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# fpieee.m4 serial 2 -*- coding: utf-8 -*-
dnl Copyright (C) 2007, 2009-2024 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 and SH
# (according to the test results of Bruno Haible's ieeefp/fenv_default.m4
# and the GCC 4.1.2 manual).
case "$host_cpu" in
alpha*)
# On Alpha systems, a compiler option provides the behaviour.
# See the ieee(3) manual page, also available at
# <https://backdrift.org/man/tru64/man3/ieee.3.html>
if test -n "$GCC"; then
# GCC has the option -mieee.
# For full IEEE compliance (rarely needed), use option -mieee-with-inexact.
CPPFLAGS="$CPPFLAGS -mieee"
else
# Compaq (ex-DEC) C has the option -ieee, equivalent to -ieee_with_no_inexact.
# For full IEEE compliance (rarely needed), use option -ieee_with_inexact.
CPPFLAGS="$CPPFLAGS -ieee"
fi
;;
sh*)
if test -n "$GCC"; then
# GCC has the option -mieee.
CPPFLAGS="$CPPFLAGS -mieee"
fi
;;
esac
])
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