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a55e2da270
This patch was based on the __memcmp_power8 and the recent __strlen_power10. Improvements from __memcmp_power8: 1. Don't need alignment code. On POWER10 lxvp and lxvl do not generate alignment interrupts, so they are safe for use on caching-inhibited memory. Notice that the comparison on the main loop will wait for both VSR to be ready. Therefore aligning one of the input address does not improve performance. In order to align both registers a vperm is necessary which add too much overhead. 2. Uses new POWER10 instructions This code uses lxvp to decrease contention on load by loading 32 bytes per instruction. The vextractbm is used to have a smaller tail code for calculating the return value. 3. Performance improvement This version has around 35% better performance on average. I saw no performance regressions for any length or alignment. Thanks Matheus for helping me out with some details. Co-authored-by: Matheus Castanho <msc@linux.ibm.com> Reviewed-by: Raphael M Zinsly <rzinsly@linux.ibm.com>
27 lines
1.0 KiB
ArmAsm
27 lines
1.0 KiB
ArmAsm
/* Optimized memcmp implementation for POWER10.
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Copyright (C) 2017-2021 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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#define MEMCMP __memcmp_power10
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#undef libc_hidden_builtin_def
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#define libc_hidden_builtin_def(name)
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#undef weak_alias
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#define weak_alias(name,alias)
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#include <sysdeps/powerpc/powerpc64/le/power10/memcmp.S>
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