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526af54142
The i386 implementation of atanhl, for small arguments, does a calculation that involves computing twice the square of the argument, resulting in spurious underflows for some arguments. This patch fixes this by just returning the argument when its exponent is below -32, with underflow being forced as needed for subnormal arguments. Tested for x86 and x86_64. [BZ #18049] * sysdeps/i386/fpu/e_atanhl.S (__ieee754_atanhl): For exponents below -32, return the argument, with underflow if subnormal. * math/auto-libm-test-in: Add more tests of atanh. * math/auto-libm-test-out: Regenerated.
127 lines
3.4 KiB
ArmAsm
127 lines
3.4 KiB
ArmAsm
/* ix87 specific implementation of arctanh function.
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Copyright (C) 1996-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <machine/asm.h>
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.section .rodata
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.align ALIGNARG(4)
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/* Please note that we use double values for 0.5 and 1.0. These
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numbers have exact representations and so we don't get accuracy
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problems. The advantage is that the code is simpler. */
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.type half,@object
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half: .double 0.5
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ASM_SIZE_DIRECTIVE(half)
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.type one,@object
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one: .double 1.0
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ASM_SIZE_DIRECTIVE(one)
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/* It is not important that this constant is precise. It is only
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a value which is known to be on the safe side for using the
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fyl2xp1 instruction. */
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.type limit,@object
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limit: .double 0.29
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ASM_SIZE_DIRECTIVE(limit)
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.align ALIGNARG(4)
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.type ln2_2,@object
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ln2_2: .tfloat 0.3465735902799726547086160
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ASM_SIZE_DIRECTIVE(ln2_2)
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#ifdef PIC
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#define MO(op) op##@GOTOFF(%edx)
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#else
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#define MO(op) op
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#endif
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.text
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ENTRY(__ieee754_atanhl)
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movl 12(%esp), %ecx
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movl %ecx, %eax
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andl $0x7fff, %eax
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cmpl $0x7fff, %eax
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je 5f
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cmpl $0x3fdf, %eax
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jge 7f
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// Exponent below -32; return x, with underflow if subnormal.
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fldt 4(%esp)
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cmpl $0, %eax
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jne 8f
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fld %st(0)
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fmul %st(0)
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fstp %st(0)
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8: ret
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7:
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#ifdef PIC
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LOAD_PIC_REG (dx)
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#endif
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andl $0x8000, %ecx // ECX == 0 iff X >= 0
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fldt MO(ln2_2) // 0.5*ln2
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xorl %ecx, 12(%esp)
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fldt 4(%esp) // |x| : 0.5*ln2
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fcoml MO(half) // |x| : 0.5*ln2
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fld %st(0) // |x| : |x| : 0.5*ln2
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fnstsw // |x| : |x| : 0.5*ln2
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sahf
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jae 2f
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fadd %st, %st(1) // |x| : 2*|x| : 0.5*ln2
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fld %st // |x| : |x| : 2*|x| : 0.5*ln2
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fsubrl MO(one) // 1-|x| : |x| : 2*|x| : 0.5*ln2
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fxch // |x| : 1-|x| : 2*|x| : 0.5*ln2
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fmul %st(2) // 2*|x|^2 : 1-|x| : 2*|x| : 0.5*ln2
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fdivp // (2*|x|^2)/(1-|x|) : 2*|x| : 0.5*ln2
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faddp // 2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
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fcoml MO(limit) // 2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
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fnstsw // 2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
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sahf
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jae 4f
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fyl2xp1 // 0.5*ln2*ld(1+2*|x|+(2*|x|^2)/(1-|x|))
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jecxz 3f
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fchs // 0.5*ln2*ld(1+2*x+(2*x^2)/(1-x))
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3: ret
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.align ALIGNARG(4)
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4: faddl MO(one) // 1+2*|x|+(2*|x|^2)/(1-|x|) : 0.5*ln2
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fyl2x // 0.5*ln2*ld(1+2*|x|+(2*|x|^2)/(1-|x|))
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jecxz 3f
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fchs // 0.5*ln2*ld(1+2*x+(2*x^2)/(1-x))
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3: ret
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.align ALIGNARG(4)
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2: faddl MO(one) // 1+|x| : |x| : 0.5*ln2
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fxch // |x| : 1+|x| : 0.5*ln2
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fsubrl MO(one) // 1-|x| : 1+|x| : 0.5*ln2
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fdivrp // (1+|x|)/(1-|x|) : 0.5*ln2
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fyl2x // 0.5*ln2*ld((1+|x|)/(1-|x|))
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jecxz 3f
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fchs // 0.5*ln2*ld((1+x)/(1-x))
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3: ret
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// x == NaN or <EFBFBD>Inf
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5: cmpl $0x80000000, 8(%esp)
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ja 6f
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cmpl $0, 4(%esp)
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je 7b
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6: fldt 4(%esp)
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ret
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END(__ieee754_atanhl)
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strong_alias (__ieee754_atanhl, __atanhl_finite)
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