new module 'fpieee'

[Bruno Haible]

The code needed for isnan() needs to construct a NaN or Inf object. But
doing so leads to a SIGFPE by default on Alpha systems. There's only one
way to get IEEE compliant behaviour of elementary arithmetic operations on
this platform: instruct the compiler to emit different (more expensive)
floating-point instructions. This module implements it.

2007-03-25  Bruno Haible  <address@hidden>

        * modules/fpieee: New file.
        * m4/fpieee.m4: New file.
        * modules/isnan-nolibm (Depends-on): Add fpieee.
        * modules/isnanl-nolibm (Depends-on): Add fpieee.
        * modules/isnanl (Depends-on): Add fpieee.

=============================== modules/fpieee ================================
Description:
Ensure IEEE compliant floating-point operations (overflow and division by zero).

Files:
m4/fpieee.m4

Depends-on:

configure.ac-early:
AC_REQUIRE([gl_FP_IEEE])

configure.ac:

Makefile.am:

Include:

License:
LGPL

Maintainer:
Bruno Haible

================================ m4/fpieee.m4 =================================
# fpieee.m4 serial 1
dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

dnl IEEE 754 standardized three items:
dnl - The formats of single-float and double-float - nowadays commonly
dnl   available as 'float' and 'double' in C and C++.
dnl   No autoconf test needed.
dnl - The overflow and division by zero behaviour: The result are values
dnl   '±Inf' and 'NaN', rather than exceptions as it was before.
dnl   This file provides an autoconf macro for ensuring this behaviour of
dnl   floating-point operations.
dnl - A set of conditions (overflow, underflow, inexact, etc.) which can
dnl   be configured to trigger an exception.
dnl   This cannot be done in a portable way: it depends on the compiler,
dnl   libc, kernel, and CPU.  No autoconf macro is provided for this.

dnl Ensure non-trapping behaviour of floating-point overflow and
dnl floating-point division by zero.
dnl (For integer overflow, see gcc's -ftrapv option; for integer division by
dnl zero, see the autoconf macro in intdiv0.m4.)

AC_DEFUN([gl_FP_IEEE],
[
  AC_REQUIRE([AC_PROG_CC])
  AC_REQUIRE([AC_CANONICAL_HOST])
  # IEEE behaviour is the default on all CPUs except Alpha
  # (according to the test results of Bruno Haible's ieeefp/fenv_default.m4).
  case "$host_cpu" in
    alpha*)
      # On Alpha systems, a compiler option provides the behaviour.
      # See the ieee(3) manual page, also available at
      # 
<http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51B_HTML/MAN/MAN3/0600____.HTM>
      if test -n "$GCC"; then
        # GCC has the option -mieee.
        CPPFLAGS="$CPPFLAGS -mieee"
      else
        # Compaq (ex-DEC) C has the option -ieee. 
        CPPFLAGS="$CPPFLAGS -mieee"
      fi
      ;;
  esac
])
===============================================================================
*** modules/isnan-nolibm        25 Mar 2007 01:06:39 -0000      1.2
--- modules/isnan-nolibm        25 Mar 2007 23:48:24 -0000
***************
*** 8,13 ****
--- 8,14 ----
  m4/isnan.m4
  
  Depends-on:
+ fpieee
  
  configure.ac:
  gl_FUNC_ISNAN_NO_LIBM
*** modules/isnanl-nolibm       25 Mar 2007 01:06:39 -0000      1.4
--- modules/isnanl-nolibm       25 Mar 2007 23:48:24 -0000
***************
*** 10,15 ****
--- 10,16 ----
  m4/longdouble.m4
  
  Depends-on:
+ fpieee
  
  configure.ac:
  gl_FUNC_ISNANL_NO_LIBM
*** modules/isnanl      25 Mar 2007 01:06:39 -0000      1.2
--- modules/isnanl      25 Mar 2007 23:48:24 -0000
***************
*** 10,15 ****
--- 10,16 ----
  m4/longdouble.m4
  
  Depends-on:
+ fpieee
  
  configure.ac:
  gl_FUNC_ISNANL