configure

        cc_default="gcc"
        add_cflags  -fsanitize=thread -pie -fPIC
        add_ldflags -fsanitize=thread -pie -fPIC
    ;;
    gcc-usan)
        cc_default="gcc"
        add_cflags  -fsanitize=undefined
        add_ldflags -fsanitize=undefined
    ;;
    valgrind-massif)
        target_exec_default=${valgrind:-"valgrind"}
        target_exec_args="--tool=massif --alloc-fn=av_malloc --alloc-fn=av_mallocz --alloc-fn=av_calloc --alloc-fn=av_fast_padded_malloc --alloc-fn=av_fast_malloc --alloc-fn=av_realloc_f --alloc-fn=av_fast_realloc --alloc-fn=av_realloc"
    ;;
    valgrind-memcheck)
        target_exec_default=${valgrind:-"valgrind"}
        target_exec_args="--error-exitcode=1 --malloc-fill=0x2a --track-origins=yes --leak-check=full --gen-suppressions=all --suppressions=$source_path/tests/fate-valgrind.supp"
    ;;
    msvc)
        # Check whether the current MSVC version needs the C99 converter.
        # From MSVC 2013 (compiler major version 18) onwards, it does actually
        # support enough of C99 to build ffmpeg. Default to the new
        # behaviour if the regexp was unable to match anything, since this
        # successfully parses the version number of existing supported
        # versions that require the converter (MSVC 2010 and 2012).
        cl_major_ver=$(cl 2>&1 | sed -n 's/.*Version \([[:digit:]]\{1,\}\)\..*/\1/p')
        if [ -z "$cl_major_ver" ] || [ $cl_major_ver -ge 18 ]; then
            cc_default="cl"
        else
            cc_default="c99wrap cl"
        fi
        ld_default="link"
        nm_default="dumpbin -symbols"
        ar_default="lib"
        target_os_default="win32"
        # Use a relative path for TMPDIR. This makes sure all the
        # ffconf temp files are written with a relative path, avoiding
        # issues with msys/win32 path conversion for MSVC parameters
        # such as -Fo<file> or -out:<file>.
        TMPDIR=.
    ;;
    icl)
        cc_default="icl"
        ld_default="xilink"
        nm_default="dumpbin -symbols"
        ar_default="xilib"
        target_os_default="win32"
        TMPDIR=.
    ;;
    gcov)
        add_cflags  -fprofile-arcs -ftest-coverage
        add_ldflags -fprofile-arcs -ftest-coverage
    ;;
    hardened)
        add_cppflags -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2
        add_cflags   -fno-strict-overflow -fstack-protector-all
        add_ldflags  -Wl,-z,relro -Wl,-z,now
    ;;
    ?*)
        die "Unknown toolchain $toolchain"
    ;;
esac

set_default arch cc cxx doxygen pkg_config ranlib strip sysinclude \
    target_exec target_os yasmexe
enabled cross_compile || host_cc_default=$cc
set_default host_cc

if ! $pkg_config --version >/dev/null 2>&1; then
    warn "$pkg_config not found, library detection may fail."
    pkg_config=false
fi

if test $doxygen != $doxygen_default && \
  ! $doxygen --version >/dev/null 2>&1; then
    warn "Specified doxygen \"$doxygen\" not found, API documentation will fail to build."
fi

exesuf() {
    case $1 in
        mingw32*|win32|win64|cygwin*|*-dos|freedos|opendos|os/2*|symbian) echo .exe ;;
    esac
}

EXESUF=$(exesuf $target_os)
HOSTEXESUF=$(exesuf $host_os)

# set temporary file name
: ${TMPDIR:=$TEMPDIR}
: ${TMPDIR:=$TMP}
: ${TMPDIR:=/tmp}

if [ -n "$tempprefix" ] ; then
    mktemp(){
        echo $tempprefix.${HOSTNAME}.${UID}
    }
elif ! check_cmd mktemp -u XXXXXX; then
    # simple replacement for missing mktemp
    # NOT SAFE FOR GENERAL USE
    mktemp(){
        echo "${2%%XXX*}.${HOSTNAME}.${UID}.$$"
    }
fi

tmpfile(){
    tmp=$(mktemp -u "${TMPDIR}/ffconf.XXXXXXXX")$2 &&
        (set -C; exec > $tmp) 2>/dev/null ||
        die "Unable to create temporary file in $TMPDIR."
    append TMPFILES $tmp
    eval $1=$tmp
}

trap 'rm -f -- $TMPFILES' EXIT

tmpfile TMPASM .asm
tmpfile TMPC   .c
tmpfile TMPCPP .cpp
tmpfile TMPE   $EXESUF
tmpfile TMPH   .h
tmpfile TMPM   .m
tmpfile TMPO   .o
tmpfile TMPS   .S
tmpfile TMPSH  .sh
tmpfile TMPV   .ver

