http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45375
--- Comment #35 from Jan Hubicka <hubicka at gcc dot gnu.org> 2011-01-15 16:42:06 UTC --- I looked briefly into effectivity of the devirtualization bits and they don't seem to work terribly well. In GCC 4.3 -O3 copmiled libxul there are 82155 indirect calls. In mainline -O3 libxul there are 83023 and with LTO there are 87763. The ipa-prop bits at LTO devirtualize 1 call that is consequently optimized away (since -fno-devirtualize seems same to -fdevirtualize). I will give a try http://gcc.gnu.org/ml/gcc-patches/2010-12/msg01214.html However we _really_ need testcases from Mozilla where devirtualization is valid and we don't do it.
