Date: Fri, 8 Sep 2023 21:23:31 GMT From: Robert Clausecker <fuz@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 7084133cde6a - main - lib/libc/amd64/string: add strspn(3) scalar, x86-64-v2 implementation Message-ID: <202309082123.388LNVNw057447@gitrepo.freebsd.org>
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The branch main has been updated by fuz: URL: https://cgit.FreeBSD.org/src/commit/?id=7084133cde6a58412d86bae9f8a55b86141fb304 commit 7084133cde6a58412d86bae9f8a55b86141fb304 Author: Robert Clausecker <fuz@FreeBSD.org> AuthorDate: 2023-08-21 16:06:42 +0000 Commit: Robert Clausecker <fuz@FreeBSD.org> CommitDate: 2023-09-08 21:21:59 +0000 lib/libc/amd64/string: add strspn(3) scalar, x86-64-v2 implementation This is conceptually very similar to the strcspn(3) implementations from D41557, but we can't do the fast paths the same way. Sponsored by: The FreeBSD Foundation Approved by: mjg MFC after: 1 week MFC to: stable/14 Differential Revision: https://reviews.freebsd.org/D41567 --- lib/libc/amd64/string/Makefile.inc | 3 +- lib/libc/amd64/string/strspn.S | 358 +++++++++++++++++++++++++++++++++++++ 2 files changed, 360 insertions(+), 1 deletion(-) diff --git a/lib/libc/amd64/string/Makefile.inc b/lib/libc/amd64/string/Makefile.inc index f01a52d9ebea..b03811f40062 100644 --- a/lib/libc/amd64/string/Makefile.inc +++ b/lib/libc/amd64/string/Makefile.inc @@ -12,4 +12,5 @@ MDSRCS+= \ strcmp.S \ strcspn.S \ strlen.S \ - strcpy.c + strcpy.c \ + strspn.S diff --git a/lib/libc/amd64/string/strspn.S b/lib/libc/amd64/string/strspn.S new file mode 100644 index 000000000000..565330f0c385 --- /dev/null +++ b/lib/libc/amd64/string/strspn.S @@ -0,0 +1,358 @@ +/*- + * Copyright (c) 2023 The FreeBSD Foundation + * + * This software was developed by Robert Clausecker <fuz@FreeBSD.org> + * under sponsorship from the FreeBSD Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ''AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE + */ + +#include <machine/asm.h> +#include <machine/param.h> + +#include "amd64_archlevel.h" + +#define ALIGN_TEXT .p2align 4,0x90 /* 16-byte alignment, nop filled */ + +ARCHFUNCS(strspn) + ARCHFUNC(strspn, scalar) + NOARCHFUNC + ARCHFUNC(strspn, x86_64_v2) +ENDARCHFUNCS(strspn) + +ARCHENTRY(strspn, scalar) + push %rbp # align stack to enable function call + mov %rsp, %rbp + sub $256, %rsp # allocate space for lookup table + + /* check for special cases */ + movzbl (%rsi), %edx # first character in the set + test %edx, %edx + jz .Lzero # empty set always returns 0 + + movzbl 1(%rsi), %eax # second character in the set + test %eax, %eax + jz .Lsingle + + /* no special case matches -- prepare lookup table */ + xor %r8d, %r8d + mov $28, %ecx +0: mov %r8, (%rsp, %rcx, 8) + mov %r8, 8(%rsp, %rcx, 8) + mov %r8, 16(%rsp, %rcx, 8) + mov %r8, 24(%rsp, %rcx, 8) + sub $4, %ecx + jnc 0b + + movb $1, (%rsp, %rdx, 1) # register first char in set + add $2, %rsi + + /* process remaining chars in set */ + ALIGN_TEXT +0: movb $1, (%rsp, %rax, 1) # register previous char + movzbl (%rsi), %eax # next char in set + test %eax, %eax # end of string? + jz 1f + + movb $1, (%rsp, %rax, 1) + add $2, %rsi + movzbl -1(%rsi), %eax + test %eax, %eax + jnz 0b + +1: mov %rdi, %rax # a copy of the