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c627209832
In the overflow fallback strncmp-avx2-rtm and wcsncmp-avx2-rtm would call strcmp-avx2 and wcscmp-avx2 respectively. This would have not checks around vzeroupper and would trigger spurious aborts. This commit fixes that. test-strcmp, test-strncmp, test-wcscmp, and test-wcsncmp all pass on AVX2 machines with and without RTM. Co-authored-by: H.J. Lu <hjl.tools@gmail.com>
1147 lines
26 KiB
ArmAsm
1147 lines
26 KiB
ArmAsm
/* strcmp/wcscmp/strncmp/wcsncmp optimized with AVX2.
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Copyright (C) 2018-2022 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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#if IS_IN (libc)
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# include <sysdep.h>
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# ifndef STRCMP
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# define STRCMP __strcmp_avx2
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# endif
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# define PAGE_SIZE 4096
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/* VEC_SIZE = Number of bytes in a ymm register. */
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# define VEC_SIZE 32
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# define VMOVU vmovdqu
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# define VMOVA vmovdqa
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# ifdef USE_AS_WCSCMP
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/* Compare packed dwords. */
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# define VPCMPEQ vpcmpeqd
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/* Compare packed dwords and store minimum. */
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# define VPMINU vpminud
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/* 1 dword char == 4 bytes. */
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# define SIZE_OF_CHAR 4
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# else
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/* Compare packed bytes. */
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# define VPCMPEQ vpcmpeqb
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/* Compare packed bytes and store minimum. */
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# define VPMINU vpminub
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/* 1 byte char == 1 byte. */
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# define SIZE_OF_CHAR 1
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# endif
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# ifdef USE_AS_STRNCMP
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# define LOOP_REG r9d
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# define LOOP_REG64 r9
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# define OFFSET_REG8 r9b
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# define OFFSET_REG r9d
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# define OFFSET_REG64 r9
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# else
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# define LOOP_REG edx
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# define LOOP_REG64 rdx
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# define OFFSET_REG8 dl
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# define OFFSET_REG edx
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# define OFFSET_REG64 rdx
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# endif
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# ifndef VZEROUPPER
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# define VZEROUPPER vzeroupper
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# endif
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# if defined USE_AS_STRNCMP
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# define VEC_OFFSET 0
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# else
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# define VEC_OFFSET (-VEC_SIZE)
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# endif
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# define xmmZERO xmm15
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# define ymmZERO ymm15
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# ifndef SECTION
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# define SECTION(p) p##.avx
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# endif
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/* Warning!
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wcscmp/wcsncmp have to use SIGNED comparison for elements.
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strcmp/strncmp have to use UNSIGNED comparison for elements.
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*/
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/* The main idea of the string comparison (byte or dword) using AVX2
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consists of comparing (VPCMPEQ) two ymm vectors. The latter can be on
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either packed bytes or dwords depending on USE_AS_WCSCMP. In order
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to check the null char, algorithm keeps the matched bytes/dwords,
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requiring two more AVX2 instructions (VPMINU and VPCMPEQ). In general,
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the costs of comparing VEC_SIZE bytes (32-bytes) are two VPCMPEQ and
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one VPMINU instructions, together with movdqu and testl instructions.
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Main loop (away from from page boundary) compares 4 vectors are a time,
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effectively comparing 4 x VEC_SIZE bytes (128 bytes) on each loop.
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The routine strncmp/wcsncmp (enabled by defining USE_AS_STRNCMP) logic
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is the same as strcmp, except that an a maximum offset is tracked. If
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the maximum offset is reached before a difference is found, zero is
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returned. */
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.section SECTION(.text), "ax", @progbits
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ENTRY(STRCMP)
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# ifdef USE_AS_STRNCMP
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# ifdef __ILP32__
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/* Clear the upper 32 bits. */
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movl %edx, %edx
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# endif
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cmp $1, %RDX_LP
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/* Signed comparison intentional. We use this branch to also
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test cases where length >= 2^63. These very large sizes can be
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handled with strcmp as there is no way for that length to
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actually bound the buffer. */
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jle L(one_or_less)
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# ifdef USE_AS_WCSCMP
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movq %rdx, %rcx
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/* Multiplying length by sizeof(wchar_t) can result in overflow.
