/* Optimized strncpy implementation for POWER9 LE. Copyright (C) 2020-2022 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 . */ #include #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+8) /* 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 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. 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