[PATCH] RISC-V: Add an implicit dependency for Zawrs

[Andrew Waterman]

On Mon, Oct 7, 2024 at 11:29 PM Xiao Zeng <zengxiao@eswincomputing.com> wrote:
>
> 2024-10-08 14:18  Andrew Waterman <andrew@sifive.com> wrote:
> >
> >But that's not what the normative text in the spec says!
> Yes.
> > Using non-normative notes to infer dependencies between extensions is
> >dangerous territory.
> >
> >It is true that the WRS instructions aren't useful without the LR
> >instruction,
> Perhaps the spec should specify more clearly:
> "Implicit dependencies should not be inferred from any direct explanation"
>
> >but it is also true that Binutils shouldn't be inventing
> >extension dependencies that aren't normatively justified.
> Yes, thank you for your suggestion.
>
> I will wait for the spec to clarify this.

Non-normative text is, well, not normative.  No clarification in the
spec is needed.

> >
> >
> >On Mon, Oct 7, 2024 at 11:07 PM Xiao Zeng <zengxiao@eswincomputing.com> wrote:
> >>
> >> There is a description in <https://github.com/riscv/riscv-isa-manual/blob/main/src/zawrs.adoc>:
> >>
> >> "The instructions in the Zawrs extension are only useful in conjunction
> >> with the LR instruction, which is provided by the Zalrsc component
> >> of the A extension."
> >>
> >> It can be concluded that: zawrs -> zalrsc.
> >>
> >> The implementation in gcc is as follows:
> >> <https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=c01e3aaae79ecd439ad35063db3dee9775f3aefa>
> >>
> >> bfd/ChangeLog:
> >>
> >>         * elfxx-riscv.c: zawrs -> zalrsc.
> >>
> >> gas/ChangeLog:
> >>
> >>         * testsuite/gas/riscv/imply.d: Add implicit dependency
> >>         testing for zawrs.
> >>         * testsuite/gas/riscv/imply.s: Updated.
> >>
> >> Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com>
> >> ---
> >>  bfd/elfxx-riscv.c               | 1 +
> >>  gas/testsuite/gas/riscv/imply.d | 1 +
> >>  gas/testsuite/gas/riscv/imply.s | 1 +
> >>  3 files changed, 3 insertions(+)
> >>
> >> diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
> >> index 4b48d8ee9f0..b7b4d95195e 100644
> >> --- a/bfd/elfxx-riscv.c
> >> +++ b/bfd/elfxx-riscv.c
> >> @@ -1184,6 +1184,7 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
> >>
> >>    {"zabha", "+zaamo", check_implicit_always},
> >>    {"zacas", "+zaamo", check_implicit_always},
> >> +  {"zawrs", "+zalrsc", check_implicit_always},
> >>    {"a", "+zaamo,+zalrsc", check_implicit_always},
> >>
> >>    {"xsfvcp", "+zve32x", check_implicit_always},
> >> diff --git a/gas/testsuite/gas/riscv/imply.d b/gas/testsuite/gas/riscv/imply.d
> >> index 26eff8c650a..64dda77a9f8 100644
> >> --- a/gas/testsuite/gas/riscv/imply.d
> >> +++ b/gas/testsuite/gas/riscv/imply.d
> >> @@ -17,6 +17,7 @@ SYMBOL TABLE:
> >>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_m2p0_zmmul1p0
> >>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zaamo1p0_zabha1p0
> >>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zaamo1p0_zacas1p0
> >> +[0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zalrsc1p0_zawrs1p0
> >>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_a2p1_zaamo1p0_zalrsc1p0
> >>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zicsr2p0_zve32x1p0_zvl32b1p0_xsfvcp1p0
> >>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_f2p2_d2p2_v1p0_zicsr2p0_zve32f1p0_zve32x1p0_zve64d1p0_zve64f1p0_zve64x1p0_zvl128b1p0_zvl32b1p0_zvl64b1p0
> >> diff --git a/gas/testsuite/gas/riscv/imply.s b/gas/testsuite/gas/riscv/imply.s
> >> index dabb08d8c8b..c831ea63f04 100644
> >> --- a/gas/testsuite/gas/riscv/imply.s
> >> +++ b/gas/testsuite/gas/riscv/imply.s
> >> @@ -18,6 +18,7 @@ imply m
> >>
> >>  imply zabha
> >>  imply zacas
> >> +imply zawrs
> >>  imply a
> >>
> >>  imply xsfvcp
> >> --
> >> 2.17.1
> >>
> Thanks
> Xiao Zeng
>