configure

#!/bin/sh

usage () {
cat <<EOF
Usage: $0 [OPTION]... [VAR=VALUE]... [TARGET]

To assign environment variables (e.g., CC, CFLAGS...), specify them as
VAR=VALUE.  See below for descriptions of some of the useful variables.

Defaults for the options are specified in brackets.

Configuration:
  --srcdir=DIR            source directory [detected]

Installation directories:
  --prefix=PREFIX         main installation prefix [/usr/local/musl]
  --exec-prefix=EPREFIX   installation prefix for executable files [PREFIX]

Fine tuning of the installation directories:
  --bindir=DIR            user executables [EPREFIX/bin]
  --libdir=DIR            library files for the linker [PREFIX/lib]
  --includedir=DIR        include files for the C compiler [PREFIX/include]
  --syslibdir=DIR         location for the dynamic linker [/lib]

System types:
  --target=TARGET         configure to run on target TARGET [detected]
  --host=HOST             same as --target

Optional features:
  --enable-optimize=...   optimize listed components for speed over size [auto]
  --enable-debug          build with debugging information [disabled]
  --enable-warnings       build with recommended warnings flags [disabled]
  --enable-visibility     use global visibility options to optimize PIC [auto]
  --enable-wrapper=...    build given musl toolchain wrapper [auto]
  --disable-shared        inhibit building shared library [enabled]
  --disable-static        inhibit building static library [enabled]

Some influential environment variables:
  CC                      C compiler command [detected]
  CFLAGS                  C compiler flags [-Os -pipe ...]
  CROSS_COMPILE           prefix for cross compiler and tools [none]
  LIBCC                   compiler runtime library [detected]

Use these variables to override the choices made by configure.

EOF
exit 0
}

# Helper functions

quote () {
tr '\n' ' ' <<EOF | grep '^[-[:alnum:]_=,./:]* $' >/dev/null 2>&1 && { echo "$1" ; return 0 ; }
$1
EOF
printf %s\\n "$1" | sed -e "s/'/'\\\\''/g" -e "1s/^/'/" -e "\$s/\$/'/" -e "s#^'\([-[:alnum:]_,./:]*\)=\(.*\)\$#\1='\2#"
}
echo () { printf "%s\n" "$*" ; }
fail () { echo "$*" ; exit 1 ; }
fnmatch () { eval "case \"\$2\" in $1) return 0 ;; *) return 1 ;; esac" ; }
cmdexists () { type "$1" >/dev/null 2>&1 ; }
trycc () { test -z "$CC" && cmdexists "$1" && CC=$1 ; }

stripdir () {
while eval "fnmatch '*/' \"\${$1}\"" ; do eval "$1=\${$1%/}" ; done
}

trycppif () {
printf "checking preprocessor condition %s... " "$1"
echo "typedef int x;" > "$tmpc"
echo "#if $1" >> "$tmpc"
echo "#error yes" >> "$tmpc"
echo "#endif" >> "$tmpc"
if $CC $2 -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
printf "false\n"
return 1
else
printf "true\n"
return 0
fi
}

tryflag () {
printf "checking whether compiler accepts %s... " "$2"
echo "typedef int x;" > "$tmpc"
if $CC $CFLAGS_TRY $2 -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
printf "yes\n"
eval "$1=\"\${$1} \$2\""
eval "$1=\${$1# }"
return 0
else
printf "no\n"
return 1
fi
}

tryldflag () {
printf "checking whether linker accepts %s... " "$2"
echo "typedef int x;" > "$tmpc"
if $CC $LDFLAGS_TRY -nostdlib -shared "$2" -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
printf "yes\n"
eval "$1=\"\${$1} \$2\""
eval "$1=\${$1# }"
return 0
else
printf "no\n"
return 1
fi
}