unset -f mktemp

chmod +x $TMPE

# make sure we can execute files in $TMPDIR
cat > $TMPSH 2>> $logfile <<EOF
#! /bin/sh
EOF
chmod +x $TMPSH >> $logfile 2>&1
if ! $TMPSH >> $logfile 2>&1; then
    cat <<EOF
Unable to create and execute files in $TMPDIR.  Set the TMPDIR environment
variable to another directory and make sure that it is not mounted noexec.
EOF
    die "Sanity test failed."
fi

armasm_flags(){
    for flag; do
        case $flag in
            # Filter out MSVC cl.exe options from cflags that shouldn't
            # be passed to gas-preprocessor
            -M[TD]*)                                            ;;
            *)                  echo $flag                      ;;
        esac
   done
}

ccc_flags(){
    for flag; do
        case $flag in
            -std=c99)           echo -c99                       ;;
            -mcpu=*)            echo -arch ${flag#*=}           ;;
            -mieee)             echo -ieee                      ;;
            -O*|-fast)          echo $flag                      ;;
            -fno-math-errno)    echo -assume nomath_errno       ;;
            -g)                 echo -g3                        ;;
            -Wall)              echo -msg_enable level2         ;;
            -Wno-pointer-sign)  echo -msg_disable ptrmismatch1  ;;
            -Wl,*)              echo $flag                      ;;
            -f*|-W*)                                            ;;
            *)                  echo $flag                      ;;
        esac
   done
}

cparser_flags(){
    for flag; do
        case $flag in
            -Wno-switch)             echo -Wno-switch-enum ;;
            -Wno-format-zero-length) ;;
            -Wdisabled-optimization) ;;
            -Wno-pointer-sign)       echo -Wno-other ;;
            *)                       echo $flag ;;
        esac
    done
}

msvc_common_flags(){
    for flag; do
        case $flag in
            # In addition to specifying certain flags under the compiler
            # specific filters, they must be specified here as well or else the
            # generic catch all at the bottom will print the original flag.
            -Wall)                ;;
            -std=c99)             ;;
            # Common flags
            -fomit-frame-pointer) ;;
            -g)                   echo -Z7 ;;
            -fno-math-errno)      ;;
            -fno-common)          ;;
            -fno-signed-zeros)    ;;
            -fPIC)                ;;
            -mthumb)              ;;
            -march=*)             ;;
            -lz)                  echo zlib.lib ;;
            -lavifil32)           echo vfw32.lib ;;
            -lavicap32)           echo vfw32.lib user32.lib ;;
            -l*)                  echo ${flag#-l}.lib ;;
            *)                    echo $flag ;;
        esac
    done
}

msvc_flags(){
    msvc_common_flags "$@"
    for flag; do
        case $flag in
            -Wall)                echo -W4 -wd4244 -wd4127 -wd4018 -wd4389     \
                                       -wd4146 -wd4057 -wd4204 -wd4706 -wd4305 \
                                       -wd4152 -wd4324 -we4013 -wd4100 -wd4214 \
                                       -wd4554 \
                                       -wd4273 -wd4701 ;;
        esac
    done
}

icl_flags(){
    msvc_common_flags "$@"
    for flag; do
        case $flag in
            # Despite what Intel's documentation says -Wall, which is supported
            # on Windows, does enable remarks so disable them here.
            -Wall)                echo $flag -Qdiag-disable:remark ;;
            -std=c99)             echo -Qstd=c99 ;;
            -flto)                echo -ipo ;;
        esac
    done
}

icc_flags(){
    for flag; do
        case $flag in
            -flto)                echo -ipo ;;
            *)                    echo $flag ;;
        esac
    done
}

pgi_flags(){
    for flag; do
        case $flag in
            -flto)                echo -Mipa=fast,libopt,libinline,vestigial ;;
            -fomit-frame-pointer) echo -Mnoframe ;;
            -g)                   echo -gopt ;;
            *)                    echo $flag ;;
        esac
    done
}

