diff options
Diffstat (limited to 'sysdeps/x86_64/multiarch/strncpy-avx2.S')
-rw-r--r-- | sysdeps/x86_64/multiarch/strncpy-avx2.S | 740 |
1 files changed, 734 insertions, 6 deletions
diff --git a/sysdeps/x86_64/multiarch/strncpy-avx2.S b/sysdeps/x86_64/multiarch/strncpy-avx2.S index ce634e94fa..e9afd8fbed 100644 --- a/sysdeps/x86_64/multiarch/strncpy-avx2.S +++ b/sysdeps/x86_64/multiarch/strncpy-avx2.S @@ -1,7 +1,735 @@ -#ifndef STRNCPY -# define STRNCPY __strncpy_avx2 -#endif +/* strncpy with AVX2 + Copyright (C) 2022 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 + <https://www.gnu.org/licenses/>. */ + +#include <isa-level.h> + +#if ISA_SHOULD_BUILD (3) + +# include <sysdep.h> + + +# ifndef VEC_SIZE +# include "x86-avx-vecs.h" +# endif + +# ifndef STRNCPY +# define STRNCPY __strncpy_avx2 +# endif + + +# ifdef USE_AS_WCSCPY +# define VPCMPEQ vpcmpeqd +# define VPMIN vpminud +# define CHAR_SIZE 4 +# else +# define VPCMPEQ vpcmpeqb +# define VPMIN vpminub +# define CHAR_SIZE 1 +# endif + +# include "strncpy-or-cat-overflow-def.h" + +# define PAGE_SIZE 4096 + +# define VZERO VMM(7) +# define VZERO_128 VMM_128(7) + + + .section SECTION(.text), "ax", @progbits +ENTRY(STRNCPY) + /* Filter zero length strings and very long strings. Zero + length strings just return, very long strings are handled by + just running rep stos{b|l} to zero set (which will almost + certainly segfault), if that succeeds then just calling + OVERFLOW_STRCPY (strcpy, stpcpy, wcscpy, wcpcpy). */ +# ifdef USE_AS_WCSCPY + decq %rdx + movq %rdx, %rax + /* 56 is end of max supported address space. */ + shr $56, %rax + jnz L(zero_len) + salq $2, %rdx +# else + decq %rdx + /* `dec` can macrofuse with `jl`. If the flag needs to become + `jb` replace `dec` with `sub`. */ + jl L(zero_len) +# endif + + vpxor %VZERO_128, %VZERO_128, %VZERO_128 + movl %esi, %eax + andl $(PAGE_SIZE - 1), %eax + cmpl $(PAGE_SIZE - VEC_SIZE), %eax + ja L(page_cross) + +L(page_cross_continue): + VMOVU (%rsi), %VMM(0) + VPCMPEQ %VMM(0), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + + /* If no STPCPY just save end ahead of time. */ +# ifndef USE_AS_STPCPY + movq %rdi, %rax +# elif defined USE_AS_WCSCPY + /* Clear dependency as nearly all return code for wcpncpy uses + `setc %al`. */ + xorl %eax, %eax +# endif + + cmpq $(VEC_SIZE - CHAR_SIZE), %rdx + /* `jb` because length rdx is now length - CHAR_SIZE. */ + jbe L(less_1x_vec) + + /* This may overset but thats fine because we still need to zero + fill. */ + VMOVU %VMM(0), (%rdi) + + testl %ecx, %ecx + jnz L(zfill) + + /* Align. */ + addq %rsi, %rdx + subq %rsi, %rdi + orq $(VEC_SIZE - 1), %rsi + incq %rsi +L(last_4x_vec): + addq %rsi, %rdi +L(loop_last_4x_vec): + subq %rsi, %rdx + + + VMOVA 0(%rsi), %VMM(1) + VPCMPEQ %VMM(1), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + + cmpq $(VEC_SIZE * 2), %rdx + jae L(more_2x_vec) + + cmpl $(VEC_SIZE), %edx + jb L(ret_vec_x1_len) + + testl %ecx, %ecx + jnz L(ret_vec_x1) + + VPCMPEQ VEC_SIZE(%rsi), %VZERO, %VMM(6) + VMOVU %VMM(1), (%rdi) + vpmovmskb %VMM(6), %ecx + shlq $VEC_SIZE, %rcx +L(ret_vec_x1_len): + tzcntq %rcx, %rcx + cmpl %ecx, %edx + jbe L(ret_vec_x1_len_no_zfill) + /* Fall through (expectation) is copy len < buffer len. */ + VMOVU %VZERO, ((0)-(VEC_SIZE - CHAR_SIZE))(%rdi, %rdx) +L(ret_vec_x1_len_no_zfill_mov): + movl %ecx, %edx +# ifdef USE_AS_STPCPY + /* clear flags. */ + xorl %ecx, %ecx +# endif +L(ret_vec_x1_len_no_zfill): + VMOVU ((0)-(VEC_SIZE - CHAR_SIZE))(%rsi, %rdx), %VMM(1) + VMOVU %VMM(1), ((0)-(VEC_SIZE - CHAR_SIZE))(%rdi, %rdx) +# ifdef USE_AS_STPCPY +# ifdef USE_AS_WCSCPY + setc %al + addq %rdx, %rdi + leaq (%rdi, %rax, CHAR_SIZE), %rax +# else + movl %edx, %eax + adcq %rdi, %rax +# endif +# endif +L(return_vzeroupper): + ZERO_UPPER_VEC_REGISTERS_RETURN + + .p2align 4,, 6 +L(ret_vec_x1): + bsfl %ecx, %ecx + VMOVU %VZERO, ((0)-(VEC_SIZE - CHAR_SIZE))(%rdi, %rdx) + subl %ecx, %edx + /* Check if we need to reload/store. */ + cmpl $VEC_SIZE, %edx + jb L(ret_vec_x1_len_no_zfill_mov) + /* Otherwise safe to just store directly. */ + VMOVU %VMM(1), (%rdi) + VMOVU %VZERO, (%rdi, %rcx) +# ifdef USE_AS_STPCPY + leaq (%rdi, %rcx), %rax +# endif + VZEROUPPER_RETURN + + .p2align 4,, 12 +L(more_2x_vec): + VMOVU %VMM(1), (%rdi) + testl %ecx, %ecx + /* Must fill at least 2x VEC. */ + jnz L(zfill_vec1) + + VMOVA VEC_SIZE(%rsi), %VMM(2) + VMOVU %VMM(2), VEC_SIZE(%rdi) + VPCMPEQ %VMM(2), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + testl %ecx, %ecx + /* Must fill at least 1x VEC. */ + jnz L(zfill_vec2) + + VMOVA (VEC_SIZE * 2)(%rsi), %VMM(3) + VPCMPEQ %VMM(3), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + + /* Check if len is more 4x VEC. -CHAR_SIZE because rdx is len - + CHAR_SIZE. */ + cmpq $(VEC_SIZE * 4 - CHAR_SIZE), %rdx + ja L(more_4x_vec) + + subl $(VEC_SIZE * 3), %edx + jb L(ret_vec_x3_len) + + testl %ecx, %ecx + jnz L(ret_vec_x3) + + VPCMPEQ (VEC_SIZE * 3)(%rsi), %VZERO, %VMM(6) + VMOVU %VMM(3), (VEC_SIZE * 2)(%rdi) + vpmovmskb %VMM(6), %ecx + tzcntl %ecx, %ecx + cmpl %ecx, %edx + jbe L(ret_vec_x4_len_no_zfill) + /* Fall through (expectation) is copy len < buffer len. */ + VMOVU %VZERO, ((VEC_SIZE * 3)-(VEC_SIZE - CHAR_SIZE))(%rdi, %rdx) + movl %ecx, %edx +L(ret_vec_x4_len_no_zfill): + VMOVU ((VEC_SIZE * 3)-(VEC_SIZE - CHAR_SIZE))(%rsi, %rdx), %VMM(1) + VMOVU %VMM(1), ((VEC_SIZE * 3)-(VEC_SIZE - CHAR_SIZE))(%rdi, %rdx) +# ifdef USE_AS_STPCPY +# ifdef USE_AS_WCSCPY + setc %al + addq %rdx, %rdi + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax +# else + leal (VEC_SIZE * 3 + 0)(%edx), %eax + adcq %rdi, %rax +# endif +# endif + VZEROUPPER_RETURN + + +L(ret_vec_x3_len): + addl $(VEC_SIZE * 1), %edx + tzcntl %ecx, %ecx + cmpl %ecx, %edx + jbe L(ret_vec_x3_len_no_zfill) + /* Fall through (expectation) is copy len < buffer len. */ + VMOVU %VZERO, ((VEC_SIZE * 2)-(VEC_SIZE - CHAR_SIZE))(%rdi, %rdx) +L(ret_vec_x3_len_no_zfill_mov): + movl %ecx, %edx +# ifdef USE_AS_STPCPY + /* clear flags. */ + xorl %ecx, %ecx +# endif + .p2align 4,, 4 +L(ret_vec_x3_len_no_zfill): + VMOVU ((VEC_SIZE * 2)-(VEC_SIZE - CHAR_SIZE))(%rsi, %rdx), %VMM(1) + VMOVU %VMM(1), ((VEC_SIZE * 2)-(VEC_SIZE - CHAR_SIZE))(%rdi, %rdx) +# ifdef USE_AS_STPCPY +# ifdef USE_AS_WCSCPY + setc %al + addq %rdx, %rdi + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax +# else + leal (VEC_SIZE * 2 + 0)(%rdx), %eax + adcq %rdi, %rax +# endif +# endif + VZEROUPPER_RETURN + + + .p2align 4,, 8 +L(ret_vec_x3): + bsfl %ecx, %ecx + VMOVU %VZERO, (VEC_SIZE * 3 +(-(VEC_SIZE - CHAR_SIZE)))(%rdi, %rdx) + subl %ecx, %edx + jl L(ret_vec_x3_len_no_zfill_mov) + VMOVU %VMM(3), (VEC_SIZE * 2)(%rdi) + VMOVU %VZERO, (VEC_SIZE * 2)(%rdi, %rcx) +# ifdef USE_AS_STPCPY + leaq (VEC_SIZE * 2)(%rdi, %rcx), %rax +# endif + VZEROUPPER_RETURN + + .p2align 4,, 8 +L(more_4x_vec): + + VMOVU %VMM(3), (VEC_SIZE * 2)(%rdi) + testl %ecx, %ecx + jnz L(zfill_vec3) + + VMOVA (VEC_SIZE * 3)(%rsi), %VMM(4) + VMOVU %VMM(4), (VEC_SIZE * 3)(%rdi) + VPCMPEQ %VMM(4), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + testl %ecx, %ecx + jnz L(zfill_vec4) + + movq %rdx, %rcx + addq %rsi, %rdx + subq %rsi, %rdi + subq $-(VEC_SIZE * 4), %rsi + /* Recheck length before aligning. */ + cmpq $(VEC_SIZE * 8 - CHAR_SIZE), %rcx + jbe L(last_4x_vec) + + andq $(VEC_SIZE * -4), %rsi + + /* Do first half of loop ahead of time so loop can just start by + storing. */ + VMOVA (VEC_SIZE * 0 + 0)(%rsi), %VMM(0) + VMOVA (VEC_SIZE * 1 + 0)(%rsi), %VMM(1) + VMOVA (VEC_SIZE * 2 + 0)(%rsi), %VMM(2) + VMOVA (VEC_SIZE * 3 + 0)(%rsi), %VMM(3) + + VPMIN %VMM(0), %VMM(1), %VMM(4) + VPMIN %VMM(2), %VMM(3), %VMM(6) + VPMIN %VMM(4), %VMM(6), %VMM(6) + VPCMPEQ %VMM(6), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %r8d + addq %rsi, %rdi + testl %r8d, %r8d + jnz L(loop_4x_done) + + /* Use r9 as end register. */ + leaq -(VEC_SIZE * 4 - CHAR_SIZE)(%rdx), %r9 -#define USE_AS_STRNCPY -#define STRCPY STRNCPY -#include "strcpy-avx2.S" + .p2align 4,, 11 +L(loop_4x_vec): + + VMOVU %VMM(0), (VEC_SIZE * 0 + 0)(%rdi) + VMOVU %VMM(1), (VEC_SIZE * 1 + 0)(%rdi) + subq $(VEC_SIZE * -4), %rsi + VMOVU %VMM(2), (VEC_SIZE * 2 + 0)(%rdi) + VMOVU %VMM(3), (VEC_SIZE * 3 + 0)(%rdi) + + subq $(VEC_SIZE * -4), %rdi + cmpq %rsi, %r9 + jbe L(loop_last_4x_vec) + + VMOVA (VEC_SIZE * 0 + 0)(%rsi), %VMM(0) + VMOVA (VEC_SIZE * 1 + 0)(%rsi), %VMM(1) + VMOVA (VEC_SIZE * 2 + 0)(%rsi), %VMM(2) + VMOVA (VEC_SIZE * 3 + 0)(%rsi), %VMM(3) + + VPMIN %VMM(0), %VMM(1), %VMM(4) + VPMIN %VMM(2), %VMM(3), %VMM(6) + VPMIN %VMM(4), %VMM(6), %VMM(6) + VPCMPEQ %VMM(6), %VZERO, %VMM(6) + + vpmovmskb %VMM(6), %r8d + + testl %r8d, %r8d + jz L(loop_4x_vec) + +L(loop_4x_done): + subq %rsi, %rdx + VMOVU %VMM(0), (VEC_SIZE * 0 + 0)(%rdi) + VPCMPEQ %VMM(0), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + testl %ecx, %ecx + jnz L(zfill_vec1) + + VMOVU %VMM(1), (VEC_SIZE * 1 + 0)(%rdi) + VPCMPEQ %VMM(1), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + testl %ecx, %ecx + jnz L(zfill_vec2) + + VMOVU %VMM(2), (VEC_SIZE * 2 + 0)(%rdi) + VPCMPEQ %VMM(2), %VZERO, %VMM(6) + vpmovmskb %VMM(6), %ecx + testl %ecx, %ecx + jnz L(zfill_vec3) + + VMOVU %VMM(3), (VEC_SIZE * 3 + 0)(%rdi) + movl %r8d, %ecx + + // Zfill more.... + + .p2align 4,, 4 +L(zfill_vec4): + addq $(VEC_SIZE * 2), %rdi + subq $(VEC_SIZE * 2), %rdx +L(zfill_vec2): + shlq $VEC_SIZE, %rcx +L(zfill): + bsfq %rcx, %rcx + subq %rcx, %rdx + addq %rcx, %rdi +# ifdef USE_AS_STPCPY + movq %rdi, %rax +# endif +L(zfill_from_page_cross): + cmpq $VEC_SIZE, %rdx + jb L(zfill_less_vec_vzeroupper) + +L(zfill_more_1x_vec): + VMOVU %VZERO, CHAR_SIZE(%rdi) + VMOVU %VZERO, (CHAR_SIZE - VEC_SIZE)(%rdi, %rdx) + cmpq $(VEC_SIZE * 2), %rdx + jae L(zfill_more_2x_vec) +L(zfill_done0): + VZEROUPPER_RETURN + + .p2align 4,, 8 +L(zfill_vec3): + addq $(VEC_SIZE * 2), %rdi + subq $(VEC_SIZE * 2), %rdx + .p2align 4,, 2 +L(zfill_vec1): + bsfl %ecx, %ecx + addq %rcx, %rdi + subq %rcx, %rdx +# ifdef USE_AS_STPCPY + movq %rdi, %rax +# endif + /* zfill from vec1/vec3 must have to set at least 2x VECS. */ + + VMOVU %VZERO, CHAR_SIZE(%rdi) + VMOVU %VZERO, (CHAR_SIZE - VEC_SIZE)(%rdi, %rdx) + cmpq $(VEC_SIZE * 2), %rdx + jb L(zfill_done0) +L(zfill_more_2x_vec): + VMOVU %VZERO, (CHAR_SIZE - VEC_SIZE * 2)(%rdi, %rdx) + VMOVU %VZERO, (VEC_SIZE + CHAR_SIZE)(%rdi) + subq $(VEC_SIZE * 4 - CHAR_SIZE), %rdx + jbe L(zfill_done) + + addq %rdi, %rdx + VMOVU %VZERO, (VEC_SIZE * 2 + CHAR_SIZE)(%rdi) + VMOVU %VZERO, (VEC_SIZE * 3 + CHAR_SIZE)(%rdi) + + + VMOVU %VZERO, (VEC_SIZE * 0 + 0)(%rdx) + VMOVU %VZERO, (VEC_SIZE * 1 + 0)(%rdx) + + subq $-(VEC_SIZE * 4 + CHAR_SIZE), %rdi + cmpq %rdi, %rdx + jbe L(zfill_done) + + andq $-(VEC_SIZE), %rdi + .p2align 4,, 12 +L(zfill_loop_4x_vec): + VMOVA %VZERO, (VEC_SIZE * 0)(%rdi) + VMOVA %VZERO, (VEC_SIZE * 1)(%rdi) + VMOVA %VZERO, (VEC_SIZE * 2)(%rdi) + VMOVA %VZERO, (VEC_SIZE * 3)(%rdi) + subq $-(VEC_SIZE * 4), %rdi + cmpq %rdi, %rdx + ja