[Bug lto/56557] [4.8 Regression] Link error about `std::fstream' or `std::stringstream' with `-flto' and `-rdynamic' options

[hubicka at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56557



Jan Hubicka <hubicka at gcc dot gnu.org> changed:



           What    |Removed                     |Added

----------------------------------------------------------------------------

          Component|libstdc++                   |lto



--- Comment #14 from Jan Hubicka <hubicka at gcc dot gnu.org> 2013-03-12 
12:53:17 UTC ---

This is the LTO symbol table I get out of the testcase now:

         U _ZNSdC2Ev

         U _ZNSdD1Ev

         U _ZNSdD2Ev

         U _ZNSiC2Ev

         U _ZNSiD1Ev

         U _ZNSiD2Ev

         U _ZNSoC2Ev

         U _ZNSoD1Ev

         U _ZNSoD2Ev

         U _ZNSt12__basic_fileIcED1Ev

         U _ZNSt13basic_filebufIcSt11char_traitsIcEE5closeEv

         U _ZNSt13basic_filebufIcSt11char_traitsIcEEC1Ev

         U _ZNSt13basic_filebufIcSt11char_traitsIcEED1Ev

         U _ZNSt13basic_fstreamIcSt11char_traitsIcEEC1Ev

         U _ZNSt13basic_fstreamIcSt11char_traitsIcEED1Ev

         U _ZNSt15basic_streambufIcSt11char_traitsIcEED1Ev

         U _ZNSt15basic_streambufIcSt11char_traitsIcEED2Ev

         U _ZNSt6localeD1Ev

         U _ZNSt8ios_baseC2Ev

         U _ZNSt8ios_baseD2Ev

         U _ZNSt9basic_iosIcSt11char_traitsIcEE4initEPSt15basic_streambufIcS1_E

         U _ZNSt9basic_iosIcSt11char_traitsIcEEC2Ev

         U _ZNSt9basic_iosIcSt11char_traitsIcEED1Ev

         U _ZNSt9basic_iosIcSt11char_traitsIcEED2Ev

         U _ZTTSd

         U _ZTTSt13basic_fstreamIcSt11char_traitsIcEE

         U _ZTVSd

         U _ZTVSi

         U _ZTVSo

         U _ZTVSt13basic_filebufIcSt11char_traitsIcEE

         U _ZTVSt13basic_fstreamIcSt11char_traitsIcEE

         U _ZTVSt15basic_streambufIcSt11char_traitsIcEE

         U _ZTVSt9basic_iosIcSt11char_traitsIcEE

         U _ZdlPv

         U __gxx_personality_v0

00000000 T main



So still quite a bit more than w/o LTO:



                 U _ZNSt13basic_fstreamIcSt11char_traitsIcEEC1Ev

                 U _ZNSt13basic_fstreamIcSt11char_traitsIcEED1Ev

0000000000000001 C __gnu_lto_v1

0000000000000000 T main



but the construction vtable is no longer on the list. Those extra symbols are

from virtual functions we hold for possible devirtualization.

We ought to make sure that linkers optimize out the dynamic table entries after

we are done with optimizing them out