Add fesetexcept.

TS 18661-1 defines an fesetexcept function for setting floating-point
exception flags without the side-effect of causing enabled traps to be
taken.

This patch series implements this function for glibc.  The present
patch adds the fallback stub implementation, x86 and x86_64
implementations, documentation, tests and ABI baseline updates.  The
remaining patches, some of them untested, add implementations for
other architectures.  The implementations generally follow those of
the fesetexceptflag function.

As for fesetexceptflag, the approach taken for architectures where
setting flags causes enabled traps to be taken is to set the flags
(and potentially cause traps) rather than refusing to set the flags
and returning an error.  Since ISO C and TS 18661 provide no way to
enable traps, this is formally in accordance with the standards.

The NEWS entry should be considered a placeholder, since this patch
series is intended to be followed by further such series adding other
TS 18661-1 features, so that the NEWS entry would end up looking more
like

* New <fenv.h> features from TS 18661-1:2014 are added to libm: the
  fesetexcept, fetestexceptflag, fegetmode and fesetmode functions,
  the femode_t type and the FE_DFL_MODE macro.

with hopefully more such entries for other features, rather than
having an entry for a single function in the end.

I believe we have consensus for adding TS 18661-1 interfaces as per
<https://sourceware.org/ml/libc-alpha/2016-06/msg00421.html>.

Tested for x86_64, x86, mips64 (hard float, and soft float to test the
fallback version), arm (hard float) and powerpc (hard float, soft
float and e500).

	* math/fesetexcept.c: New file.
	* sysdeps/i386/fpu/fesetexcept.c: Likewise.
	* sysdeps/x86_64/fpu/fesetexcept.c: Likewise.
	* math/fenv.h: Define
	__GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION and include
	<bits/libc-header-start.h> instead of including <features.h>.
	[__GLIBC_USE (IEC_60559_BFP_EXT)] (fesetexcept): New function
	declaration.
	* manual/arith.texi (fesetexcept): Document function.
	* math/Versions (fesetexcept): New libm symbol at version
	GLIBC_2.25.
	* math/Makefile (libm-support): Add fesetexcept.
	(tests): Add test-fesetexcept and test-fesetexcept-traps.
	* math/test-fesetexcept.c: New file.
	* math/test-fesetexcept-traps.c: Likewise.
	* sysdeps/nacl/libm.abilist: Update.
	* sysdeps/unix/sysv/linux/aarch64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/alpha/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/arm/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/hppa/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/i386/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/microblaze/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/nios2/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sh/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.

