http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50483
Bug #: 50483
Summary: lto turns visibility from HIDDEN to DEFAULT
Classification: Unclassified
Product: gcc
Version: lto
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: vincenzo.innoce...@cern.ch
Host: x86
Target: x86_64-unknown-linux-gnu
Build: 4.7.0 20110919
not sure how relevant is in practice BUT in the example below one may notice
that the visibility of "bar" is turned to DEFAULT by lto
no lto
17: 0000000000000597 11 FUNC LOCAL HIDDEN 11 bar()
lto
11: 0000000000000597 11 FUNC LOCAL DEFAULT 11 bar() .2238
cat vislto.cc
void ext();
void bar() __attribute((visibility( "hidden" )));
void foo() __attribute((visibility( "default" )));
void foo() { bar();}
void bar() { ext();}
g++ -fPIC vislto.cc -Wall -shared -o libvislto.so
[vinavx0] ~/public/ctest $ readelf -sW libvislto.so | grep -v UND | sed 's/\./
\./g' | c++filt
Symbol table ' .dynsym' contains 11 entries:
Num: Value Size Type Bind Vis Ndx Name
2: 0000000000000478 0 FUNC GLOBAL DEFAULT 9 _init
3: 00000000000005e8 0 FUNC GLOBAL DEFAULT 12 _fini
6: 000000000000058c 11 FUNC GLOBAL DEFAULT 11 foo()
8: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS _edata
9: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
10: 00000000000018e0 0 NOTYPE GLOBAL DEFAULT ABS _end
Symbol table ' .symtab' contains 31 entries:
Num: Value Size Type Bind Vis Ndx Name
1: 00000000000004c0 0 FUNC LOCAL DEFAULT 11 call_gmon_start
2: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff .c
3: 00000000000018a8 0 OBJECT LOCAL DEFAULT 19 __CTOR_LIST__
4: 00000000000018b8 0 OBJECT LOCAL DEFAULT 20 __DTOR_LIST__
5: 00000000000018c8 0 OBJECT LOCAL DEFAULT 21 __JCR_LIST__
6: 00000000000004e0 0 FUNC LOCAL DEFAULT 11
__do_global_dtors_aux
7: 00000000000018d0 1 OBJECT LOCAL DEFAULT 22 completed .5901
8: 00000000000018d8 8 OBJECT LOCAL DEFAULT 22 dtor_idx .5903
9: 0000000000000560 0 FUNC LOCAL DEFAULT 11 frame_dummy
10: 0000000000000000 0 FILE LOCAL DEFAULT ABS vislto .cc
11: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff .c
12: 00000000000018b0 0 OBJECT LOCAL DEFAULT 19 __CTOR_END__
13: 0000000000000650 0 OBJECT LOCAL DEFAULT 13 __FRAME_END__
14: 00000000000018c8 0 OBJECT LOCAL DEFAULT 21 __JCR_END__
15: 00000000000005b0 0 FUNC LOCAL DEFAULT 11
__do_global_ctors_aux
16: 00000000000018a0 0 OBJECT LOCAL HIDDEN 18 __dso_handle
17: 0000000000000597 11 FUNC LOCAL HIDDEN 11 bar()
18: 00000000000018c0 0 OBJECT LOCAL HIDDEN 20 __DTOR_END__
19: 0000000000001670 496 OBJECT LOCAL HIDDEN 15 _DYNAMIC
20: 0000000000001878 40 OBJECT LOCAL HIDDEN 17
_GLOBAL_OFFSET_TABLE_
22: 0000000000000478 0 FUNC GLOBAL DEFAULT 9 _init
23: 00000000000005e8 0 FUNC GLOBAL DEFAULT 12 _fini
26: 000000000000058c 11 FUNC GLOBAL DEFAULT 11 foo()
28: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS _edata
29: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
30: 00000000000018e0 0 NOTYPE GLOBAL DEFAULT ABS _end
[vinavx0] ~/public/ctest $ g++ -fPIC vislto.cc -Wall -shared -o libvislto.so
-flto
[vinavx0] ~/public/ctest $ readelf -sW libvislto.so | grep -v UND | sed 's/\./
\./g' | c++filt
Symbol table ' .dynsym' contains 11 entries:
Num: Value Size Type Bind Vis Ndx Name
2: 0000000000000478 0 FUNC GLOBAL DEFAULT 9 _init
3: 00000000000005e8 0 FUNC GLOBAL DEFAULT 12 _fini
6: 000000000000058c 11 FUNC GLOBAL DEFAULT 11 foo()
8: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS _edata
9: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
10: 00000000000018e0 0 NOTYPE GLOBAL DEFAULT ABS _end
Symbol table ' .symtab' contains 31 entries:
Num: Value Size Type Bind Vis Ndx Name
1: 00000000000004c0 0 FUNC LOCAL DEFAULT 11 call_gmon_start
2: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff .c
3: 00000000000018a8 0 OBJECT LOCAL DEFAULT 19 __CTOR_LIST__
4: 00000000000018b8 0 OBJECT LOCAL DEFAULT 20 __DTOR_LIST__
5: 00000000000018c8 0 OBJECT LOCAL DEFAULT 21 __JCR_LIST__
6: 00000000000004e0 0 FUNC LOCAL DEFAULT 11
__do_global_dtors_aux
7: 00000000000018d0 1 OBJECT LOCAL DEFAULT 22 completed .5901
8: 00000000000018d8 8 OBJECT LOCAL DEFAULT 22 dtor_idx .5903
9: 0000000000000560 0 FUNC LOCAL DEFAULT 11 frame_dummy
10: 0000000000000000 0 FILE LOCAL DEFAULT ABS cclww4iv .ltrans0 .o
11: 0000000000000597 11 FUNC LOCAL DEFAULT 11 bar() .2238
12: 0000000000000000 0 FILE LOCAL DEFAULT ABS crtstuff .c
13: 00000000000018b0 0 OBJECT LOCAL DEFAULT 19 __CTOR_END__
14: 0000000000000650 0 OBJECT LOCAL DEFAULT 13 __FRAME_END__
15: 00000000000018c8 0 OBJECT LOCAL DEFAULT 21 __JCR_END__
16: 00000000000005b0 0 FUNC LOCAL DEFAULT 11
__do_global_ctors_aux
17: 00000000000018a0 0 OBJECT LOCAL HIDDEN 18 __dso_handle
18: 00000000000018c0 0 OBJECT LOCAL HIDDEN 20 __DTOR_END__
19: 0000000000001670 496 OBJECT LOCAL HIDDEN 15 _DYNAMIC
20: 0000000000001878 40 OBJECT LOCAL HIDDEN 17
_GLOBAL_OFFSET_TABLE_
22: 0000000000000478 0 FUNC GLOBAL DEFAULT 9 _init
23: 00000000000005e8 0 FUNC GLOBAL DEFAULT 12 _fini
26: 000000000000058c 11 FUNC GLOBAL DEFAULT 11 foo()
28: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS _edata
29: 00000000000018d0 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
30: 00000000000018e0 0 NOTYPE GLOBAL DEFAULT ABS _end