suncc_flags(){
    for flag; do
        case $flag in
            -march=*|-mcpu=*)
                case "${flag#*=}" in
                    native)                   echo -xtarget=native       ;;
                    v9|niagara)               echo -xarch=sparc          ;;
                    ultrasparc)               echo -xarch=sparcvis       ;;
                    ultrasparc3|niagara2)     echo -xarch=sparcvis2      ;;
                    i586|pentium)             echo -xchip=pentium        ;;
                    i686|pentiumpro|pentium2) echo -xtarget=pentium_pro  ;;
                    pentium3*|c3-2)           echo -xtarget=pentium3     ;;
                    pentium-m)          echo -xarch=sse2 -xchip=pentium3 ;;
                    pentium4*)          echo -xtarget=pentium4           ;;
                    prescott|nocona)    echo -xarch=sse3 -xchip=pentium4 ;;
                    *-sse3)             echo -xarch=sse3                 ;;
                    core2)              echo -xarch=ssse3 -xchip=core2   ;;
                    bonnell)                   echo -xarch=ssse3         ;;
                    corei7|nehalem)            echo -xtarget=nehalem     ;;
                    westmere)                  echo -xtarget=westmere    ;;
                    silvermont)                echo -xarch=sse4_2        ;;
                    corei7-avx|sandybridge)    echo -xtarget=sandybridge ;;
                    core-avx*|ivybridge|haswell|broadwell)
                                               echo -xarch=avx           ;;
                    amdfam10|barcelona)        echo -xtarget=barcelona   ;;
                    btver1)                    echo -xarch=amdsse4a      ;;
                    btver2|bdver*)             echo -xarch=avx           ;;
                    athlon-4|athlon-[mx]p)     echo -xarch=ssea          ;;
                    k8|opteron|athlon64|athlon-fx)
                                               echo -xarch=sse2a         ;;
                    athlon*)                   echo -xarch=pentium_proa  ;;
                esac
                ;;
            -std=c99)             echo -xc99              ;;
            -fomit-frame-pointer) echo -xregs=frameptr    ;;
            -fPIC)                echo -KPIC -xcode=pic32 ;;
            -W*,*)                echo $flag              ;;
            -f*-*|-W*|-mimpure-text)                      ;;
            -shared)              echo -G                 ;;
            *)                    echo $flag              ;;
        esac
    done
}

tms470_flags(){
    for flag; do
        case $flag in
            -march=*|-mcpu=*)
                case "${flag#*=}" in
                    armv7-a|cortex-a*)      echo -mv=7a8 ;;
                    armv7-r|cortex-r*)      echo -mv=7r4 ;;
                    armv7-m|cortex-m*)      echo -mv=7m3 ;;
                    armv6*|arm11*)          echo -mv=6   ;;
                    armv5*e|arm[79]*e*|arm9[24]6*|arm96*|arm102[26])
                                            echo -mv=5e  ;;
                    armv4*|arm7*|arm9[24]*) echo -mv=4   ;;
                esac
                ;;
            -mfpu=neon)     echo --float_support=vfpv3 --neon ;;
            -mfpu=vfp)      echo --float_support=vfpv2        ;;
            -mfpu=vfpv3)    echo --float_support=vfpv3        ;;
            -mfpu=vfpv3-d16) echo --float_support=vfpv3d16    ;;
            -msoft-float)   echo --float_support=vfplib       ;;
            -O[0-3]|-mf=*)  echo $flag                        ;;
            -g)             echo -g -mn                       ;;
            -pds=*)         echo $flag                        ;;
            -D*|-I*)        echo $flag                        ;;
            --gcc|--abi=*)  echo $flag                        ;;
            -me)            echo $flag                        ;;
        esac
    done
}

probe_cc(){
    pfx=$1
    _cc=$2

    unset _type _ident _cc_c _cc_e _cc_o _flags _cflags
    unset _ld_o _ldflags _ld_lib _ld_path
    unset _depflags _DEPCMD _DEPFLAGS
    _flags_filter=echo