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Check if that is possible. All cases where overflow are possible
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are cases where length is large enough that it can never be a
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bound on valid memory so just use wcscmp. */
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shrq $56, %rcx
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jnz __wcscmp_avx2
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leaq (, %rdx, 4), %rdx
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# endif
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# endif
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vpxor %xmmZERO, %xmmZERO, %xmmZERO
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movl %edi, %eax
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orl %esi, %eax
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sall $20, %eax
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/* Check if s1 or s2 may cross a page in next 4x VEC loads. */
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cmpl $((PAGE_SIZE -(VEC_SIZE * 4)) << 20), %eax
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ja L(page_cross)
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L(no_page_cross):
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/* Safe to compare 4x vectors. */
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VMOVU (%rdi), %ymm0
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/* 1s where s1 and s2 equal. */
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VPCMPEQ (%rsi), %ymm0, %ymm1
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/* 1s at null CHAR. */
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VPCMPEQ %ymm0, %ymmZERO, %ymm2
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/* 1s where s1 and s2 equal AND not null CHAR. */
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vpandn %ymm1, %ymm2, %ymm1
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/* All 1s -> keep going, any 0s -> return. */
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vpmovmskb %ymm1, %ecx
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# ifdef USE_AS_STRNCMP
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cmpq $VEC_SIZE, %rdx
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jbe L(vec_0_test_len)
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# endif
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/* All 1s represents all equals. incl will overflow to zero in
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all equals case. Otherwise 1s will carry until position of first
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mismatch. */
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incl %ecx
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jz L(more_3x_vec)
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.p2align 4,, 4
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L(return_vec_0):
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tzcntl %ecx, %ecx
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# ifdef USE_AS_WCSCMP
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movl (%rdi, %rcx), %edx
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xorl %eax, %eax
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cmpl (%rsi, %rcx), %edx
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je L(ret0)
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setl %al
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negl %eax
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orl $1, %eax
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# else
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movzbl (%rdi, %rcx), %eax
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movzbl (%rsi, %rcx), %ecx
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subl %ecx, %eax
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# endif
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L(ret0):
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L(return_vzeroupper):
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ZERO_UPPER_VEC_REGISTERS_RETURN
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# ifdef USE_AS_STRNCMP
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.p2align 4,, 8
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L(vec_0_test_len):
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notl %ecx
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bzhil %edx, %ecx, %eax
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jnz L(return_vec_0)
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/* Align if will cross fetch block. */
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.p2align 4,, 2
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L(ret_zero):
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xorl %eax, %eax
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VZEROUPPER_RETURN
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.p2align 4,, 5
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L(one_or_less):
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jb L(ret_zero)
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/* 'nbe' covers the case where length is negative (large
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unsigned). */
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jnbe OVERFLOW_STRCMP
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# ifdef USE_AS_WCSCMP
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movl (%rdi), %edx
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xorl %eax, %eax
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cmpl (%rsi), %edx
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je L(ret1)
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setl %al
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negl %eax
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orl $1, %eax
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# else
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movzbl (%rdi), %eax
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movzbl (%rsi), %ecx
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subl %ecx, %eax
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# endif
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L(ret1):
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ret
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# endif
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.p2align 4,, 10
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L(return_vec_1):
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tzcntl %ecx, %ecx
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# ifdef USE_AS_STRNCMP
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/* rdx must be > CHAR_PER_VEC so save to subtract w.o fear of
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overflow. */
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addq $-VEC_SIZE, %rdx
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cmpq %rcx, %rdx
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jbe L(ret_zero)
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# endif
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# ifdef USE_AS_WCSCMP
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movl VEC_SIZE(%rdi, %rcx), %edx
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xorl %eax, %eax
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cmpl VEC_SIZE(%rsi, %rcx), %edx
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je L(ret2)
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setl %al
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negl %eax
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orl $1, %eax
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# else
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movzbl VEC_SIZE(%rdi, %rcx), %eax
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movzbl VEC_SIZE(%rsi, %rcx), %ecx
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subl %ecx, %eax
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# endif
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L(ret2):
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VZEROUPPER_RETURN
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.p2align 4,, 10
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# ifdef USE_AS_STRNCMP
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L(return_vec_3):
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salq $32, %rcx
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# endif
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L(return_vec_2):
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# ifndef USE_AS_STRNCMP
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tzcntl %ecx, %ecx
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# else
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tzcntq %rcx, %rcx
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cmpq %rcx, %rdx
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jbe L(ret_zero)
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# endif
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# ifdef USE_AS_WCSCMP
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movl (VEC_SIZE * 2)(%rdi, %rcx), %edx
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xorl %eax, %eax
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cmpl (VEC_SIZE * 2)(%rsi, %rcx), %edx
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je L(ret3)
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setl %al
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negl %eax
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orl $1, %eax
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# else
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movzbl (VEC_SIZE * 2)(%rdi, %rcx), %eax
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movzbl (VEC_SIZE * 2)(%rsi, %rcx), %ecx
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subl %ecx, %eax
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# endif
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L(ret3):
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VZEROUPPER_RETURN
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# ifndef USE_AS_STRNCMP
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.p2align 4,, 10
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L(return_vec_3):
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tzcntl %ecx, %ecx
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# ifdef USE_AS_WCSCMP
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movl (VEC_SIZE * 3)(%rdi, %rcx), %edx
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xorl %eax, %eax
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cmpl (VEC_SIZE * 3)(%rsi, %rcx), %edx
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je L(ret4)
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setl %al
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negl %eax
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orl $1, %eax
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# else
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movzbl (VEC_SIZE * 3)(%rdi, %rcx), %eax
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movzbl (VEC_SIZE * 3)(%rsi, %rcx), %ecx
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subl %ecx, %eax
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# endif
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L(ret4):
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VZEROUPPER_RETURN
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# endif
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.p2align 4,, 10
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L(more_3x_vec):
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/* Safe to compare 4x vectors. */
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VMOVU VEC_SIZE(%rdi), %ymm0
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VPCMPEQ VEC_SIZE(%rsi), %ymm0, %ymm1
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VPCMPEQ %ymm0, %ymmZERO, %ymm2
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vpandn %ymm1, %ymm2, %ymm1
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vpmovmskb %ymm1, %ecx
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incl %ecx
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jnz L(return_vec_1)
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# ifdef USE_AS_STRNCMP
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subq $(VEC_SIZE * 2), %rdx
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jbe L(ret_zero)
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# endif
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VMOVU (VEC_SIZE * 2)(%rdi), %ymm0
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VPCMPEQ (VEC_SIZE * 2)(%rsi), %ymm0, %ymm1
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VPCMPEQ %ymm0, %ymmZERO, %ymm2
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vpandn %ymm1, %ymm2, %ymm1
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vpmovmskb %ymm1, %ecx
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incl %ecx
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jnz L(return_vec_2)
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VMOVU (VEC_SIZE * 3)(%rdi), %ymm0
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VPCMPEQ (VEC_SIZE * 3)(%rsi), %ymm0, %ymm1
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VPCMPEQ %ymm0, %ymmZERO, %ymm2
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vpandn %ymm1, %ymm2, %ymm1
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vpmovmskb %ymm1, %ecx
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incl %ecx
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jnz L(return_vec_3)
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# ifdef USE_AS_STRNCMP
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cmpq $(VEC_SIZE * 2), %rdx
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jbe L(ret_zero)
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# endif
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# ifdef USE_AS_WCSCMP
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/* any non-zero positive value that doesn't inference with 0x1.
