YunQiang Su <yunqiang...@cipunited.com> 于2023年5月12日周五 18:30写道：
>
> speculation_barrier for MIPS needs sync+jr.hb (r2+),
> so we implement __speculation_barrier in libgcc, like arm32 does.
>
> gcc/ChangeLog:
> * config/mips/mips-protos.h (mips_emit_speculation_barrier): New
> prototype.
> * config/mips/mips.cc (speculation_barrier_libfunc): New static
> variable.
> (mips_init_libfuncs): Initialize it.
> (mips_emit_speculation_barrier): New function.
> * config/mips/mips.md (speculation_barrier): Call
> mips_emit_speculation_barrier.
> * configure.ac: error if gas doesn't accept ssnop for mips1.
> * configure: regenerated.
> * doc/install.texi: documents mips requires binutils 2.21+.
>
> libgcc/ChangeLog:
> * config/mips/lib1funcs.S: New file.
> define __speculation_barrier and include mips16.S.
> * config/mips/t-mips: define LIB1ASMSRC as mips/lib1funcs.S.
> define LIB1ASMFUNCS as _speculation_barrier.
> set version info for __speculation_barrier.
> * config/mips/libgcc-mips.ver: New file.
> * config/mips/t-mips16: don't define LIB1ASMSRC as mips16.S is
> included in lib1funcs.S now.
If no objection, I will commit this V4 patch.
> ---
> gcc/config/mips/mips-protos.h | 2 +
> gcc/config/mips/mips.cc | 13 +++++++
> gcc/config/mips/mips.md | 12 ++++++
> gcc/configure | 32 +++++++++++++++
> gcc/configure.ac | 7 ++++
> gcc/doc/install.texi | 2 +
> libgcc/config/mips/lib1funcs.S | 62 ++++++++++++++++++++++++++++++
> libgcc/config/mips/libgcc-mips.ver | 21 ++++++++++
> libgcc/config/mips/t-mips | 7 ++++
> libgcc/config/mips/t-mips16 | 3 +-
> 10 files changed, 159 insertions(+), 2 deletions(-)
> create mode 100644 libgcc/config/mips/lib1funcs.S
> create mode 100644 libgcc/config/mips/libgcc-mips.ver
>
> diff --git a/gcc/config/mips/mips-protos.h b/gcc/config/mips/mips-protos.h
> index 20483469105..da7902c235b 100644
> --- a/gcc/config/mips/mips-protos.h
> +++ b/gcc/config/mips/mips-protos.h
> @@ -388,4 +388,6 @@ extern void mips_register_frame_header_opt (void);
> extern void mips_expand_vec_cond_expr (machine_mode, machine_mode, rtx *);
> extern void mips_expand_vec_cmp_expr (rtx *);
>
> +extern void mips_emit_speculation_barrier_function (void);
> +
> #endif /* ! GCC_MIPS_PROTOS_H */
> diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
> index ca822758b41..139707fda34 100644
> --- a/gcc/config/mips/mips.cc
> +++ b/gcc/config/mips/mips.cc
> @@ -13611,6 +13611,9 @@ mips_autovectorize_vector_modes (vector_modes *modes,
> bool)
> return 0;
> }
>
> +
> +static GTY(()) rtx speculation_barrier_libfunc;
> +
> /* Implement TARGET_INIT_LIBFUNCS. */
>
> static void
> @@ -13680,6 +13683,7 @@ mips_init_libfuncs (void)
> synchronize_libfunc = init_one_libfunc ("__sync_synchronize");
> init_sync_libfuncs (UNITS_PER_WORD);
> }
> + speculation_barrier_libfunc = init_one_libfunc ("__speculation_barrier");
> }
>
> /* Build up a multi-insn sequence that loads label TARGET into $AT. */
> @@ -19092,6 +19096,15 @@ mips_avoid_hazard (rtx_insn *after, rtx_insn *insn,
> int *hilo_delay,
> }
> }
>
> +/* Emit a speculation barrier.