    if $_cc --version 2>&1 | grep -q '^GNU assembler'; then
        true # no-op to avoid reading stdin in following checks
    elif $_cc -v 2>&1 | grep -q '^gcc.*LLVM'; then
        _type=llvm_gcc
        gcc_extra_ver=$(expr "$($_cc --version | head -n1)" : '.*\((.*)\)')
        _ident="llvm-gcc $($_cc -dumpversion) $gcc_extra_ver"
        _depflags='-MMD -MF $(@:.o=.d) -MT $@'
        _cflags_speed='-O3'
        _cflags_size='-Os'
    elif $_cc -v 2>&1 | grep -qi ^gcc; then
        _type=gcc
        gcc_version=$($_cc --version | head -n1)
        gcc_basever=$($_cc -dumpversion)
        gcc_pkg_ver=$(expr "$gcc_version" : '[^ ]* \(([^)]*)\)')
        gcc_ext_ver=$(expr "$gcc_version" : ".*$gcc_pkg_ver $gcc_basever \\(.*\\)")
        _ident=$(cleanws "gcc $gcc_basever $gcc_pkg_ver $gcc_ext_ver")
        if ! $_cc -dumpversion | grep -q '^2\.'; then
            _depflags='-MMD -MF $(@:.o=.d) -MT $@'
        fi
        _cflags_speed='-O3'
        _cflags_size='-Os'
    elif $_cc --version 2>/dev/null | grep -q ^icc; then
        _type=icc
        _ident=$($_cc --version | head -n1)
        _depflags='-MMD'
        _cflags_speed='-O3'
        _cflags_size='-Os'
        _cflags_noopt='-O1'
        _flags_filter=icc_flags
    elif $_cc -v 2>&1 | grep -q xlc; then
        _type=xlc
        _ident=$($_cc -qversion 2>/dev/null | head -n1)
        _cflags_speed='-O5'
        _cflags_size='-O5 -qcompact'
    elif $_cc -V 2>/dev/null | grep -q Compaq; then
        _type=ccc
        _ident=$($_cc -V | head -n1 | cut -d' ' -f1-3)
        _DEPFLAGS='-M'
        _cflags_speed='-fast'
        _cflags_size='-O1'
        _flags_filter=ccc_flags
    elif $_cc --vsn 2>/dev/null | grep -Eq "ARM (C/C\+\+ )?Compiler"; then
        test -d "$sysroot" || die "No valid sysroot specified."
        _type=armcc
        _ident=$($_cc --vsn | grep -i build | head -n1 | sed 's/.*: //')
        armcc_conf="$PWD/armcc.conf"
        $_cc --arm_linux_configure                 \
             --arm_linux_config_file="$armcc_conf" \
             --configure_sysroot="$sysroot"        \
             --configure_cpp_headers="$sysinclude" >>$logfile 2>&1 ||
             die "Error creating armcc configuration file."
        $_cc --vsn | grep -q RVCT && armcc_opt=rvct || armcc_opt=armcc
        _flags="--arm_linux_config_file=$armcc_conf --translate_gcc"
        as_default="${cross_prefix}gcc"
        _depflags='-MMD'
        _cflags_speed='-O3'
        _cflags_size='-Os'
    elif $_cc -version 2>/dev/null | grep -Eq 'TMS470|TI ARM'; then
        _type=tms470
        _ident=$($_cc -version | head -n1 | tr -s ' ')
        _flags='--gcc --abi=eabi -me'
        _cc_e='-ppl -fe=$@'
        _cc_o='-fe=$@'
        _depflags='-ppa -ppd=$(@:.o=.d)'
        _cflags_speed='-O3 -mf=5'
        _cflags_size='-O3 -mf=2'
        _flags_filter=tms470_flags
    elif $_cc -v 2>&1 | grep -q clang; then
        _type=clang
        _ident=$($_cc --version | head -n1)
        _depflags='-MMD -MF $(@:.o=.d) -MT $@'
        _cflags_speed='-O3'
        _cflags_size='-Os'
    elif $_cc -V 2>&1 | grep -q Sun; then
        _type=suncc
        _ident=$($_cc -V 2>&1 | head -n1 | cut -d' ' -f 2-)
        _DEPCMD='$(DEP$(1)) $(DEP$(1)FLAGS) $($(1)DEP_FLAGS) $< | sed -e "1s,^.*: ,$@: ," -e "\$$!s,\$$, \\\," -e "1!s,^.*: , ," > $(@:.o=.d)'
        _DEPFLAGS='-xM1 -xc99'
        _ldflags='-std=c99'
        _cflags_speed='-O5'
        _cflags_size='-O5 -xspace'
        _flags_filter=suncc_flags