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*/
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movl $2, %r8d
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# else
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xorl %r8d, %r8d
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# endif
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/* The prepare labels are various entry points from the page
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cross logic. */
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L(prepare_loop):
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# ifdef USE_AS_STRNCMP
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/* Store N + (VEC_SIZE * 4) and place check at the begining of
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the loop. */
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leaq (VEC_SIZE * 2)(%rdi, %rdx), %rdx
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# endif
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L(prepare_loop_no_len):
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/* Align s1 and adjust s2 accordingly. */
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subq %rdi, %rsi
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andq $-(VEC_SIZE * 4), %rdi
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addq %rdi, %rsi
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# ifdef USE_AS_STRNCMP
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subq %rdi, %rdx
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# endif
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L(prepare_loop_aligned):
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/* eax stores distance from rsi to next page cross. These cases
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need to be handled specially as the 4x loop could potentially
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read memory past the length of s1 or s2 and across a page
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boundary. */
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movl $-(VEC_SIZE * 4), %eax
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subl %esi, %eax
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andl $(PAGE_SIZE - 1), %eax
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/* Loop 4x comparisons at a time. */
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.p2align 4
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L(loop):
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/* End condition for strncmp. */
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# ifdef USE_AS_STRNCMP
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subq $(VEC_SIZE * 4), %rdx
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jbe L(ret_zero)
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# endif
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subq $-(VEC_SIZE * 4), %rdi
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subq $-(VEC_SIZE * 4), %rsi
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/* Check if rsi loads will cross a page boundary. */
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addl $-(VEC_SIZE * 4), %eax
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jnb L(page_cross_during_loop)
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/* Loop entry after handling page cross during loop. */
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L(loop_skip_page_cross_check):
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VMOVA (VEC_SIZE * 0)(%rdi), %ymm0
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VMOVA (VEC_SIZE * 1)(%rdi), %ymm2
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VMOVA (VEC_SIZE * 2)(%rdi), %ymm4
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VMOVA (VEC_SIZE * 3)(%rdi), %ymm6
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/* ymm1 all 1s where s1 and s2 equal. All 0s otherwise. */
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VPCMPEQ (VEC_SIZE * 0)(%rsi), %ymm0, %ymm1
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VPCMPEQ (VEC_SIZE * 1)(%rsi), %ymm2, %ymm3
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VPCMPEQ (VEC_SIZE * 2)(%rsi), %ymm4, %ymm5
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VPCMPEQ (VEC_SIZE * 3)(%rsi), %ymm6, %ymm7
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/* If any mismatches or null CHAR then 0 CHAR, otherwise non-
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zero. */
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vpand %ymm0, %ymm1, %ymm1
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vpand %ymm2, %ymm3, %ymm3
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vpand %ymm4, %ymm5, %ymm5
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vpand %ymm6, %ymm7, %ymm7
