Add float128 support for x86_64, x86.

This patch enables float128 support for x86_64 and x86.  All GCC
versions that can build glibc provide the required support, but since
GCC 6 and before don't provide __builtin_nanq / __builtin_nansq, sNaN
tests and some tests of NaN payloads need to be disabled with such
compilers (this does not affect the generated glibc binaries at all,
just the tests).  bits/floatn.h declares float128 support to be
available for GCC versions that provide the required libgcc support
(4.3 for x86_64, 4.4 for i386 GNU/Linux, 4.5 for i386 GNU/Hurd);
compilation-only support was present some time before then, but not
really useful without the libgcc functions.

fenv_private.h needed updating to avoid trying to put _Float128 values
in registers.  I make no assertion of optimality of the
math_opt_barrier / math_force_eval definitions for this case; they are
simply intended to be sufficient to work correctly.

Tested for x86_64 and x86, with GCC 7 and GCC 6.  (Testing for x32 was
compilation tests only with build-many-glibcs.py to verify the ABI
baseline updates.  I have not done any testing for Hurd, although the
float128 support is enabled there as for GNU/Linux.)

	* sysdeps/i386/Implies: Add ieee754/float128.
	* sysdeps/x86_64/Implies: Likewise.
	* sysdeps/x86/bits/floatn.h: New file.
	* sysdeps/x86/float128-abi.h: Likewise.
	* manual/math.texi (Mathematics): Document support for _Float128
	on x86_64 and x86.
	* sysdeps/i386/fpu/fenv_private.h: Include <bits/floatn.h>.
	(math_opt_barrier): Do not put _Float128 values in floating-point
	registers.
	(math_force_eval): Likewise.
	[__x86_64__] (SET_RESTORE_ROUNDF128): New macro.
	* sysdeps/x86/fpu/Makefile [$(subdir) = math] (CPPFLAGS): Append
	to Makefile variable.
	* sysdeps/x86/fpu/e_sqrtf128.c: New file.
	* sysdeps/x86/fpu/sfp-machine.h: Likewise.  Based on libgcc.
	* sysdeps/x86/math-tests.h: New file.
	* math/libm-test-support.h (XFAIL_FLOAT128_PAYLOAD): New macro.
	* math/libm-test-getpayload.inc (getpayload_test_data): Use
	XFAIL_FLOAT128_PAYLOAD.
	* math/libm-test-setpayload.inc (setpayload_test_data): Likewise.
	* math/libm-test-totalorder.inc (totalorder_test_data): Likewise.
	* math/libm-test-totalordermag.inc (totalordermag_test_data):
	Likewise.
	* sysdeps/unix/sysv/linux/i386/libc.abilist: Update.
	* sysdeps/unix/sysv/linux/i386/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.
	* sysdeps/i386/fpu/libm-test-ulps: Likewise.
	* sysdeps/i386/i686/fpu/multiarch/libm-test-ulps: Likewise.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.

