CFLAGS="-march=core2 -O2 -pipe"

gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/9.3.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /var/tmp/portage/sys-devel/gcc-9.3.0-r1/work/gcc-9.3.0/configure --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/9.3.0 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/9.3.0 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/9.3.0/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/9.3.0/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/include/g++-v9 --with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/9.3.0/python --enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt --disable-werror --with-system-zlib --enable-nls --without-included-gettext --enable-checking=release --with-bugurl=https://bugs.gentoo.org/ --with-pkgversion='Gentoo 9.3.0-r1 p3' --disable-esp --enable-libstdcxx-time --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-multilib --with-multilib-list=m32,m64 --disable-fixed-point --enable-targets=all --enable-libgomp --disable-libssp --disable-libada --disable-systemtap --enable-vtable-verify --enable-lto --without-isl --enable-default-pie --enable-default-ssp
Thread model: posix
gcc version 9.3.0 (Gentoo 9.3.0-r1 p3)

emerge --info
Portage 3.0.28 (python 3.9.0-final-0, default/linux/amd64/17.1/desktop/plasma, gcc-9.3.0, glibc-2.32-r2, 4.14.209-gentoo-x86_64 x86_64)
=================================================================
System uname: Linux-4.14.209-gentoo-x86_64-x86_64-Intel-R-_Atom-TM-_CPU_N2800_@_1.86GHz-with-glibc2.32
KiB Mem:     4020956 total,   2109784 free
KiB Swap:   33554428 total,  32839676 free
Timestamp of repository gentoo: Mon, 01 Nov 2021 19:00:01 +0000
Head commit of repository gentoo: d79c15054338c7327acbc04aa33b8fcba16d8052
sh bash 5.0_p18
ld GNU ld (Gentoo 2.34 p6) 2.34.0
app-shells/bash:          5.0_p18::gentoo
dev-java/java-config:     2.3.1::gentoo
dev-lang/perl:            5.30.3::gentoo
dev-lang/python:          2.7.18-r4::gentoo, 3.7.9::gentoo, 3.8.6::gentoo, 3.9.0::gentoo
dev-lang/rust:            1.47.0-r2::gentoo
dev-util/cmake:           3.20.5::gentoo
sys-apps/baselayout:      2.7::gentoo
sys-apps/openrc:          0.42.1-r1::gentoo
sys-apps/sandbox:         2.20::gentoo
sys-devel/autoconf:       2.13-r1::gentoo, 2.69-r5::gentoo
sys-devel/automake:       1.13.4-r2::gentoo, 1.16.2-r1::gentoo
sys-devel/binutils:       2.34-r2::gentoo
sys-devel/gcc:            9.3.0-r1::gentoo, 9.4.0::last, 10.3.0-r2::last, 11.2.0::last
sys-devel/gcc-config:     2.3.2-r1::gentoo
sys-devel/libtool:        2.4.6-r6::gentoo
sys-devel/make:           4.2.1-r4::gentoo
sys-kernel/linux-headers: 5.4-r1::gentoo (virtual/os-headers)
sys-libs/glibc:           2.32-r2::gentoo
Repositories:

gentoo
    location: /var/db/repos/gentoo
    sync-type: rsync
    sync-uri: rsync://rsync.gentoo.org/gentoo-portage
    priority: -1000
    sync-rsync-verify-max-age: 24
    sync-rsync-verify-jobs: 1
    sync-rsync-extra-opts: 
    sync-rsync-verify-metamanifest: yes