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VPMINU %ymm1, %ymm3, %ymm3
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VPMINU %ymm5, %ymm7, %ymm7
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/* Reduce all 0 CHARs for the 4x VEC into ymm7. */
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VPMINU %ymm3, %ymm7, %ymm7
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/* If any 0 CHAR then done. */
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VPCMPEQ %ymm7, %ymmZERO, %ymm7
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vpmovmskb %ymm7, %LOOP_REG
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testl %LOOP_REG, %LOOP_REG
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jz L(loop)
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/* Find which VEC has the mismatch of end of string. */
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VPCMPEQ %ymm1, %ymmZERO, %ymm1
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vpmovmskb %ymm1, %ecx
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testl %ecx, %ecx
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jnz L(return_vec_0_end)
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VPCMPEQ %ymm3, %ymmZERO, %ymm3
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vpmovmskb %ymm3, %ecx
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testl %ecx, %ecx
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jnz L(return_vec_1_end)
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L(return_vec_2_3_end):
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# ifdef USE_AS_STRNCMP
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subq $(VEC_SIZE * 2), %rdx
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jbe L(ret_zero_end)
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# endif
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VPCMPEQ %ymm5, %ymmZERO, %ymm5
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vpmovmskb %ymm5, %ecx
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testl %ecx, %ecx
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jnz L(return_vec_2_end)
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/* LOOP_REG contains matches for null/mismatch from the loop. If
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VEC 0,1,and 2 all have no null and no mismatches then mismatch
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must entirely be from VEC 3 which is fully represented by
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LOOP_REG. */
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tzcntl %LOOP_REG, %LOOP_REG
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# ifdef USE_AS_STRNCMP
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subl $-(VEC_SIZE), %LOOP_REG
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cmpq %LOOP_REG64, %rdx
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jbe L(ret_zero_end)
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# endif
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# ifdef USE_AS_WCSCMP
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movl (VEC_SIZE * 2 - VEC_OFFSET)(%rdi, %LOOP_REG64), %ecx
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xorl %eax, %eax
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cmpl (VEC_SIZE * 2 - VEC_OFFSET)(%rsi, %LOOP_REG64), %ecx
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je L(ret5)
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setl %al
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negl %eax
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xorl %r8d, %eax
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# else
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movzbl (VEC_SIZE * 2 - VEC_OFFSET)(%rdi, %LOOP_REG64), %eax
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movzbl (VEC_SIZE * 2 - VEC_OFFSET)(%rsi, %LOOP_REG64), %ecx
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subl %ecx, %eax
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xorl %r8d, %eax
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subl %r8d, %eax
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# endif
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L(ret5):
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VZEROUPPER_RETURN
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# ifdef USE_AS_STRNCMP
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.p2align 4,, 2
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L(ret_zero_end):
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xorl %eax, %eax
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VZEROUPPER_RETURN
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# endif
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|
|
/* The L(return_vec_N_end) differ from L(return_vec_N) in that
|
|
they use the value of `r8` to negate the return value. This is
|
|