# Beginning of actual script

CFLAGS_C99FSE=
CFLAGS_AUTO=
CFLAGS_MEMOPS=
CFLAGS_NOSSP=
CFLAGS_TRY=
LDFLAGS_AUTO=
LDFLAGS_TRY=
OPTIMIZE_GLOBS=
srcdir=
prefix=/usr/local/musl
exec_prefix='$(prefix)'
bindir='$(exec_prefix)/bin'
libdir='$(prefix)/lib'
includedir='$(prefix)/include'
syslibdir='/lib'
tools=
tool_libs=
target=
optimize=auto
debug=no
warnings=no
visibility=auto
shared=auto
static=yes
wrapper=auto
gcc_wrapper=no
clang_wrapper=no

for arg ; do
case "$arg" in
--help|-h) usage ;;
--srcdir=*) srcdir=${arg#*=} ;;
--prefix=*) prefix=${arg#*=} ;;
--exec-prefix=*) exec_prefix=${arg#*=} ;;
--bindir=*) bindir=${arg#*=} ;;
--libdir=*) libdir=${arg#*=} ;;
--includedir=*) includedir=${arg#*=} ;;
--syslibdir=*) syslibdir=${arg#*=} ;;
--enable-shared|--enable-shared=yes) shared=yes ;;
--disable-shared|--enable-shared=no) shared=no ;;
--enable-static|--enable-static=yes) static=yes ;;
--disable-static|--enable-static=no) static=no ;;
--enable-optimize) optimize=yes ;;
--enable-optimize=*) optimize=${arg#*=} ;;
--disable-optimize) optimize=no ;;
--enable-debug|--enable-debug=yes) debug=yes ;;
--disable-debug|--enable-debug=no) debug=no ;;
--enable-warnings|--enable-warnings=yes) warnings=yes ;;
--disable-warnings|--enable-warnings=no) warnings=no ;;
--enable-visibility|--enable-visibility=yes) visibility=yes ;;
--disable-visibility|--enable-visibility=no) visibility=no ;;
--enable-wrapper|--enable-wrapper=yes) wrapper=detect ;;
--enable-wrapper=all) wrapper=yes ; gcc_wrapper=yes ; clang_wrapper=yes ;;
--enable-wrapper=gcc) wrapper=yes ; gcc_wrapper=yes ;;
--enable-wrapper=clang) wrapper=yes ; clang_wrapper=yes ;;
--disable-wrapper|--enable-wrapper=no) wrapper=no ;;
--enable-gcc-wrapper|--enable-gcc-wrapper=yes) wrapper=yes ; gcc_wrapper=yes ;;
--disable-gcc-wrapper|--enable-gcc-wrapper=no) wrapper=no ;;
--enable-*|--disable-*|--with-*|--without-*|--*dir=*|--build=*) ;;
--host=*|--target=*) target=${arg#*=} ;;
-* ) echo "$0: unknown option $arg" ;;
CC=*) CC=${arg#*=} ;;
CFLAGS=*) CFLAGS=${arg#*=} ;;
CPPFLAGS=*) CPPFLAGS=${arg#*=} ;;
LDFLAGS=*) LDFLAGS=${arg#*=} ;;
CROSS_COMPILE=*) CROSS_COMPILE=${arg#*=} ;;
LIBCC=*) LIBCC=${arg#*=} ;;
*=*) ;;
*) target=$arg ;;
esac
done

for i in srcdir prefix exec_prefix bindir libdir includedir syslibdir ; do
stripdir $i
done

#
# Get the source dir for out-of-tree builds
#
if test -z "$srcdir" ; then
srcdir="${0%/configure}"
stripdir srcdir
fi
abs_builddir="$(pwd)" || fail "$0: cannot determine working directory"
abs_srcdir="$(cd $srcdir && pwd)" || fail "$0: invalid source directory $srcdir"
test "$abs_srcdir" = "$abs_builddir" && srcdir=.
test "$srcdir" != "." -a -f Makefile -a ! -h Makefile && fail "$0: Makefile already exists in the working directory"

#
# Get a temp filename we can use
#
i=0
set -C
while : ; do i=$(($i+1))
tmpc="./conf$$-$PPID-$i.c"
2>|/dev/null > "$tmpc" && break
test "$i" -gt 50 && fail "$0: cannot create temporary file $tmpc"
done
set +C
trap 'rm "$tmpc"' EXIT INT QUIT TERM HUP

