| # fpieee.m4 serial 2 -*- coding: utf-8 -*- |
| dnl Copyright (C) 2007, 2009-2021 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 |
| ]) |