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39775f00b1
It removes the wrapper by moving the error/EDOM handling to an out-of-line implementation (__math_invalidf_i/__math_invalidf_li). Also, __glibc_unlikely is used on errors case since it helps code generation on recent gcc. The code now builds to with gcc-14 on aarch64: 0000000000000000 <__ilogbf>: 0: 1e260000 fmov w0, s0 4: d3577801 ubfx x1, x0, #23, #8 8: 340000e1 cbz w1, 24 <__ilogbf+0x24> c: 5101fc20 sub w0, w1, #0x7f 10: 7103fc3f cmp w1, #0xff 14: 54000040 b.eq 1c <__ilogbf+0x1c> // b.none 18: d65f03c0 ret 1c: 12b00000 mov w0, #0x7fffffff // #2147483647 20: 14000000 b 0 <__math_invalidf_i> 24: 53175800 lsl w0, w0, #9 28: 340000a0 cbz w0, 3c <__ilogbf+0x3c> 2c: 5ac01000 clz w0, w0 30: 12800fc1 mov w1, #0xffffff81 // #-127 34: 4b000020 sub w0, w1, w0 38: d65f03c0 ret 3c: 320107e0 mov w0, #0x80000001 // #-2147483647 40: 14000000 b 0 <__math_invalidf_i> Some ABI requires additional adjustments: * i386 and m68k requires to use the template version, since both provide __ieee754_ilogb implementatations. * loongarch uses a custom implementation as well. * powerpc64le also has a custom implementation for POWER9, which is also used for float and float128 version. The generic e_ilogb.c implementation is moved on powerpc to keep the current code as-is. Checked on aarch64-linux-gnu and x86_64-linux-gnu. Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
42 lines
1.4 KiB
C
42 lines
1.4 KiB
C
/* Get integer exponent of a floating-point value.
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Copyright (C) 1999-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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<https://www.gnu.org/licenses/>. */
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#include <limits.h>
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#include <math.h>
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#include <stdbit.h>
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#include "sysdeps/ieee754/flt-32/math_config.h"
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int
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__ieee754_ilogbf (float x)
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{
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uint32_t ux = asuint (x);
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int ex = (ux & ~SIGN_MASK) >> MANTISSA_WIDTH;
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if (ex == 0) /* zero or subnormal */
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{
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/* Clear sign and exponent. */
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ux <<= 1 + EXPONENT_WIDTH;
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if (ux == 0)
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return FP_ILOGB0;
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/* sbunormal */
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return -127 - stdc_leading_zeros (ux);
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}
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if (ex == EXPONENT_MASK >> MANTISSA_WIDTH) /* NaN or Inf */
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return ux << (1 + EXPONENT_WIDTH) ? FP_ILOGBNAN : INT_MAX;
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return ex - 127;
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}
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