[Bug lto/47916] Using -flto leads to halved performance of unrar unarchiver

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47916

--- Comment #6 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-02-27 23:13:02 UTC ---
(In reply to comment #5)
> Thanks for the explanation!
> 
> I'm not sure if it's worth opening a new bug report, but GCC crashes when I try
> to use -fprofile-generate/-fprofile-use together with -flto:
> 
> g++ -o unrar -O3 -march=core2 -fomit-frame-pointer -fprofile-use -flto rar.o
> strlist.o strfn.o pathfn.o savepos.o smallfn.o global.o file.o filefn.o
> filcreat.o archive.o arcread.o unicode.o system.o isnt.o crypt.o crc.o
> rawread.o encname.o resource.o match.o timefn.o rdwrfn.o consio.o options.o
> ulinks.o errhnd.o rarvm.o rijndael.o getbits.o sha1.o extinfo.o extract.o
> volume.o list.o find.o unpack.o cmddata.o filestr.o recvol.o rs.o scantree.o
> In file included from :43:0:
> unpack.cpp: In member function âUnpack29â:
> unpack.cpp:202:6: internal compiler error: in duplicate_loop_to_header_edge, at
> cfgloopmanip.c:1115
> Please submit a full bug report,
> with preprocessed source if appropriate.
> See <http://gcc.gnu.org/bugs.html> for instructions.
> 
> At first I built unrar using:
> CXXFLAGS=LDFLAGS=-O3 -march=core2 -fomit-frame-pointer -fprofile-generate -flto 
> 
> then I made a testrun of unrar, then erased object files, then tried to compile
> it again using:
> 
> CXXFLAGS=LDFLAGS=-O3 -march=core2 -fomit-frame-pointer -fprofile-use -flto

That should work.  The error is a sanity check that profile information
is sane.