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Joseph Myers 30dcf959d2 Avoid "inexact" exceptions in i386/x86_64 trunc functions (bug 15479).
As discussed in
<https://sourceware.org/ml/libc-alpha/2016-05/msg00577.html>, TS
18661-1 disallows ceil, floor, round and trunc functions from raising
the "inexact" exception, in accordance with general IEEE 754 semantics
for when that exception is raised.  Fixing this for x87 floating point
is more complicated than for the other versions of these functions,
because they use the frndint instruction that raises "inexact" and
this can only be avoided by saving and restoring the whole
floating-point environment.

As I noted in
<https://sourceware.org/ml/libc-alpha/2016-06/msg00128.html>, I have
now implemented a GCC option -fno-fp-int-builtin-inexact for GCC 7,
such that GCC will inline these functions on x86, without caring about
"inexact", when the default -ffp-int-builtin-inexact is in effect.
This allows users to get optimized code depending on the options they
pass to the compiler, while making the out-of-line functions follow TS
18661-1 semantics and avoid "inexact".

This patch duly fixes the out-of-line trunc function implementations
to avoid "inexact", in the same way as the nearbyint implementations.

I do not know how the performance of implementations such as these
based on saving the environment and changing the rounding mode
temporarily compares to that of the C versions or SSE 4.1 versions (of
course, for 32-bit x86 SSE implementations still need to get the
return value in an x87 register); it's entirely possible other
implementations could be faster in some cases.

Tested for x86_64 and x86.