#
# Find a C compiler to use
#
printf "checking for C compiler... "
trycc ${CROSS_COMPILE}gcc
trycc ${CROSS_COMPILE}c99
trycc ${CROSS_COMPILE}cc
printf "%s\n" "$CC"
test -n "$CC" || { echo "$0: cannot find a C compiler" ; exit 1 ; }

printf "checking whether C compiler works... "
echo "typedef int x;" > "$tmpc"
if output=$($CC $CPPFLAGS $CFLAGS -c -o /dev/null "$tmpc" 2>&1) ; then
printf "yes\n"
else
printf "no; compiler output follows:\n%s\n" "$output"
exit 1
fi

#
# Figure out options to force errors on unknown flags.
#
tryflag   CFLAGS_TRY  -Werror=unknown-warning-option
tryflag   CFLAGS_TRY  -Werror=unused-command-line-argument
tryldflag LDFLAGS_TRY -Werror=unknown-warning-option
tryldflag LDFLAGS_TRY -Werror=unused-command-line-argument

#
# Need to know if the compiler is gcc or clang to decide which toolchain
# wrappers to build.
#
printf "checking for C compiler family... "
cc_ver="$(LC_ALL=C $CC -v 2>&1)"
cc_family=unknown
if fnmatch '*gcc\ version*' "$cc_ver" ; then
cc_family=gcc
elif fnmatch '*clang\ version*' "$cc_ver" ; then
cc_family=clang
fi
echo "$cc_family"

#
# Figure out toolchain wrapper to build
#
if test "$wrapper" = auto -o "$wrapper" = detect ; then
echo "#include <stdlib.h>" > "$tmpc"
echo "#if ! __GLIBC__" >> "$tmpc"
echo "#error no" >> "$tmpc"
echo "#endif" >> "$tmpc"
printf "checking for toolchain wrapper to build... "
if test "$wrapper" = auto && ! $CC -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
echo "none"
elif test "$cc_family" = gcc ; then
gcc_wrapper=yes
echo "gcc"
elif test "$cc_family" = clang ; then
clang_wrapper=yes
echo "clang"
else
echo "none"
if test "$wrapper" = detect ; then
fail "$0: could not find an appropriate toolchain wrapper"
fi
fi
fi

if test "$gcc_wrapper" = yes ; then
tools="$tools obj/musl-gcc"
tool_libs="$tool_libs lib/musl-gcc.specs"
fi
if test "$clang_wrapper" = yes ; then
tools="$tools obj/musl-clang obj/ld.musl-clang"
fi

#
# Find the target architecture
#
printf "checking target system type... "
test -n "$target" || target=$($CC -dumpmachine 2>/dev/null) || target=unknown
printf "%s\n" "$target"

#
# Convert to just ARCH
#
case "$target" in
# Catch these early to simplify matching for 32-bit archs
powerpc64*) fail "$0: unsupported target \"$target\"" ;;
arm*) ARCH=arm ;;
aarch64*) ARCH=aarch64 ;;
i?86-nt32*) ARCH=nt32 ;;
i?86*) ARCH=i386 ;;
x86_64-x32*|x32*|x86_64*x32) ARCH=x32 ;;
x86_64-nt64*) ARCH=nt64 ;;
x86_64*) ARCH=x86_64 ;;
mips64*) ARCH=mips64 ;;
mips*) ARCH=mips ;;
microblaze*) ARCH=microblaze ;;
or1k*) ARCH=or1k ;;
powerpc*) ARCH=powerpc ;;
sh[1-9bel-]*|sh|superh*) ARCH=sh ;;
unknown) fail "$0: unable to detect target arch; try $0 --target=..." ;;
*) fail "$0: unknown or unsupported target \"$target\"" ;;
esac

#
# Try to get a conforming C99 freestanding environment
#
tryflag CFLAGS_C99FSE -std=c99
tryflag CFLAGS_C99FSE -nostdinc
tryflag CFLAGS_C99FSE -ffreestanding \
|| tryflag CFLAGS_C99FSE -fno-builtin
tryflag CFLAGS_C99FSE -fexcess-precision=standard \
|| { test "$ARCH" = i386 && tryflag CFLAGS_C99FSE -ffloat-store ; }
tryflag CFLAGS_C99FSE -frounding-math

