path: root/sysdeps/mips/memset.S

/* Copyright (C) 2013-2025 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/>.  */

#ifdef ANDROID_CHANGES
# include "machine/asm.h"
# include "machine/regdef.h"
# define PREFETCH_STORE_HINT PREFETCH_HINT_PREPAREFORSTORE
#elif _LIBC
# include <sysdep.h>
# include <regdef.h>
# include <sys/asm.h>
# define PREFETCH_STORE_HINT PREFETCH_HINT_PREPAREFORSTORE
#elif defined _COMPILING_NEWLIB
# include "machine/asm.h"
# include "machine/regdef.h"
# define PREFETCH_STORE_HINT PREFETCH_HINT_PREPAREFORSTORE
#else
# include <regdef.h>
# include <sys/asm.h>
#endif

/* Check to see if the MIPS architecture we are compiling for supports
   prefetching.  */

#if (__mips == 4) || (__mips == 5) || (__mips == 32) || (__mips == 64)
# ifndef DISABLE_PREFETCH
#  define USE_PREFETCH
# endif
#endif

#if defined(_MIPS_SIM) && ((_MIPS_SIM == _ABI64) || (_MIPS_SIM == _ABIN32))
# ifndef DISABLE_DOUBLE
#  define USE_DOUBLE
# endif
#endif

#ifndef USE_DOUBLE
# ifndef DISABLE_DOUBLE_ALIGN
#  define DOUBLE_ALIGN
# endif
#endif


/* Some asm.h files do not have the L macro definition.  */
#ifndef L
# if _MIPS_SIM == _ABIO32
#  define L(label) $L ## label
# else
#  define L(label) .L ## label
# endif
#endif

/* Some asm.h files do not have the PTR_ADDIU macro definition.  */
#ifndef PTR_ADDIU
# ifdef USE_DOUBLE
#  define PTR_ADDIU	daddiu
# else
#  define PTR_ADDIU	addiu
# endif
#endif

/* New R6 instructions that may not be in asm.h.  */
#ifndef PTR_LSA
# if _MIPS_SIM == _ABI64
#  define PTR_LSA        dlsa
# else
#  define PTR_LSA        lsa
# endif
#endif

/* Using PREFETCH_HINT_PREPAREFORSTORE instead of PREFETCH_STORE
   or PREFETCH_STORE_STREAMED offers a large performance advantage
   but PREPAREFORSTORE has some special restrictions to consider.

   Prefetch with the 'prepare for store' hint does not copy a memory
   location into the cache, it just allocates a cache line and zeros
   it out.  This means that if you do not write to the entire cache
   line before writing it out to memory some data will get zero'ed out
   when the cache line is written back to memory and data will be lost.

   There are ifdef'ed sections of this memcpy to make sure that it does not
   do prefetches on cache lines that are not going to be completely written.
   This code is only needed and only used when PREFETCH_STORE_HINT is set to
   PREFETCH_HINT_PREPAREFORSTORE.  This code assumes that cache lines are
   less than MAX_PREFETCH_SIZE bytes and if the cache line is larger it will
   not work correctly.  */

#ifdef USE_PREFETCH
# define PREFETCH_HINT_STORE		1
# define PREFETCH_HINT_STORE_STREAMED	5
# define PREFETCH_HINT_STORE_RETAINED	7
# define PREFETCH_HINT_PREPAREFORSTORE	30

/* If we have not picked out what hints to use at this point use the
   standard load and store prefetch hints.  */
# ifndef PREFETCH_STORE_HINT
#  define PREFETCH_STORE_HINT PREFETCH_HINT_STORE
# endif

/* We double everything when USE_DOUBLE is true so we do 2 prefetches to
   get 64 bytes in that case.  The assumption is that each individual
   prefetch brings in 32 bytes.  */
# ifdef USE_DOUBLE
#  define PREFETCH_CHUNK 64
#  define PREFETCH_FOR_STORE(chunk, reg) \
    pref PREFETCH_STORE_HINT, (chunk)*64(reg); \
    pref PREFETCH_STORE_HINT, ((chunk)*64)+32(reg)
# else
#  define PREFETCH_C