glibc/sysdeps/i386/fpu/e_hypotf.S
Joseph Myers 6f0f237bf5 Avoid excess range in results from i386 exp, hypot, pow functions (bug 18980).
i386 exp, hypot and pow functions can return overflowing and
underflowing values with excess range and precision; ; Wilco
Dijkstra's patches to make isfinite etc. expand inline cause this
pre-existing issue to result in test failures.

This patch fixes those functions to avoid excess range and precision
in their return values.  Appropriate macros are added for the repeated
code sequences; in future I'll add more such macros and refactor
existing code forcing underflow (with or without also eliminating
excess range and precision from the return value) to use such macros.

Tested for x86.  If, after this patch, you still see x86 libm test
failures with excess range or precision, please file bugs in Bugzilla.

	[BZ #18980]
	* sysdeps/i386/fpu/i386-math-asm.h (DEFINE_FLT_MIN): New macro.
	(DEFINE_DBL_MIN): Likewise.
	(FLT_NARROW_EVAL_UFLOW_NONNEG_NAN): Likewise.
	(DBL_NARROW_EVAL_UFLOW_NONNEG_NAN): Likewise.
	(FLT_NARROW_EVAL_UFLOW_NONNEG): Likewise.
	(DBL_NARROW_EVAL_UFLOW_NONNEG): Likewise.
	* sysdeps/i386/fpu/e_exp.S: Include <i386-math-asm.h>.
	(dbl_min): Replace with use of DEFINE_DBL_MIN.
	(__ieee754_exp): Use DBL_NARROW_EVAL_UFLOW_NONNEG_NAN.
	(__exp_finite): Use DBL_NARROW_EVAL_UFLOW_NONNEG.
	* sysdeps/i386/fpu/e_exp10.S: Include <i386-math-asm.h>.
	(dbl_min): Replace with use of DEFINE_DBL_MIN.
	(__ieee754_exp10): Use DBL_NARROW_EVAL_UFLOW_NONNEG_NAN.
	* sysdeps/i386/fpu/e_exp10f.S: Include <i386-math-asm.h>.
	(flt_min): Replace with use of DEFINE_FLT_MIN.
	(__ieee754_exp10f): Use FLT_NARROW_EVAL_UFLOW_NONNEG_NAN.
	* sysdeps/i386/fpu/e_exp2.S: Include <i386-math-asm.h>.
	(dbl_min): Replace with use of DEFINE_DBL_MIN.
	(__ieee754_exp2): Use DBL_NARROW_EVAL_UFLOW_NONNEG_NAN.
	* sysdeps/i386/fpu/e_exp2f.S: Include <i386-math-asm.h>.
	(flt_min): Replace with use of DEFINE_FLT_MIN.
	(__ieee754_exp2f): Use FLT_NARROW_EVAL_UFLOW_NONNEG_NAN.
	* sysdeps/i386/fpu/e_expf.S: Include <i386-math-asm.h>.
	(flt_min): Replace with use of DEFINE_FLT_MIN.
	(__ieee754_expf): Use FLT_NARROW_EVAL_UFLOW_NONNEG_NAN.
	(__expf_finite): Use FLT_NARROW_EVAL_UFLOW_NONNEG.
	* sysdeps/i386/fpu/e_hypot.S: Include <i386-math-asm.h>.
	(__ieee754_hypot): Use DBL_NARROW_EVAL.
	* sysdeps/i386/fpu/e_hypotf.S: Include <i386-math-asm.h>.
	(__ieee754_hypotf): Use FLT_NARROW_EVAL.
	* sysdeps/i386/fpu/e_pow.S: Include <i386-math-asm.h>.
	(__ieee754_pow): Use DBL_NARROW_EVAL.
	* sysdeps/i386/fpu/e_powf.S: Include <i386-math-asm.h>.
	(__ieee754_powf): Use FLT_NARROW_EVAL.
	* sysdeps/i386/i686/fpu/multiarch/e_expf-sse2.S
	(__ieee754_expf_sse2): Convert double-precision result to single
	precision.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
2015-09-18 21:53:22 +00:00

65 lines
1.6 KiB
ArmAsm

/* Compute the hypothenuse of X and Y.
Copyright (C) 1998-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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 <sysdep.h>
#include <i386-math-asm.h>
.text
ENTRY(__ieee754_hypotf)
flds 4(%esp) // x
fxam
fnstsw
flds 8(%esp) // y : x
movb %ah, %ch
fxam
fnstsw
movb %ah, %al
orb %ch, %ah
sahf
jc 1f
fmul %st(0) // y * y : x
fxch // x : y * y
fmul %st(0) // x * x : y * y
faddp // x * x + y * y
fsqrt
FLT_NARROW_EVAL
2: ret
// We have to test whether any of the parameters is Inf.
// In this case the result is infinity.
1: andb $0x45, %al
cmpb $5, %al
je 3f // jump if y is Inf
andb $0x45, %ch
cmpb $5, %ch
jne 4f // jump if x is not Inf
fxch
3: fstp %st(1)
fabs
jmp 2b
4: testb $1, %al
jnz 5f // y is NaN
fxch
5: fstp %st(1)
jmp 2b
END(__ieee754_hypotf)
strong_alias (__ieee754_hypotf, __hypotf_finite)