#
# We may use the may_alias attribute if __GNUC__ is defined, so
# if the compiler defines __GNUC__ but does not provide it,
# it must be defined away as part of the CFLAGS.
#
printf "checking whether compiler needs attribute((may_alias)) suppression... "
cat > "$tmpc" <<EOF
typedef int
#ifdef __GNUC__
__attribute__((__may_alias__))
#endif
x;
EOF
if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS \
  -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
printf "no\n"
else
printf "yes\n"
CFLAGS_C99FSE="$CFLAGS_C99FSE -D__may_alias__="
fi

#
# The GNU toolchain defaults to assuming unmarked files need an
# executable stack, potentially exposing vulnerabilities in programs
# linked with such object files. Fix this.
#
tryflag CFLAGS_C99FSE -Wa,--noexecstack

#
# Check for options to disable stack protector, which needs to be
# disabled for a few early-bootstrap translation units. If not found,
# this is not an error; we assume the toolchain does not do ssp.
#
tryflag CFLAGS_NOSSP -fno-stack-protector

#
# Check for options that may be needed to prevent the compiler from
# generating self-referential versions of memcpy,, memmove, memcmp,
# and memset. Really, we should add a check to determine if this
# option is sufficient, and if not, add a macro to cripple these
# functions with volatile...
#
tryflag CFLAGS_MEMOPS -fno-tree-loop-distribute-patterns

#
# Enable debugging if requessted.
#
test "$debug" = yes && CFLAGS_AUTO=-g

#
# Preprocess asm files to add extra debugging information if debug is
# enabled, our assembler supports the needed directives, and the
# preprocessing script has been written for our architecture.
#
printf "checking whether we should preprocess assembly to add debugging information... "
if fnmatch '-g*|*\ -g*' "$CFLAGS_AUTO $CFLAGS" &&
   test -f "tools/add-cfi.$ARCH.awk" &&
   printf ".file 1 \"srcfile.s\"\n.line 1\n.cfi_startproc\n.cfi_endproc" | $CC -g -x assembler -c -o /dev/null 2>/dev/null -
then
  ADD_CFI=yes
else
  ADD_CFI=no
fi
printf "%s\n" "$ADD_CFI"

#
# Possibly add a -O option to CFLAGS and select modules to optimize with
# -O3 based on the status of --enable-optimize and provided CFLAGS.
#
printf "checking for optimization settings... "
case "x$optimize" in
xauto)
if fnmatch '-O*|*\ -O*' "$CFLAGS_AUTO $CFLAGS" ; then
printf "using provided CFLAGS\n" ;optimize=no
else
printf "using defaults\n" ; optimize=yes
fi
;;
xsize|xnone) printf "minimize size\n" ; optimize=size ;;
xno|x) printf "disabled\n" ; optimize=no ;;
*) printf "custom\n" ;;
esac

test "$optimize" = no || tryflag CFLAGS_AUTO -Os || tryflag CFLAGS_AUTO -O2
test "$optimize" = yes && optimize="internal,malloc,string"

if fnmatch 'no|size' "$optimize" ; then :
else
printf "components to be optimized for speed:"
while test "$optimize" ; do
case "$optimize" in
*,*) this=${optimize%%,*} optimize=${optimize#*,} ;;
*) this=$optimize optimize=
esac
printf " $this"
case "$this" in
*/*.c) ;;
*/*) this=$this*.c ;;
*) this=$this/*.c ;;
esac
OPTIMIZE_GLOBS="$OPTIMIZE_GLOBS $this"
done
OPTIMIZE_GLOBS=${OPTIMIZE_GLOBS# }
printf "\n"
fi

# Always try -pipe
tryflag CFLAGS_AUTO -pipe

#
# If debugging is disabled, omit frame pointer. Modern GCC does this
# anyway on most archs even when debugging is enabled since the frame
# pointer is no longer needed for debugging.
#
if fnmatch '-g*|*\ -g*' "$CFLAGS_AUTO $CFLAGS" ; then :
else 
tryflag CFLAGS_AUTO -fomit-frame-pointer
fi