source to iterate over + + /* find mismatch */ + ALIGN_TEXT +0: movzbl (%rax), %ecx + cmpb $0, (%rsp, %rcx, 1) + je 2f + + movzbl 1(%rax), %ecx + cmpb $0, (%rsp, %rcx, 1) + je 3f + + movzbl 2(%rax), %ecx + cmpb $0, (%rsp, %rcx, 1) + je 4f + + movzbl 3(%rax), %ecx + add $4, %rax + cmpb $0, (%rsp, %rcx, 1) + jne 0b + + sub $3, %rax +4: dec %rdi +3: inc %rax +2: sub %rdi, %rax # number of characters preceding match + leave + ret + + /* empty set never matches */ +.Lzero: xor %eax, %eax + leave + ret + + /* find repeated single character */ + ALIGN_TEXT +.Lsingle: + cmpb %dl, (%rdi, %rax, 1) + jne 1f + + cmpb %dl, 1(%rdi, %rax, 1) + jne 2f + + cmpb %dl, 2(%rdi, %rax, 1) + jne 3f + + cmpb %dl, 3(%rdi, %rax, 1) + lea 4(%rax), %rax + je .Lsingle + + sub $3, %rax +3: inc %rax +2: inc %rax +1: leave + ret +ARCHEND(strspn, scalar) + + /* + * This kernel uses pcmpistri to do the heavy lifting. + * We provide three code paths, depending on set size: + * + * 0--16: one pcmpistri per 16 bytes of input + * 17--32: two pcmpistri per 16 bytes of input + * >=33: fall back to look up table + */ +ARCHENTRY(strspn, x86_64_v2) + push %rbp + mov %rsp, %rbp + sub $256, %rsp + + /* find set size and copy up to 32 bytes to (%rsp) */ + mov %esi, %ecx + and $~0xf, %rsi # align set pointer + movdqa (%rsi), %xmm0 + pxor %xmm1, %xmm1 + and $0xf, %ecx # amount of bytes rsi is past alignment + xor %edx, %edx + pcmpeqb %xmm0, %xmm1 # end of string reached? + movdqa %xmm0, 32(%rsp) # transfer head of set to stack + pmovmskb %xmm1, %eax + shr %cl, %eax # clear out junk before string + test %eax, %eax # end of set reached? + jnz 0f + + movdqa 16(%rsi), %xmm0 # second chunk of the set + mov $16, %edx + sub %ecx, %edx # length of set preceding xmm0 + pxor %xmm1, %xmm1 + pcmpeqb %xmm0, %xmm1 + movdqa %xmm0, 48(%rsp) + movdqu 32(%rsp, %rcx, 1), %xmm2 # head of set + pmovmskb %xmm1, %eax + test %eax, %eax + jnz 1f + + movdqa 32(%rsi), %xmm0 # third chunk + add $16, %edx + pxor %xmm1, %xmm1 + pcmpeqb %xmm0, %xmm1 + movdqa %xmm0, 64(%rsp) + pmovmskb %xmm1, %eax + test %eax, %eax # still not done? + jz .Lgt32v2 + +0: movdqu 32(%rsp, %rcx, 1), %xmm2 # head of set +1: tzcnt %eax, %eax + add %eax, %edx # length of set (excluding NUL byte) + cmp $32, %edx # above 32 bytes? + ja .Lgt32v2 + + /* + * At this point we know that we want to use pcmpistri. + * one last problem obtains: the head of the string is not + * aligned and may cross a cacheline. If this is the case, + * we take the part before the page boundary and repeat the + * last byte to fill up the xmm register. + */ + mov %rdi, %rax # save original string pointer + lea 15(%rdi), %esi # last byte of the head + xor %edi, %esi + test $PAGE_SIZE, %esi # does the head cross a page? + jz 0f + + /* head crosses page: copy to stack to fix up */ + and $~0xf, %rax # align head pointer temporarily + movzbl 15(%rax), %esi # last head byte on the page + movdqa (%rax), %xmm0 + movabs $0x0101010101010101, %r8 + imul %r8, %rsi # repeated 8 times + movdqa %xmm0, (%rsp) # head word on stack + mov %rsi, 16(%rsp) # followed by filler (last byte x8) + mov %rsi, 24(%rsp) + mov %edi, %eax + and $0xf, %eax # offset of head from alignment + add %rsp, %rax # pointer to fake head + +0: movdqu (%rax), %xmm1 # load head (fake or real) + lea 16(%rdi), %rax + and $~0xf, %rax # second 16 bytes of string (aligned) +1: cmp $16, %edx # 16--32 bytes? + ja .Lgt16v2 + + + /* set is 2--16 bytes in size */ + + /* _SIDD_UBYTE_OPS|_SIDD_CMP_EQUAL_ANY|_SIDD_LEAST_SIGNIFICANT|_SIDD_NEGATIVE_POLARITY */ + pcmpistri $0x10, %xmm1, %xmm2 # match in head? + jc .Lheadmismatchv2 + + ALIGN_TEXT +0: pcmpistri $0x10, (%rax), %xmm2 + jc 1f # match or end of string? + pcmpistri $0x10, 16(%rax), %xmm2 + lea 32(%rax), %rax + jnc 0b # match or end of string? + + sub $16, %rax # go back to second half +1: sub %rdi, %rax # offset of (%rax) from beginning of string + add %rcx, %rax # prefix length before match/NUL + leave + ret + +.Lheadmismatchv2: + mov %ecx, %eax # prefix length before mismatch/NUL + leave + ret + + /* set is 17--32 bytes in size */ +.Lgt16v2: + movdqu 48(%rsp, %rcx, 1), %xmm3 # second part of set + + /* _SIDD_UBYTE_OPS|_SIDD_CMP_EQUAL_ANY|_SIDD_BIT_MASK|_SIDD_NEGATIVE_POLARITY */ + pcmpistrm $0x10, %xmm1, %xmm2 # any mismatch in first half? + movdqa %xmm0, %xmm4 + pcmpistrm $0x10, %xmm1, %xmm3 # any mismatch in the second half? + ptest %xmm0, %xmm4 # any entry that doesn't match either? + jnz 2f + + ALIGN_TEXT +0: movdqa (%rax), %xmm1 + pcmpistrm $0x10, %xmm1, %xmm2 + movdqa %xmm0, %xmm4 + pcmpistrm $0x10, %xmm1, %xmm3 + ptest %xmm0, %xmm4 + jnz 1f + movdqa 16(%rax), %xmm1 + add $32, %rax + pcmpistrm $0x10, %xmm1, %xmm2 + movdqa %xmm0, %xmm4 + pcmpistrm $0x10, %xmm1, %xmm3 + ptest %xmm0, %xmm4 + jz 0b + + sub $16, %rax +1: pand %xmm4, %xmm0 + movd %xmm0, %ecx + sub %rdi, %rax # offset of %xmm1 from beginning of string + tzcnt %ecx, %ecx + add %rcx, %rax # prefix length before match/NUL + leave + ret + + /* mismatch or string end in head */ +2: pand %xmm4, %xmm0 # bit mask of mismatches (end of string counts) + movd %xmm0, %eax + tzcnt %eax, %eax # prefix length before mismatch/NUL + leave + ret + + /* set is >=33 bytes in size */ +.Lgt32v2: + xorps %xmm0, %xmm0 + mov $256-64, %edx + + /* clear out look up table */ +0: movaps %xmm0, (%rsp, %rdx, 1) + movaps %xmm0, 16(%rsp, %rdx, 1) + movaps %xmm0, 32(%rsp, %rdx, 1) + movaps %xmm0, 48(%rsp, %rdx, 1) + sub $64, %edx + jnc 0b + + add %rcx, %rsi # restore string pointer + mov %rdi, %rax # keep a copy of the string + + /* initialise look up table */ + movzbl (%rsi), %ecx # string is known not to be empty + + ALIGN_TEXT +0: movb $1, (%rsp, %rcx, 1) + movzbl 1(%rsi), %ecx + test %ecx, %ecx + jz 1f + + movb $1, (%rsp, %rcx, 1) + movzbl 2(%rsi), %ecx + test %ecx, %ecx + jz 1f + + movb $1, (%rsp, %rcx, 1) + movzbl 3(%rsi), %ecx + add $4, %rsi + test %ecx, %ecx + jz 1f + + movb $1, (%rsp, %rcx, 1) + movzbl (%rsi), %ecx + test %ecx, %ecx + jnz 0b + + /* find match */ + ALIGN_TEXT +1: movzbl (%rax), %ecx + cmpb $0, (%rsp, %rcx, 1) + je 2f + + movzbl 1(%rax), %ecx + cmpb $0, (%rsp, %rcx, 1) + je 3f + + movzbl 2(%rax), %ecx + cmpb $0, (%rsp, %rcx, 1) + je 4f + + movzbl 3(%rax), %ecx + add $4, %rax + cmpb $0, (%rsp, %rcx, 1) + jne 1b + + sub $3, %rax +4: dec %rdi +3: inc %rax +2: sub %rdi, %rax # number of characters preceding match + leave + ret +ARCHEND(strspn, x86_64_v2) + + .section .note.GNU-stack,"",%progbits
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