because the page cross logic can swap `rdi` and `rsi`. */
|
|
.p2align 4,, 10
|
|
# ifdef USE_AS_STRNCMP
|
|
L(return_vec_1_end):
|
|
salq $32, %rcx
|
|
# endif
|
|
L(return_vec_0_end):
|
|
# ifndef USE_AS_STRNCMP
|
|
tzcntl %ecx, %ecx
|
|
# else
|
|
tzcntq %rcx, %rcx
|
|
cmpq %rcx, %rdx
|
|
jbe L(ret_zero_end)
|
|
# endif
|
|
|
|
# ifdef USE_AS_WCSCMP
|
|
movl (%rdi, %rcx), %edx
|
|
xorl %eax, %eax
|
|
cmpl (%rsi, %rcx), %edx
|
|
je L(ret6)
|
|
setl %al
|
|
negl %eax
|
|
xorl %r8d, %eax
|
|
# else
|
|
movzbl (%rdi, %rcx), %eax
|
|
movzbl (%rsi, %rcx), %ecx
|
|
subl %ecx, %eax
|
|
xorl %r8d, %eax
|
|
subl %r8d, %eax
|
|
# endif
|
|
L(ret6):
|
|
VZEROUPPER_RETURN
|
|
|
|
# ifndef USE_AS_STRNCMP
|
|
.p2align 4,, 10
|
|
L(return_vec_1_end):
|
|
tzcntl %ecx, %ecx
|
|
# ifdef USE_AS_WCSCMP
|
|
movl VEC_SIZE(%rdi, %rcx), %edx
|
|
xorl %eax, %eax
|
|
cmpl VEC_SIZE(%rsi, %rcx), %edx
|
|
je L(ret7)
|
|
setl %al
|
|
negl %eax
|
|
xorl %r8d, %eax
|
|
# else
|
|
movzbl VEC_SIZE(%rdi, %rcx), %eax
|
|
movzbl VEC_SIZE(%rsi, %rcx), %ecx
|
|
subl %ecx, %eax
|
|
xorl %r8d, %eax
|
|
subl %r8d, %eax
|
|
# endif
|
|
L(ret7):
|
|
VZEROUPPER_RETURN
|
|
# endif
|
|
|
|
.p2align 4,, 10
|
|
L(return_vec_2_end):
|
|
tzcntl %ecx, %ecx
|
|
# ifdef USE_AS_STRNCMP
|
|
cmpq %rcx, %rdx
|
|
jbe L(ret_zero_page_cross)
|
|
# endif
|
|
# ifdef USE_AS_WCSCMP
|
|
movl (VEC_SIZE * 2)(%rdi, %rcx), %edx
|
|
xorl %eax, %eax
|
|
cmpl (VEC_SIZE * 2)(%rsi, %rcx), %edx
|
|
je L(ret11)
|
|
setl %al
|
|
negl %eax
|
|
xorl %r8d, %eax
|
|
# else
|
|
movzbl (VEC_SIZE * 2)(%rdi, %rcx), %eax
|
|
movzbl (VEC_SIZE * 2)(%rsi, %rcx), %ecx
|
|
subl %ecx, %eax
|
|
xorl %r8d, %eax
|
|
subl %r8d, %eax
|
|
# endif
|
|
L(ret11):
|
|
VZEROUPPER_RETURN
|
|
|
|
|
|
/* Page cross in rsi in next 4x VEC. */
|
|
|
|
/* TODO: Improve logic here. */
|
|
.p2align 4,, 10
|
|
L(page_cross_during_loop):
|
|
/* eax contains [distance_from_page - (VEC_SIZE * 4)]. */
|
|
|
|
/* Optimistically rsi and rdi and both aligned inwhich case we
|
|
don't need any logic here. */
|
|
cmpl $-(VEC_SIZE * 4), %eax
|
|
/* Don't adjust eax before jumping back to loop and we will
|
|
never hit page cross case again. */
|
|
je L(loop_skip_page_cross_check)
|
|
|
|
/* Check if we can safely load a VEC. */
|
|
cmpl $-(VEC_SIZE * 3), %eax
|
|
jle L(less_1x_vec_till_page_cross)
|
|
|
|
VMOVA (%rdi), %ymm0
|
|
VPCMPEQ (%rsi), %ymm0, %ymm1
|
|
VPCMPEQ %ymm0, %ymmZERO, %ymm2
|
|
vpandn %ymm1, %ymm2, %ymm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incl %ecx
|
|
jnz L(return_vec_0_end)
|
|
|
|
/* if distance >= 2x VEC then eax > -(VEC_SIZE * 2). */
|
|
cmpl $-(VEC_SIZE * 2), %eax
|
|
jg L(more_2x_vec_till_page_cross)
|
|
|
|
.p2align 4,, 4
|
|
L(less_1x_vec_till_page_cross):
|
|
subl $-(VEC_SIZE * 4), %eax
|
|
/* Guranteed safe to read from rdi - VEC_SIZE here. The only
|
|
concerning case is first iteration if incoming s1 was near start
|
|
of a page and s2 near end. If s1 was near the start of the page
|
|
we already aligned up to nearest VEC_SIZE * 4 so gurnateed safe
|
|
to read back -VEC_SIZE. If rdi is truly at the start of a page
|
|
here, it means the previous page (rdi - VEC_SIZE) has already
|
|
been loaded earlier so must be valid. */
|
|
VMOVU -VEC_SIZE(%rdi, %rax), %ymm0
|
|
VPCMPEQ -VEC_SIZE(%rsi, %rax), %ymm0, %ymm1
|
|
VPCMPEQ %ymm0, %ymmZERO, %ymm2
|
|
vpandn %ymm1, %ymm2, %ymm1
|
|
vpmovmskb %ymm1, %ecx
|
|
|
|
/* Mask of potentially valid bits. The lower bits can be out of
|
|
range comparisons (but safe regarding page crosses). */
|
|
movl $-1, %r10d
|
|
shlxl %esi, %r10d, %r10d
|
|
notl %ecx
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
cmpq %rax, %rdx
|
|
jbe L(return_page_cross_end_check)
|
|
# endif
|
|
movl %eax, %OFFSET_REG
|
|
addl $(PAGE_SIZE - VEC_SIZE * 4), %eax
|
|
|
|
andl %r10d, %ecx
|
|
jz L(loop_skip_page_cross_check)
|
|
|
|
.p2align 4,, 3
|
|
L(return_page_cross_end):
|
|
tzcntl %ecx, %ecx
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
leal -VEC_SIZE(%OFFSET_REG64, %rcx), %ecx
|
|
L(return_page_cross_cmp_mem):
|
|
# else
|
|
addl %OFFSET_REG, %ecx
|
|
# endif
|
|
# ifdef USE_AS_WCSCMP
|
|
movl VEC_OFFSET(%rdi, %rcx), %edx
|
|
xorl %eax, %eax
|
|
cmpl VEC_OFFSET(%rsi, %rcx), %edx
|
|
je L(ret8)
|
|
setl %al
|
|
negl %eax
|
|
xorl %r8d, %eax
|
|
# else
|
|
movzbl VEC_OFFSET(%rdi, %rcx), %eax
|
|
movzbl VEC_OFFSET(%rsi, %rcx), %ecx
|
|
subl %ecx, %eax
|
|
xorl %r8d, %eax
|
|
subl %r8d, %eax
|
|
# endif
|
|
L(ret8):
|
|
VZEROUPPER_RETURN
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
.p2align 4,, 10
|
|
L(return_page_cross_end_check):
|
|
andl %r10d, %ecx
|
|
tzcntl %ecx, %ecx
|
|
leal -VEC_SIZE(%rax, %rcx), %ecx
|
|
cmpl %ecx, %edx
|
|
ja L(return_page_cross_cmp_mem)
|
|
xorl %eax, %eax
|
|
VZEROUPPER_RETURN
|
|
# endif
|
|
|
|
|
|
.p2align 4,, 10
|
|
L(more_2x_vec_till_page_cross):
|
|
/* If more 2x vec till cross we will complete a full loop