26 files changed, 52 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/aarch64/libm.abilist b/sysdeps/unix/sysv/linux/aarch64/libm.abilist
index 781d2d3571..01b01b72b3 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libm.abilist
@@ -410,3 +410,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
diff --git a/sysdeps/unix/sysv/linux/alpha/libm.abilist b/sysdeps/unix/sysv/linux/alpha/libm.abilist
index f342c6b1da..9ba817d5ee 100644
--- a/sysdeps/unix/sysv/linux/alpha/libm.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libm.abilist
@@ -420,6 +420,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.3.4 GLIBC_2.3.4 A
 GLIBC_2.3.4 __c1_cabsf F
 GLIBC_2.3.4 __c1_cacosf F
diff --git a/sysdeps/unix/sysv/linux/arm/libm.abilist b/sysdeps/unix/sysv/linux/arm/libm.abilist
index 7a02fb1726..d9a6f6f9aa 100644
--- a/sysdeps/unix/sysv/linux/arm/libm.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libm.abilist
@@ -68,6 +68,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 _LIB_VERSION D 0x4
 GLIBC_2.4 __clog10 F
diff --git a/sysdeps/unix/sysv/linux/hppa/libm.abilist b/sysdeps/unix/sysv/linux/hppa/libm.abilist
index bf40ddf929..75d4797084 100644
--- a/sysdeps/unix/sysv/linux/hppa/libm.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libm.abilist
@@ -380,5 +380,7 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 exp2l F
diff --git a/sysdeps/unix/sysv/linux/i386/libm.abilist b/sysdeps/unix/sysv/linux/i386/libm.abilist
index 92e94022c7..17b6d6d1ee 100644
--- a/sysdeps/unix/sysv/linux/i386/libm.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libm.abilist
@@ -422,4 +422,6 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
diff --git a/sysdeps/unix/sysv/linux/ia64/libm.abilist b/sysdeps/unix/sysv/linux/ia64/libm.abilist
index e2737a2ba9..d2d89785fe 100644
--- a/sysdeps/unix/sysv/linux/ia64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libm.abilist
@@ -351,4 +351,6 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist
index 7a02fb1726..d9a6f6f9aa 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist
@@ -68,6 +68,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 _LIB_VERSION D 0x4
 GLIBC_2.4 __clog10 F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist
index 9af59d7d90..3edf8ae305 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist
@@ -420,4 +420,6 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
diff --git a/sysdeps/unix/sysv/linux/microblaze/libm.abilist b/sysdeps/unix/sysv/linux/microblaze/libm.abilist
index 0b1f1360e0..e93410186d 100644
--- a/sysdeps/unix/sysv/linux/microblaze/libm.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/libm.abilist
@@ -379,3 +379,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/libm.abilist b/sysdeps/unix/sysv/linux/mips/mips32/libm.abilist
index 2e2bb00738..88cd724c67 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/libm.abilist
@@ -381,6 +381,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 exp2l F
 _gp_disp _gp_disp A
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/libm.abilist b/sysdeps/unix/sysv/linux/mips/mips64/libm.abilist
index 7daa595282..52d5cb306d 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/libm.abilist
@@ -412,4 +412,6 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
diff --git a/sysdeps/unix/sysv/linux/nios2/libm.abilist b/sysdeps/unix/sysv/linux/nios2/libm.abilist
index a36e2f32fc..37f7a88210 100644
--- a/sysdeps/unix/sysv/linux/nios2/libm.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libm.abilist
@@ -379,3 +379,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist
index abe8c5d8a8..ad61a97f93 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist
@@ -421,6 +421,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 __clog10l F
 GLIBC_2.4 __finitel F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist
index 1c25f56c4c..85422382f6 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist
@@ -420,6 +420,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 __clog10l F
 GLIBC_2.4 __finitel F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist
index 9d19474c34..b2f06083db 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist
@@ -415,3 +415,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist
index cedb18945c..e5d36a1707 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist
@@ -96,6 +96,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 _LIB_VERSION D 0x4
 GLIBC_2.3 __clog10 F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist
index 9b567c6356..457aa719c3 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist
@@ -410,6 +410,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 __clog10l F
 GLIBC_2.4 __finitel F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist
index 78a82fbd71..217d76b2b5 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist
@@ -408,6 +408,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 __clog10l F
 GLIBC_2.4 __finitel F
diff --git a/sysdeps/unix/sysv/linux/sh/libm.abilist b/sysdeps/unix/sysv/linux/sh/libm.abilist
index f98ade7642..d1da0df347 100644
--- a/sysdeps/unix/sysv/linux/sh/libm.abilist
+++ b/sysdeps/unix/sysv/linux/sh/libm.abilist
@@ -380,5 +380,7 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 exp2l F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist
index d2e8421967..1c582558b8 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist
@@ -413,6 +413,8 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 __clog10l F
 GLIBC_2.4 __finitel F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist
index e000221432..6915c872d0 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist
@@ -411,4 +411,6 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist
index 00e82c1425..6ebaa0f163 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist
@@ -380,3 +380,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist
index 00e82c1425..6ebaa0f163 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist
@@ -380,3 +380,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
diff --git a/sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist b/sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist
index 00e82c1425..6ebaa0f163 100644
--- a/sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist
@@ -380,3 +380,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libm.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libm.abilist
index 65b470817c..2e77c3db96 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libm.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libm.abilist
@@ -411,4 +411,6 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F
 GLIBC_2.4 GLIBC_2.4 A
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist
index d35e9f0207..b9ccb1af65 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist
@@ -410,3 +410,5 @@ GLIBC_2.24 nextdownl F
 GLIBC_2.24 nextup F
 GLIBC_2.24 nextupf F
 GLIBC_2.24 nextupl F
+GLIBC_2.25 GLIBC_2.25 A
+GLIBC_2.25 fesetexcept F