When building a library in IMA mode, several used functions are optimized away:
gcc-4.1-HEAD -W -Wall -pedantic -funit-at-a-time -DPIC -fPIC -o liblib.o -c
lib.c lib1.c lib2.c
strip -x -R .note -R .comment liblib.o
ar cr liblib.a liblib.o
ld -shared --warn-common --warn-once -z combreloc -z defs -s -rpath . \
-soname=liblib.so -o liblib.so --whole-archive liblib.a --no-whole-archive -lc
Do we have all of libmain, __func1, __func2 ?
nm -D --defined-only liblib.so
00001260 A __bss_start
000011e4 A _DYNAMIC
00001260 A _edata
00001260 A _end
000001bc T __func2
gcc-4.1-HEAD -W -Wall -pedantic -I. test.c -o libtest -L. -llib
/tmp/ccsGhigf.o: In function `main':
test.c:(.text+0x43): undefined reference to `libmain'
collect2: ld returned 1 exit status
make: *** [libtest] Error 1
This would be the expected result:
nm -D --defined-only liblib.so
0000138c A __bss_start
000012e8 A _DYNAMIC
0000138c A _edata
0000138c A _end
00000234 T __func1
0000025b T __func2
00000282 T libmain
--
Summary: -funit-at-a-time drops used functions (IMA mode)
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: critical
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rep dot nop at aon dot at
GCC build triplet: i686-linux-gnu
GCC host triplet: i686-linux-gnu
GCC target triplet: i686-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24395