|
|
iteration here. */
|
|
|
|
VMOVU VEC_SIZE(%rdi), %ymm0
|
|
VPCMPEQ VEC_SIZE(%rsi), %ymm0, %ymm1
|
|
VPCMPEQ %ymm0, %ymmZERO, %ymm2
|
|
vpandn %ymm1, %ymm2, %ymm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incl %ecx
|
|
jnz L(return_vec_1_end)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
cmpq $(VEC_SIZE * 2), %rdx
|
|
jbe L(ret_zero_in_loop_page_cross)
|
|
# endif
|
|
|
|
subl $-(VEC_SIZE * 4), %eax
|
|
|
|
/* Safe to include comparisons from lower bytes. */
|
|
VMOVU -(VEC_SIZE * 2)(%rdi, %rax), %ymm0
|
|
VPCMPEQ -(VEC_SIZE * 2)(%rsi, %rax), %ymm0, %ymm1
|
|
VPCMPEQ %ymm0, %ymmZERO, %ymm2
|
|
vpandn %ymm1, %ymm2, %ymm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incl %ecx
|
|
jnz L(return_vec_page_cross_0)
|
|
|
|
VMOVU -(VEC_SIZE * 1)(%rdi, %rax), %ymm0
|
|
VPCMPEQ -(VEC_SIZE * 1)(%rsi, %rax), %ymm0, %ymm1
|
|
VPCMPEQ %ymm0, %ymmZERO, %ymm2
|
|
vpandn %ymm1, %ymm2, %ymm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incl %ecx
|
|
jnz L(return_vec_page_cross_1)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
/* Must check length here as length might proclude reading next
|
|
page. */
|
|
cmpq %rax, %rdx
|
|
jbe L(ret_zero_in_loop_page_cross)
|
|
# endif
|
|
|
|
/* Finish the loop. */
|
|
VMOVA (VEC_SIZE * 2)(%rdi), %ymm4
|
|
VMOVA (VEC_SIZE * 3)(%rdi), %ymm6
|
|
|
|
VPCMPEQ (VEC_SIZE * 2)(%rsi), %ymm4, %ymm5
|
|
VPCMPEQ (VEC_SIZE * 3)(%rsi), %ymm6, %ymm7
|
|
vpand %ymm4, %ymm5, %ymm5
|
|
vpand %ymm6, %ymm7, %ymm7
|
|
VPMINU %ymm5, %ymm7, %ymm7
|
|
VPCMPEQ %ymm7, %ymmZERO, %ymm7
|
|
vpmovmskb %ymm7, %LOOP_REG
|
|
testl %LOOP_REG, %LOOP_REG
|
|
jnz L(return_vec_2_3_end)
|
|
|
|
/* Best for code size to include ucond-jmp here. Would be faster
|
|
if this case is hot to duplicate the L(return_vec_2_3_end) code
|
|
as fall-through and have jump back to loop on mismatch
|
|
comparison. */
|
|
subq $-(VEC_SIZE * 4), %rdi
|
|
subq $-(VEC_SIZE * 4), %rsi
|
|
addl $(PAGE_SIZE - VEC_SIZE * 8), %eax
|
|
# ifdef USE_AS_STRNCMP
|
|
subq $(VEC_SIZE * 4), %rdx
|
|
ja L(loop_skip_page_cross_check)
|
|
L(ret_zero_in_loop_page_cross):
|
|
xorl %eax, %eax
|
|
VZEROUPPER_RETURN
|
|
# else
|
|
jmp L(loop_skip_page_cross_check)
|
|
# endif
|
|
|
|
|
|
.p2align 4,, 10
|
|
L(return_vec_page_cross_0):
|
|
addl $-VEC_SIZE, %eax
|
|
L(return_vec_page_cross_1):
|
|
tzcntl %ecx, %ecx
|
|
# ifdef USE_AS_STRNCMP
|
|
leal -VEC_SIZE(%rax, %rcx), %ecx
|
|
cmpq %rcx, %rdx
|
|
jbe L(ret_zero_in_loop_page_cross)
|
|
# else
|
|
addl %eax, %ecx
|
|
# endif
|
|
|
|
# ifdef USE_AS_WCSCMP
|
|
movl VEC_OFFSET(%rdi, %rcx), %edx
|
|
xorl %eax, %eax
|
|
cmpl VEC_OFFSET(%rsi, %rcx), %edx
|
|
je L(ret9)
|
|
setl %al
|
|
negl %eax
|
|
xorl %r8d, %eax
|
|
# else
|
|
movzbl VEC_OFFSET(%rdi, %rcx), %eax
|
|
movzbl VEC_OFFSET(%rsi, %rcx), %ecx
|
|
subl %ecx, %eax
|
|
xorl %r8d, %eax
|
|
subl %r8d, %eax
|
|
# endif
|
|
L(ret9):
|
|
VZEROUPPER_RETURN
|
|
|
|
|
|
.p2align 4,, 10
|
|
L(page_cross):
|
|
# ifndef USE_AS_STRNCMP
|
|
/* If both are VEC aligned we don't need any special logic here.
|
|
Only valid for strcmp where stop condition is guranteed to be
|
|
reachable by just reading memory. */
|
|
testl $((VEC_SIZE - 1) << 20), %eax
|
|
jz L(no_page_cross)
|
|
# endif
|
|
|
|
movl %edi, %eax
|
|
movl %esi, %ecx
|
|
andl $(PAGE_SIZE - 1), %eax
|
|
andl $(PAGE_SIZE - 1), %ecx
|
|
|
|
xorl %OFFSET_REG, %OFFSET_REG
|
|
|
|
/* Check which is closer to page cross, s1 or s2. */
|
|
cmpl %eax, %ecx
|
|
jg L(page_cross_s2)
|
|
|
|
/* The previous page cross check has false positives. Check for
|
|
true positive as page cross logic is very expensive. */
|
|
subl $(PAGE_SIZE - VEC_SIZE * 4), %eax
|
|
jbe L(no_page_cross)
|
|
|
|
/* Set r8 to not interfere with normal return value (rdi and rsi
|
|
did not swap). */
|
|
# ifdef USE_AS_WCSCMP
|
|
/* any non-zero positive value that doesn't inference with 0x1.
|
|
*/
|
|
movl $2, %r8d
|
|
# else
|
|
xorl %r8d, %r8d
|
|
# endif
|
|
|
|
/* Check if less than 1x VEC till page cross. */
|
|
subl $(VEC_SIZE * 3), %eax
|
|
jg L(less_1x_vec_till_page)
|
|
|
|
/* If more than 1x VEC till page cross, loop throuh safely
|
|
loadable memory until within 1x VEC of page cross. */
|
|
|
|
.p2align 4,, 10
|
|
L(page_cross_loop):
|
|
|
|
VMOVU (%rdi, %OFFSET_REG64), %ymm0
|
|
VPCMPEQ (%rsi, %OFFSET_REG64), %ymm0, %ymm1
|
|
VPCMPEQ %ymm0, %ymmZERO, %ymm2
|
|
vpandn %ymm1, %ymm2, %ymm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incl %ecx
|
|
|
|
jnz L(check_ret_vec_page_cross)
|
|
addl $VEC_SIZE, %OFFSET_REG
|
|
# ifdef USE_AS_STRNCMP
|
|
cmpq %OFFSET_REG64, %rdx
|
|
jbe L(ret_zero_page_cross)
|
|
# endif
|
|
addl $VEC_SIZE, %eax
|
|
jl L(page_cross_loop)
|
|
|
|
subl %eax, %OFFSET_REG
|
|
/* OFFSET_REG has distance to page cross - VEC_SIZE. Guranteed
|
|
to not cross page so is safe to load. Since we have already
|
|
loaded at least 1 VEC from rsi it is also guranteed to be safe.
