According to the GCC manual -fprofile-generate is equivalent to: -fprofile-arcs -fprofile-values -fvpt
Similarly -fprofile-use is equivalent to: -fbranch-probabilities -fvpt -funroll-loops -fpeel-loops -ftracer However if I use -fprofile-generate the .gcda/.gcno files are not generated in the local directory, but only with process number specific names in ~/.ccache. Similarly if I use -fprofile-use, it searches unsuccessfully in ~/.ccache. However if I use the explicit sets of component flags, the .gcda/.gcno files are created in the correct place and subsequently found correctly. The attached is a tiny (two source file) program and script which demonstrates this Use this script as follows: 1) ./script -fprofile-generate 2) ./script -fprofile-arcs -fprofile-values -fvpt Observe that these should be equivalent, but only 2) generates the .gcda and .gcno files in the correct place. 1) generates them in ~/.ccache with names derived from process numbers. Having run 2), try: 3) ./script -fprofile-use 4) ./script -fbranch-probabilities -fvpt -funroll-loops -fpeel-loops -ftracer Observe that these should be equivalent, but 3) looks in the wrong place (~/.ccache) for the profile data. I feel this is such an obvious problem that it should have been already reported, or I am missing something in the user manual. However an afternoon's searching has been fruitless. Perhaps it is a peculiarity of GCC 4.3.0 on Fedora 9. Platform details (uname -a): Linux thomas 2.6.27.12-78.2.8.fc9.i686 #1 SMP Mon Jan 19 20:14:35 EST 2009 i686 i686 i386 GNU/Linux Compiler details (gcc -v): Using built-in specs. Target: i386-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-cpu=generic --build=i386-redhat-linux Thread model: posix gcc version 4.3.0 20080428 (Red Hat 4.3.0-8) (GCC) -- Summary: -fprofile-generate and -fprofile-use are not equivalent to their component flags. Get directories wrong Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: gcov-profile AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: jeremy at jeremybennett dot com GCC build triplet: i386-redhat-linux GCC host triplet: i386-redhat-linux GCC target triplet: i386-redhat-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39220
