http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60622
Bug ID: 60622
Summary: [4.9 Regression] symbol missing when compiled with
-flto
Product: gcc
Version: lto
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: raj.khem at gmail dot com
trying to compile systemd with gcc 4.9 snapshot there appears to be a lot of
undefined symbols, I traced it down to the fact that system uses -flto option
during compilation, and when thats used the symbol table is completely bald.
e.g.
extern int arg;
__attribute__ ((visibility("default"))) extern int foo() {
return arg;
}
$ mips-angstrom-linux-uclibc-gcc test.c -c -flto
$ readelf -s test.o
Symbol table '.symtab' contains 19 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000 0 FILE LOCAL DEFAULT ABS test.c
2: 00000000 0 SECTION LOCAL DEFAULT 1
3: 00000000 0 SECTION LOCAL DEFAULT 2
4: 00000000 0 SECTION LOCAL DEFAULT 3
5: 00000000 0 SECTION LOCAL DEFAULT 6
6: 00000000 0 SECTION LOCAL DEFAULT 7
7: 00000000 0 SECTION LOCAL DEFAULT 8
8: 00000000 0 SECTION LOCAL DEFAULT 9
9: 00000000 0 SECTION LOCAL DEFAULT 10
10: 00000000 0 SECTION LOCAL DEFAULT 11
11: 00000000 0 SECTION LOCAL DEFAULT 12
12: 00000000 0 SECTION LOCAL DEFAULT 13
13: 00000000 0 SECTION LOCAL DEFAULT 4
14: 00000000 0 SECTION LOCAL DEFAULT 5
15: 00000000 0 SECTION LOCAL DEFAULT 14
16: 00000000 0 SECTION LOCAL DEFAULT 15
17: 00000001 1 OBJECT GLOBAL DEFAULT COM __gnu_lto_v1
18: 00000001 1 OBJECT GLOBAL DEFAULT COM __gnu_lto_slim
$ mips-angstrom-linux-uclibc-gcc test.c -c
$ readelf -s test.o
Symbol table '.symtab' contains 13 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000 0 FILE LOCAL DEFAULT ABS test.c
2: 00000000 0 SECTION LOCAL DEFAULT 1
3: 00000000 0 SECTION LOCAL DEFAULT 3
4: 00000000 0 SECTION LOCAL DEFAULT 4
5: 00000000 0 SECTION LOCAL DEFAULT 8
6: 00000000 0 SECTION LOCAL DEFAULT 5
7: 00000000 0 SECTION LOCAL DEFAULT 6
8: 00000000 0 SECTION LOCAL DEFAULT 9
9: 00000000 0 SECTION LOCAL DEFAULT 10
10: 00000000 52 FUNC GLOBAL DEFAULT 1 foo
^^^
symbol is there
11: 00000000 0 NOTYPE GLOBAL DEFAULT UND __gnu_local_gp
12: 00000000 0 NOTYPE GLOBAL DEFAULT UND arg
This issue I did not see on arm, only on ppc and mips
here gcc configure
Target: mips-angstrom-linux-uclibc
Configured with:
/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/work-shared/gcc-4.9-20140316-r0/gcc-4.9-20140316/configure
--build=x86_64-linux --host=x86_64-linux --target=mips-angstrom-linux-uclibc
--prefix=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr
--exec_prefix=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr
--bindir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/bin/mips32-angstrom-linux-uclibc
--sbindir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/bin/mips32-angstrom-linux-uclibc
--libexecdir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/libexec/mips32-angstrom-linux-uclibc
--datadir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/share
--sysconfdir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/etc
--sharedstatedir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/com
--localstatedir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/var
--libdir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/lib/mips32-angstrom-linux-uclibc
--includedir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/include
--oldincludedir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/include
--infodir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/share/info
--mandir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr/share/man
--disable-silent-rules --disable-dependency-tracking
--with-libtool-sysroot=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux
--enable-clocale=generic --with-gnu-ld --enable-shared --enable-languages=c,c++
--enable-threads=posix --disable-multilib --enable-c99 --enable-long-long
--enable-symvers=gnu --enable-libstdcxx-pch
--program-prefix=mips-angstrom-linux-uclibc- --without-local-prefix
--enable-target-optspace --enable-lto --enable-libssp --disable-bootstrap
--disable-libmudflap --with-system-zlib --with-linker-hash-style=sysv
--enable-linker-build-id --with-ppl=no --with-cloog=no
--enable-checking=release --enable-cheaders=c_global
--with-gxx-include-dir=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/qemumips/usr/include/c++
--with-sysroot=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/qemumips
--with-build-sysroot=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/qemumips
--enable-poison-system-directories --disable-libunwind-exceptions
--with-mpfr=/home/kraj/angstrom/build/tmp-angstrom_next-uclibc/sysroots/x86_64-linux/usr
--with-system-zlib --disable-nls --disable-decimal-float --enable-__cxa_atexit
Thread model: posix
gcc version 4.9.0 20140316 (experimental) (GCC)
