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1 # alloca.m4 serial 8
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2 dnl Copyright (C) 2002-2004, 2006, 2007 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 AC_DEFUN([gl_FUNC_ALLOCA],
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8 [
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9 dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
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10 AC_REQUIRE([AC_PROG_CPP])
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11 AC_REQUIRE([AC_PROG_EGREP])
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12
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13 AC_REQUIRE([AC_FUNC_ALLOCA])
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14 if test $ac_cv_func_alloca_works = no; then
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15 gl_PREREQ_ALLOCA
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16 fi
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17
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18 # Define an additional variable used in the Makefile substitution.
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19 if test $ac_cv_working_alloca_h = yes; then
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20 AC_CACHE_CHECK([for alloca as a compiler built-in], [gl_cv_rpl_alloca], [
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21 AC_EGREP_CPP([Need own alloca], [
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22 #if defined __GNUC__ || defined _AIX || defined _MSC_VER
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23 Need own alloca
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24 #endif
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25 ], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no])
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26 ])
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27 if test $gl_cv_rpl_alloca = yes; then
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28 dnl OK, alloca can be implemented through a compiler built-in.
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29 AC_DEFINE([HAVE_ALLOCA], 1,
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30 [Define to 1 if you have 'alloca' after including <alloca.h>,
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31 a header that may be supplied by this distribution.])
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32 ALLOCA_H=alloca.h
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33 else
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34 dnl alloca exists as a library function, i.e. it is slow and probably
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35 dnl a memory leak. Don't define HAVE_ALLOCA in this case.
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36 ALLOCA_H=
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37 fi
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38 else
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39 ALLOCA_H=alloca.h
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40 fi
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41 AC_SUBST([ALLOCA_H])
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42 ])
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43
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44 # Prerequisites of lib/alloca.c.
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45 # STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
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46 AC_DEFUN([gl_PREREQ_ALLOCA], [:])
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