#
# Modern GCC wants to put DWARF tables (used for debugging and
# unwinding) in the loaded part of the program where they are
# unstrippable. These options force them back to debug sections (and
# cause them not to get generated at all if debugging is off).
#
tryflag CFLAGS_AUTO -fno-unwind-tables
tryflag CFLAGS_AUTO -fno-asynchronous-unwind-tables

#
# Attempt to put each function and each data object in its own
# section. This both allows additional size optimizations at link
# time and works around a dangerous class of compiler/assembler bugs
# whereby relative address expressions are constant-folded by the
# assembler even when one or more of the symbols involved is
# replaceable. See gas pr 18561 and gcc pr 66609, 68178, etc.
#
tryflag CFLAGS_AUTO -ffunction-sections
tryflag CFLAGS_AUTO -fdata-sections

#
# On x86, make sure we don't have incompatible instruction set
# extensions enabled by default. This is bad for making static binaries.
# We cheat and use i486 rather than i386 because i386 really does not
# work anyway (issues with atomic ops).
# Some build environments pass -march and -mtune options via CC, so
# check both CC and CFLAGS.
#
if test "$ARCH" = "i386" ; then
fnmatch '-march=*|*\ -march=*' "$CC $CFLAGS" || tryldflag CFLAGS_AUTO -march=i486
fnmatch '-mtune=*|*\ -mtune=*' "$CC $CFLAGS" || tryldflag CFLAGS_AUTO -mtune=generic
fi

#
# Even with -std=c99, gcc accepts some constructs which are constraint
# violations. We want to treat these as errors regardless of whether
# other purely stylistic warnings are enabled -- especially implicit
# function declarations, which are a dangerous programming error.
#
tryflag CFLAGS_AUTO -Werror=implicit-function-declaration
tryflag CFLAGS_AUTO -Werror=implicit-int
tryflag CFLAGS_AUTO -Werror=pointer-sign
tryflag CFLAGS_AUTO -Werror=pointer-arith

if test "x$warnings" = xyes ; then
tryflag CFLAGS_AUTO -Wall
tryflag CFLAGS_AUTO -Wno-parentheses
tryflag CFLAGS_AUTO -Wno-uninitialized
tryflag CFLAGS_AUTO -Wno-missing-braces
tryflag CFLAGS_AUTO -Wno-unused-value
tryflag CFLAGS_AUTO -Wno-unused-but-set-variable
tryflag CFLAGS_AUTO -Wno-unknown-pragmas
tryflag CFLAGS_AUTO -Wno-pointer-to-int-cast
fi

if test "x$visibility" = xauto ; then
# This test checks toolchain support for several things:
# - the -include option
# - the attributes/pragmas used in vis.h
# - linking code that takes the address of protected symbols
# - gcc 3.x bug that wrongly claims declarations mismatch
printf "checking whether global visibility preinclude works... "
cat > "$tmpc" <<EOF
__attribute__((__visibility__("default")))
extern struct a *const x;
typedef struct a b;
extern b *const x;
b *const x;
int (*fp)(void);
int foo(void) { }
int bar(void) { fp = foo; return foo(); }
EOF
if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS \
  -DSHARED -fPIC -I$srcdir/src/internal -include vis.h \
  -nostdlib -shared -Wl,-Bsymbolic-functions \
  -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
visibility=yes
else
visibility=no
fi
printf "%s\n" "$visibility"
fi

if test "x$visibility" = xyes ; then
CFLAGS_AUTO="$CFLAGS_AUTO -include vis.h"
CFLAGS_AUTO="${CFLAGS_AUTO# }"
fi

# Determine if the compiler produces position-independent code (PIC)
# by default. If so, we don't need to compile separate object files
# for libc.a and libc.so.
if trycppif __PIC__ "$CFLAGS_C99FSE $CPPFLAGS $CFLAGS" ; then
pic_default=yes
else
pic_default=no
fi

# Reduce space lost to padding for alignment purposes by sorting data
# objects according to their alignment reqirements. This approximates
# optimal packing.
tryldflag LDFLAGS_AUTO -Wl,--sort-section,alignment
tryldflag LDFLAGS_AUTO -Wl,--sort-common

# When linking shared library, drop dummy weak definitions that were
# replaced by strong definitions from other translation units.
tryldflag LDFLAGS_AUTO -Wl,--gc-sections

