emacs/m4/alloca.m4
Paul Eggert 39c2fa3f4e Merge from gnulib and try to repair bad merge
This attempts to repair problems introduced by the bad merge
5491fd1098.  The easiest way for me
to fix the badly-merged gnulib files was to run
'admin/merge-gnulib', so I did that, which also imported the
following changes:
* build-aux/update-copyright, m4/gnulib.m4:
Update from gnulib, incorporating:
2015-01-15 time: port to MinGW32 3.21
2015-01-15 update-copyright: apply to self
2015-01-11 update-copyright: recognize groff's \(co marker
2015-01-27 22:24:47 -08:00

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4.2 KiB
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# alloca.m4 serial 14
dnl Copyright (C) 2002-2004, 2006-2007, 2009-2015 Free Software Foundation,
dnl 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.
AC_DEFUN([gl_FUNC_ALLOCA],
[
AC_REQUIRE([AC_FUNC_ALLOCA])
if test $ac_cv_func_alloca_works = no; then
gl_PREREQ_ALLOCA
fi
# Define an additional variable used in the Makefile substitution.
if test $ac_cv_working_alloca_h = yes; then
AC_CACHE_CHECK([for alloca as a compiler built-in], [gl_cv_rpl_alloca], [
AC_EGREP_CPP([Need own alloca], [
#if defined __GNUC__ || defined _AIX || defined _MSC_VER
Need own alloca
#endif
], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no])
])
if test $gl_cv_rpl_alloca = yes; then
dnl OK, alloca can be implemented through a compiler built-in.
AC_DEFINE([HAVE_ALLOCA], [1],
[Define to 1 if you have 'alloca' after including <alloca.h>,
a header that may be supplied by this distribution.])
ALLOCA_H=alloca.h
else
dnl alloca exists as a library function, i.e. it is slow and probably
dnl a memory leak. Don't define HAVE_ALLOCA in this case.
ALLOCA_H=
fi
else
ALLOCA_H=alloca.h
fi
AC_SUBST([ALLOCA_H])
AM_CONDITIONAL([GL_GENERATE_ALLOCA_H], [test -n "$ALLOCA_H"])
])
# Prerequisites of lib/alloca.c.
# STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
AC_DEFUN([gl_PREREQ_ALLOCA], [:])
# This works around a bug in autoconf <= 2.68.
# See <http://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00277.html>.
m4_version_prereq([2.69], [] ,[
# This is taken from the following Autoconf patch:
# http://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=6cd9f12520b0d6f76d3230d7565feba1ecf29497
# _AC_LIBOBJ_ALLOCA
# -----------------
# Set up the LIBOBJ replacement of 'alloca'. Well, not exactly
# AC_LIBOBJ since we actually set the output variable 'ALLOCA'.
# Nevertheless, for Automake, AC_LIBSOURCES it.
m4_define([_AC_LIBOBJ_ALLOCA],
[# The SVR3 libPW and SVR4 libucb both contain incompatible functions
# that cause trouble. Some versions do not even contain alloca or
# contain a buggy version. If you still want to use their alloca,
# use ar to extract alloca.o from them instead of compiling alloca.c.
AC_LIBSOURCES(alloca.c)
AC_SUBST([ALLOCA], [\${LIBOBJDIR}alloca.$ac_objext])dnl
AC_DEFINE(C_ALLOCA, 1, [Define to 1 if using 'alloca.c'.])
AC_CACHE_CHECK(whether 'alloca.c' needs Cray hooks, ac_cv_os_cray,
[AC_EGREP_CPP(webecray,
[#if defined CRAY && ! defined CRAY2
webecray
#else
wenotbecray
#endif
], ac_cv_os_cray=yes, ac_cv_os_cray=no)])
if test $ac_cv_os_cray = yes; then
for ac_func in _getb67 GETB67 getb67; do
AC_CHECK_FUNC($ac_func,
[AC_DEFINE_UNQUOTED(CRAY_STACKSEG_END, $ac_func,
[Define to one of '_getb67', 'GETB67',
'getb67' for Cray-2 and Cray-YMP
systems. This function is required for
'alloca.c' support on those systems.])
break])
done
fi
AC_CACHE_CHECK([stack direction for C alloca],
[ac_cv_c_stack_direction],
[AC_RUN_IFELSE([AC_LANG_SOURCE(
[AC_INCLUDES_DEFAULT
int
find_stack_direction (int *addr, int depth)
{
int dir, dummy = 0;
if (! addr)
addr = &dummy;
*addr = addr < &dummy ? 1 : addr == &dummy ? 0 : -1;
dir = depth ? find_stack_direction (addr, depth - 1) : 0;
return dir + dummy;
}
int
main (int argc, char **argv)
{
return find_stack_direction (0, argc + !argv + 20) < 0;
}])],
[ac_cv_c_stack_direction=1],
[ac_cv_c_stack_direction=-1],
[ac_cv_c_stack_direction=0])])
AH_VERBATIM([STACK_DIRECTION],
[/* If using the C implementation of alloca, define if you know the
direction of stack growth for your system; otherwise it will be
automatically deduced at runtime.
STACK_DIRECTION > 0 => grows toward higher addresses
STACK_DIRECTION < 0 => grows toward lower addresses
STACK_DIRECTION = 0 => direction of growth unknown */
@%:@undef STACK_DIRECTION])dnl
AC_DEFINE_UNQUOTED(STACK_DIRECTION, $ac_cv_c_stack_direction)
])# _AC_LIBOBJ_ALLOCA
])