Re: [PATCH] testsuite: Skip fission-dw-form-strx with clang

[Guinevere Larsen <guinevere@redhat.com>]

On 4/16/26 11:00 AM, Bratislav Filipovic wrote:
> Clang's integrated assembler incorrectly sets the SHF_EXCLUDE flag
> on .debug_*.dwo sections when assembling DWARF fission debug info.
> This causes all linkers (both lld and GNU ld) to strip these
> sections from the final output, breaking the test.
>
> This is a limitation of clang's integrated assembler, not a GDB
> issue. The test works correctly with GCC's assembler, which does
> not set this flag.
>
> A workaround exists (-fno-integrated-as to use GNU's external
> assembler), but it is not practical to apply in the testsuite.
> Therefore, restrict this test to GCC only.
> ---
>
> I've investigated this thoroughly and found that clang's integrated
> assembler hardcodes the SHF_EXCLUDE flag on .debug_*.dwo sections.
> The only workaround I found is -fno-integrated-as, which forces clang
> to use GNU's external assembler.
>
> Does anyone have suggestions for making this test work with clang
> without skipping it entirely? Or should we report this to LLVM as a bug?

My approach for these kinds of things in the past was to open a bug with 
LLVM and mark the tests as XFAIL in our testsuite (at least if the rest 
of the test still make sense to run)

>
>   gdb/testsuite/gdb.dwarf2/fission-dw-form-strx.exp | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/gdb/testsuite/gdb.dwarf2/fission-dw-form-strx.exp b/gdb/testsuite/gdb.dwarf2/fission-dw-form-strx.exp
> index b0b842fe911..fb39cab9c75 100644
> --- a/gdb/testsuite/gdb.dwarf2/fission-dw-form-strx.exp
> +++ b/gdb/testsuite/gdb.dwarf2/fission-dw-form-strx.exp
> @@ -20,6 +20,13 @@ load_lib dwarf.exp
>   # This test can only be run on targets which support DWARF-2 and use gas.
>   require dwarf2_support
>   
> +# This test requires GCC. Clang's integrated assembler incorrectly sets
> +# the SHF_EXCLUDE flag on .debug_*.dwo sections, causing linkers to strip
> +# them from the final output. This is a limitation of clang's integrated
> +# assembler, not a GDB issue. The workaround (-fno-integrated-as) is not
> +# practical for the testsuite.
> +require {[test_compiler_info {gcc-*}]}
> +
>   standard_testfile main.c -dw.S -dwo.S
>   
>   set main_asm_file [standard_output_file $srcfile2]


-- 
Cheers,
Guinevere Larsen
It/she