> + JR.HB is needed, so we need to put
> + speculation_barrier_libfunc in libgcc */
> +void
> +mips_emit_speculation_barrier_function ()
> +{
> + emit_library_call (speculation_barrier_libfunc, LCT_NORMAL, VOIDmode);
> +}
> +
> /* A SEQUENCE is breakable iff the branch inside it has a compact form
> and the target has compact branches. */
>
> diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
> index ac1d77afc7d..5d04ac566dd 100644
> --- a/gcc/config/mips/mips.md
> +++ b/gcc/config/mips/mips.md
> @@ -160,6 +160,8 @@
> ;; The `.insn' pseudo-op.
> UNSPEC_INSN_PSEUDO
> UNSPEC_JRHB
> +
> + VUNSPEC_SPECULATION_BARRIER
> ])
>
> (define_constants
> @@ -7455,6 +7457,16 @@
> mips_expand_conditional_move (operands);
> DONE;
> })
> +
> +(define_expand "speculation_barrier"
> + [(unspec_volatile [(const_int 0)] VUNSPEC_SPECULATION_BARRIER)]
> + ""
> + "
> + mips_emit_speculation_barrier_function ();
> + DONE;
> + "
> +)
> +
>
> ;;
> ;; ....................
> diff --git a/gcc/configure b/gcc/configure
> index 191f68581b3..e55b40d7f4c 100755
> --- a/gcc/configure
> +++ b/gcc/configure
> @@ -28699,6 +28699,38 @@ $as_echo "#define HAVE_LD_PERSONALITY_RELAXATION 1"
> >>confdefs.h
>
> fi
>
> + { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for mips1
> recognize ssnop" >&5
> +$as_echo_n "checking assembler for mips1 recognize ssnop... " >&6; }
> +if ${gcc_cv_as_mips1_ssnop+:} false; then :
> + $as_echo_n "(cached) " >&6
> +else
> + gcc_cv_as_mips1_ssnop=no
> + if test x$gcc_cv_as != x; then
> + $as_echo 'ssnop' > conftest.s
> + if { ac_try='$gcc_cv_as $gcc_cv_as_flags -mabi=32 -mips1 -o conftest.o
> conftest.s >&5'
> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> + echo $ac_try
> + (eval $ac_try) 2>&5
> + ac_status=$?
> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> + test $ac_status = 0; }; }
> + then
> + gcc_cv_as_mips1_ssnop=yes
> + else
> + echo "configure: failed program was" >&5
> + cat conftest.s >&5
> + fi
> + rm -f conftest.o conftest.s
> + fi
> +fi
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_mips1_ssnop" >&5
> +$as_echo "$gcc_cv_as_mips1_ssnop" >&6; }
> +
> +
> + if test x$gcc_cv_as_mips1_ssnop = xno; then
> + as_fn_error $? "New binutils is required to support ssnop even for
> MIPS I: 2.21+" "$LINENO" 5
> + fi
> +
> { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for -mnan=
> support" >&5
> $as_echo_n "checking assembler for -mnan= support... " >&6; }
> if ${gcc_cv_as_mips_nan+:} false; then :
> diff --git a/gcc/configure.ac b/gcc/configure.ac
> index 075424669c9..6d2cb4c51a0 100644
> --- a/gcc/configure.ac
> +++ b/gcc/configure.ac
> @@ -5270,6 +5270,13 @@ EOF
> pointers into PC-relative form.])
