On Fri, 2016-03-11 at 16:27 +0100, Ralph Boehme wrote: > I'm seeing a problem when building Samba with LTO. Linking fails > reproducibly at this stage: > > [4086/4247] Linking default/source4/torture/smbtorture > 13:31:06 runner /usr/bin/gcc > default/source4/lib/registry/tests/generic_20.o ... > ... many many object files and libraries ... > > /tmp/cc9skRWL.ltrans3.ltrans.o: In function > `smbsrv_accept.lto_priv.11': > <artificial>:(.text+0x4cd6): undefined reference to > `timeval_current.lto_priv.641' > /tmp/cc9skRWL.ltrans4.ltrans.o: In function > `smbsrv_recv_smb2_request': > <artificial>:(.text+0xf661): undefined reference to > `timeval_current.lto_priv.641' > ... many more undefined references to timeval_* ... > > Full build log: > <https://www.samba.org/~slow/files/log.gz> > > $ gcc --version > gcc (GCC) 5.3.1 20151207 (Red Hat 5.3.1-2) > > The buildsystem correctly passes -flto when compiling .c files and > the > link steps has it as well. > > The missing symbols are in libsamba-util which is among the linked > libraries: > > $ nm bin/shared/libsamba-util.so.0 | egrep > 'timeval_current$|timeval_elapsed$' > 000000000001cd6b T timeval_current > 000000000001a206 T timeval_elapsed > > The build works just fine without -flto. > > I'd appreciate any pointers on how to get -flto going. I ran into similar issues when building something without LTO vs. with LTO. Sometimes the link order needs to be changed for an LTO build. Sometimes it's required to use -Wl,--whole-archive on some of the libs and some libs need to be put in a -Wl,-start-group ... -Wl,--end-group. You might want to try out playing with those and see if it helps in your case. Cheers, Oleg
