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/* Copyright (C) 2023-2024 Free Software Foundation, Inc.
This file is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
This file 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
General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "mips16.S"
#ifdef L_speculation_barrier
/* MIPS16e1 has no sync/jr.hb instructions, and MIPS16e2 lacks of jr.hb.
So, we use normal MIPS code here, just like what we do for __sync_*. */
.set nomips16
.set noreorder
.globl __speculation_barrier
.ent __speculation_barrier
__speculation_barrier:
.set push
#if __mips >= 2
sync /* complementation barrier for memory. */
#elif defined (__linux)
/* MIPS1 has no sync, while Linux can trap&emu sync. */
/* FIXME: Will somebody use linux/gcc for MIPS1/baremetal? */
.word 0x0000000f
#endif
#if __mips_isa_rev >= 1
/* Binutils claims that JR in R1 can do same as jr.hb.
R6 changes the encoding of jr.hb. */
jr.hb $ra /* Jump with instruction hazard barrier. */
#else
/* ssnop is actually available since R5500,
and it will be decoded as nop on earlier processors.
gas can only recognize it with -march=mips1 since 2.21.
MIPS1 to MIPSr1: R10000 have 7 stage pipeline,
so 8 ssnop is sufficient to block all speculation on all CPUs. */
.rept 8
.word 0x00000040 /* The encoding of ssnop. */
.endr
/* jr.hb will be decoded as jr on earlier processors. */
.word 0x03e00408 /* The encoding of jr.hb $ra. */
#endif
.set pop
.end __speculation_barrier
.set reorder
#endif
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