From dc485ceb2ac596d27294cc1942adf3181f15e8bf Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 9 Jun 2017 05:18:03 -0700 Subject: x86-64: Optimize strlen/strnlen/wcslen/wcsnlen with AVX2 Optimize strlen/strnlen/wcslen/wcsnlen with AVX2 to check 32 bytes with a single vector compare instruction. It is as fast as SSE2 versions for size <= 16 bytes and up to 1X faster for or size > 16 bytes on Haswell. Select AVX2 version on AVX2 machines where vzeroupper is preferred and AVX unaligned load is fast. NB: It uses TZCNT instead of BSF since TZCNT produces the same result as BSF for non-zero input. TZCNT is faster than BSF and is executed as BSF if machine doesn't support TZCNT. * sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add strlen-sse2, strnlen-sse2, strlen-avx2, strnlen-avx2, wcslen-sse2, wcslen-avx2 and wcsnlen-avx2. * sysdeps/x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Add tests for __strlen_avx2, __strlen_sse2, __strnlen_avx2, __strnlen_sse2, __wcslen_avx2, __wcslen_sse2 and __wcsnlen_avx2. * sysdeps/x86_64/multiarch/strlen-avx2.S: New file. * sysdeps/x86_64/multiarch/strlen-sse2.S: Likewise. * sysdeps/x86_64/multiarch/strlen.c: Likewise. * sysdeps/x86_64/multiarch/strnlen-avx2.S: Likewise. * sysdeps/x86_64/multiarch/strnlen-sse2.S: Likewise. * sysdeps/x86_64/multiarch/strnlen.c: Likewise. * sysdeps/x86_64/multiarch/wcslen-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcslen-sse2.S: Likewise. * sysdeps/x86_64/multiarch/wcslen.c: Likewise. * sysdeps/x86_64/multiarch/wcsnlen-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcsnlen.c (OPTIMIZE (avx2)): New. (IFUNC_SELECTOR): Return OPTIMIZE (avx2) on AVX2 machines where vzeroupper is preferred and AVX unaligned load is fast. --- sysdeps/x86_64/multiarch/strnlen-sse2.S | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 sysdeps/x86_64/multiarch/strnlen-sse2.S (limited to 'sysdeps/x86_64/multiarch/strnlen-sse2.S') diff --git a/sysdeps/x86_64/multiarch/strnlen-sse2.S b/sysdeps/x86_64/multiarch/strnlen-sse2.S new file mode 100644 index 0000000000..b5ddf07361 --- /dev/null +++ b/sysdeps/x86_64/multiarch/strnlen-sse2.S @@ -0,0 +1,28 @@ +/* strnlen optimized with SSE2. + Copyright (C) 2017 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 + . */ + +#if IS_IN (libc) +# define __strnlen __strnlen_sse2 + +# undef weak_alias +# define weak_alias(__strnlen, strnlen) +# undef libc_hidden_builtin_def +# define libc_hidden_builtin_def(strnlen) +#endif + +#include "../strnlen.S" -- cgit 1.4.1