[PATCH 2/2] RISC-V: Check for conflicting extensions when the linker merges arch attributes
Nelson Chu
nelson.chu@sifive.com
Thu Jul 9 01:10:24 GMT 2026
Sorry, forgot to commit. Committed, thanks.
Nelson
On Wed, Jul 8, 2026 at 11:07 AM Nelson Chu <nelson.chu@sifive.com> wrote:
>
>
> On Tue, Jul 7, 2026 at 10:05 AM Ethan Y. C. Liang <ycl669@andestech.com>
> wrote:
>
>> I think you can try testing it with the soft-float ABI to avoid the
>> linker error you ran into.
>
>
> I meant if we already got an error, then why not just call check confflict
> without calling riscv_parse_add_implicit_subsets, since adding implicits
> may waste link time, but whatever...
>
>
>>
>> You can also refer to the attr-merge-arch-failed-04 test case that I
>> added.
>>
>
> Okay, the attr-merge-arch-failed-04 looks reasonable since we only check
> if zcmp and zcd exist for now, without the riscv_parse_add_implicit_subsets,
> zcd won't be added so the testcase won't be expected failed.
>
> Thanks
> Nelson
>
>
>> Ethan
>>
>> On Tue, Jul 07, 2026 at 09:51:22AM +0800, Nelson Chu wrote:
>> > Ummm, I linked a.o with c and b.o with d. It seems this isn't allowed
>> already because we cannot link double-float with soft-float modules. So do
>> we have any case where implicit extensions haven't been added for all input
>> objects, requiring us to call riscv_parse_add_implicit_subsets for the
>> merged string? If yes please also add the testcases.
>> >
>> > Thanks
>> > Nelson
>> >
>> >
>> > On Tue, Jul 7, 2026 at 9:26 AM Nelson Chu <nelson.chu@sifive.com
>> <mailto:nelson.chu@sifive.com>> wrote:
>> > Oh, okay, I see the case: inputs with 'c' and inputs with 'd' will need
>> zcd after merging. Looks reasonable to call
>> riscv_parse_add_implicit_subsets for merged string, too.
>> >
>> > Thanks
>> > Nelson
>> >
>> > On Tue, Jul 7, 2026 at 9:19 AM Nelson Chu <nelson.chu@sifive.com
>> <mailto:nelson.chu@sifive.com>> wrote:
>> >
>> >
>> > On Mon, Jul 6, 2026 at 7:46 PM Ethan Y. C. Liang <ycl669@andestech.com
>> <mailto:ycl669@andestech.com>> wrote:
>> > The linker validates the arch of each input when parsing it, but never
>> > checks the merged arch as a whole, so conflicting extensions could
>> > silently slip through. The merge can even imply extensions that
>> > neither input implies alone, e.g. `c' from one input and `d' from
>> > another imply `zcd', which conflicts with `zcmp'.
>> >
>> > After merging the input archs, add the implicit extensions to the
>> > merged arch, then run the conflict checks on it and reject the merge
>> > if any conflict is found. Add tests for such merges.
>> > ---
>> > bfd/elfxx-riscv.c | 8 ++++++++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.d | 5 +++++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.l | 2 ++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01a.s | 1 +
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01b.s | 1 +
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.d | 5 +++++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.l | 2 ++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02a.s | 1 +
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02b.s | 1 +
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.d | 5 +++++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.l | 2 ++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03a.s | 1 +
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03b.s | 1 +
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.d | 5 +++++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.l | 2 ++
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04a.s | 1 +
>> > ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04b.s | 1 +
>> > ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp | 4 ++++
>> > 18 files changed, 48 insertions(+)
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.d
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.l
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01a.s
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01b.s
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.d
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.l
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02a.s
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02b.s
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.d
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.l
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03a.s
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03b.s
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.d
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.l
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04a.s
>> > create mode 100644
>> ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04b.s
>> >
>> > diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
>> > index fa2f1759f31..128c0eda8c4 100644
>> > --- a/bfd/elfxx-riscv.c
>> > +++ b/bfd/elfxx-riscv.c
>> > @@ -3750,6 +3750,14 @@ riscv_merge_arch_attr_info (bfd *ibfd, char
>> *in_arch, char *out_arch,
>> > goto cleanup;
>> > }
>> >
>> > + /* Add the implicit subsets implied by the merged subset list, then
>> > + check if the result is conflicting. */
>> > + riscv_parse_subset_t riscv_rps_ld_merged =
>> > + {&merged_subsets, _bfd_error_handler, &xlen_in, NULL, false};
>> > + riscv_parse_add_implicit_subsets (&riscv_rps_ld_merged);
>> > + if (!riscv_parse_check_conflicts (&riscv_rps_ld_merged))
>> > + goto cleanup;
>> > +
>> >
>> > Looks reasonable to call riscv_parse_check_conflicts for the merged
>> architecture string. But do we need to call
>> riscv_parse_add_implicit_subsets? Since I checked all current
>> check_implicit_* functions (always/for_i/for_zcf/for_zcd), I think all
>> implicit extensions should be added in the each input object already.
