| Issue |
91055
|
| Summary |
`--retain-symbols-file` is not compatible with GNU
|
| Labels |
lld:ELF
|
| Assignees |
|
| Reporter |
rui314
|
It looks like lld uses `--retain-symbols-file` to control whether a symbol is put into .dynsym or not. However, for GNU ld, the option doesn't seem to have any effect on .dynsym. Instead, it controls whether a symbol is put into the output .symtab or not.
Here is a test script:
```shell
cat <<EOF | cc -c -o a.o -xc -
void foo() {}
void bar() {}
void baz() {}
EOF
cat <<EOF > symbols
foo
baz
EOF
cc -shared -o b.so a.o -Wl,--retain-symbols-file=symbols
nm b.so
readelf -W --dyn-syms b.so
cc -fuse-ld=lld -shared -o c.so a.o -Wl,--retain-symbols-file=symbols
nm c.so
readelf -W --dyn-syms c.so
```
You can see that the symbols in .dynsym and .symtab are different between lld and GNU ld.
```
$ bash -x /tmp/foo
+ cat
+ cc -c -o a.o -xc -
+ cat
+ cc -shared -o b.so a.o -Wl,--retain-symbols-file=symbols
+ nm b.so
000000000000110f T baz
00000000000010f9 T foo
+ readelf -W --dyn-syms b.so
Symbol table '.dynsym' contains 8 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __cxa_finalize
2: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_registerTMCloneTable
3: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_deregisterTMCloneTable
4: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
5: 00000000000010f9 11 FUNC GLOBAL DEFAULT 10 foo
6: 0000000000001104 11 FUNC GLOBAL DEFAULT 10 bar
7: 000000000000110f 11 FUNC GLOBAL DEFAULT 10 baz
+ cc -fuse-ld=lld -shared -o c.so a.o -Wl,--retain-symbols-file=symbols
+ nm c.so
0000000000001674 t bar
000000000000167f T baz
0000000000003888 b completed.0
w __cxa_finalize
00000000000015b0 t deregister_tm_clones
0000000000001620 t __do_global_dtors_aux
00000000000026f0 d __do_global_dtors_aux_fini_array_entry
0000000000003860 d __dso_handle
0000000000002700 d _DYNAMIC
00000000000016a8 t _fini
0000000000001669 T foo
0000000000001660 t frame_dummy
00000000000026f8 d __frame_dummy_init_array_entry
0000000000000530 r __FRAME_END__
0000000000003868 d _GLOBAL_OFFSET_TABLE_
w __gmon_start__
000000000000168c t _init
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
00000000000015e0 t register_tm_clones
0000000000003868 d __TMC_END__
0000000000003868 d __TMC_LIST__
+ readelf -W --dyn-syms c.so
Symbol table '.dynsym' contains 7 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
2: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_deregisterTMCloneTable
3: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_registerTMCloneTable
4: 0000000000000000 0 FUNC WEAK DEFAULT UND __cxa_finalize
5: 0000000000001669 11 FUNC GLOBAL DEFAULT 10 foo
6: 000000000000167f 11 FUNC GLOBAL DEFAULT 10 baz
```
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