glibc/sysdeps/s390/fpu/fsetexcptflg.c
Stefan Liebler e9b424881a S390: Do not set FE_INEXACT with feraiseexcept (FE_OWERFLOW|FE_UNDERFLOW).
On s390 feraiseexcept (FE_OVERFLOW|FE_UNDERFLOW) sets FE_INEXACT, too.
This patch uses z196 zarch load rounded instruction which can suppress
FE_INEXACT exception if gcc has z196 support in used configuration.
Otherwise FE_INEXACT flag is set as before. The gcc support is tested
in a new configure-check.

A comment in fsetexcptflg.c is corrected as new exceptions are not
executed with the next floating-point instruction if fpc is set with
_FPU_SETCW macro. It seems the comment was copied e.g. from
sysdeps/x86_64/fpu/fsetexcptflg.c file.

ChangeLog:

	* config.h.in (HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT):
	New undefine.
	* sysdeps/s390/configure.ac: Add test for z196 zarch support.
	* sysdeps/s390/configure: Regenerated.
	* sysdeps/s390/fpu/fraiseexcpt.c (__feraiseexcept): Use ledbra
	instruction for raising over-/underflow if z196 zarch is supported
	by default.
	* sysdeps/s390/fpu/fsetexcptflg.c (fesetexceptflag):
	Correct comment.
2016-08-31 14:54:55 +02:00

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C

/* Set floating-point environment exception handling.
Copyright (C) 2000-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Denis Joseph Barrow (djbarrow@de.ibm.com).
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <fenv_libc.h>
#include <math.h>
#include <fpu_control.h>
int
fesetexceptflag (const fexcept_t *flagp, int excepts)
{
fexcept_t temp, newexcepts;
/* Get the current environment. We have to do this since we cannot
separately set the status word. */
_FPU_GETCW (temp);
/* Install the new exception bits in the Accrued Exception Byte. */
excepts = excepts & FE_ALL_EXCEPT;
newexcepts = excepts << FPC_FLAGS_SHIFT;
temp &= ~newexcepts;
if ((temp & FPC_NOT_FPU_EXCEPTION) == 0)
/* Bits 6, 7 of dxc-byte are zero,
thus bits 0-5 of dxc-byte correspond to the flag-bits.
Clear given exceptions in dxc-field. */
temp &= ~(excepts << FPC_DXC_SHIFT);
/* Integrate dxc-byte of flagp into flags. The dxc-byte of flagp contains
either an ieee-exception or 0 (see fegetexceptflag). */
temp |= (*flagp | ((*flagp >> FPC_DXC_SHIFT) << FPC_FLAGS_SHIFT))
& newexcepts;
/* Store the new status word (along with the rest of the environment.
Possibly new exceptions are set but they won't get executed. */
_FPU_SETCW (temp);
/* Success. */
return 0;
}