RE: [PATCH] testsuite: ada-valprint-error relocation issue

["Filipovic, Bratislav" <Bratislav.Filipovic@amd.com>]

[AMD Official Use Only - AMD Internal Distribution Only]

Hi Tom,

Yes, blanket assignment. About pushing, I was told to ask you to push it since I've only recently started contributing and
I don't have write-after-approval access.

Regards Bratislav


-----Original Message-----
From: Tom de Vries <tdevries@suse.de>
Sent: Wednesday, April 1, 2026 8:12 PM
To: Filipovic, Bratislav <Bratislav.Filipovic@amd.com>
Cc: gdb-patches@sourceware.org; simon.marchi@efficios.com
Subject: Re: [PATCH] testsuite: ada-valprint-error relocation issue

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On 4/1/26 4:10 PM, Bratislav Filipovic wrote:
> The ada-valprint-error.exp test links a nodebug .o file with a
> separate DWARF .o file generated by lib/dwarf.exp. This requires the
> linker to apply relocations for initialized pointers in the .data section.
>
> Some clang + linker combinations fail to apply these relocations,
> leaving fd__global as NULL instead of pointing to buffer. This causes
> the test to print null instead of the expected error message.
>
> Binary evidence from .comment section confirms which compiler and
> linker were used. Testing shows:
> - GCC 13 + GNU ld 2.42: PASS
> - clang 20 + GNU ld 2.42: FAIL
> - clang 22 + ld.lld 22: FAIL
> - clang 17/19 + GNU ld 2.45.0: PASS
>
> The failure is a linker limitation when handling this specific
> relocation pattern, not a GDB bug. Document this in the test file to
> help users understand why the test may fail with certain toolchains.

Hi,

the patch LGTM, but I'm wondering, do you have a copyright assignment, or are you covered by an AMD blanket assignment perhaps?

Thanks,
- Tom

> ---
>   .../gdb.dwarf2/ada-valprint-error.exp         | 21 +++++++++++++++++++
>   1 file changed, 21 insertions(+)
>
> diff --git a/gdb/testsuite/gdb.dwarf2/ada-valprint-error.exp
> b/gdb/testsuite/gdb.dwarf2/ada-valprint-error.exp
> index f3d61e91..00e737bc 100644
> --- a/gdb/testsuite/gdb.dwarf2/ada-valprint-error.exp
> +++ b/gdb/testsuite/gdb.dwarf2/ada-valprint-error.exp
> @@ -107,6 +107,27 @@ if { [prepare_for_testing ${testfile}.exp ${testfile} \
>       return -1
>   }
>
> +# Note: This test may fail with certain clang + linker combinations #
> +Specifically, clang + ld.lld can fail to apply relocations when
> +linking # nodebug .o with separate DWARF .o, leaving fd__global as
> +NULL instead # of pointing to buffer. The failure is a linker limitation, not a GDB bug.
> +#
> +# Known to fail: clang 20/22 + GNU ld 2.42, clang 22 + ld.lld 22 #
> +Known to pass: GCC + GNU ld, clang 17/19 + GNU ld 2.45.0 set
> +unsupported 0 gdb_test_multiple "print /x fd__global" "check
> +fd__global value" {
> +    -re -wrap "@0x0: 0x0" {
> +     set unsupported 1
> +    }
> +    -re -wrap "" {
> +     pass $gdb_test_name
> +    }
> +}
> +if {$unsupported} {
> +    unsupported "linker failed to apply relocation for fd__global"
> +    return
> +}
> +
>   gdb_test_no_output "set language ada"
>
>   gdb_test "print fd.global" \