    elif $_cc -v 2>&1 | grep -q 'PathScale\|Path64'; then
        _type=pathscale
        _ident=$($_cc -v 2>&1 | head -n1 | tr -d :)
        _depflags='-MMD -MF $(@:.o=.d) -MT $@'
        _cflags_speed='-O2'
        _cflags_size='-Os'
        _flags_filter='filter_out -Wdisabled-optimization'
    elif $_cc -v 2>&1 | grep -q Open64; then
        _type=open64
        _ident=$($_cc -v 2>&1 | head -n1 | tr -d :)
        _depflags='-MMD -MF $(@:.o=.d) -MT $@'
        _cflags_speed='-O2'
        _cflags_size='-Os'
        _flags_filter='filter_out -Wdisabled-optimization|-Wtype-limits|-fno-signed-zeros'
    elif $_cc -V 2>&1 | grep -q Portland; then
        _type=pgi
        _ident="PGI $($_cc -V 2>&1 | awk '/^pgcc/ { print $2; exit }')"
        opt_common='-alias=ansi -Mdse -Mlre -Mpre'
        _cflags_speed="-O3 -Mautoinline -Munroll=c:4 $opt_common"
        _cflags_size="-O2 -Munroll=c:1 $opt_common"
        _cflags_noopt="-O"
        _flags_filter=pgi_flags
    elif $_cc 2>&1 | grep -q 'Microsoft.*ARM.*Assembler'; then
        _type=armasm
        _ident=$($_cc | head -n1)
        # 4509: "This form of conditional instruction is deprecated"
        _flags="-nologo -ignore 4509"
        _flags_filter=armasm_flags
    elif $_cc 2>&1 | grep -q Intel; then
        _type=icl
        _ident=$($cc 2>&1 | head -n1)
        _depflags='-QMMD -QMF$(@:.o=.d) -QMT$@'
        # Not only is O3 broken on 13.x+ but it is slower on all previous
        # versions (tested) as well.
        _cflags_speed="-O2"
        _cflags_size="-O1 -Oi" # -O1 without -Oi miscompiles stuff
        if $_cc 2>&1 | grep -q Linker; then
            _ld_o='-out:$@'
        else
            _ld_o='-Fe$@'
        fi
        _cc_o='-Fo$@'
        _cc_e='-P'
        _flags_filter=icl_flags
        _ld_lib='lib%.a'
        _ld_path='-libpath:'
        # -Qdiag-error to make icl error when seeing certain unknown arguments
        _flags='-nologo -Qdiag-error:4044,10157'
        # -Qvec- -Qsimd- to prevent miscompilation, -GS, fp:precise for consistency
        # with MSVC which enables it by default.
        _cflags='-D_USE_MATH_DEFINES -FIstdlib.h -Dstrtoll=_strtoi64 -Qms0 -Qvec- -Qsimd- -GS -fp:precise'
        if [ $pfx = hostcc ]; then
            append _cflags -Dsnprintf=_snprintf
        fi
    elif $_cc 2>&1 | grep -q Microsoft; then
        _type=msvc
        _ident=$($cc 2>&1 | head -n1)
        _DEPCMD='$(DEP$(1)) $(DEP$(1)FLAGS) $($(1)DEP_FLAGS) $< 2>&1 | awk '\''/including/ { sub(/^.*file: */, ""); gsub(/\\/, "/"); if (!match($$0, / /)) print "$@:", $$0 }'\'' > $(@:.o=.d)'
        _DEPFLAGS='$(CPPFLAGS) $(CFLAGS) -showIncludes -Zs'
        _cflags_speed="-O2"
        _cflags_size="-O1"
        if $_cc 2>&1 | grep -q Linker; then
            _ld_o='-out:$@'
        else
            _ld_o='-Fe$@'
        fi
        _cc_o='-Fo$@'
        _cc_e='-P -Fi$@'
        _flags_filter=msvc_flags
        _ld_lib='lib%.a'
        _ld_path='-libpath:'
        _flags='-nologo'
        _cflags='-D_USE_MATH_DEFINES -D_CRT_SECURE_NO_WARNINGS -Dinline=__inline -FIstdlib.h -Dstrtoll=_strtoi64'
        if [ $pfx = hostcc ]; then
            append _cflags -Dsnprintf=_snprintf
        fi
        disable stripping
    elif $_cc --version 2>/dev/null | grep -q ^cparser; then
        _type=cparser
        _ident=$($_cc --version | head -n1)
        _depflags='-MMD'
        _cflags_speed='-O4'
        _cflags_size='-O2'
        _flags_filter=cparser_flags
    fi

