[PATCH][MIPS] GAS: Fix Loongson3 LLSC errata.

[Paul Hua]

> > In some older Loongson 3A1000 processors there is a LL/SC errata that
>
> This problem only exists on "some older Loongson 3A1000"?
> Does it exists on current 3A 3000 machines?

Theoretically does not exist on 3A 3000.

> > gas/
> >         * NEWS: Mention -m[no-]fix-loongson3-llsc.
> >         * configure.ac: Add --enable-mips-fix-loongson3-llsc.
> >         Define DEFAULT_MIPS_FIX_LOONGSON3_LLSC.
> >         * config.in: Regenerated.
> >         * configure: Likewise.
>
> Is configure patch needed here?
> It seems been generated by some newer version autotools.

Yes, We change the configure.ac file, so regenerated.

> >         * config/tc-mips.c (sync_insn, mips_fix_loongson3_llsc):
> >         New variables.
> >         (options): New OPTION_FIX_LOONGSON3_LLSC,
> >         OPTION_NO_FIX_LOONGSON3_LLSC.
> >         (md_longopts): Add -m[no-]fix-loongson3-llsc.
> >         (md_begin): Initialize sync insn.
> >         (fix_loongson3_llsc): New.
> >         (append_insn): Call fix_loongson3_llsc.
> >         (md_parse_option): Handle OPTION_FIX_LOONGSON3_LLSC,
> >         OPTION_NO_FIX_LOONGSON3_LLSC.
> >         (md_show_usage): Display -m[no-]fix-loongson3-llsc.
> >         * doc/c-mips.texi: Document -m[no-]fix-loongson3-llsc,
> >         --enable-mips-fix-loongson3-llsc=[yes|no].
>
> https://sourceware.org/ml/binutils/2018-01/msg00303.html
> here is an older version of patch.
> While somebody told me that it will generate a .fixup section.
> What about this one?
Both patch does not generate a .fixup section.