|
|
*/
|
|
|
|
VMOVU (%rdi, %OFFSET_REG64), %ymm0
|
|
VPCMPEQ (%rsi, %OFFSET_REG64), %ymm0, %ymm1
|
|
VPCMPEQ %ymm0, %ymmZERO, %ymm2
|
|
vpandn %ymm1, %ymm2, %ymm1
|
|
vpmovmskb %ymm1, %ecx
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
leal VEC_SIZE(%OFFSET_REG64), %eax
|
|
cmpq %rax, %rdx
|
|
jbe L(check_ret_vec_page_cross2)
|
|
addq %rdi, %rdx
|
|
# endif
|
|
incl %ecx
|
|
jz L(prepare_loop_no_len)
|
|
|
|
.p2align 4,, 4
|
|
L(ret_vec_page_cross):
|
|
# ifndef USE_AS_STRNCMP
|
|
L(check_ret_vec_page_cross):
|
|
# endif
|
|
tzcntl %ecx, %ecx
|
|
addl %OFFSET_REG, %ecx
|
|
L(ret_vec_page_cross_cont):
|
|
# ifdef USE_AS_WCSCMP
|
|
movl (%rdi, %rcx), %edx
|
|
xorl %eax, %eax
|
|
cmpl (%rsi, %rcx), %edx
|
|
je L(ret12)
|
|
setl %al
|
|
negl %eax
|
|
xorl %r8d, %eax
|
|
# else
|
|
movzbl (%rdi, %rcx), %eax
|
|
movzbl (%rsi, %rcx), %ecx
|
|
subl %ecx, %eax
|
|
xorl %r8d, %eax
|
|
subl %r8d, %eax
|
|
# endif
|
|
L(ret12):
|
|
VZEROUPPER_RETURN
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
.p2align 4,, 10
|
|
L(check_ret_vec_page_cross2):
|
|
incl %ecx
|
|
L(check_ret_vec_page_cross):
|
|
tzcntl %ecx, %ecx
|
|
addl %OFFSET_REG, %ecx
|
|
cmpq %rcx, %rdx
|
|
ja L(ret_vec_page_cross_cont)
|
|
.p2align 4,, 2
|
|
L(ret_zero_page_cross):
|
|
xorl %eax, %eax
|
|
VZEROUPPER_RETURN
|
|
# endif
|
|
|
|
.p2align 4,, 4
|
|
L(page_cross_s2):
|
|
/* Ensure this is a true page cross. */
|
|
subl $(PAGE_SIZE - VEC_SIZE * 4), %ecx
|
|
jbe L(no_page_cross)
|
|
|
|
|
|
movl %ecx, %eax
|
|
movq %rdi, %rcx
|
|
movq %rsi, %rdi
|
|
movq %rcx, %rsi
|
|
|
|
/* set r8 to negate return value as rdi and rsi swapped. */
|
|
# ifdef USE_AS_WCSCMP
|
|
movl $-4, %r8d
|
|
# else
|
|
movl $-1, %r8d
|
|
# endif
|
|
xorl %OFFSET_REG, %OFFSET_REG
|
|
|
|
/* Check if more than 1x VEC till page cross. */
|
|
subl $(VEC_SIZE * 3), %eax
|
|
jle L(page_cross_loop)
|
|
|
|
.p2align 4,, 6
|
|
L(less_1x_vec_till_page):
|
|
/* Find largest load size we can use. */
|
|
cmpl $16, %eax
|
|
ja L(less_16_till_page)
|
|
|
|
VMOVU (%rdi), %xmm0
|
|
VPCMPEQ (%rsi), %xmm0, %xmm1
|
|
VPCMPEQ %xmm0, %xmmZERO, %xmm2
|
|
vpandn %xmm1, %xmm2, %xmm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incw %cx
|
|
jnz L(check_ret_vec_page_cross)
|
|
movl $16, %OFFSET_REG
|
|
# ifdef USE_AS_STRNCMP
|
|
cmpq %OFFSET_REG64, %rdx
|
|
jbe L(ret_zero_page_cross_slow_case0)
|
|
subl %eax, %OFFSET_REG
|
|
# else
|
|
/* Explicit check for 16 byte alignment. */
|
|
subl %eax, %OFFSET_REG
|
|
jz L(prepare_loop)
|
|
# endif
|
|
|
|
VMOVU (%rdi, %OFFSET_REG64), %xmm0
|
|
VPCMPEQ (%rsi, %OFFSET_REG64), %xmm0, %xmm1
|
|
VPCMPEQ %xmm0, %xmmZERO, %xmm2
|
|
vpandn %xmm1, %xmm2, %xmm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incw %cx
|
|
jnz L(check_ret_vec_page_cross)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
addl $16, %OFFSET_REG
|
|
subq %OFFSET_REG64, %rdx
|
|
jbe L(ret_zero_page_cross_slow_case0)
|
|
subq $-(VEC_SIZE * 4), %rdx
|
|
|
|
leaq -(VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi
|
|
leaq -(VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi
|
|
# else
|
|
leaq (16 - VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi
|
|
leaq (16 - VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi
|
|
# endif
|
|
jmp L(prepare_loop_aligned)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
.p2align 4,, 2
|
|
L(ret_zero_page_cross_slow_case0):
|
|
xorl %eax, %eax
|
|
ret
|
|
# endif
|
|
|
|
|
|
.p2align 4,, 10
|
|
L(less_16_till_page):
|
|
/* Find largest load size we can use. */
|
|
cmpl $24, %eax
|
|
ja L(less_8_till_page)
|
|
|
|
vmovq (%rdi), %xmm0
|
|
vmovq (%rsi), %xmm1
|
|
VPCMPEQ %xmm0, %xmmZERO, %xmm2
|
|
VPCMPEQ %xmm1, %xmm0, %xmm1
|
|
vpandn %xmm1, %xmm2, %xmm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incb %cl
|
|
jnz L(check_ret_vec_page_cross)
|
|
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
cmpq $8, %rdx
|
|
jbe L(ret_zero_page_cross_slow_case0)
|
|
# endif
|
|
movl $24, %OFFSET_REG
|
|
/* Explicit check for 16 byte alignment. */
|
|
subl %eax, %OFFSET_REG
|
|
|
|
|
|
|
|
vmovq (%rdi, %OFFSET_REG64), %xmm0
|
|
vmovq (%rsi, %OFFSET_REG64), %xmm1
|
|
VPCMPEQ %xmm0, %xmmZERO, %xmm2
|
|
VPCMPEQ %xmm1, %xmm0, %xmm1
|
|
vpandn %xmm1, %xmm2, %xmm1
|
|
vpmovmskb %ymm1, %ecx
|
|
incb %cl
|
|
jnz L(check_ret_vec_page_cross)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
addl $8, %OFFSET_REG
|
|
subq %OFFSET_REG64, %rdx
|
|
jbe L(ret_zero_page_cross_slow_case0)
|
|
subq $-(VEC_SIZE * 4), %rdx
|
|
|
|
leaq -(VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi
|
|
leaq -(VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi
|
|
# else
|
|
leaq (8 - VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi
|
|
leaq (8 - VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi
|
|
# endif
|
|
jmp L(prepare_loop_aligned)
|
|
|
|
|
|
.p2align 4,, 10
|
|
L(less_8_till_page):
|
|
# ifdef USE_AS_WCSCMP
|
|
/* If using wchar then this is the only check before we reach
|
|
the page boundary. */
|
|
movl (%rdi), %eax
|
|
movl (%rsi), %ecx
|
|
cmpl %ecx, %eax
|
|
jnz L(ret_less_8_wcs)
|
|
# ifdef USE_AS_STRNCMP
|
|
addq %rdi, %rdx
|
|
/* We already checked for len <= 1 so cannot hit that case here.
