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

[t.artem at mailcity dot com]

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

--- Comment #5 from Artem S. Tashkinov <t.artem at mailcity dot com> 2011-02-27 21:06:04 UTC ---
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 ‘Unpack29’:
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