# Some patched GCC builds have these defaults messed up...
tryldflag LDFLAGS_AUTO -Wl,--hash-style=both

# Prevent linking if there are undefined symbols; if any exist,
# libc.so will crash at runtime during relocation processing.
# The common way this can happen is failure to link the compiler
# runtime library; implementation error is also a possibility.
tryldflag LDFLAGS_AUTO -Wl,--no-undefined

# Avoid exporting symbols from compiler runtime libraries. They
# should be hidden anyway, but some toolchains including old gcc
# versions built without shared library support and pcc are broken.
tryldflag LDFLAGS_AUTO -Wl,--exclude-libs=ALL

# Linking with -Bsymbolic-functions is no longer mandatory for
# the dynamic linker to work, but enable it if it works as
# a linking optimization.
tryldflag LDFLAGS_AUTO -Wl,-Bsymbolic-functions

# Find compiler runtime library
test -z "$LIBCC" && tryldflag LIBCC -lgcc && tryldflag LIBCC -lgcc_eh
test -z "$LIBCC" && tryldflag LIBCC -lcompiler_rt
test -z "$LIBCC" && try_libcc=`$CC -print-file-name=libpcc.a 2>/dev/null` \
                 && tryldflag LIBCC "$try_libcc"
printf "using compiler runtime libraries: %s\n" "$LIBCC"

# Figure out arch variants for archs with variants
SUBARCH=
t="$CFLAGS_C99FSE $CPPFLAGS $CFLAGS"

if test "$ARCH" = "x86_64" ; then
trycppif __ILP32__ "$t" && ARCH=x32
fi

if test "$ARCH" = "arm" ; then
trycppif __ARMEB__ "$t" && SUBARCH=${SUBARCH}eb
trycppif __ARM_PCS_VFP "$t" && SUBARCH=${SUBARCH}hf
# Versions of clang up until at least 3.8 have the wrong constraint codes
# for floating point operands to inline asm. Detect this so the affected
# source files can just disable the asm.
if test "$cc_family" = clang ; then
printf "checking whether clang's vfp asm constraints work... "
echo 'float f(float x) { __asm__("":"+t"(x)); return x; }' > "$tmpc"
if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
printf "yes\n"
else
printf "no\n"
CFLAGS_AUTO="$CFLAGS_AUTO -DBROKEN_VFP_ASM"
CFLAGS_AUTO="${CFLAGS_AUTO# }"
fi
fi
fi

if test "$ARCH" = "aarch64" ; then
trycppif __AARCH64EB__ "$t" && SUBARCH=${SUBARCH}_be
fi

if test "$ARCH" = "mips" ; then
trycppif "__mips_isa_rev >= 6" "$t" && SUBARCH=${SUBARCH}r6
trycppif "_MIPSEL || __MIPSEL || __MIPSEL__" "$t" && SUBARCH=${SUBARCH}el
trycppif __mips_soft_float "$t" && SUBARCH=${SUBARCH}-sf
fi

if test "$ARCH" = "mips64" ; then
trycppif "__mips_isa_rev >= 6" "$t" && SUBARCH=${SUBARCH}r6
trycppif "_MIPSEL || __MIPSEL || __MIPSEL__" "$t" && SUBARCH=${SUBARCH}el
trycppif __mips_soft_float "$t" && SUBARCH=${SUBARCH}-sf
fi

if test "$ARCH" = "powerpc" ; then
trycppif "__NO_FPRS__ && !_SOFT_FLOAT" "$t" && fail \
  "$0: error: compiler's floating point configuration is unsupported"
trycppif _SOFT_FLOAT "$t" && SUBARCH=${SUBARCH}-sf
fi

test "$ARCH" = "microblaze" && trycppif __MICROBLAZEEL__ "$t" \
&& SUBARCH=${SUBARCH}el

