Why are dwarf2 symbols getting assigned hidden visibility?
John Marino
gnugcc@marino.st
Thu Jan 13 07:12:00 GMT 2011
I've successfully built the GNAT front-end of gcc 4.6 on several BSD
platforms. The NetBSD versions (i386 and AMD64) have a problem that I
can't figure out, and I suspect it can be fixed with a change to the
build configuration.
Although NetBSD passes its regression tests cleanly, there are some
dwarf2 functions it doesn't seem to recognize. When I listed hidden
symbols embedded in a pre-stripped gnat1 executable, here is the result:
> readelf -s gnat1 | grep HIDDEN
19135: 0000000000fc68c0 389 FUNC LOCAL HIDDEN 11 _Unwind_Find_FDE
19136: 0000000000fc4dc0 21 FUNC LOCAL HIDDEN 11 _Unwind_GetIPInfo
19137: 0000000000fc4db0 8 FUNC LOCAL HIDDEN 11 _Unwind_GetIP
19138: 0000000000fc66a0 38 FUNC LOCAL HIDDEN 11 __register_frame
19139: 0000000000fc52b0 241 FUNC LOCAL HIDDEN 11
_Unwind_Resume_or_Rethrow
19140: 0000000000fc4e00 8 FUNC LOCAL HIDDEN 11
_Unwind_GetRegionStart
19141: 0000000000fc53d0 155 FUNC LOCAL HIDDEN 11 _Unwind_Backtrace
19142: 0000000001299720 256 OBJECT LOCAL HIDDEN 13 __popcount_tab
19143: 0000000000fc4d50 8 FUNC LOCAL HIDDEN 11 _Unwind_GetCFA
19144: 00000000014b8820 0 OBJECT LOCAL HIDDEN 17 __DTOR_END__
19145: 00000000014b9168 0 OBJECT LOCAL HIDDEN 22 __dso_handle
19146: 0000000000fc4e60 269 FUNC LOCAL HIDDEN 11 __frame_state_for
19147: 0000000000fc6760 26 FUNC LOCAL HIDDEN 11
__register_frame_table
19148: 0000000000fc6600 130 FUNC LOCAL HIDDEN 11
__register_frame_info_bas
19149: 0000000000fc6880 5 FUNC LOCAL HIDDEN 11
__deregister_frame_info
19150: 0000000000fc51e0 193 FUNC LOCAL HIDDEN 11 _Unwind_Resume
19151: 0000000000fc53b0 26 FUNC LOCAL HIDDEN 11
_Unwind_DeleteException
19152: 0000000000fc6780 256 FUNC LOCAL HIDDEN 11
__deregister_frame_info_b
19153: 0000000000fc4f80 358 FUNC LOCAL HIDDEN 11
_Unwind_RaiseException
19154: 0000000000fc4de0 8 FUNC LOCAL HIDDEN 11 _Unwind_SetIP
19155: 0000000000fc66d0 114 FUNC LOCAL HIDDEN 11
__register_frame_info_tab
19156: 0000000000fc6890 33 FUNC LOCAL HIDDEN 11
__deregister_frame
19157: 0000000000fc4e50 8 FUNC LOCAL HIDDEN 11
_Unwind_GetTextRelBase
19158: 0000000000fc4e10 36 FUNC LOCAL HIDDEN 11
_Unwind_FindEnclosingFunc
19159: 0000000000fc4df0 8 FUNC LOCAL HIDDEN 11
_Unwind_GetLanguageSpecif
19160: 0000000000fc50f0 230 FUNC LOCAL HIDDEN 11
_Unwind_ForcedUnwind
19161: 00000000014b8a28 0 OBJECT LOCAL HIDDEN 21
_GLOBAL_OFFSET_TABLE_
19162: 0000000000fc2bf0 44 FUNC LOCAL HIDDEN 11 __popcountdi2
19163: 0000000000fc4d60 80 FUNC LOCAL HIDDEN 11 _Unwind_SetGR
19164: 0000000000fc4d00 72 FUNC LOCAL HIDDEN 11 _Unwind_GetGR
19165: 0000000000fc4e40 8 FUNC LOCAL HIDDEN 11
_Unwind_GetDataRelBase
19166: 0000000000fc6750 9 FUNC LOCAL HIDDEN 11
