On 1/3/22 15:48, Richard Biener wrote:
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?
No, but it's planned to be added:
https://github.com/rui314/mold/issues/181
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.
Yep, that's consequence of the fact a compiler is not built with such linker.
Maybe we can add a documentation note, what do you think?
Cheers,
Martin
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