last
    location: /var/db/repos/last
    masters: gentoo

local
    location: /var/db/repos/local
    masters: gentoo

ACCEPT_KEYWORDS="amd64"
ACCEPT_LICENSE="*"
CBUILD="x86_64-pc-linux-gnu"
CFLAGS="-march=core2 -O2 -pipe"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/lib64/libreoffice/program/sofficerc /usr/share/config /usr/share/gnupg/qualified.txt /usr/share/themes/oxygen-gtk/gtk-2.0 /var/bind"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/php/apache2-php7.4/ext-active/ /etc/php/cgi-php7.4/ext-active/ /etc/php/cli-php7.4/ext-active/ /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo"
CXXFLAGS="-march=core2 -O2 -pipe"
DISTDIR="/var/db/distfiles/"
ENV_UNSET="CARGO_HOME DBUS_SESSION_BUS_ADDRESS DISPLAY GOBIN GOPATH PERL5LIB PERL5OPT PERLPREFIX PERL_CORE PERL_MB_OPT PERL_MM_OPT XAUTHORITY XDG_CACHE_HOME XDG_CONFIG_HOME XDG_DATA_HOME XDG_RUNTIME_DIR"
FCFLAGS="-march=core2 -O2 -pipe"
FEATURES="assume-digests binpkg-docompress binpkg-dostrip binpkg-logs config-protect-if-modified distlocks ebuild-locks fixlafiles ipc-sandbox merge-sync multilib-strict network-sandbox news parallel-fetch pid-sandbox preserve-libs protect-owned qa-unresolved-soname-deps sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr"
FFLAGS="-march=core2 -O2 -pipe"
GENTOO_MIRRORS="https://gentoo-mirror.alexxy.name/ https://mirror.yandex.ru/gentoo-distfiles/ ftp://mirror.yandex.ru/gentoo-distfiles/ http://mirror.yandex.ru/gentoo-distfiles/ https://mirrors.gethosted.online/gentoo http://gentoo.cs.utah.edu/"
LANG="en_US.UTF-8"
LDFLAGS="-Wl,-O1 -Wl,--as-needed"
LINGUAS="en_GB ru"
MAKEOPTS="-j4"
PKGDIR="/var/cache/binpkgs"
PORTAGE_CONFIGROOT="/"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --exclude=/.git"
PORTAGE_TMPDIR="/var/tmp"
USE="X a52 aac acl acpi activities alsa amd64 apache2 bluetooth branding build bzip2 cairo cdda cdr cgi chrome cli crypt ctype cups curl dbus declarative dri dts dvd dvdr egl elogind emboss encode exif fam fastcgi ffmpeg firefox flac fortran g3dvl gd gdbm gif gpm gtk gui hal handbook hpcups iconv icu id3tag ipv6 jpeg kde kipi kwallet lcms ldap libglvnd libnotify libtirpc mad mailwrapper melt mikmod mng mp3 mp4 mpeg mpm-event multilib mysql mysqli ncurses networkmanager nls nptl nvidia ogg opengl openmp opera pam pango pcre pdf perl phonon php plasma png policykit ppds python qml qt3support qt4 qt5 readline samba sdl seccomp semantic-desktop sftp snmp spell split-usr ssl startup-notification suexec svg symlink tcpd threads tiff truetype udev udisks unicode upower usb v4l video vorbis widgets wxwidgets x264 xattr xcb xml xsl xulrunner xv xvid xvmc zlib" ABI_X86="64 32" ADA_TARGET="gnat_2019" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="karbon sheets words" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="mmx mmxext sse sse3" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock greis isync itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="evdev synaptics" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LUA_SINGLE_TARGET="lua5-1" LUA_TARGETS="lua5-1" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php7-3 php7-4" POSTGRES_TARGETS="postgres12 postgres13" PYTHON_SINGLE_TARGET="python3_9" PYTHON_TARGETS="python3_9 python3_8" RUBY_TARGETS="ruby26 ruby27" USERLAND="GNU" VIDEO_CARDS="amdgpu fbdev intel nouveau radeon radeonsi vesa dummy v4l" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq proto steal rawnat logmark ipmark dhcpmac delude chaos account"
Unset:  CC, CPPFLAGS, CTARGET, CXX, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, PORTAGE_BINHOST, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, RUSTFLAGS