How stable is LTO in gcc 5?

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Uzytkownik · Post by **Uzytkownik** » Fri Apr 21, 2017 7:36 pm

How stable is LTO in gcc 5? I found information for gcc 4.8 and 4.9 when it was not but not for 5+.

freke · Post by **freke** » Fri Apr 21, 2017 9:48 pm

For me - on my headless mail-/web-/sql-server, I have:

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## LTO
# System
=sys-apps/man-db-2.7.6.1-r2 no-lto.conf
=dev-libs/libgcrypt-1.7.6 no-lto.conf
=net-misc/wget-1.19.1-r1 no-lto.conf

# World
=sys-apps/pciutils-3.4.1 no-lto.conf
=app-antivirus/clamav-0.99.2 no-lto.conf
=dev-lang/php-7.0.15 no-lto.conf

in my package.env

postfix started to compile with LTO for me at 3.2.0.

emerge --info

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sys-devel/binutils:       2.27::gentoo
sys-devel/gcc:            5.4.0-r3::gentoo
...
CFLAGS="-O2 -march=native -pipe -fomit-frame-pointer -flto=3 -fuse-linker-plugin -fno-fat-lto-objects -floop-interchange -ftree-loop-distribution -floop-strip-mine -floop-block -ftree-vectorize"
...
CXXFLAGS="-O2 -march=native -pipe -fomit-frame-pointer -flto=3 -fuse-linker-plugin -fno-fat-lto-objects -floop-interchange -ftree-loop-distribution -floop-strip-mine -floop-block -ftree-vectorize
...
LDFLAGS="-Wl,-O1 -Wl,--as-needed -O2 -march=native -pipe -fomit-frame-pointer -flto=3 -fuse-linker-plugin -fno-fat-lto-objects -floop-interchange -ftree-loop-distribution -floop-strip-mine -floop-block -ftree-vectorize