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/* Optimized strncpy implementation for POWER9 LE.
Copyright (C) 2020-2024 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 <sysdep.h>
#ifdef USE_AS_STPNCPY
# ifndef STPNCPY
# define FUNC_NAME __stpncpy
# else
# define FUNC_NAME STPNCPY
# endif
#else
# ifndef STRNCPY
# define FUNC_NAME strncpy
# else
# define FUNC_NAME STRNCPY
# endif
#endif /* !USE_AS_STPNCPY */
#ifndef MEMSET
/* For builds without IFUNC support, local calls should be made to internal
GLIBC symbol (created by libc_hidden_builtin_def). */
# ifdef SHARED
# define MEMSET_is_local
# define MEMSET __GI_memset
# else
# define MEMSET memset
# endif
#endif
#define FRAMESIZE (FRAME_MIN_SIZE+16)
/* Implements the function
char * [r3] strncpy (char *dest [r3], const char *src [r4], size_t n [r5])
or
char * [r3] stpncpy (char *dest [r3], const char *src [r4], size_t n [r5])
if USE_AS_STPNCPY is defined.
The implementation can load bytes past a null terminator, but only
up to the next 16-byte aligned address, so it never crosses a page. */
.machine power9
#ifdef MEMSET_is_local
ENTRY_TOCLESS (FUNC_NAME, 4)
#else
ENTRY (FUNC_NAME, 4)
#endif
CALL_MCOUNT 2
/* NULL string optimizations */
cmpdi r5, 0
beqlr
lbz r0,0(r4)
stb r0,0(r3)
addi r11,r3,1
addi r5,r5,-1
vspltisb v18,0 /* Zeroes in v18 */
cmpdi r0,0
beq L(zero_padding)
/* Empty/1-byte string optimization */
cmpdi r5,0
#ifdef USE_AS_STPNCPY
bgt L(cont)
/* Compute pointer to last byte copied into dest. */
addi r3,r3,1
blr
L(cont):
#else
beqlr
#endif
addi r4,r4,1
neg r7,r4
rldicl r9,r7,0,60 /* How many bytes to get source 16B aligned? */
/* Get source 16B aligned */
lvx v0,0,r4
lvsr v1,0,r4
vperm v0,v18,v0,v1
vcmpequb v6,v0,v18 /* 0xff if byte is NULL, 0x00 otherwise */
vctzlsbb r7,v6 /* Number of trailing zeroes */
addi r8,r7,1 /* Add null terminator */
/* r8 = bytes including null
r9 = bytes to get source 16B aligned
if r8 > r9
no null, copy r9 bytes
else
there is a null, copy r8 bytes and return. */
cmpld r8,r9
bgt L(no_null)
cmpld cr6,r8,r5 /* r8 <= n? */
ble cr6,L(null)
sldi r10,r5,56 /* stxvl wants size in top 8 bits */
stxvl 32+v0,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r5
#endif
blr
L(null):
sldi r10,r8,56 /* stxvl wants size in top 8 bits */
stxvl 32+v0,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r7
#endif
add r11,r11,r8
sub r5,r5,r8
b L(zero_padding)
L(no_null):
cmpld r9,r5 /* Check if length was reached. */
bge L(n_tail1)
sldi r10,r9,56 /* stxvl wants size in top 8 bits */
stxvl 32+v0,r11,r10 /* Partial store */
add r4,r4,r9
add r11,r11,r9
sub r5,r5,r9
L(loop):
cmpldi cr6,r5,64 /* Check if length was reached. */
ble cr6,L(final_loop)
lxv 32+v0,0(r4)
vcmpequb. v6,v0,v18 /* Any zero bytes? */
bne cr6,L(prep_tail1)
lxv 32+v1,16(r4)
vcmpequb. v6,v1,v18 /* Any zero bytes? */
bne cr6,L(prep_tail2)
lxv 32+v2,32(r4)
vcmpequb. v6,v2,v18 /* Any zero bytes? */
bne cr6,L(prep_tail3)
lxv 32+v3,48(r4)
vcmpequb. v6,v3,v18 /* Any zero bytes? */
bne cr6,L(prep_tail4)
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
stxv 32+v2,32(r11)
stxv 32+v3,48(r11)
addi r4,r4,64
addi r11,r11,64
addi r5,r5,-64
b L(loop)
L(final_loop):
cmpldi cr5,r5,16
lxv 32+v0,0(r4)
vcmpequb. v6,v0,v18 /* Any zero bytes? */
ble cr5,L(prep_n_tail1)
bne cr6,L(count_tail1)
addi r5,r5,-16
cmpldi cr5,r5,16
lxv 32+v1,16(r4)
vcmpequb. v6,v1,v18 /* Any zero bytes? */
ble cr5,L(prep_n_tail2)
bne cr6,L(count_tail2)
addi r5,r5,-16
cmpldi cr5,r5,16
lxv 32+v2,32(r4)
vcmpequb. v6,v2,v18 /* Any zero bytes? */
ble cr5,L(prep_n_tail3)
bne cr6,L(count_tail3)
addi r5,r5,-16
lxv 32+v3,48(r4)
vcmpequb. v6,v3,v18 /* Any zero bytes? */
beq cr6,L(n_tail4)
vctzlsbb r8,v6 /* Number of trailing zeroes */
cmpld r8,r5 /* r8 < n? */
blt L(tail4)
L(n_tail4):
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
stxv 32+v2,32(r11)
sldi r10,r5,56 /* stxvl wants size in top 8 bits */
addi r11,r11,48 /* Offset */
stxvl 32+v3,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r5
#endif
blr
L(prep_n_tail1):
beq cr6,L(n_tail1) /* Any zero bytes? */
