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/* Clear a block of memory for calloc. Generic version.
Copyright (C) 2024-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://www.gnu.org/licenses/>. */
static __always_inline void *
clear_memory (INTERNAL_SIZE_T *d, unsigned long clearsize)
{
/* Unroll clear memory size up to 9 * INTERNAL_SIZE_T bytes. We know
that contents have an odd number of INTERNAL_SIZE_T-sized words;
minimally 3 words. */
unsigned long nclears = clearsize / sizeof (INTERNAL_SIZE_T);
if (nclears > 9)
return memset (d, 0, clearsize);
/* NB: The VRP pass in GCC 14.2 will optimize it out. */
if (nclears < 3)
__builtin_unreachable ();
/* Use repeated stores with 1 branch, instead of up to 3. */
*(d + 0) = 0;
*(d + 1) = 0;
*(d + 2) = 0;
*(d + nclears - 2) = 0;
*(d + nclears - 2 + 1) = 0;
if (nclears > 5)
{
*(d + 3) = 0;
*(d + 3 + 1) = 0;
*(d + nclears - 4) = 0;
*(d + nclears - 4 + 1) = 0;
}
return d;
}
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