>> >
>> > Thanks
>> > Nelson
>> >
>> > /* Free the previous merged_arch_str which called xmalloc. */
>> > free (merged_arch_str);
>> >
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.d
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.d
>> > new file mode 100644
>> > index 00000000000..f99677cb767
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.d
>> > @@ -0,0 +1,5 @@
>> > +#source: attr-merge-arch-failed-01a.s
>> > +#source: attr-merge-arch-failed-01b.s
>> > +#as: -mabi=ilp32
>> > +#ld: -r -m[riscv_choose_ilp32_emul]
>> > +#error_output: attr-merge-arch-failed-01.l
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.l
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.l
>> > new file mode 100644
>> > index 00000000000..ad6d2630211
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01.l
>> > @@ -0,0 +1,2 @@
>> > +.*: `zfinx' conflicts with the `f/d/q/zfh/zfhmin' extension
>> > +.*: failed to merge target specific data of file .*
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01a.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01a.s
>> > new file mode 100644
>> > index 00000000000..8f2a98f95f3
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01a.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32i_zfinx"
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01b.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01b.s
>> > new file mode 100644
>> > index 00000000000..a44b2a0d346
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-01b.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32if"
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.d
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.d
>> > new file mode 100644
>> > index 00000000000..4fb1980c97d
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.d
>> > @@ -0,0 +1,5 @@
>> > +#source: attr-merge-arch-failed-02a.s
>> > +#source: attr-merge-arch-failed-02b.s
>> > +#as: -mabi=ilp32
>> > +#ld: -r -m[riscv_choose_ilp32_emul]
>> > +#error_output: attr-merge-arch-failed-02.l
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.l
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.l
>> > new file mode 100644
>> > index 00000000000..930e03123e1
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02.l
>> > @@ -0,0 +1,2 @@
>> > +.*: zcmp' is incompatible with `d' and `c', or `zcd' extension
>> > +.*: failed to merge target specific data of file .*
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02a.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02a.s
>> > new file mode 100644
>> > index 00000000000..3f79059d5d0
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02a.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32i_zcmp"
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02b.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02b.s
>> > new file mode 100644
>> > index 00000000000..95bfe1f6d9f
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-02b.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32i_zcd"
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.d
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.d
>> > new file mode 100644
>> > index 00000000000..def49c3fb3f
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.d
>> > @@ -0,0 +1,5 @@
>> > +#source: attr-merge-arch-failed-03a.s
>> > +#source: attr-merge-arch-failed-03b.s
>> > +#as: -mabi=ilp32
>> > +#ld: -r -m[riscv_choose_ilp32_emul]
>> > +#error_output: attr-merge-arch-failed-03.l
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.l
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.l
>> > new file mode 100644
>> > index 00000000000..d9075d0c30e
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03.l
>> > @@ -0,0 +1,2 @@
>> > +.*: `zclsd' conflicts with the `c\+f'/`zcf' extension
>> > +.*: failed to merge target specific data of file .*
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03a.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03a.s
>> > new file mode 100644
>> > index 00000000000..f7f9ceb11f6
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03a.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32i_zclsd"
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03b.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03b.s
>> > new file mode 100644
>> > index 00000000000..f18129dc55d
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-03b.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32i_zcf"
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.d
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.d
>> > new file mode 100644
>> > index 00000000000..5445936df44
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.d
>> > @@ -0,0 +1,5 @@
>> > +#source: attr-merge-arch-failed-04a.s
>> > +#source: attr-merge-arch-failed-04b.s
>> > +#as: -mabi=ilp32
>> > +#ld: -r -m[riscv_choose_ilp32_emul]
>> > +#error_output: attr-merge-arch-failed-04.l
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.l
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.l
>> > new file mode 100644
>> > index 00000000000..930e03123e1
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04.l
>> > @@ -0,0 +1,2 @@
>> > +.*: zcmp' is incompatible with `d' and `c', or `zcd' extension
>> > +.*: failed to merge target specific data of file .*
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04a.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04a.s
>> > new file mode 100644
>> > index 00000000000..e79c25b7828
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04a.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32ic"
>> > diff --git a/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04b.s
>> b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04b.s
>> > new file mode 100644
>> > index 00000000000..c7468e4e072
>> > --- /dev/null
>> > +++ b/ld/testsuite/ld-riscv-elf/attr-merge-arch-failed-04b.s
>> > @@ -0,0 +1 @@
>> > + .attribute arch, "rv32id_zcmp"
>> > diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
>> b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
>> > index 8e26ccff10a..57f3139c9f6 100644
>> > --- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
>> > +++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
>> > @@ -157,6 +157,10 @@ if [istarget "riscv*-*-*"] {
>> > run_dump_test "attr-merge-arch-01"
>> > run_dump_test "attr-merge-arch-02"
>> > run_dump_test "attr-merge-arch-03"
>> > + run_dump_test "attr-merge-arch-failed-01"
>> > + run_dump_test "attr-merge-arch-failed-02"
>> > + run_dump_test "attr-merge-arch-failed-03"
>> > + run_dump_test "attr-merge-arch-failed-04"
>> > run_dump_test "attr-merge-strict-align-01"
>> > run_dump_test "attr-merge-strict-align-02"
>> > run_dump_test "attr-merge-strict-align-03"
>> > --
>> > 2.54.0
>> >
>>
>
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