|
|
*/
|
|
# endif
|
|
testl %eax, %eax
|
|
jnz L(prepare_loop_no_len)
|
|
ret
|
|
|
|
.p2align 4,, 8
|
|
L(ret_less_8_wcs):
|
|
setl %OFFSET_REG8
|
|
negl %OFFSET_REG
|
|
movl %OFFSET_REG, %eax
|
|
xorl %r8d, %eax
|
|
ret
|
|
|
|
# else
|
|
|
|
/* Find largest load size we can use. */
|
|
cmpl $28, %eax
|
|
ja L(less_4_till_page)
|
|
|
|
vmovd (%rdi), %xmm0
|
|
vmovd (%rsi), %xmm1
|
|
VPCMPEQ %xmm0, %xmmZERO, %xmm2
|
|
VPCMPEQ %xmm1, %xmm0, %xmm1
|
|
vpandn %xmm1, %xmm2, %xmm1
|
|
vpmovmskb %ymm1, %ecx
|
|
subl $0xf, %ecx
|
|
jnz L(check_ret_vec_page_cross)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
cmpq $4, %rdx
|
|
jbe L(ret_zero_page_cross_slow_case1)
|
|
# endif
|
|
movl $28, %OFFSET_REG
|
|
/* Explicit check for 16 byte alignment. */
|
|
subl %eax, %OFFSET_REG
|
|
|
|
|
|
|
|
vmovd (%rdi, %OFFSET_REG64), %xmm0
|
|
vmovd (%rsi, %OFFSET_REG64), %xmm1
|
|
VPCMPEQ %xmm0, %xmmZERO, %xmm2
|
|
VPCMPEQ %xmm1, %xmm0, %xmm1
|
|
vpandn %xmm1, %xmm2, %xmm1
|
|
vpmovmskb %ymm1, %ecx
|
|
subl $0xf, %ecx
|
|
jnz L(check_ret_vec_page_cross)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
addl $4, %OFFSET_REG
|
|
subq %OFFSET_REG64, %rdx
|
|
jbe L(ret_zero_page_cross_slow_case1)
|
|
subq $-(VEC_SIZE * 4), %rdx
|
|
|
|
leaq -(VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi
|
|
leaq -(VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi
|
|
# else
|
|
leaq (4 - VEC_SIZE * 4)(%rdi, %OFFSET_REG64), %rdi
|
|
leaq (4 - VEC_SIZE * 4)(%rsi, %OFFSET_REG64), %rsi
|
|
# endif
|
|
jmp L(prepare_loop_aligned)
|
|
|
|
# ifdef USE_AS_STRNCMP
|
|
.p2align 4,, 2
|
|
L(ret_zero_page_cross_slow_case1):
|
|
xorl %eax, %eax
|
|
ret
|
|
# endif
|
|
|
|
.p2align 4,, 10
|
|
L(less_4_till_page):
|
|
subq %rdi, %rsi
|
|
/* Extremely slow byte comparison loop. */
|
|
L(less_4_loop):
|
|
movzbl (%rdi), %eax
|
|
movzbl (%rsi, %rdi), %ecx
|
|
subl %ecx, %eax
|
|
jnz L(ret_less_4_loop)
|
|
testl %ecx, %ecx
|
|
jz L(ret_zero_4_loop)
|
|
# ifdef USE_AS_STRNCMP
|
|
decq %rdx
|
|
jz L(ret_zero_4_loop)
|
|
# endif
|
|
incq %rdi
|
|
/* end condition is reach page boundary (rdi is aligned). */
|
|
testl $31, %edi
|
|
jnz L(less_4_loop)
|
|
leaq -(VEC_SIZE * 4)(%rdi, %rsi), %rsi
|
|
addq $-(VEC_SIZE * 4), %rdi
|
|
# ifdef USE_AS_STRNCMP
|
|
subq $-(VEC_SIZE * 4), %rdx
|
|
# endif
|
|
jmp L(prepare_loop_aligned)
|
|
|
|
L(ret_zero_4_loop):
|
|
xorl %eax, %eax
|
|
ret
|
|
L(ret_less_4_loop):
|
|
xorl %r8d, %eax
|
|
subl %r8d, %eax
|
|
ret
|
|
# endif
|
|
END(STRCMP)
|
|
#endif
|