Remove --with-fp / --without-fp.

There is a configure option --without-fp that specifies that nofpu
sysdeps directories should be used instead of fpu directories.

For most glibc configurations, this option is of no use: either there
is no valid nofpu variant of that configuration, or there are no fpu
or nofpu sysdeps directories for that processor and so the option does
nothing.  For a few configurations, if you are using a soft-float
compiler this option is required, and failing to use it generally
results in compilation errors from inline asm using unavailable
floating-point instructions.

We're moving away from --with-cpu to configuring glibc based on how
the compiler generates code, and it is natural to do so for
--without-fp as well; in most cases the soft-float and hard-float ABIs
are incompatible so you have no hope of building a working glibc with
an inappropriately configured compiler or libgcc.

This patch eliminates --without-fp, replacing it entirely by automatic
configuration based on the compiler.  Configurations for which this is
relevant (coldfire / mips / powerpc32 / sh) define a variable
with_fp_cond in their preconfigure fragments (under the same
conditions under which those fragments do anything); this is a
preprocessor conditional which the toplevel configure script then uses
in a test to determine which sysdeps directories to use.

The config.make with-fp variable remains.  It's used only by powerpc
(sysdeps/powerpc/powerpc32/Makefile) to add -mhard-float to various
flags variables.  For powerpc, -mcpu= options can imply use of
soft-float.  That could be an issue if you want to build for
e.g. 476fp, but are using --with-cpu=476 because there isn't a 476fp
sysdeps directory.  If in future we eliminate --with-cpu and replace
it entirely by testing the compiler, it would be natural at that point
to eliminate that code as well (as the user should then just use a
compiler defaulting to 476fp and the 476 sysdeps directory would be
used automatically).

Tested for x86_64, and tested with build-many-glibcs.py that installed
shared libraries are unchanged by this patch.

	* configure.ac (--with-fp): Remove configure option.
	(with_fp_cond): New variable.
	(libc_cv_with_fp): New configure test.  Use this variable instead
	of with_fp.
	* configure: Regenerated.
	* config.make.in (with-fp): Use @libc_cv_with_fp@.
	* manual/install.texi (Configuring and compiling): Remove
	--without-fp.
	* INSTALL: Regenerated.
	* sysdeps/m68k/preconfigure (with_fp_cond): Define for ColdFire.
	* sysdeps/mips/preconfigure (with_fp_cond): Define.
	* sysdeps/powerpc/preconfigure (with_fp_cond): Define for 32-bit.
	* sysdeps/sh/preconfigure (with_fp_cond): Define.
	* scripts/build-many-glibcs.py (Context.add_all_configs): Do not
	use --without-fp to configure glibc.

1 files changed, 31 insertions, 13 deletions

diff --git a/configure b/configure
index dd8b8c95e6..4a85706862 100755
--- a/configure
+++ b/configure
@@ -666,6 +666,7 @@ multi_arch
 no_stack_protector
 stack_protector
 libc_cv_ssp
+libc_cv_with_fp
 base_machine
 have_tunables
 build_pt_chown
@@ -683,7 +684,6 @@ hardcoded_path_in_tests
 enable_timezone_tools
 use_default_link
 sysheaders
-with_fp
 ac_ct_CXX
 CXXFLAGS
 CXX
@@ -756,7 +756,6 @@ with_bugurl
 with_gd
 with_gd_include
 with_gd_lib
-with_fp
 with_binutils
 with_selinux
 with_headers
@@ -1467,7 +1466,6 @@ Optional Packages:
   --with-gd=DIR           find libgd include dir and library with prefix DIR
   --with-gd-include=DIR   find libgd include files in DIR
   --with-gd-lib=DIR       find libgd library files in DIR
-  --with-fp               if using floating-point hardware [default=yes]
   --with-binutils=PATH    specify location of binutils (as and ld)
   --with-selinux          if building with SELinux support
   --with-headers=PATH     location of system headers to use (for example
@@ -3294,15 +3292,6 @@ libgd-LDFLAGS = $libgd_ldflags"
 fi
 
 
-# Check whether --with-fp was given.
-if test "${with_fp+set}" = set; then :
-  withval=$with_fp; with_fp=$withval
-else
-  with_fp=yes
-fi
-
-
-
 # Check whether --with-binutils was given.
 if test "${with_binutils+set}" = set; then :
   withval=$with_binutils; path_binutils=$withval
@@ -3778,6 +3767,11 @@ fi
 # check below.
 libc_config_ok=no
 
+# A preconfigure script for a system that may or may not use fpu
+# sysdeps directories sets this to a preprocessor conditional for
+# whether to use such directories.
+with_fp_cond=1
+
 if frags=`ls -d $srcdir/sysdeps/*/preconfigure 2> /dev/null`
 then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sysdeps preconfigure fragments" >&5
@@ -3816,6 +3810,30 @@ fi
 test -n "$base_machine" || base_machine=$machine
 
 
+# Determine whether to use fpu or nofpu sysdeps directories.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for use of fpu sysdeps directories" >&5
+$as_echo_n "checking for use of fpu sysdeps directories... " >&6; }
+if ${libc_cv_with_fp+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.c <<EOF
+#if $with_fp_cond
+int dummy;
+#else
+# error "no hardware floating point"
+#endif
+EOF
+libc_cv_with_fp=no
+if ${CC-cc} $CFLAGS $CPPFLAGS -S conftest.c -o conftest.s \
+   1>&5 2>&5 ; then
+  libc_cv_with_fp=yes
+fi
+rm -f conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_with_fp" >&5
+$as_echo "$libc_cv_with_fp" >&6; }
+
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -fstack-protector" >&5
 $as_echo_n "checking for -fstack-protector... " >&6; }
 if ${libc_cv_ssp+:} false; then :
@@ -4085,7 +4103,7 @@ tail=$machine${submachine:+/$submachine}
 while m=`echo $tail | sed 's@^\(.*\)/\([^/]*\)$@& \1@'`; test -n "$m"; do
   set $m
   # Prepend the machine's FPU directory unless --without-fp.
-  if test "$with_fp" = yes; then
+  if test "$libc_cv_with_fp" = yes; then
     maybe_fpu=/fpu
   else
     maybe_fpu=/nofpu