L(zfill_loop_4x_vec) +L(zfill_done): + VZEROUPPER_RETURN + + + .p2align 4,, 8 +L(copy_1x): + VMOVU %VMM(0), (%rdi) + testl %ecx, %ecx + jz L(ret_32_32) +L(zfill_less_vec): + bsfl %ecx, %ecx +L(zfill_less_vec_no_bsf): + subq %rcx, %rdx + addq %rcx, %rdi +# ifdef USE_AS_STPCPY + movq %rdi, %rax +# endif +L(zfill_less_vec_vzeroupper): + COND_VZEROUPPER + /* We are taking advantage of the fact that to be here we must + be writing null-term as (%rdi, %rcx) we have a byte of lee- + way for overwriting. */ + cmpl $16, %edx + jb L(zfill_less_16) + VMOVU %VZERO_128, (%rdi) + VMOVU %VZERO_128, -(16 - CHAR_SIZE)(%rdi, %rdx) + ret +# ifdef USE_AS_STPCPY +L(ret_32_32): + leaq CHAR_SIZE(%rdi, %rdx), %rax + VZEROUPPER_RETURN +# endif + + .p2align 4,, 4 +L(copy_16_31): + /* Overfill to avoid branches. */ + vmovdqu -(16 - CHAR_SIZE)(%rsi, %rdx), %xmm1 + vmovdqu %xmm0, (%rdi) + vmovdqu %xmm1, -(16 - CHAR_SIZE)(%rdi, %rdx) + cmpl %ecx, %edx + ja L(zfill_less_vec_no_bsf) +# ifndef USE_AS_STPCPY +L(ret_32_32): +# else +# ifdef USE_AS_WCSCPY + setc %al + addq %rdx, %rdi + leaq (%rdi, %rax, CHAR_SIZE), %rax +# else + movl %edx, %eax + adcq %rdi, %rax +# endif +# endif + VZEROUPPER_RETURN + + .p2align 4,, 4 +L(copy_8_15): + /* Overfill to avoid branches. */ + movq -(8 - CHAR_SIZE)(%rsi, %rdx), %rsi + vmovq %xmm0, (%rdi) + movq %rsi, -(8 - CHAR_SIZE)(%rdi, %rdx) + cmpl %ecx, %edx + jbe L(ret_8_15) + subq %rcx, %rdx + addq %rcx, %rdi +# ifdef USE_AS_STPCPY + movq %rdi, %rax +# endif + .p2align 4,, 8 +L(zfill_less_16): + xorl %ecx, %ecx + cmpl $8, %edx + jb L(zfill_less_8) + movq %rcx, (%rdi) + movq %rcx, -(8 - CHAR_SIZE)(%rdi, %rdx) +# ifndef USE_AS_STPCPY +L(ret_8_15): +# endif + ret + + + .p2align 4,, 8 +L(less_1x_vec): + /* Reuse flag from `cmp $VEC_SIZE, %rdx`. The idea is many + buffer sizes are aligned conventially. */ + je L(copy_1x) + + tzcntl %ecx, %ecx + cmpl $16, %edx + jae L(copy_16_31) + + COND_VZEROUPPER + cmpl $8, %edx + jae L(copy_8_15) +# ifdef USE_AS_WCSCPY + testl %ecx, %ecx + jz L(zfill_less_8_set_ret) + + movl (%rsi, %rdx), %esi + vmovd %xmm0, (%rdi) + movl %esi, (%rdi, %rdx) + +# ifdef USE_AS_STPCPY + cmpl %ecx, %edx +L(ret_8_15): + setc %al + addq %rdx, %rdi + leaq (%rdi, %rax, CHAR_SIZE), %rax +# endif + ret +L(zfill_less_8_set_ret): + xorl %ecx, %ecx +# ifdef USE_AS_STPCPY + movq %rdi, %rax +# endif +L(zfill_less_8): + movl %ecx, (%rdi) + movl %ecx, (%rdi, %rdx) + ret + +# else + cmpl $3, %edx + jb L(copy_0_3) + /* Overfill to avoid branches. */ + movl -3(%rsi, %rdx), %esi + vmovd %xmm0, (%rdi) + movl %esi, -3(%rdi, %rdx) + cmpl %ecx, %edx + jbe L(ret_4_7) + subq %rcx, %rdx + addq %rcx, %rdi +# ifdef USE_AS_STPCPY + movq %rdi, %rax +# endif + xorl %ecx, %ecx + .p2align 4,, 8 +L(zfill_less_8): + cmpl $3, %edx + jb L(zfill_less_3) + movl %ecx, (%rdi) + movl %ecx, -3(%rdi, %rdx) +# ifdef USE_AS_STPCPY + ret +# endif + +L(ret_4_7): +# ifdef USE_AS_STPCPY +L(ret_8_15): + movl %edx, %eax + adcq %rdi, %rax +# endif + ret + + .p2align 4,, 4 +L(zfill_less_3): + testl %edx, %edx + jz L(zfill_1) + movw %cx, (%rdi) +L(zfill_1): + movb %cl, (%rdi, %rdx) + ret + + .p2align 4,, 8 +L(copy_0_3): + vmovd %xmm0, %r8d + testl %edx, %edx + jz L(copy_1) + movw %r8w, (%rdi) + cmpl %ecx, %edx + ja L(zfill_from_1) + movzbl (%rsi, %rdx), %r8d +# ifdef USE_AS_STPCPY + movl %edx, %eax + adcq %rdi, %rax + movb %r8b, (%rdi, %rdx) + ret +# endif + +L(copy_1): +# ifdef USE_AS_STPCPY + movl %edx, %eax + cmpl %ecx, %edx + adcq %rdi, %rax +# endif +# ifdef USE_AS_WCSCPY + vmovd %xmm0, (%rdi) +# else + movb %r8b, (%rdi, %rdx) +# endif + ret +# endif + + .p2align 4,, 2 +L(zero_len): + movq %rdi, %rax + ret +# ifndef USE_AS_WCSCPY + .p2align 4,, 8 +L(zfill_from_1): +# ifdef USE_AS_STPCPY + leaq (%rdi, %rcx), %rax +# endif + movw $0, -1(%rdi, %rdx) + ret +# endif + + .p2align 4,, 4 + .p2align 6,, 8 +L(page_cross): + movq %rsi, %rax + andq $(VEC_SIZE * -1), %rax + + VPCMPEQ (%rax), %VZERO, %VMM(6) + + vpmovmskb %VMM(6), %ecx + shrxl %esi, %ecx, %ecx + + subl %esi, %eax + andl $(VEC_SIZE - 1), %eax + cmpq %rax, %rdx + jb L(page_cross_small) + /* Optimizing more aggressively for space as this is very cold + code. This saves 2x cache lines. */ + + /* If rcx is non-zero then continue. */ + shl $CHAR_SIZE, %ecx + jz L(page_cross_continue) + bsf %ecx, %ecx + + subq %rcx, %rdx +# ifdef USE_AS_STPCPY + leaq -CHAR_SIZE(%rdi, %rcx), %rax +# else + movq %rdi, %rax +# endif + + rep movsb +# ifdef USE_AS_WCSCPY + movl $0, (%rdi) +# else + movb $0, (%rdi) +# endif + jmp L(zfill_from_page_cross) + +L(page_cross_small): + tzcntl %ecx, %ecx + xorl %eax, %eax + cmpl %ecx, %edx + jbe L(page_cross_copy_only) + + /* Do a zfill of the tail before copying. */ + movq %rdi, %r9 + movl %ecx, %r8d + + subl %ecx, %edx + leaq CHAR_SIZE(%rdi, %rcx), %rdi + movl %edx, %ecx + rep stosb + movq %r9, %rdi + movl %r8d, %edx +L(page_cross_copy_only): + leal CHAR_SIZE(%rdx), %ecx +# ifdef USE_AS_STPCPY +# ifdef USE_AS_WCSCPY + setc %al + addq %rdi, %rdx + leaq (%rdx, %rax, CHAR_SIZE), %rax +# else + movl %edx, %eax + adcq %rdi, %rax +# endif +# else + movq %rdi, %rax +# endif + rep movsb + ret + + +L(best_effort_strncpy): + movq %rdx, %rcx + xorl %eax, %eax + movq %rdi, %r8 + /* The length is >= 2^63. We very much so expect to segfault at + rep stos. If that doesn't happen then just strcpy to finish. + */ +# ifdef USE_AS_WCSCPY + rep stosl +# else + rep stosb +# endif + movq %r8, %rdi + jmp OVERFLOW_STRCPY +END(STRNCPY) +#endif |