:15 +01:00
nss nss: Adjust tests to use nss_files only 2018-01-30 14:26:31 +01:00
po Update translations from the Translation Project 2018-01-17 22:00:50 +00:00
posix Define char16_t, char32_t consistently with uint_least16_t, uint_least32_t (bug 17979). 2018-02-07 20:33:55 +00:00
pwd Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
resolv hurd: fix warning 2018-01-27 16:43:16 +01:00
resource resource/tst-getrlimit.c: Add copyright header 2018-01-05 20:34:10 +01:00
rt Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
scripts Use MPFR 4.0.1 in build-many-glibcs.py. 2018-02-07 17:38:13 +00:00
setjmp Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
shadow Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
signal Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
socket Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
soft-fp Do not use packed structures in soft-fp. 2018-02-01 20:44:49 +00:00
stdio-common Remove some unnecessary redefinitions of std symbols. 2018-02-05 19:58:01 -05:00
stdlib hurd: Fix build 2018-02-04 14:02:36 +01:00
streams Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
string Unify and simplify bits/byteswap.h, bits/byteswap-16.h headers (bug 14508, bug 15512, bug 17082, bug 20530). 2018-02-06 21:55:08 +00:00
sunrpc Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
support support: Preserve errno in write_message, TEST_VERIFY and other checks 2018-01-12 13:35:01 +01:00
sysdeps Add build infrastructure for narrowing libm functions. 2018-02-09 21:18:52 +00:00
sysvipc Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
termios Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
time time: Reference CLOCKS_PER_SEC in clock comment [BZ #22735] 2018-02-02 11:59:31 +01:00
timezone Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
wcsmbs Define char16_t, char32_t consistently with uint_least16_t, uint_least32_t (bug 17979). 2018-02-07 20:33:55 +00:00
wctype Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
.gitattributes Assume __NR_openat is always defined 2016-03-23 23:35:08 +01:00
.gitignore Add *.pyc to .gitignore 2015-05-18 15:26:26 +05:30
abi-tags Remove the bulk of the NaCl port. 2017-05-20 08:09:10 -04:00
aclocal.m4 LIBC_SLIBDIR_RTLDDIR: substitute arguments in single quotes 2018-01-25 17:20:28 +01:00
ChangeLog Add build infrastructure for narrowing libm functions. 2018-02-09 21:18:52 +00:00
config.h.in Add RISC-V entries to config.h.in 2018-01-29 10:24:57 -08:00
config.make.in Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
configure Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
configure.ac Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
COPYING Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
COPYING.LIB Update to latest versions of GPL-2.0 and LGPL-2.1 2013-09-09 12:52:48 +10:00
extra-lib.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
gen-locales.mk Split locale generation snippet into a separate file 2015-05-13 13:05:28 +05:30
INSTALL Fix typo in the previous commit 2018-01-31 23:13:00 +00:00
libc-abis
libof-iterator.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
LICENSES Expand LICENSES file. 2012-12-05 21:56:15 +00:00
MAINTAINERS Add MAINTAINERS 2017-05-11 13:38:30 -04:00
Makeconfig Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile.in New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
Makerules Allow make-link-multidir to make subdirectories 2018-01-06 23:35:46 -08:00
NEWS Don't install libio.h or _G_config.h. 2018-02-07 10:07:31 -05:00
o-iterator.mk
README Skeleton documentation for the RISC-V port 2018-01-29 10:22:26 -08:00
Rules Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
shlib-versions Extend NSS test suite 2017-07-17 15:52:44 -04:00
test-skeleton.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
version.h Open master branch for glibc 2.28 development 2018-02-01 17:18:19 +00:00

This directory contains the sources of the GNU C Library.
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