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+# fpieee.m4 serial 2 -*- coding: utf-8 -*-
+dnl Copyright (C) 2007, 2009-2022 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
+])