On Wed, Jan 18, 2023 at 11:17 AM Andreas Schwab via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The -funwind-tables and -fasynchronous-unwind-tables options are relevant
> for the output pass, thus they need to be passed through by the lto
> wrapper.
>
> gcc/
> * lto-wrapper.cc (merge_and_complain): Pass through
> -funwind-tables and -fasynchronous-unwind-tables.
> (append_compiler_options): Likewise.
> ---
> gcc/lto-wrapper.cc | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/gcc/lto-wrapper.cc b/gcc/lto-wrapper.cc
> index 11c4d1b38a4..627e8238606 100644
> --- a/gcc/lto-wrapper.cc
> +++ b/gcc/lto-wrapper.cc
> @@ -314,6 +314,8 @@ merge_and_complain (vec<cl_decoded_option>
> &decoded_options,
> case OPT_fshow_column:
> case OPT_fcommon:
> case OPT_fgnu_tm:
> + case OPT_funwind_tables:
> + case OPT_fasynchronous_unwind_tables:
> case OPT_g:
> /* Do what the old LTO code did - collect exactly one option
> setting per OPT code, we pick the first we encounter.
A better place is
case OPT_fopenmp:
case OPT_fopenacc:
/* For selected options we can merge conservatively. */
if (existing_opt == -1)
decoded_options.safe_push (*foption);
/* -fopenmp > -fno-openmp,
-fopenacc > -fno-openacc */
else if (foption->value > decoded_options[existing_opt].value)
decoded_options[existing_opt] = *foption;
break;
where we'd prefer -funwind-tables over -fno-unwind-tables when the
options do not match
across TUs. Note that you likely want to add
-f[asynchronous-]unwind-tables handling
in lto-options.cc:lto_write_options as well so the default is streamed
as explicit option.
Otherwise a single TU with -fno-unwind-tables on x86-64 would cause
the whole LTO
compilation to be built without.
> @@ -737,6 +739,8 @@ append_compiler_options (obstack *argv_obstack,
> vec<cl_decoded_option> opts)
> case OPT_fopenacc_dim_:
> case OPT_foffload_abi_:
> case OPT_fcf_protection_:
> + case OPT_funwind_tables:
> + case OPT_fasynchronous_unwind_tables:
> case OPT_g:
> case OPT_O:
> case OPT_Ofast:
> --
> 2.39.1
>
>
> --
> Andreas Schwab, SUSE Labs, sch...@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."
