2012-10-24 Jeff Johnston <jjohnstn@redhat.com>

        * configure.in: Comment out the --enable-newlib-fp-hw option
        as the mathfp library is inaccurate and should not be used.
        * Makefile.am: Add comment regarding the mathfp directory.
        * configure: Regenerated.
        * Makefile.in: Ditto.
        * libm/mathfp/README: New file that details why the mathfp
        directory is not used.

6 files changed, 53 insertions, 22 deletions

diff --git a/newlib/ChangeLog b/newlib/ChangeLog
index 1f175b0c9..8f8ed212e 100644
--- a/newlib/ChangeLog
+++ b/newlib/ChangeLog
@@ -1,3 +1,13 @@
+2012-10-24  Jeff Johnston  <jjohnstn@redhat.com>
+
+	* configure.in: Comment out the --enable-newlib-fp-hw option
+	as the mathfp library is inaccurate and should not be used.
+	* Makefile.am: Add comment regarding the mathfp directory.
+	* configure: Regenerated.
+	* Makefile.in: Ditto.
+	* libm/mathfp/README: New file that details why the mathfp
+	directory is not used.
+
 2012-10-22  Jon TURNEY  <jon.turney@dronecode.org.uk>
 
 	* libc/include/string.h (strdup, strndup): Declare if not
diff --git a/newlib/Makefile.am b/newlib/Makefile.am
index 41de26f25..5ecce4c10 100644
--- a/newlib/Makefile.am
+++ b/newlib/Makefile.am
@@ -13,6 +13,10 @@ MULTICLEAN = true
 
 LIBTOOL_VERSION_INFO = 0:0:0
 
+# The newlib hardware floating-point routines have been disabled due to
+# inaccuracy.  If you wish to work on them, you will need to edit the
+# configure.in file to re-enable the configuration option.  By default,
+# the NEWLIB_HW_FP variable will always be false.
 if NEWLIB_HW_FP
 MATHDIR = mathfp
 else
diff --git a/newlib/Makefile.in b/newlib/Makefile.in
index 9b013e624..f7dbe82fe 100644
--- a/newlib/Makefile.in
+++ b/newlib/Makefile.in
@@ -297,6 +297,11 @@ MULTIDO = true
 MULTICLEAN = true
 LIBTOOL_VERSION_INFO = 0:0:0
 @NEWLIB_HW_FP_FALSE@MATHDIR = math
+
+# The newlib hardware floating-point routines have been disabled due to
+# inaccuracy.  If you wish to work on them, you will need to edit the
+# configure.in file to re-enable the configuration option.  By default,
+# the NEWLIB_HW_FP variable will always be false.
 @NEWLIB_HW_FP_TRUE@MATHDIR = mathfp
 
 # Work around what appears to be a GNU make bug handling MAKEFLAGS
diff --git a/newlib/configure b/newlib/configure
index 9e1906555..7d37f296f 100755
--- a/newlib/configure
+++ b/newlib/configure
@@ -804,7 +804,6 @@ with_pic
 enable_fast_install
 with_gnu_ld
 enable_libtool_lock
-enable_newlib_hw_fp
 '
       ac_precious_vars='build_alias
 host_alias
@@ -1469,7 +1468,6 @@ Optional Features:
   --enable-fast-install[=PKGS]
                           optimize for fast installation [default=yes]
   --disable-libtool-lock  avoid locking (might break parallel builds)
-  --enable-newlib-hw-fp    Turn on hardware floating point math
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -11641,7 +11639,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11644 "configure"
+#line 11642 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11747,7 +11745,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11750 "configure"
+#line 11748 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11986,17 +11984,14 @@ CC="$lt_save_CC"
 
 fi
 
-# Check whether --enable-newlib_hw_fp was given.
-if test "${enable_newlib_hw_fp+set}" = set; then :
-  enableval=$enable_newlib_hw_fp; case "${enableval}" in
-   yes) newlib_hw_fp=true ;;
-   no)  newlib_hw_fp=false ;;
-   *) as_fn_error $? "bad value ${enableval} for --enable-newlib-hw-fp" "$LINENO" 5 ;;
- esac
-else
-  newlib_hw_fp=false
-fi
-
+newlib_hw_fp=false
+#AC_ARG_ENABLE(newlib_hw_fp,
+#[  --enable-newlib-hw-fp    Turn on hardware floating point math],
+#[case "${enableval}" in
+#   yes) newlib_hw_fp=true ;;
+#   no)  newlib_hw_fp=false ;;
+#   *) AC_MSG_ERROR(bad value ${enableval} for --enable-newlib-hw-fp) ;;
+# esac],[newlib_hw_fp=false])
  if test x$newlib_hw_fp = xtrue; then
   NEWLIB_HW_FP_TRUE=
   NEWLIB_HW_FP_FALSE='#'
diff --git a/newlib/configure.in b/newlib/configure.in
index b6e5dee3c..35a5d070b 100644
--- a/newlib/configure.in
+++ b/newlib/configure.in
@@ -137,13 +137,19 @@ AC_LIBTOOL_WIN32_DLL
 AM_PROG_LIBTOOL
 fi
 
-AC_ARG_ENABLE(newlib_hw_fp,
-[  --enable-newlib-hw-fp    Turn on hardware floating point math],
-[case "${enableval}" in
-   yes) newlib_hw_fp=true ;;
-   no)  newlib_hw_fp=false ;;
-   *) AC_MSG_ERROR(bad value ${enableval} for --enable-newlib-hw-fp) ;;
- esac],[newlib_hw_fp=false])
+dnl The following is being disabled because the mathfp library is
+dnl not up to standard due to inaccuracies caused by some of the
+dnl floating-point algorithms used.  If you wish to work on this,
+dnl comment out the following line and uncomment out the lines
+dnl following it to re-enable the feature.
+newlib_hw_fp=false
+#AC_ARG_ENABLE(newlib_hw_fp,
+#[  --enable-newlib-hw-fp    Turn on hardware floating point math],
+#[case "${enableval}" in
+#   yes) newlib_hw_fp=true ;;
+#   no)  newlib_hw_fp=false ;;
+#   *) AC_MSG_ERROR(bad value ${enableval} for --enable-newlib-hw-fp) ;;
+# esac],[newlib_hw_fp=false])
 AM_CONDITIONAL(NEWLIB_HW_FP, test x$newlib_hw_fp = xtrue)
 
 # These get added in the top-level configure.in, except in the case where
diff --git a/newlib/libm/mathfp/README b/newlib/libm/mathfp/README
new file mode 100644
index 000000000..7eba79cb7
--- /dev/null
+++ b/newlib/libm/mathfp/README
@@ -0,0 +1,11 @@
+This directory was an experiment to use floating-point operations to implement
+the math library when a processor had a floating-point instruction set.  The
+experiment was a failure in that some of the algorithms chosen (e.g. recursive
+algorithms for sin/cos, etc..) are too simple and do not provide proper accuracy 
+nor handle very large or very small inputs adequately.
+
+The code is considered moth-balled.  The stable math library routines can be
+found in libm/math and the configuration option to use this has been removed.
+
+If you wish to experiment with the concept, please feel free and report back if
+you have major improvements.