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0f4840be25
To make a strtok faster and improve performance in general we need to do one additional change. A comment: /* It doesn't make sense to send libc-internal strcspn calls through a PLT. The speedup we get from using SSE4.2 instruction is likely eaten away by the indirect call in the PLT. */ Does not make sense at all because nobody bothered to check it. Gap between these implementations is quite big, when haystack is empty a sse2 is around 40 cycles slower because it needs to populate a lookup table and difference only increases with size. That is much bigger than plt slowdown which is few cycles. Even benchtest show a gap which also may be reverse by branch misprediction but my internal benchmark shown. simple_strspn stupid_strspn __strspn_sse42 __strspn_sse2 Length 0, alignment 0, acc len 6: 18.6562 35.2344 17.0469 61.6719 Length 6, alignment 0, acc len 6: 59.5469 72.5781 16.4219 73.625 This patch also handles strpbrk which is implemented by including a x86_64/multiarch/strcspn.S file. * sysdeps/x86_64/multiarch/strspn.S: Remove plt indirection. * sysdeps/x86_64/multiarch/strcspn.S: Likewise.
58 lines
1.6 KiB
ArmAsm
58 lines
1.6 KiB
ArmAsm
/* Multiple versions of strspn
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All versions must be listed in ifunc-impl-list.c.
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Copyright (C) 2009-2015 Free Software Foundation, Inc.
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Contributed by Intel Corporation.
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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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<http://www.gnu.org/licenses/>. */
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#include <config.h>
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#ifdef HAVE_SSE4_SUPPORT
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#include <sysdep.h>
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#include <init-arch.h>
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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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.text
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ENTRY(strspn)
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.type strspn, @gnu_indirect_function
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cmpl $0, __cpu_features+KIND_OFFSET(%rip)
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jne 1f
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call __init_cpu_features
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1: leaq __strspn_sse2(%rip), %rax
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testl $bit_SSE4_2, __cpu_features+CPUID_OFFSET+index_SSE4_2(%rip)
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jz 2f
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leaq __strspn_sse42(%rip), %rax
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2: ret
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END(strspn)
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# undef ENTRY
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# define ENTRY(name) \
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.type __strspn_sse2, @function; \
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.globl __strspn_sse2; \
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.align 16; \
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__strspn_sse2: cfi_startproc; \
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CALL_MCOUNT
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# undef END
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# define END(name) \
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cfi_endproc; .size __strspn_sse2, .-__strspn_sse2
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#endif
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#endif /* HAVE_SSE4_SUPPORT */
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#include "../strspn.S"
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