vctzlsbb r8,v6 /* Number of trailing zeroes */
cmpld r8,r5 /* r8 < n? */
blt L(tail1)
L(n_tail1):
sldi r10,r5,56 /* stxvl wants size in top 8 bits */
stxvl 32+v0,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r5
#endif
blr
L(prep_n_tail2):
beq cr6,L(n_tail2) /* Any zero bytes? */
vctzlsbb r8,v6 /* Number of trailing zeroes */
cmpld r8,r5 /* r8 < n? */
blt L(tail2)
L(n_tail2):
stxv 32+v0,0(r11)
sldi r10,r5,56 /* stxvl wants size in top 8 bits */
addi r11,r11,16 /* offset */
stxvl 32+v1,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r5
#endif
blr
L(prep_n_tail3):
beq cr6,L(n_tail3) /* Any zero bytes? */
vctzlsbb r8,v6 /* Number of trailing zeroes */
cmpld r8,r5 /* r8 < n? */
blt L(tail3)
L(n_tail3):
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
sldi r10,r5,56 /* stxvl wants size in top 8 bits */
addi r11,r11,32 /* Offset */
stxvl 32+v2,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r5
#endif
blr
L(prep_tail1):
L(count_tail1):
vctzlsbb r8,v6 /* Number of trailing zeroes */
L(tail1):
addi r9,r8,1 /* Add null terminator */
sldi r10,r9,56 /* stxvl wants size in top 8 bits */
stxvl 32+v0,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r8
#endif
add r11,r11,r9
sub r5,r5,r9
b L(zero_padding)
L(prep_tail2):
addi r5,r5,-16
L(count_tail2):
vctzlsbb r8,v6 /* Number of trailing zeroes */
L(tail2):
addi r9,r8,1 /* Add null terminator */
stxv 32+v0,0(r11)
sldi r10,r9,56 /* stxvl wants size in top 8 bits */
addi r11,r11,16 /* offset */
stxvl 32+v1,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r8
#endif
add r11,r11,r9
sub r5,r5,r9
b L(zero_padding)
L(prep_tail3):
addi r5,r5,-32
L(count_tail3):
vctzlsbb r8,v6 /* Number of trailing zeroes */
L(tail3):
addi r9,r8,1 /* Add null terminator */
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
sldi r10,r9,56 /* stxvl wants size in top 8 bits */
addi r11,r11,32 /* offset */
stxvl 32+v2,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r8
#endif
add r11,r11,r9
sub r5,r5,r9
b L(zero_padding)
L(prep_tail4):
addi r5,r5,-48
vctzlsbb r8,v6 /* Number of trailing zeroes */
L(tail4):
addi r9,r8,1 /* Add null terminator */
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
stxv 32+v2,32(r11)
sldi r10,r9,56 /* stxvl wants size in top 8 bits */
addi r11,r11,48 /* offset */
stxvl 32+v3,r11,r10 /* Partial store */
#ifdef USE_AS_STPNCPY
/* Compute pointer to last byte copied into dest. */
add r3,r11,r8
#endif
add r11,r11,r9
sub r5,r5,r9
/* This code pads the remainder of dest with NULL bytes. For large numbers
memset gives a better performance, 255 was chosen through experimentation.
*/
L(zero_padding):
cmpldi r5,255
bge L(zero_padding_memset)
L(zero_padding_loop):
cmpldi cr6,r5,16 /* Check if length was reached. */
ble cr6,L(zero_padding_end)
stxv 32+v18,0(r11)
addi r11,r11,16
addi r5,r5,-16
b L(zero_padding_loop)
L(zero_padding_end):
sldi r10,r5,56 /* stxvl wants size in top 8 bits */
stxvl 32+v18,r11,r10 /* Partial store */
blr
.align 4
L(zero_padding_memset):
std r30,-8(r1) /* Save r30 on the stack. */
cfi_offset(r30, -8)
mr r30,r3 /* Save the return value of strncpy. */
/* Prepare the call to memset. */
mr r3,r11 /* Pointer to the area to be zero-filled. */
li r4,0 /* Byte to be written (zero). */
/* We delayed the creation of the stack frame, as well as the saving of
the link register, because only at this point, we are sure that
doing so is actually needed. */
/* Save the link register. */
mflr r0
std r0,16(r1)
/* Create the stack frame. */
stdu r1,-FRAMESIZE(r1)
cfi_adjust_cfa_offset(FRAMESIZE)
cfi_offset(lr, 16)
bl MEMSET
#ifndef MEMSET_is_local
nop
#endif
ld r0,FRAMESIZE+16(r1)
mr r3,r30 /* Restore the return value of strncpy, i.e.:
dest. For stpncpy, the return value is the
same as return value of memset. */
ld r30,FRAMESIZE-8(r1) /* Restore r30. */
/* Restore the stack frame. */
addi r1,r1,FRAMESIZE
cfi_adjust_cfa_offset(-FRAMESIZE)
/* Restore the link register. */
mtlr r0
cfi_restore(lr)
blr
END (FUNC_NAME)
#ifndef USE_AS_STPNCPY
libc_hidden_builtin_def (strncpy)
#endif
|
