| 1 | # fpieee.m4 serial 2 -*- coding: utf-8 -*-
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| 2 | dnl Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | dnl IEEE 754 standardized three items:
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| 8 | dnl - The formats of single-float and double-float - nowadays commonly
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| 9 | dnl available as 'float' and 'double' in C and C++.
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| 10 | dnl No autoconf test needed.
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| 11 | dnl - The overflow and division by zero behaviour: The result are values
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| 12 | dnl '±Inf' and 'NaN', rather than exceptions as it was before.
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| 13 | dnl This file provides an autoconf macro for ensuring this behaviour of
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| 14 | dnl floating-point operations.
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| 15 | dnl - A set of conditions (overflow, underflow, inexact, etc.) which can
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| 16 | dnl be configured to trigger an exception.
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| 17 | dnl This cannot be done in a portable way: it depends on the compiler,
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| 18 | dnl libc, kernel, and CPU. No autoconf macro is provided for this.
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| 19 |
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| 20 | dnl Ensure non-trapping behaviour of floating-point overflow and
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| 21 | dnl floating-point division by zero.
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| 22 | dnl (For integer overflow, see gcc's -ftrapv option; for integer division by
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| 23 | dnl zero, see the autoconf macro in intdiv0.m4.)
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| 24 |
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| 25 | AC_DEFUN([gl_FP_IEEE],
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| 26 | [
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| 27 | AC_REQUIRE([AC_PROG_CC])
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| 28 | AC_REQUIRE([AC_CANONICAL_HOST])
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| 29 | # IEEE behaviour is the default on all CPUs except Alpha and SH
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| 30 | # (according to the test results of Bruno Haible's ieeefp/fenv_default.m4
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| 31 | # and the GCC 4.1.2 manual).
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| 32 | case "$host_cpu" in
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| 33 | alpha*)
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| 34 | # On Alpha systems, a compiler option provides the behaviour.
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| 35 | # See the ieee(3) manual page, also available at
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| 36 | # <https://backdrift.org/man/tru64/man3/ieee.3.html>
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| 37 | if test -n "$GCC"; then
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| 38 | # GCC has the option -mieee.
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| 39 | # For full IEEE compliance (rarely needed), use option -mieee-with-inexact.
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| 40 | CPPFLAGS="$CPPFLAGS -mieee"
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| 41 | else
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| 42 | # Compaq (ex-DEC) C has the option -ieee, equivalent to -ieee_with_no_inexact.
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| 43 | # For full IEEE compliance (rarely needed), use option -ieee_with_inexact.
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| 44 | CPPFLAGS="$CPPFLAGS -ieee"
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| 45 | fi
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| 46 | ;;
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| 47 | sh*)
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| 48 | if test -n "$GCC"; then
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| 49 | # GCC has the option -mieee.
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| 50 | CPPFLAGS="$CPPFLAGS -mieee"
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| 51 | fi
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| 52 | ;;
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| 53 | esac
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| 54 | ])
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