m4/fpieee.m4

   1 # fpieee.m4 serial 2
   2 dnl Copyright (C) 2007, 2009-2014 Free Software Foundation, Inc.
   3 dnl This file is free software; the Free Software Foundation
   4 dnl gives unlimited permission to copy and/or distribute it,
   5 dnl with or without modifications, as long as this notice is preserved.
   6
   7 dnl IEEE 754 standardized three items:
   8 dnl - The formats of single-float and double-float - nowadays commonly
   9 dnl   available as 'float' and 'double' in C and C++.
  10 dnl   No autoconf test needed.
  11 dnl - The overflow and division by zero behaviour: The result are values
  12 dnl   '±Inf' and 'NaN', rather than exceptions as it was before.
  13 dnl   This file provides an autoconf macro for ensuring this behaviour of
  14 dnl   floating-point operations.
  15 dnl - A set of conditions (overflow, underflow, inexact, etc.) which can
  16 dnl   be configured to trigger an exception.
  17 dnl   This cannot be done in a portable way: it depends on the compiler,
  18 dnl   libc, kernel, and CPU.  No autoconf macro is provided for this.
  19
  20 dnl Ensure non-trapping behaviour of floating-point overflow and
  21 dnl floating-point division by zero.
  22 dnl (For integer overflow, see gcc's -ftrapv option; for integer division by
  23 dnl zero, see the autoconf macro in intdiv0.m4.)
  24
  25 AC_DEFUN([gl_FP_IEEE],
  26 [
  27   AC_REQUIRE([AC_PROG_CC])
  28   AC_REQUIRE([AC_CANONICAL_HOST])
  29   # IEEE behaviour is the default on all CPUs except Alpha and SH
  30   # (according to the test results of Bruno Haible's ieeefp/fenv_default.m4
  31   # and the GCC 4.1.2 manual).
  32   case "$host_cpu" in
  33     alpha*)
  34       # On Alpha systems, a compiler option provides the behaviour.
  35       # See the ieee(3) manual page, also available at
  36       # <http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51B_HTML/MAN/MAN3/0600____.HTM>
  37       if test -n "$GCC"; then
  38         # GCC has the option -mieee.
  39         # For full IEEE compliance (rarely needed), use option -mieee-with-inexact.
  40         CPPFLAGS="$CPPFLAGS -mieee"
  41       else
  42         # Compaq (ex-DEC) C has the option -ieee, equivalent to -ieee_with_no_inexact.
  43         # For full IEEE compliance (rarely needed), use option -ieee_with_inexact.
  44         CPPFLAGS="$CPPFLAGS -ieee"
  45       fi
  46       ;;
  47     sh*)
  48       if test -n "$GCC"; then
  49         # GCC has the option -mieee.
  50         CPPFLAGS="$CPPFLAGS -mieee"
  51       fi
  52       ;;
  53   esac
  54 ])