1# alloca.m4 serial 14 2dnl Copyright (C) 2002-2004, 2006-2007, 2009-2012 Free Software Foundation, 3dnl Inc. 4dnl This file is free software; the Free Software Foundation 5dnl gives unlimited permission to copy and/or distribute it, 6dnl with or without modifications, as long as this notice is preserved. 7 8AC_DEFUN([gl_FUNC_ALLOCA], 9[ 10 AC_REQUIRE([AC_FUNC_ALLOCA]) 11 if test $ac_cv_func_alloca_works = no; then 12 gl_PREREQ_ALLOCA 13 fi 14 15 # Define an additional variable used in the Makefile substitution. 16 if test $ac_cv_working_alloca_h = yes; then 17 AC_CACHE_CHECK([for alloca as a compiler built-in], [gl_cv_rpl_alloca], [ 18 AC_EGREP_CPP([Need own alloca], [ 19#if defined __GNUC__ || defined _AIX || defined _MSC_VER 20 Need own alloca 21#endif 22 ], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no]) 23 ]) 24 if test $gl_cv_rpl_alloca = yes; then 25 dnl OK, alloca can be implemented through a compiler built-in. 26 AC_DEFINE([HAVE_ALLOCA], [1], 27 [Define to 1 if you have 'alloca' after including <alloca.h>, 28 a header that may be supplied by this distribution.]) 29 ALLOCA_H=alloca.h 30 else 31 dnl alloca exists as a library function, i.e. it is slow and probably 32 dnl a memory leak. Don't define HAVE_ALLOCA in this case. 33 ALLOCA_H= 34 fi 35 else 36 ALLOCA_H=alloca.h 37 fi 38 AC_SUBST([ALLOCA_H]) 39 AM_CONDITIONAL([GL_GENERATE_ALLOCA_H], [test -n "$ALLOCA_H"]) 40]) 41 42# Prerequisites of lib/alloca.c. 43# STACK_DIRECTION is already handled by AC_FUNC_ALLOCA. 44AC_DEFUN([gl_PREREQ_ALLOCA], [:]) 45 46# This works around a bug in autoconf <= 2.68. 47# See <http://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00277.html>. 48 49m4_version_prereq([2.69], [] ,[ 50 51# This is taken from the following Autoconf patch: 52# http://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=6cd9f12520b0d6f76d3230d7565feba1ecf29497 53 54# _AC_LIBOBJ_ALLOCA 55# ----------------- 56# Set up the LIBOBJ replacement of 'alloca'. Well, not exactly 57# AC_LIBOBJ since we actually set the output variable 'ALLOCA'. 58# Nevertheless, for Automake, AC_LIBSOURCES it. 59m4_define([_AC_LIBOBJ_ALLOCA], 60[# The SVR3 libPW and SVR4 libucb both contain incompatible functions 61# that cause trouble. Some versions do not even contain alloca or 62# contain a buggy version. If you still want to use their alloca, 63# use ar to extract alloca.o from them instead of compiling alloca.c. 64AC_LIBSOURCES(alloca.c) 65AC_SUBST([ALLOCA], [\${LIBOBJDIR}alloca.$ac_objext])dnl 66AC_DEFINE(C_ALLOCA, 1, [Define to 1 if using 'alloca.c'.]) 67 68AC_CACHE_CHECK(whether 'alloca.c' needs Cray hooks, ac_cv_os_cray, 69[AC_EGREP_CPP(webecray, 70[#if defined CRAY && ! defined CRAY2 71webecray 72#else 73wenotbecray 74#endif 75], ac_cv_os_cray=yes, ac_cv_os_cray=no)]) 76if test $ac_cv_os_cray = yes; then 77 for ac_func in _getb67 GETB67 getb67; do 78 AC_CHECK_FUNC($ac_func, 79 [AC_DEFINE_UNQUOTED(CRAY_STACKSEG_END, $ac_func, 80 [Define to one of '_getb67', 'GETB67', 81 'getb67' for Cray-2 and Cray-YMP 82 systems. This function is required for 83 'alloca.c' support on those systems.]) 84 break]) 85 done 86fi 87 88AC_CACHE_CHECK([stack direction for C alloca], 89 [ac_cv_c_stack_direction], 90[AC_RUN_IFELSE([AC_LANG_SOURCE( 91[AC_INCLUDES_DEFAULT 92int 93find_stack_direction (int *addr, int depth) 94{ 95 int dir, dummy = 0; 96 if (! addr) 97 addr = &dummy; 98 *addr = addr < &dummy ? 1 : addr == &dummy ? 0 : -1; 99 dir = depth ? find_stack_direction (addr, depth - 1) : 0; 100 return dir + dummy; 101} 102 103int 104main (int argc, char **argv) 105{ 106 return find_stack_direction (0, argc + !argv + 20) < 0; 107}])], 108 [ac_cv_c_stack_direction=1], 109 [ac_cv_c_stack_direction=-1], 110 [ac_cv_c_stack_direction=0])]) 111AH_VERBATIM([STACK_DIRECTION], 112[/* If using the C implementation of alloca, define if you know the 113 direction of stack growth for your system; otherwise it will be 114 automatically deduced at runtime. 115 STACK_DIRECTION > 0 => grows toward higher addresses 116 STACK_DIRECTION < 0 => grows toward lower addresses 117 STACK_DIRECTION = 0 => direction of growth unknown */ 118@%:@undef STACK_DIRECTION])dnl 119AC_DEFINE_UNQUOTED(STACK_DIRECTION, $ac_cv_c_stack_direction) 120])# _AC_LIBOBJ_ALLOCA 121]) 122