if test "$ARCH" = "sh" ; then
tryflag CFLAGS_AUTO -Wa,--isa=any
trycppif __BIG_ENDIAN__ "$t" && SUBARCH=${SUBARCH}eb
if trycppif "__SH_FPU_ANY__ || __SH4__" "$t" ; then
# Some sh configurations are broken and replace double with float
# rather than using softfloat when the fpu is present but only
# supports single precision. Reject them.
printf "checking whether compiler's double type is IEEE double... "
echo 'typedef char dblcheck[(int)sizeof(double)-5];' > "$tmpc"
if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
printf "yes\n"
else
printf "no\n"
fail "$0: error: compiler's floating point configuration is unsupported"
fi
else
SUBARCH=${SUBARCH}-nofpu
fi
if trycppif __SH_FDPIC__ "$t" ; then
SUBARCH=${SUBARCH}-fdpic
fi
fi

test "$SUBARCH" \
&& printf "configured for %s variant: %s\n" "$ARCH" "$ARCH$SUBARCH"

case "$ARCH$SUBARCH" in
arm) ASMSUBARCH=el ;;
*) ASMSUBARCH=$SUBARCH ;;
esac

#
# Some archs (powerpc) have different possible long double formats
# that the compiler can be configured for. The logic for whether this
# is supported is in bits/float.h; in general, it is not. We need to
# check for mismatches here or code in printf, strotd, and scanf will
# be dangerously incorrect because it depends on (1) the macros being
# correct, and (2) IEEE semantics.
#
printf "checking whether compiler's long double definition matches float.h... "
echo '#include <float.h>' > "$tmpc"
echo '#if LDBL_MANT_DIG == 53' >> "$tmpc"
echo 'typedef char ldcheck[9-(int)sizeof(long double)];' >> "$tmpc"
echo '#endif' >> "$tmpc"
if $CC $CFLAGS_C99FSE \
  -I$srcdir/arch/$ARCH -I$srcdir/arch/generic -I$srcdir/include \
  $CPPFLAGS $CFLAGS -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
printf "yes\n"
else
printf "no\n"
fail "$0: error: unsupported long double type"
fi

#
# Some build systems globally pass in broken CFLAGS like -ffast-math
# for all packages. On recent GCC we can detect this and error out
# early rather than producing a seriously-broken math library.
#
if trycppif "__FAST_MATH__" \
  "$CFLAGS_C99FSE $CPPFLAGS $CFLAGS" ; then
fail "$0: error: compiler has broken floating point; check CFLAGS"
fi

printf "creating config.mak... "

cmdline=$(quote "$0")
for i ; do cmdline="$cmdline $(quote "$i")" ; done

exec 3>&1 1>config.mak


cat << EOF
# This version of config.mak was generated by:
# $cmdline
# Any changes made here will be lost if configure is re-run
ARCH = $ARCH
SUBARCH = $SUBARCH
ASMSUBARCH = $ASMSUBARCH
srcdir = $srcdir
prefix = $prefix
exec_prefix = $exec_prefix
bindir = $bindir
libdir = $libdir
includedir = $includedir
syslibdir = $syslibdir
CC = $CC
CFLAGS = $CFLAGS
CFLAGS_AUTO = $CFLAGS_AUTO
CFLAGS_C99FSE = $CFLAGS_C99FSE
CFLAGS_MEMOPS = $CFLAGS_MEMOPS
CFLAGS_NOSSP = $CFLAGS_NOSSP
CPPFLAGS = $CPPFLAGS
LDFLAGS = $LDFLAGS
LDFLAGS_AUTO = $LDFLAGS_AUTO
CROSS_COMPILE = $CROSS_COMPILE
LIBCC = $LIBCC
OPTIMIZE_GLOBS = $OPTIMIZE_GLOBS
ALL_TOOLS = $tools
TOOL_LIBS = $tool_libs
ADD_CFI = $ADD_CFI
EOF
test "x$static" = xno && echo "STATIC_LIBS ="
test "x$shared" = xno && echo "SHARED_LIBS ="
test "x$cc_family" = xgcc && echo 'WRAPCC_GCC = $(CC)'
test "x$cc_family" = xclang && echo 'WRAPCC_CLANG = $(CC)'
test "x$pic_default" = xyes && echo 'AOBJS = $(LOBJS)'
exec 1>&3 3>&-

test "$srcdir" = "." || ln -sf $srcdir/Makefile .

printf "done\n"