    eval ${pfx}_type=\$_type
    eval ${pfx}_ident=\$_ident
}

set_ccvars(){
    eval ${1}_C=\${_cc_c-\${${1}_C}}
    eval ${1}_E=\${_cc_e-\${${1}_E}}
    eval ${1}_O=\${_cc_o-\${${1}_O}}

    if [ -n "$_depflags" ]; then
        eval ${1}_DEPFLAGS=\$_depflags
    else
        eval ${1}DEP=\${_DEPCMD:-\$DEPCMD}
        eval ${1}DEP_FLAGS=\${_DEPFLAGS:-\$DEPFLAGS}
        eval DEP${1}FLAGS=\$_flags
    fi
}

probe_cc cc "$cc"
cflags_filter=$_flags_filter
cflags_speed=$_cflags_speed
cflags_size=$_cflags_size
cflags_noopt=$_cflags_noopt
add_cflags $_flags $_cflags
cc_ldflags=$_ldflags
set_ccvars CC

probe_cc hostcc "$host_cc"
host_cflags_filter=$_flags_filter
add_host_cflags  $_flags $_cflags
set_ccvars HOSTCC

test -n "$cc_type" && enable $cc_type ||
    warn "Unknown C compiler $cc, unable to select optimal CFLAGS"

: ${as_default:=$cc}
: ${dep_cc_default:=$cc}
: ${ld_default:=$cc}
: ${host_ld_default:=$host_cc}
set_default ar as dep_cc ld host_ld windres

probe_cc as "$as"
asflags_filter=$_flags_filter
add_asflags $_flags $_cflags
set_ccvars AS

probe_cc ld "$ld"
ldflags_filter=$_flags_filter
add_ldflags $_flags $_ldflags
test "$cc_type" != "$ld_type" && add_ldflags $cc_ldflags
LD_O=${_ld_o-$LD_O}
LD_LIB=${_ld_lib-$LD_LIB}
LD_PATH=${_ld_path-$LD_PATH}

probe_cc hostld "$host_ld"
host_ldflags_filter=$_flags_filter
add_host_ldflags $_flags $_ldflags
HOSTLD_O=${_ld_o-$HOSTLD_O}

if [ -z "$CC_DEPFLAGS" ] && [ "$dep_cc" != "$cc" ]; then
    probe_cc depcc "$dep_cc"
    CCDEP=${_DEPCMD:-$DEPCMD}
    CCDEP_FLAGS=${_DEPFLAGS:=$DEPFLAGS}
    DEPCCFLAGS=$_flags
fi

if $ar 2>&1 | grep -q Microsoft; then
    arflags="-nologo"
    ar_o='-out:$@'
elif $ar 2>&1 | grep -q 'Texas Instruments'; then
    arflags="rq"
    ar_o='$@'
elif $ar 2>&1 | grep -q 'Usage: ar.*-X.*any'; then
    arflags='-Xany -r -c'
    ar_o='$@'
else
    arflags="rc"
    ar_o='$@'
fi

add_cflags $extra_cflags
add_cxxflags $extra_cxxflags
add_asflags $extra_cflags

if test -n "$sysroot"; then
    case "$cc_type" in
        gcc|llvm_gcc|clang)
            add_cppflags --sysroot="$sysroot"
            add_ldflags --sysroot="$sysroot"
# On Darwin --sysroot may be ignored, -isysroot always affects headers and linking
            add_cppflags -isysroot "$sysroot"
            add_ldflags -isysroot "$sysroot"
        ;;
        tms470)
            add_cppflags -I"$sysinclude"
            add_ldflags  --sysroot="$sysroot"
        ;;
    esac
fi

if test "$cpu" = host; then
    enabled cross_compile &&
        die "--cpu=host makes no sense when cross-compiling."

    case "$cc_type" in
        gcc|llvm_gcc)
            check_native(){
                $cc $1=native -v -c -o $TMPO $TMPC >$TMPE 2>&1 || return
                sed -n "/cc1.*$1=/{
                            s/.*$1=\\([^ ]*\\).*/\\1/
                            p
                            q
                        }" $TMPE
            }
            cpu=$(check_native -march || check_native -mcpu)
        ;;
    esac

    test "${cpu:-host}" = host &&
        die "--cpu=host not supported with compiler $cc"
fi

# Deal with common $arch aliases
case "$arch" in
    aarch64|arm64)
        arch="aarch64"
    ;;
    arm*|iPad*|iPhone*)
        arch="arm"
    ;;
    mips*|IP*)
        arch="mips"
    ;;
    parisc*|hppa*)
        arch="parisc"
    ;;
    "Power Macintosh"|ppc*|powerpc*)
        arch="ppc"
    ;;
    s390|s390x)
        arch="s390"
    ;;
    sh4|sh)
        arch="sh4"
    ;;
    sun4u|sparc*)
        arch="sparc"
    ;;
    tilegx|tile-gx)
        arch="tilegx"
    ;;
    i[3-6]86*|i86pc|BePC|x86pc|x86_64|x86_32|amd64)
        arch="x86"
    ;;
esac

is_in $arch $ARCH_LIST || warn "unknown architecture $arch"
enable $arch

# Add processor-specific flags
if enabled aarch64; then

    case $cpu in
        armv*)
            cpuflags="-march=$cpu"
        ;;
        *)
            cpuflags="-mcpu=$cpu"
        ;;
    esac

elif enabled alpha; then

    cpuflags="-mcpu=$cpu"

elif enabled arm; then

    check_arm_arch() {
        check_cpp_condition stddef.h \
            "defined __ARM_ARCH_${1}__ || defined __TARGET_ARCH_${2:-$1}" \
            $cpuflags
    }

    probe_arm_arch() {
        if   check_arm_arch 4;        then echo armv4;
        elif check_arm_arch 4T;       then echo armv4t;
        elif check_arm_arch 5;        then echo armv5;
        elif check_arm_arch 5E;       then echo armv5e;
        elif check_arm_arch 5T;       then echo armv5t;
        elif check_arm_arch 5TE;      then echo armv5te;
        elif check_arm_arch 5TEJ;     then echo armv5te;
        elif check_arm_arch 6;        then echo armv6;
        elif check_arm_arch 6J;       then echo armv6j;
        elif check_arm_arch 6K;       then echo armv6k;
        elif check_arm_arch 6Z;       then echo armv6z;
        elif check_arm_arch 6ZK;      then echo armv6zk;
        elif check_arm_arch 6T2;      then echo armv6t2;
        elif check_arm_arch 7;        then echo armv7;
        elif check_arm_arch 7A  7_A;  then echo armv7-a;
        elif check_arm_arch 7R  7_R;  then echo armv7-r;
        elif check_arm_arch 7M  7_M;  then echo armv7-m;
        elif check_arm_arch 7EM 7E_M; then echo armv7-m;
        elif check_arm_arch 8A  8_A;  then echo armv8-a;
        fi
    }

