m4/alloca.m4

   1 # alloca.m4 serial 10
   2 dnl Copyright (C) 2002-2004, 2006-2007, 2009-2011 Free Software Foundation,
   3 dnl Inc.
   4 dnl This file is free software; the Free Software Foundation
   5 dnl gives unlimited permission to copy and/or distribute it,
   6 dnl with or without modifications, as long as this notice is preserved.
   7
   8 AC_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 ])
  40
  41 # Prerequisites of lib/alloca.c.
  42 # STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
  43 AC_DEFUN([gl_PREREQ_ALLOCA], [:])