2 files changed, 145 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index 2ff1998ac9..12e77bd7f2 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2021,11 +2021,18 @@ GLIBC_2.25 strfromd F
 GLIBC_2.25 strfromf F
 GLIBC_2.25 strfroml F
 GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 __strtof128_internal F
+GLIBC_2.26 __wcstof128_internal F
 GLIBC_2.26 preadv2 F
 GLIBC_2.26 preadv64v2 F
 GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
+GLIBC_2.26 strfromf128 F
+GLIBC_2.26 strtof128 F
+GLIBC_2.26 strtof128_l F
+GLIBC_2.26 wcstof128 F
+GLIBC_2.26 wcstof128_l F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/i386/libm.abilist b/sysdeps/unix/sysv/linux/i386/libm.abilist
index 761e4420f9..2aef7e5aed 100644
--- a/sysdeps/unix/sysv/linux/i386/libm.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libm.abilist
@@ -473,4 +473,142 @@ GLIBC_2.25 ufromfpl F
 GLIBC_2.25 ufromfpx F
 GLIBC_2.25 ufromfpxf F
 GLIBC_2.25 ufromfpxl F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 __acosf128_finite F
+GLIBC_2.26 __acoshf128_finite F
+GLIBC_2.26 __asinf128_finite F
+GLIBC_2.26 __atan2f128_finite F
+GLIBC_2.26 __atanhf128_finite F
+GLIBC_2.26 __coshf128_finite F
+GLIBC_2.26 __exp10f128_finite F
+GLIBC_2.26 __exp2f128_finite F
+GLIBC_2.26 __expf128_finite F
+GLIBC_2.26 __finitef128 F
+GLIBC_2.26 __fmodf128_finite F
+GLIBC_2.26 __fpclassifyf128 F
+GLIBC_2.26 __gammaf128_r_finite F
+GLIBC_2.26 __hypotf128_finite F
+GLIBC_2.26 __iseqsigf128 F
+GLIBC_2.26 __isinff128 F
+GLIBC_2.26 __isnanf128 F
+GLIBC_2.26 __issignalingf128 F
+GLIBC_2.26 __j0f128_finite F
+GLIBC_2.26 __j1f128_finite F
+GLIBC_2.26 __jnf128_finite F
+GLIBC_2.26 __lgammaf128_r_finite F
+GLIBC_2.26 __log10f128_finite F
+GLIBC_2.26 __log2f128_finite F
+GLIBC_2.26 __logf128_finite F
+GLIBC_2.26 __powf128_finite F
+GLIBC_2.26 __remainderf128_finite F
+GLIBC_2.26 __signbitf128 F
+GLIBC_2.26 __sinhf128_finite F
+GLIBC_2.26 __sqrtf128_finite F
+GLIBC_2.26 __y0f128_finite F
+GLIBC_2.26 __y1f128_finite F
+GLIBC_2.26 __ynf128_finite F
+GLIBC_2.26 acosf128 F
+GLIBC_2.26 acoshf128 F
+GLIBC_2.26 asinf128 F
+GLIBC_2.26 asinhf128 F
+GLIBC_2.26 atan2f128 F
+GLIBC_2.26 atanf128 F
+GLIBC_2.26 atanhf128 F
+GLIBC_2.26 cabsf128 F
+GLIBC_2.26 cacosf128 F
+GLIBC_2.26 cacoshf128 F
+GLIBC_2.26 canonicalizef128 F
+GLIBC_2.26 cargf128 F
+GLIBC_2.26 casinf128 F
+GLIBC_2.26 casinhf128 F
+GLIBC_2.26 catanf128 F
+GLIBC_2.26 catanhf128 F
+GLIBC_2.26 cbrtf128 F
+GLIBC_2.26 ccosf128 F
+GLIBC_2.26 ccoshf128 F
+GLIBC_2.26 ceilf128 F
+GLIBC_2.26 cexpf128 F
+GLIBC_2.26 cimagf128 F
+GLIBC_2.26 clog10f128 F
+GLIBC_2.26 clogf128 F
+GLIBC_2.26 conjf128 F
+GLIBC_2.26 copysignf128 F
+GLIBC_2.26 cosf128 F
+GLIBC_2.26 coshf128 F
+GLIBC_2.26 cpowf128 F
+GLIBC_2.26 cprojf128 F
+GLIBC_2.26 crealf128 F
+GLIBC_2.26 csinf128 F
+GLIBC_2.26 csinhf128 F
+GLIBC_2.26 csqrtf128 F
+GLIBC_2.26 ctanf128 F
+GLIBC_2.26 ctanhf128 F
+GLIBC_2.26 erfcf128 F
+GLIBC_2.26 erff128 F
+GLIBC_2.26 exp10f128 F
+GLIBC_2.26 exp2f128 F
+GLIBC_2.26 expf128 F
+GLIBC_2.26 expm1f128 F
+GLIBC_2.26 fabsf128 F
+GLIBC_2.26 fdimf128 F
+GLIBC_2.26 floorf128 F
+GLIBC_2.26 fmaf128 F
+GLIBC_2.26 fmaxf128 F
+GLIBC_2.26 fmaxmagf128 F
+GLIBC_2.26 fminf128 F
+GLIBC_2.26 fminmagf128 F
+GLIBC_2.26 fmodf128 F
+GLIBC_2.26 frexpf128 F
+GLIBC_2.26 fromfpf128 F
+GLIBC_2.26 fromfpxf128 F
+GLIBC_2.26 getpayloadf128 F
+GLIBC_2.26 hypotf128 F
+GLIBC_2.26 ilogbf128 F
+GLIBC_2.26 j0f128 F
+GLIBC_2.26 j1f128 F
+GLIBC_2.26 jnf128 F
+GLIBC_2.26 ldexpf128 F
+GLIBC_2.26 lgammaf128 F
+GLIBC_2.26 lgammaf128_r F
+GLIBC_2.26 llogbf128 F
+GLIBC_2.26 llrintf128 F
+GLIBC_2.26 llroundf128 F
+GLIBC_2.26 log10f128 F
+GLIBC_2.26 log1pf128 F
+GLIBC_2.26 log2f128 F
+GLIBC_2.26 logbf128 F
+GLIBC_2.26 logf128 F
+GLIBC_2.26 lrintf128 F
+GLIBC_2.26 lroundf128 F
+GLIBC_2.26 modff128 F
+GLIBC_2.26 nanf128 F
+GLIBC_2.26 nearbyintf128 F
+GLIBC_2.26 nextafterf128 F
+GLIBC_2.26 nextdownf128 F
+GLIBC_2.26 nextupf128 F
+GLIBC_2.26 powf128 F
+GLIBC_2.26 remainderf128 F
+GLIBC_2.26 remquof128 F
+GLIBC_2.26 rintf128 F
+GLIBC_2.26 roundevenf128 F
+GLIBC_2.26 roundf128 F
+GLIBC_2.26 scalblnf128 F
+GLIBC_2.26 scalbnf128 F
+GLIBC_2.26 setpayloadf128 F
+GLIBC_2.26 setpayloadsigf128 F
+GLIBC_2.26 sincosf128 F
+GLIBC_2.26 sinf128 F
+GLIBC_2.26 sinhf128 F
+GLIBC_2.26 sqrtf128 F
+GLIBC_2.26 tanf128 F
+GLIBC_2.26 tanhf128 F
+GLIBC_2.26 tgammaf128 F
+GLIBC_2.26 totalorderf128 F
+GLIBC_2.26 totalordermagf128 F
+GLIBC_2.26 truncf128 F
+GLIBC_2.26 ufromfpf128 F
+GLIBC_2.26 ufromfpxf128 F
+GLIBC_2.26 y0f128 F
+GLIBC_2.26 y1f128 F
+GLIBC_2.26 ynf128 F
 GLIBC_2.4 GLIBC_2.4 A