	[BZ #15479]
	* sysdeps/i386/fpu/s_trunc.S (__trunc): Save and restore
	floating-point environment rather than just control word.
	* sysdeps/i386/fpu/s_truncf.S (__truncf): Likewise.
	* sysdeps/i386/fpu/s_truncl.S (__truncl): Save and restore
	floating-point environment, with "invalid" exceptions merged in,
	rather than just control word.
	* sysdeps/x86_64/fpu/s_truncl.S (__truncl): Likewise.
	* math/libm-test.inc (trunc_test_data): Do not allow spurious
	"inexact" exceptions.
2016-06-27 17:26:52 +00:00
argp argp: Use fwrite_unlocked instead of __fxprintf when !_LIBC 2016-01-07 04:25:54 -05:00
assert Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
benchtests Clear destination buffer updated by the previous run 2016-05-18 05:51:59 -07:00
bits Move sysdeps/generic/bits/hwcap.h to top-level bits/ 2016-06-22 05:48:11 -07:00
catgets Fix building glibc master with NDEBUG and --with-cpu. 2016-03-15 23:23:24 -04:00
conform Revert {send,sendm,recv,recvm}msg conformance changes 2016-06-10 11:58:16 -03:00
crypt Fix build failures with -DDEBUG. 2016-01-15 11:07:41 -07:00
csu Update copyright dates not handled by scripts/update-copyrights. 2016-01-04 16:26:30 +00:00
ctype Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
debug libio: Implement vtable verification [BZ #20191] 2016-06-23 20:01:52 +02:00
dirent Deprecate readdir_r, readdir64_r [BZ #19056] 2016-02-20 12:56:55 +01:00
dlfcn tst-rec-dlopen: Fix build fail due to missing inclusion of string.h 2016-06-06 11:03:04 +02:00
elf Reduce number of mmap calls from __libc_memalign in ld.so 2016-04-23 06:05:15 -07:00
gmon Copy x86_64 _mcount.op from _mcount.o 2016-03-03 06:56:22 -08:00
gnulib Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
grp NSS: Implement group merging support. 2016-04-29 22:18:21 -04:00
gshadow Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
hesiod hesiod: Avoid heap overflow in get_txt_records [BZ #20031] 2016-05-02 16:04:32 +02:00
hurd Fix O_DIRECTORY lookup on trivial translators 2016-01-13 00:48:30 +01:00
iconv Fix UTF-16 surrogate handling. [BZ #19727] 2016-05-25 17:18:06 +02:00
iconvdata Fix UTF-16 surrogate handling. [BZ #19727] 2016-05-25 17:18:06 +02:00
include Remove atomic_compare_and_exchange_bool_rel. 2016-06-24 23:04:40 +03:00
inet Fix macro API for __USE_KERNEL_IPV6_DEFS. 2016-06-02 23:52:06 -04:00
intl Enable --localedir to set message catalog directory (Bug 14259) 2016-02-24 20:06:04 -05:00
io 2016-06-11 Paul Pluzhnikov <ppluzhnikov@google.com> 2016-06-11 14:50:16 -07:00
libidn Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
libio libio: Implement vtable verification [BZ #20191] 2016-06-23 20:01:52 +02:00
locale localedef: drop unused --old-style 2016-06-11 01:37:04 -04:00
localedata localedata: ro_RO: update Tuesday translation [BZ #18911] 2016-06-16 01:28:42 -04:00
login 2016-06-11 Paul Pluzhnikov <ppluzhnikov@google.com> 2016-06-11 14:50:16 -07:00
mach mach: Add mach_print sycsall declaration 2016-06-09 01:43:49 +02:00
malloc test-skeleton.c: Add write_message function 2016-06-23 11:00:36 +02:00
manual Add nextup and nextdown math functions 2016-06-16 21:37:45 +05:30
math Avoid "inexact" exceptions in i386/x86_64 trunc functions (bug 15479). 2016-06-27 17:26:52 +00:00
mathvec Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
misc Fix p{readv,writev}{64} consolidation implementation 2016-06-21 11:29:18 -03:00
nis Suppress GCC 6 warning about ambiguous 'else' with -Wparentheses 2016-04-15 13:30:55 +02:00
nptl Remove atomic_compare_and_exchange_bool_rel. 2016-06-24 23:04:40 +03:00
nptl_db Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
nscd Remove atomic_compare_and_exchange_bool_rel. 2016-06-24 23:04:40 +03:00
nss nss_db: Fix initialization of iteration position [BZ #20237] 2016-06-11 12:12:56 +02:00
po Enable --localedir to set message catalog directory (Bug 14259) 2016-02-24 20:06:04 -05:00
posix Avoid attempt for runtime checks if all environments are defined 2016-06-24 02:00:12 +05:30
pwd Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
resolv resolv: Call gmtime_r instead of gmtime in p_secstodate [BZ #20017] 2016-05-10 10:50:24 +02:00
resource Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
rt Fix rt/tst-aio64.c as well, and mention login/tst-utmp.c in ChangeLog 2016-06-11 14:59:27 -07:00
scripts Add more hurd exception to local headers list 2016-05-30 19:03:01 +02:00
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soft-fp Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
stdio-common libio: Implement vtable verification [BZ #20191] 2016-06-23 20:01:52 +02:00
stdlib libio: Implement vtable verification [BZ #20191] 2016-06-23 20:01:52 +02:00
streams Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
string Clear destination buffer updated by the previous run 2016-05-18 05:51:59 -07:00
sunrpc CVE-2016-4429: sunrpc: Do not use alloca in clntudp_call [BZ #20112] 2016-05-23 20:18:34 +02:00
sysdeps Avoid "inexact" exceptions in i386/x86_64 trunc functions (bug 15479). 2016-06-27 17:26:52 +00:00
sysvipc Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
termios Declare tcgetsid for XPG4 (bug 20055). 2016-05-11 18:05:37 +00:00
time Fix build failures with -DDEBUG. 2016-01-15 11:07:41 -07:00
timezone Remove mention of checktab.awk in timezone/README. 2016-03-14 14:11:51 -04:00
wcsmbs Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
wctype Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +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 Add arm-nacl port. 2015-04-17 09:02:19 -07:00
aclocal.m4 Rename localedir to complocaledir (bug 14259). 2015-11-27 10:22:38 -05:00
BUGS
ChangeLog Avoid "inexact" exceptions in i386/x86_64 trunc functions (bug 15479). 2016-06-27 17:26:52 +00:00
ChangeLog.1
ChangeLog.2
ChangeLog.3
ChangeLog.4
ChangeLog.5
ChangeLog.6 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.7 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.8 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.9
ChangeLog.10 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.11 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.12 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.13
ChangeLog.14 Revert "ChangeLogs: convert to utf-8" 2016-02-12 16:35:27 -05:00
ChangeLog.15
ChangeLog.16
ChangeLog.17
ChangeLog.old-ports
ChangeLog.old-ports-aarch64
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ChangeLog.old-ports-m68k
ChangeLog.old-ports-microblaze
ChangeLog.old-ports-mips
ChangeLog.old-ports-powerpc
ChangeLog.old-ports-tile
config.h.in S390: Configure check for vector support in gcc. 2016-05-25 17:18:04 +02:00
config.make.in Enable --localedir to set message catalog directory (Bug 14259) 2016-02-24 20:06:04 -05:00
configure Avoid an extra branch to PLT for -z now 2016-05-24 08:44:23 -07:00
configure.ac Avoid an extra branch to PLT for -z now 2016-05-24 08:44:23 -07:00
CONFORMANCE
COPYING
COPYING.LIB
cppflags-iterator.mk
extra-lib.mk
extra-modules.mk
gen-locales.mk Split locale generation snippet into a separate file 2015-05-13 13:05:28 +05:30
INSTALL 2016-06-05 Paul Pluzhnikov <ppluzhnikov@google.com> 2016-06-05 08:41:13 -07:00
libc-abis
LICENSES
Makeconfig Enable --localedir to set message catalog directory (Bug 14259) 2016-02-24 20:06:04 -05:00
Makefile Fix edito in last change. 2016-03-04 15:45:35 -08:00
Makefile.in New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
Makerules libio: Implement vtable verification [BZ #20191] 2016-06-23 20:01:52 +02:00
NAMESPACE
NEWS Add nextup and nextdown math functions 2016-06-16 21:37:45 +05:30
o-iterator.mk
PROJECTS
README Require Linux 3.2 except on x86 / x86_64, 3.2 headers everywhere. 2016-02-24 17:15:12 +00:00
Rules New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
shlib-versions This is update for configure, build and install of vector math library. 2015-05-14 18:07:06 +03:00
test-skeleton.c test-skeleton.c (xrealloc): Support realloc-as-free 2016-06-23 16:12:48 +02:00
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