> fi
>
> + gcc_GAS_CHECK_FEATURE([mips1 recognize ssnop], gcc_cv_as_mips1_ssnop,
> + [-mabi=32 -mips1], [ssnop],,,)
> + if test x$gcc_cv_as_mips1_ssnop = xno; then
> + AC_MSG_ERROR(
> + [New binutils is required to support ssnop even for MIPS I: 2.21+])
> + fi
> +
> gcc_GAS_CHECK_FEATURE([-mnan= support],
> gcc_cv_as_mips_nan,
> [-mnan=2008],,,
> diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
> index fa91ce1953d..fae6ec5f7a9 100644
> --- a/gcc/doc/install.texi
> +++ b/gcc/doc/install.texi
> @@ -4610,6 +4610,8 @@ the use of break, use the @option{--with-divide=breaks}
> @command{configure} option when configuring GCC@. The default is to
> use traps on systems that support them.
>
> +GNU Binutils 2.21 or newer is required.
> +
> @html
> <hr />
> @end html
> diff --git a/libgcc/config/mips/lib1funcs.S b/libgcc/config/mips/lib1funcs.S
> new file mode 100644
> index 00000000000..12314953a7f
> --- /dev/null
> +++ b/libgcc/config/mips/lib1funcs.S
> @@ -0,0 +1,62 @@
> +/* Copyright (C) 2023 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 || defined(__linux)
> + /* MIPS1 has no sync. while Linux can trap&emu sync */
> + /* FIXME: Will somebody use linux/gcc for MIPS1/baremetal? */
> + sync /* complementation barrier for memory */
> +#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 recognize it even 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
> + ssnop
> + .endr
> + .word 0x03e00408 /* The encoding of jr.hb $ra */
> +#endif
> + .set pop
> + .end __speculation_barrier
> +
> + .set reorder
> +#endif
> diff --git a/libgcc/config/mips/libgcc-mips.ver
> b/libgcc/config/mips/libgcc-mips.ver
> new file mode 100644
> index 00000000000..68f8d2bbd51
> --- /dev/null
> +++ b/libgcc/config/mips/libgcc-mips.ver
> @@ -0,0 +1,21 @@
> +# Copyright (C) 2023 Free Software Foundation, Inc.
> +#
> +# This file is part of GCC.
> +#
> +# GCC 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.
> +#
> +# GCC 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.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with GCC; see the file COPYING3. If not see
> +# <http://www.gnu.org/licenses/>.
> +
> +GCC_14.0 {
> + __speculation_barrier
> +}
> diff --git a/libgcc/config/mips/t-mips b/libgcc/config/mips/t-mips
> index 4fb8e136217..d05ef7cbf74 100644
> --- a/libgcc/config/mips/t-mips
> +++ b/libgcc/config/mips/t-mips
> @@ -7,3 +7,10 @@ softfp_truncations :=
> softfp_exclude_libgcc2 := n
>
> LIB2ADD_ST += $(srcdir)/config/mips/lib2funcs.c
> +
> +
> +LIB1ASMSRC = mips/lib1funcs.S
> +LIB1ASMFUNCS = _speculation_barrier
> +
> +# Version these symbols if building libgcc.so.
> +SHLIB_MAPFILES += $(srcdir)/config/mips/libgcc-mips.ver
> diff --git a/libgcc/config/mips/t-mips16 b/libgcc/config/mips/t-mips16
> index 2bad5119d51..5fd9d60d7a3 100644
> --- a/libgcc/config/mips/t-mips16
> +++ b/libgcc/config/mips/t-mips16
> @@ -16,8 +16,7 @@
> # along with GCC; see the file COPYING3. If not see
> # <http://www.gnu.org/licenses/>.
>
> -LIB1ASMSRC = mips/mips16.S
> -LIB1ASMFUNCS = _m16addsf3 _m16subsf3 _m16mulsf3 _m16divsf3 \
> +LIB1ASMFUNCS += _m16addsf3 _m16subsf3 _m16mulsf3 _m16divsf3 \
> _m16eqsf2 _m16nesf2 _m16gtsf2 _m16gesf2 _m16lesf2 _m16ltsf2 \
> _m16unordsf2 \
> _m16fltsisf _m16fix_truncsfsi _m16fltunsisf \
> --
> 2.30.2
>