    [ "$cpu" = generic ] && cpu=$(probe_arm_arch)

    case $cpu in
        armv*)
            cpuflags="-march=$cpu"
            subarch=$(echo $cpu | sed 's/[^a-z0-9]//g')
        ;;
        *)
            cpuflags="-mcpu=$cpu"
            case $cpu in
                cortex-a*)                               subarch=armv7a  ;;
                cortex-r*)                               subarch=armv7r  ;;
                cortex-m*)                 enable thumb; subarch=armv7m  ;;
                arm11*)                                  subarch=armv6   ;;
                arm[79]*e*|arm9[24]6*|arm96*|arm102[26]) subarch=armv5te ;;
                armv4*|arm7*|arm9[24]*)                  subarch=armv4   ;;
                *)                             subarch=$(probe_arm_arch) ;;
            esac
        ;;
    esac

    case "$subarch" in
        armv5t*)    enable fast_clz                ;;
        armv[6-8]*)
            enable fast_clz
            disabled fast_unaligned || enable fast_unaligned
            ;;
    esac

elif enabled avr32; then

    case $cpu in
        ap7[02]0[0-2])
            subarch="avr32_ap"
            cpuflags="-mpart=$cpu"
        ;;
        ap)
            subarch="avr32_ap"
            cpuflags="-march=$cpu"
        ;;
        uc3[ab]*)
            subarch="avr32_uc"
            cpuflags="-mcpu=$cpu"
        ;;
        uc)
            subarch="avr32_uc"
            cpuflags="-march=$cpu"
        ;;
    esac

elif enabled bfin; then

    cpuflags="-mcpu=$cpu"

elif enabled mips; then

    cpuflags="-march=$cpu"

    case $cpu in
        24kc)
            disable mipsfpu
            disable mipsdspr1
            disable mipsdspr2
        ;;
        24kf*)
            disable mipsdspr1
            disable mipsdspr2
        ;;
        24kec|34kc|1004kc)
            disable mipsfpu
            disable mipsdspr2
        ;;
        24kef*|34kf*|1004kf*)
            disable mipsdspr2
        ;;
        74kc)
            disable mipsfpu
        ;;
    esac

elif enabled ppc; then

    disable ldbrx
    disable vsx

    case $(tolower $cpu) in
        601|ppc601|powerpc601)
            cpuflags="-mcpu=601"
            disable altivec
        ;;
        603*|ppc603*|powerpc603*)
            cpuflags="-mcpu=603"
            disable altivec
        ;;
        604*|ppc604*|powerpc604*)
            cpuflags="-mcpu=604"
            disable altivec
        ;;
        g3|75*|ppc75*|powerpc75*)
            cpuflags="-mcpu=750"
            disable altivec
        ;;
        g4|745*|ppc745*|powerpc745*)
            cpuflags="-mcpu=7450"
        ;;
        74*|ppc74*|powerpc74*)
            cpuflags="-mcpu=7400"
        ;;
        g5|970|ppc970|powerpc970)
            cpuflags="-mcpu=970"
        ;;
        power[3-8]*)
            cpuflags="-mcpu=$cpu"
        ;;
        cell)
            cpuflags="-mcpu=cell"
            enable ldbrx
        ;;
        e500mc)
            cpuflags="-mcpu=e500mc"
            disable altivec
        ;;
        e500v2)
            cpuflags="-mcpu=8548 -mhard-float -mfloat-gprs=double"
            disable altivec
            disable dcbzl
        ;;
        e500)
            cpuflags="-mcpu=8540 -mhard-float"
            disable altivec
            disable dcbzl
        ;;
    esac

elif enabled sparc; then

    case $cpu in
        cypress|f93[04]|tsc701|sparcl*|supersparc|hypersparc|niagara|v[789])
            cpuflags="-mcpu=$cpu"
        ;;
        ultrasparc*|niagara[234])
            cpuflags="-mcpu=$cpu"
        ;;
    esac

