+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=`$CC -print-libgcc-file-name 2>/dev/null` \
+ && tryldflag LIBCC "$try_libcc"
+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
+if trycppif __thumb2__ "$t" ; then
+tryflag CFLAGS_AUTO -Wa,-mimplicit-it=always
+tryflag CFLAGS_AUTO -Wa,-mthumb
+fi
+trycppif __ARMEB__ "$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 "$ARCH" = "mips64" ; then
+trycppif "_MIPS_SIM != _ABI64" "$t" && ARCH=mipsn32
+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