__register_frame_info_tab
19167: 0000000000fc6690 9 FUNC LOCAL HIDDEN 11
__register_frame_info
The other BSDs consider these symbols global. For example, here is a
subset of the same symbols taken from a stripped DragonFly BSD gnat1:
419: 0000000000fb10e0 373 FUNC GLOBAL DEFAULT 10 _Unwind_Find_FDE
582: 0000000000fad8f0 21 FUNC GLOBAL DEFAULT 10
_Unwind_GetIPInfo
920: 0000000000fad8e0 8 FUNC GLOBAL DEFAULT 10 _Unwind_GetIP
2116: 0000000000fafb40 235 FUNC GLOBAL DEFAULT 10
_Unwind_Resume_or_Rethrow
2762: 0000000000fad930 8 FUNC GLOBAL DEFAULT 10
_Unwind_GetRegionStart
3171: 0000000000fafc50 155 FUNC GLOBAL DEFAULT 10
_Unwind_Backtrace
4035: 0000000000fad880 8 FUNC GLOBAL DEFAULT 10 _Unwind_GetCFA
9786: 0000000000fafa60 212 FUNC GLOBAL DEFAULT 10 _Unwind_Resume
9841: 0000000000fafc30 21 FUNC GLOBAL DEFAULT 10
_Unwind_DeleteException
12631: 0000000000faf800 359 FUNC GLOBAL DEFAULT 10
_Unwind_RaiseException
13229: 0000000000fad910 8 FUNC GLOBAL DEFAULT 10 _Unwind_SetIP
15888: 0000000000fad980 8 FUNC GLOBAL DEFAULT 10
_Unwind_GetTextRelBase
16508: 0000000000fad940 36 FUNC GLOBAL DEFAULT 10
_Unwind_FindEnclosingFunc
16814: 0000000000fad920 8 FUNC GLOBAL DEFAULT 10
_Unwind_GetLanguageSpecif
17568: 0000000000faf970 230 FUNC GLOBAL DEFAULT 10
_Unwind_ForcedUnwind
18388: 0000000000fad890 75 FUNC GLOBAL DEFAULT 10 _Unwind_SetGR
19462: 0000000000fad830 72 FUNC GLOBAL DEFAULT 10 _Unwind_GetGR
20086: 0000000000fad970 8 FUNC GLOBAL DEFAULT 10
_Unwind_GetDataRelBase
1345: 0000000000fb0ec0 38 FUNC GLOBAL DEFAULT 10 __register_frame
8011: 0000000000fb0f80 26 FUNC GLOBAL DEFAULT 10
__register_frame_table
8532: 0000000000fb0e20 130 FUNC GLOBAL DEFAULT 10
__register_frame_info_bas
14325: 0000000000fb0ef0 114 FUNC GLOBAL DEFAULT 10
__register_frame_info_tab
20736: 0000000000fb0f70 9 FUNC GLOBAL DEFAULT 10
__register_frame_info_tab
20856: 0000000000fb0eb0 9 FUNC GLOBAL DEFAULT 10
__register_frame_info
9544: 0000000000fb10a0 5 FUNC GLOBAL DEFAULT 10
__deregister_frame_info
10772: 0000000000fb0fa0 256 FUNC GLOBAL DEFAULT 10
__deregister_frame_info_b
15277: 0000000000fb10b0 33 FUNC GLOBAL DEFAULT 10
__deregister_frame
3677: 0000000001284260 256 OBJECT GLOBAL DEFAULT 12 __popcount_tab
18046: 0000000000fad460 44 FUNC GLOBAL DEFAULT 10 __popcountdi2
I'm pretty well convinced that the NetBSD symbols should also be
classified as GLOBAL DEFAULT and this explains NetBSD's issue with
functions such as _Unwind_Resume and _Unwind_GetIPInfo. I've gone over
config.gcc and the various NetBSD headers many times, but I don't see
what's causing this or what omission might be causing it.
Can anybody suggest what may be wrong and how to correct it?
Thanks,
John
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