diff options
Diffstat (limited to 'lib/libc/amd64/string/strcat.S')
| -rw-r--r-- | lib/libc/amd64/string/strcat.S | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/lib/libc/amd64/string/strcat.S b/lib/libc/amd64/string/strcat.S new file mode 100644 index 000000000000..081e98840cee --- /dev/null +++ b/lib/libc/amd64/string/strcat.S @@ -0,0 +1,203 @@ +/*- + * Copyright (c) 2023, The FreeBSD Foundation + * + * SPDX-License-Expression: BSD-2-Clause + * + * Portions of this software were developed by Robert Clausecker + * <fuz@FreeBSD.org> under sponsorship from the FreeBSD Foundation. + * + * Adapted from NetBSD's common/lib/libc/arch/x86_64/string/strcat.S + * written by J.T. Conklin <jtc@acorntoolworks.com> + * that was originally dedicated to the public domain + */ + +#include <machine/asm.h> +#if 0 + RCSID("$NetBSD: strcat.S,v 1.4 2004/07/26 18:51:21 drochner Exp $") +#endif + +#include "amd64_archlevel.h" + +ARCHFUNCS(strcat) + ARCHFUNC(strcat, scalar) + ARCHFUNC(strcat, baseline) +ENDARCHFUNCS(strcat) + +ARCHENTRY(strcat, scalar) + movq %rdi,%rax + movabsq $0x0101010101010101,%r8 + movabsq $0x8080808080808080,%r9 + + /* + * Align destination to word boundary. + * Consider unrolling loop? + */ +.Lscan: +.Lscan_align: + testb $7,%dil + je .Lscan_aligned + cmpb $0,(%rdi) + je .Lcopy + incq %rdi + jmp .Lscan_align + + .align 4 +.Lscan_aligned: +.Lscan_loop: + movq (%rdi),%rdx + addq $8,%rdi + subq %r8,%rdx + testq %r9,%rdx + je .Lscan_loop + + /* + * In rare cases, the above loop may exit prematurely. We must + * return to the loop if none of the bytes in the word equal 0. + */ + + cmpb $0,-8(%rdi) /* 1st byte == 0? */ + jne 1f + subq $8,%rdi + jmp .Lcopy + +1: cmpb $0,-7(%rdi) /* 2nd byte == 0? */ + jne 1f + subq $7,%rdi + jmp .Lcopy + +1: cmpb $0,-6(%rdi) /* 3rd byte == 0? */ + jne 1f + subq $6,%rdi + jmp .Lcopy + +1: cmpb $0,-5(%rdi) /* 4th byte == 0? */ + jne 1f + subq $5,%rdi + jmp .Lcopy + +1: cmpb $0,-4(%rdi) /* 5th byte == 0? */ + jne 1f + subq $4,%rdi + jmp .Lcopy + +1: cmpb $0,-3(%rdi) /* 6th byte == 0? */ + jne 1f + subq $3,%rdi + jmp .Lcopy + +1: cmpb $0,-2(%rdi) /* 7th byte == 0? */ + jne 1f + subq $2,%rdi + jmp .Lcopy + +1: cmpb $0,-1(%rdi) /* 8th byte == 0? */ + jne .Lscan_loop + subq $1,%rdi + + /* + * Align source to a word boundary. + * Consider unrolling loop? + */ +.Lcopy: +.Lcopy_align: + testb $7,%sil + je .Lcopy_aligned + movb (%rsi),%dl + incq %rsi + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl + jne .Lcopy_align + ret + + .align 4 +.Lcopy_loop: + movq %rdx,(%rdi) + addq $8,%rdi +.Lcopy_aligned: + movq (%rsi),%rdx + movq %rdx,%rcx + addq $8,%rsi + subq %r8,%rcx + testq %r9,%rcx + je .Lcopy_loop + + /* + * In rare cases, the above loop may exit prematurely. We must + * return to the loop if none of the bytes in the word equal 0. + */ + + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 1st byte == 0? */ + je .Ldone + + shrq $8,%rdx + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 2nd byte == 0? */ + je .Ldone + + shrq $8,%rdx + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 3rd byte == 0? */ + je .Ldone + + shrq $8,%rdx + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 4th byte == 0? */ + je .Ldone + + shrq $8,%rdx + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 5th byte == 0? */ + je .Ldone + + shrq $8,%rdx + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 6th byte == 0? */ + je .Ldone + + shrq $8,%rdx + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 7th byte == 0? */ + je .Ldone + + shrq $8,%rdx + movb %dl,(%rdi) + incq %rdi + testb %dl,%dl /* 8th byte == 0? */ + jne .Lcopy_aligned + +.Ldone: + ret +ARCHEND(strcat, scalar) + +/* + * Call into strlen + strcpy if we have any SIMD at all. + * The scalar implementation above is better for the scalar + * case as it avoids the function call overhead, but pessimal + * if we could call SIMD routines instead. + */ +ARCHENTRY(strcat, baseline) + push %rbp + mov %rsp, %rbp + push %rsi + push %rbx + mov %rdi, %rbx # remember destination for later + call CNAME(strlen) # strlen(dest) + mov -8(%rbp), %rsi + lea (%rbx, %rax, 1), %rdi # dest + strlen(dest) + call CNAME(__stpcpy) # stpcpy(dest + strlen(dest), src) + mov %rbx, %rax # return dest + pop %rbx + leave + ret +ARCHEND(strcat, baseline) + + .section .note.GNU-stack,"",%progbits |