[Bug c/60622] New: [4.9 Regression] symbol missing when compiled with -flto

["raj.khem at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

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)