I have adapted existing gcc-7.1.0 ebuild and flag-o-matic eclass so
that it allows me to build gcc with my flags without filtering them.
It works fine, when built with prefiltered flags, but I wanted to
compile it with flto and pgo steps ( and later do same with binutils)
to see if that would shorten long compile times.
It surely should be noteable on packages like mesa, which I have to
compile fort 32/64-ti ABIs and where flto is a practical must -
difference in performance is simply too great to ignore.
I'd like to speed up compiling and linking ( which can take eternity
on bigger packages, compiled with LTO, even with gold)
So I tried to do a make priofiledboostrap with xxFLAGS and setting below:
COMMON_FLAGS="-march=native -pipe -O3 -flto=8 -ffat-lto-objects
-flto-partition=none -fuse-linker-plugin -fuse-ld=gold
-fno-delete-null-pointer-checks -fgraphite-identity -floop-nest-optimize"
CFLAGS="${COMMON_FLAGS}"
CXXFLAGS="${COMMON_FLAGS} -fpermissive"
LDFLAGS="-Wl,-O3 -Wl,--sort-common -Wl,-flto -Wl,--as-needed
-ffat-lto-objects -fuse-linker-plugin -fuse-ld=gold
-fno-delete-null-pointer-checks -fgraphite-identity -floop-nest-optimize"
LD="/usr/bin/ld.gold"
but build fails somewhere at the end of stage3 with:
^
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libgcc/libgcov-driver.c:885:1:
note: ‘__gcov_exit’ was previously declared here
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libstdc++-v3/libsupc++/vterminate.cc:82:
error: undefined reference to '_Unwind_Resume'
collect2: error: ld returned 1 exit status
make[3]: *** [Makefile:2792: build/genenums] Error 1
make[3]: *** Waiting for unfinished jobs....
<built-in>: warning: type of ‘__gcov_exit’ does not match original
declaration [-Wlto-type-mismatch]
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libgcc/libgcov-driver.c:885:1:
note: types have different parameter counts
__gcov_exit (void)
^
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libgcc/libgcov-driver.c:885:1:
note: ‘__gcov_exit’ was previously declared here
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libstdc++-v3/libsupc++/vterminate.cc:82:
error: undefined reference to '_Unwind_Resume'
collect2: error: ld returned 1 exit status
make[3]: *** [Makefile:2792: build/genconstants] Error 1
<built-in>: warning: type of ‘__gcov_exit’ does not match original
declaration [-Wlto-type-mismatch]
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libgcc/libgcov-driver.c:885:1:
note: types have different parameter counts
__gcov_exit (void)
^
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libgcc/libgcov-driver.c:885:1:
note: ‘__gcov_exit’ was previously declared here
/var/tmp/portage/sys-devel/gcc-7.1.0-r4/work/gcc-7.1.0/libstdc++-v3/libsupc++/vterminate.cc:82:
error: undefined reference to '_Unwind_Resume'
collect2: error: ld returned 1 exit status
Has anyone tried to compile gcc-7 with such combination ?
I used gcc-7.1.0 for compilation, along with binutils-2.28