--- /dev/null
+/* Optimized strncpy implementation for POWER9 LE.
+ Copyright (C) 2020 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>
+
+# ifndef STRNCPY
+# define FUNC_NAME strncpy
+# else
+# define FUNC_NAME STRNCPY
+# endif
+
+#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+8)
+
+/* Implements the function
+
+ char * [r3] strncpy (char *dest [r3], const char *src [r4], size_t n [r5])
+
+ 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
+ beqlr
+
+ 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 */
+
+ blr
+
+L(null):
+ sldi r10,r8,56 /* stxvl wants size in top 8 bits */
+ stxvl 32+v0,r11,r10 /* Partial store */
+
+ 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 */
+ 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 */
+ 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 */
+ 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 */
+ 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 */
+ 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 */
+ 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 */
+ 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 */
+ 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 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 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. */
+ 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)
projects / thirdparty / glibc.git / commitdiff
