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104c7b1967
No bug. This commit adds a new implementation for EVEX memchr that is not safe for RTM because it uses vzeroupper. The benefit is that by using ymm0-ymm15 it can use vpcmpeq and vpternlogd in the 4x loop which is faster than the RTM safe version which cannot use vpcmpeq because there is no EVEX encoding for the instruction. All parts of the implementation aside from the 4x loop are the same for the two versions and the optimization is only relevant for large sizes. Tigerlake: size , algn , Pos , Cur T , New T , Win , Dif 512 , 6 , 192 , 9.2 , 9.04 , no-RTM , 0.16 512 , 7 , 224 , 9.19 , 8.98 , no-RTM , 0.21 2048 , 0 , 256 , 10.74 , 10.54 , no-RTM , 0.2 2048 , 0 , 512 , 14.81 , 14.87 , RTM , 0.06 2048 , 0 , 1024 , 22.97 , 22.57 , no-RTM , 0.4 2048 , 0 , 2048 , 37.49 , 34.51 , no-RTM , 2.98 <-- Icelake: size , algn , Pos , Cur T , New T , Win , Dif 512 , 6 , 192 , 7.6 , 7.3 , no-RTM , 0.3 512 , 7 , 224 , 7.63 , 7.27 , no-RTM , 0.36 2048 , 0 , 256 , 8.48 , 8.38 , no-RTM , 0.1 2048 , 0 , 512 , 11.57 , 11.42 , no-RTM , 0.15 2048 , 0 , 1024 , 17.92 , 17.38 , no-RTM , 0.54 2048 , 0 , 2048 , 30.37 , 27.34 , no-RTM , 3.03 <-- test-memchr, test-wmemchr, and test-rawmemchr are all passing. Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
39 lines
1.4 KiB
C
39 lines
1.4 KiB
C
/* Multiple versions of rawmemchr
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All versions must be listed in ifunc-impl-list.c.
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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 multiple versions only for the definition in libc. */
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#if IS_IN (libc)
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# define rawmemchr __redirect_rawmemchr
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# define __rawmemchr __redirect___rawmemchr
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# include <string.h>
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# undef rawmemchr
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# undef __rawmemchr
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# define SYMBOL_NAME rawmemchr
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# include "ifunc-evex.h"
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libc_ifunc_redirected (__redirect_rawmemchr, __rawmemchr,
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IFUNC_SELECTOR ());
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weak_alias (__rawmemchr, rawmemchr)
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# ifdef SHARED
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__hidden_ver1 (__rawmemchr, __GI___rawmemchr, __redirect___rawmemchr)
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__attribute__((visibility ("hidden")));
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# endif
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#endif
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