Re: [PATCH v5] MIPS: Add speculation_barrier support

[YunQiang Su <syq@debian.org>]

Richard Earnshaw (lists) via Gcc-patches <gcc-patches@gcc.gnu.org>
于2023年6月8日周四 20:36写道：
>
>
> On 01/06/2023 05:26, YunQiang Su wrote:
> > 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.
> >
> > 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
> >       included in lib1funcs.S now.
> > ---
>
> Please remember to cite PR86793 when committing this fix.
>

Ohh, sorry. I forget it. I commented there.
I have no permission to close this bug report. Can you help to close it?

> R.
>
> >   gcc/config/mips/mips-protos.h      |  2 +
> >   gcc/config/mips/mips.cc            | 12 ++++++
> >   gcc/config/mips/mips.md            | 12 ++++++
> >   libgcc/config/mips/lib1funcs.S     | 65 ++++++++++++++++++++++++++++++
> >   libgcc/config/mips/libgcc-mips.ver | 21 ++++++++++
> >   libgcc/config/mips/t-mips          |  7 ++++
> >   libgcc/config/mips/t-mips16        |  3 +-
> >   7 files changed, 120 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 ca491b981a3..c1d1691306e 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 +19096,14 @@ mips_avoid_hazard (rtx_insn *after, rtx_insn *insn, int *hilo_delay,
> >         }
> >   }
> >
> > +/* Emit a speculation barrier.
> > +   JR.HB is needed, so we 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/libgcc/config/mips/lib1funcs.S b/libgcc/config/mips/lib1funcs.S
> > new file mode 100644
> > index 00000000000..97a3655e8ab
> > --- /dev/null
> > +++ b/libgcc/config/mips/lib1funcs.S
> > @@ -0,0 +1,65 @@
> > +/* 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
> > +     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
> > 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 \
>