elif enabled x86; then

    case $cpu in
        i[345]86|pentium)
            cpuflags="-march=$cpu"
            disable i686
            disable mmx
        ;;
        # targets that do NOT support nopl and conditional mov (cmov)
        pentium-mmx|k6|k6-[23]|winchip-c6|winchip2|c3)
            cpuflags="-march=$cpu"
            disable i686
        ;;
        # targets that do support nopl and conditional mov (cmov)
        i686|pentiumpro|pentium[23]|pentium-m|athlon|athlon-tbird|athlon-4|athlon-[mx]p|athlon64*|k8*|opteron*|athlon-fx\
        |core*|atom|bonnell|nehalem|westmere|silvermont|sandybridge|ivybridge|haswell|broadwell|amdfam10|barcelona|b[dt]ver*)
            cpuflags="-march=$cpu"
            enable i686
            enable fast_cmov
        ;;
        # targets that do support conditional mov but on which it's slow
        pentium4|pentium4m|prescott|nocona)
            cpuflags="-march=$cpu"
            enable i686
            disable fast_cmov
        ;;
    esac

fi

if [ "$cpu" != generic ]; then
    add_cflags  $cpuflags
    add_asflags $cpuflags
fi

# compiler sanity check
check_exec <<EOF
int main(void){ return 0; }
EOF
if test "$?" != 0; then
    echo "$cc is unable to create an executable file."
    if test -z "$cross_prefix" && ! enabled cross_compile ; then
        echo "If $cc is a cross-compiler, use the --enable-cross-compile option."
        echo "Only do this if you know what cross compiling means."
    fi
    die "C compiler test failed."
fi

add_cppflags -D_ISOC99_SOURCE
add_cxxflags -D__STDC_CONSTANT_MACROS
check_cflags -std=c99
check_cc -D_FILE_OFFSET_BITS=64 <<EOF && add_cppflags -D_FILE_OFFSET_BITS=64
#include <stdlib.h>
EOF
check_cc -D_LARGEFILE_SOURCE <<EOF && add_cppflags -D_LARGEFILE_SOURCE
#include <stdlib.h>
EOF

add_host_cppflags -D_ISOC99_SOURCE
check_host_cflags -std=c99
check_host_cflags -Wall
check_host_cflags -O3

check_64bit(){
    arch32=$1
    arch64=$2
    expr=$3
    check_code cc "" "int test[2*($expr) - 1]" &&
        subarch=$arch64 || subarch=$arch32
}

case "$arch" in
    aarch64|alpha|ia64)
        spic=$shared
    ;;
    mips)
        check_64bit mips mips64 '_MIPS_SIM > 1'
        spic=$shared
    ;;
    parisc)
        check_64bit parisc parisc64 'sizeof(void *) > 4'
        spic=$shared
    ;;
    ppc)
        check_64bit ppc ppc64 'sizeof(void *) > 4'
        spic=$shared
    ;;
    s390)
        check_64bit s390 s390x 'sizeof(void *) > 4'
        spic=$shared
    ;;
    sparc)
        check_64bit sparc sparc64 'sizeof(void *) > 4'
        spic=$shared
    ;;
    x86)
        check_64bit x86_32 x86_64 'sizeof(void *) > 4'
        # Treat x32 as x64 for now. Note it also needs spic=$shared
        test "$subarch" = "x86_32" && check_cpp_condition stddef.h 'defined(__x86_64__)' &&
            subarch=x86_64
        if test "$subarch" = "x86_64"; then
            spic=$shared
        fi
    ;;
    ppc)
        check_cc <<EOF && subarch="ppc64"
        int test[(int)sizeof(char*) - 7];
EOF
    ;;
esac

enable $subarch
enabled spic && enable_weak pic

# OS specific
case $target_os in
    aix)
        SHFLAGS=-shared
        add_cppflags '-I\$(SRC_PATH)/compat/aix'
        enabled shared && add_ldflags -Wl,-brtl
        ;;
    android)
        disable symver
        SLIB_INSTALL_NAME='$(SLIBNAME)'
        SLIB_INSTALL_LINKS=
        # soname not set on purpose
        SHFLAGS=-shared
        ;;
    haiku)
        prefix_default="/boot/common"
        network_extralibs="-lnetwork"
        host_libs=
        ;;
    sunos)
        SHFLAGS='-shared -Wl,-h,$$(@F)'
        enabled x86 && SHFLAGS="-mimpure-text $SHFLAGS"
        network_extralibs="-lsocket -lnsl"
        # When using suncc to build, the Solaris linker will mark
        # an executable with each instruction set encountered by
        # the Solaris assembler.  As our libraries contain their own
        # guards for processor-specific code, instead suppress
        # generation of the HWCAPS ELF section on Solaris x86 only.
        enabled_all suncc x86 &&
            echo "hwcap_1 = OVERRIDE;" > mapfile &&
            add_ldflags -Wl,-M,mapfile