On Tue, Dec 28, 2021 at 2:10 PM Martin Liška <mli...@suse.cz> wrote:
>
> Hello.
>
> The mold linker is getting quite popular and I think we should support it:
> https://github.com/rui314/mold
Does it support the gold plugin API/ABI and thus proper LTO? If not
I'm not sure we should encourage use. For example using
-flto -fuse-ld=lld will report strange
ld.lld: error: undefined symbol: main
>>> referenced by start.S:104 (../sysdeps/x86_64/start.S:104)
>>> /usr/lib/../lib64/crt1.o:(_start)
collect2: error: ld returned 1 exit status
on a simple test with a main() unless I manually add -fno-use-linker-plugin.
Richard.
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
> Ready to be installed?
> Thanks,
> Martin
>
> ---
> gcc/collect2.c | 10 +++++++---
> gcc/common.opt | 4 ++++
> gcc/gcc.c | 4 ++++
> gcc/opts.c | 1 +
> 4 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/collect2.c b/gcc/collect2.c
> index d47fe3f9195..b322527847c 100644
> --- a/gcc/collect2.c
> +++ b/gcc/collect2.c
> @@ -776,6 +776,7 @@ main (int argc, char **argv)
> USE_GOLD_LD,
> USE_BFD_LD,
> USE_LLD_LD,
> + USE_MOLD_LD,
> USE_LD_MAX
> } selected_linker = USE_DEFAULT_LD;
> static const char *const ld_suffixes[USE_LD_MAX] =
> @@ -784,7 +785,8 @@ main (int argc, char **argv)
> PLUGIN_LD_SUFFIX,
> "ld.gold",
> "ld.bfd",
> - "ld.lld"
> + "ld.lld",
> + "ld.mold"
> };
> static const char *const real_ld_suffix = "real-ld";
> static const char *const collect_ld_suffix = "collect-ld";
> @@ -957,6 +959,8 @@ main (int argc, char **argv)
> selected_linker = USE_GOLD_LD;
> else if (strcmp (argv[i], "-fuse-ld=lld") == 0)
> selected_linker = USE_LLD_LD;
> + else if (strcmp (argv[i], "-fuse-ld=mold") == 0)
> + selected_linker = USE_MOLD_LD;
> else if (startswith (argv[i], "-o"))
> {
> /* Parse the output filename if it's given so that we can make
> @@ -1048,7 +1052,7 @@ main (int argc, char **argv)
> ld_file_name = 0;
> #ifdef DEFAULT_LINKER
> if (selected_linker == USE_BFD_LD || selected_linker == USE_GOLD_LD ||
> - selected_linker == USE_LLD_LD)
> + selected_linker == USE_LLD_LD || selected_linker == USE_MOLD_LD)
> {
> char *linker_name;
> # ifdef HOST_EXECUTABLE_SUFFIX
> @@ -1283,7 +1287,7 @@ main (int argc, char **argv)
> else if (!use_collect_ld
> && startswith (arg, "-fuse-ld="))
> {
> - /* Do not pass -fuse-ld={bfd|gold|lld} to the linker. */
> + /* Do not pass -fuse-ld={bfd|gold|lld|mold} to the linker.
> */
> ld1--;
> ld2--;
> }
> diff --git a/gcc/common.opt b/gcc/common.opt
> index 2ed818d6057..dba3fa886f9 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -3046,6 +3046,10 @@ fuse-ld=lld
> Common Driver Negative(fuse-ld=lld)
> Use the lld LLVM linker instead of the default linker.
>
> +fuse-ld=mold
> +Common Driver Negative(fuse-ld=mold)
> +Use the Modern linker (MOLD) linker instead of the default linker.
> +
> fuse-linker-plugin
> Common Undocumented Var(flag_use_linker_plugin)
>
> diff --git a/gcc/gcc.c b/gcc/gcc.c
> index b75b50b87b2..06e18a75b52 100644
> --- a/gcc/gcc.c
> +++ b/gcc/gcc.c
> @@ -4282,6 +4282,10 @@ driver_handle_option (struct gcc_options *opts,
> use_ld = ".gold";
> break;
>
> + case OPT_fuse_ld_mold:
> + use_ld = ".mold";
> + break;
> +
> case OPT_fcompare_debug_second:
> compare_debug_second = 1;
> break;
> diff --git a/gcc/opts.c b/gcc/opts.c
> index cdd6463e49b..60f1cf045c9 100644
> --- a/gcc/opts.c
> +++ b/gcc/opts.c
> @@ -3094,6 +3094,7 @@ common_handle_option (struct gcc_options *opts,
> case OPT_fuse_ld_bfd:
> case OPT_fuse_ld_gold:
> case OPT_fuse_ld_lld:
> + case OPT_fuse_ld_mold:
> case OPT_fuse_linker_plugin:
> /* No-op. Used by the driver and passed to us because it starts with
> f.*/
> break;
> --
> 2.34.1
>
