#!/bin/sh -e

# This kw hook is meant to replace the now deprecated kissLTO repo.

# kissLTO link: https://github.com/git-bruh/kissLTO

# GentooLTO make.conf
# https://github.com/InBetweenNames/gentooLTO/blob/master/sys-config/ltoize/files/make.conf.lto.defines

# Broken Packages (that build):
# * clang

# Won't Build
# * rust

# Our initial C/CXX/LD Flags, are modified in the first case statement below.
export CFLAGS="-O3 -pipe -march=native -mtune=native -fno-math-errno -fdevirtualize-at-ltrans -fno-semantic-interposition -fipa-pta -flto=auto -fuse-linker-plugin -fgraphite-identity -floop-nest-optimize -fuse-ld=gold"
export CXXFLAGS="$CFLAGS"
export LDFLAGS="-Wl,-O1 -Wl,--as-needed $CFLAGS"

# Add the CFLAGS/CXXFLAGS/LDFLAGS to the build script, since we can't set
# the environment itself.
add_flags() {
    sed -i "1a export CFLAGS=\"$CFLAGS\"\nexport CXXFLAGS=\"\$CFLAGS\"\nexport LDFLAGS=\"$LDFLAGS\"" "$1/build"
}

saneflags() {
    export CFLAGS="-O2 -pipe -march=native -mtune=native"
    export CXXFLAGS="$CFLAGS"
    unset LDFLAGS
}

flagsed() {
    CFLAGS="$(printf %s "$CFLAGS" | sed "$1")"
    CXXFLAGS="$(printf %s "$CXXFLAGS" | sed "$1")"
    LDFLAGS="$(printf %s "$LDFLAGS" | sed "$1")"

    export CFLAGS
    export CXXFLAGS
    export LDFLAGS
}

saneflags() {
    export CFLAGS="-O2 -pipe -march=native -mtune=native"
    export CXXFLAGS="$CFLAGS"
    unset LDFLAGS
}

nolto() {
    flagsed "s/-flto=auto//"
}

addflag() {
    flagsed "s/$/ $1/"
}

delflag() {
    flagsed "s/$1//"
}

nographite() {
    delflag "-fgraphite-identity"
    delflag "-floop-nest-optimize"
}

clang_flags() {
    # Unsupported flags.
    delflag "-fipa-pta"
    delflag "-fdevirtualize-at-ltrans"
    nographite
}

usemold() {
    delflag "-fuse-ld=gold"
    addflag "-fuse-ld=mold"
}

# Supported Environment Variables:
# 0 to disable, anything else to enable
# * KW_LTO_LTO - toggles lto flag
# * KW_LTO_GRA - toggles graphite flags
# * KW_LTO_ON  - toggles saneflags
KW_LTO_LTO=${KW_LTO_LTO:-1}
KW_LTO_GRA=${KW_LTO_LTO:-1}
KW_LTO_ON=${KW_LTO_LTO:-1}
if [ "$KW_LTO_ON" -eq 0 ]; then
    saneflags
fi
if [ "$KW_LTO_LTO" -eq 0 ]; then
    nolto
fi
if [ "$KW_LTO_GRA" -eq 0 ]; then
    nographite
fi

# Compiler check.
case $CC in
clang)
    # Remove GCC only flags.
    clang_flags
    ;;
tcc)
    # tcc doesn't support these optimizations.
    saneflags
    ;;
esac

# Linker check.
if command -v mold > /dev/null; then
    usemold
fi

# Flag modification.
case $1 in
alsa-lib | \
    efivar)
    addflag "-flto-partition=none"
    ;;
curl | \
    libressl | \
    openssl | \
    libtermkey | \
    lua | \
    lzo | \
    ncurses | \
    zlib | \
    zstd)
    addflag "-ffat-lto-objects"
    ;;
ffmpeg | \
    python)
    # These packages have custom configuration for LTO.
    nolto
    ;;
gcc)
    nolto
    delflag "-fipa-pta"
    ;;
binutils)
    delflag "-fipa-pta"
    ;;
chromium)
    nolto
    delflag "-fdevirtualize-at-ltrans"
    ;;
firefox)
    nolto
    clang_flags
    delflag "-fuse-ld=gold"
    ;;
llvm)
    addflag "-ffat-lto-objects"
    # clang segfaults.
    delflag "-fno-semantic-interposition"
    ;;
git | \
    github-cli | \
    nodejs | \
    python2 | \
    ruby | \
    rust | \
    strace | \
    webkit2gtk | \
    xorg-server)
    nolto
    ;;
musl)
    nolto
    delflag "-fuse-ld=gold"
    ;;
glibc)
    saneflags
    ;;
# Other packages that I've tested.
chez-scheme | \
    gprolog)
    nolto
    ;;
*)
    if [ -e "$2/depends" ]; then
        if grep rust "$2/depends"; then
            addflag "-ffat-lto-objects"
        fi
    fi
    ;;
esac

# Add our LTO Flags to the build script.
add_flags "$2"

# Package specific build script modification.
case $1 in
binutils)
    # Enable gold linker for binutils.
    sed -E -i \
        -e "s/(--enable-targets=).*$/\1$(cc -dumpmachine) \\\\/" \
        -e "s/ld.bfd/ld.gold/" \
        "$2/build"
    ;;
ffmpeg)
    # Build system expects lto to be enabled via configure.
    sed -E -i \
        -e "s~(--prefix=/usr)~\1 --enable-lto~" \
        "$2/build"
    ;;
gcc)
    # Change the make command to be PGO, and to use sane CFLAGS in stage1 of bootstrap.
    # Add the configure flag to tell gcc to build with lto/bootstrap
    # Ensure that we perform a bootstrap build
    sed -E -i \
        -e "s/^(make)$/\1 BOOT_CFLAGS=\"\${CFLAGS}\" STAGE1_CFLAGS=\"-O2 -pipe -march=native\" profiledbootstrap/" \
        -e "/prefix/s/(--prefix)/--with-build-config=bootstrap-lto \1/" \
        -e "/bootstrap=/d" \
        "$2/build"

    # Enable graphite optimizations.
    sed -E -i \
        "/prefix/s/(--prefix)/--with-isl \1/" \
        "$2/build"
    sed -E -i \
        "/gcc$/a https://libisl.sourceforge.io/isl-0.23.tar.xz gcc/isl" \
        "$2/sources"
    (
        cd "$2"
        KISS_HOOK='' kiss checksum
    )
    ;;
pigz)
    # Static linking breaks?
    sed -E -i \
        -e "s/-static//" \
        "$2/build"
    ;;
git)
    # Static linking breaks?
    sed -E -i \
        -e "/^make LIBS/s/.*/make/" \
        -e "/LDFLAGS -static/d" \
        "$2/build"
    ;;
curl)
    # Static linking breaks?
    sed -E -i \
        -e "/Makefile.in/d" \
        "$2/build"
    ;;
python)
    # Build with PGO.
    sed -E -i \
        -e "s/(configure)/\1 --with-lto --enable-optimizations/" \
        "$2/build"
    ;;
zstd)
    # Build with PGO & remove static linking flags.
    sed -E -i \
        -e "/programs/d" \
        -e "s#(HAVE_LZ4=0)#\1 -C programs/ zstd-pgo#" \
        "$2/build"
    ;;
esac