| # alloca.m4 serial 20 |
| dnl Copyright (C) 2002-2004, 2006-2007, 2009-2021 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"]) |
| |
| if test $ac_cv_working_alloca_h = yes; then |
| HAVE_ALLOCA_H=1 |
| else |
| HAVE_ALLOCA_H=0 |
| fi |
| AC_SUBST([HAVE_ALLOCA_H]) |
| ]) |
| |
| # Prerequisites of lib/alloca.c. |
| # STACK_DIRECTION is already handled by AC_FUNC_ALLOCA. |
| AC_DEFUN([gl_PREREQ_ALLOCA], [:]) |
| |
| m4_version_prereq([2.70], [], [ |
| |
| # This works around a bug in autoconf <= 2.68 and has simplifications |
| # from 2.70. See: |
| # https://lists.gnu.org/r/bug-gnulib/2011-06/msg00277.html |
| # https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=6cd9f12520b0d6f76d3230d7565feba1ecf29497 |
| # https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=15edf7fd8094fd14a89d9891dd72a9624762597a |
| |
| # _AC_LIBOBJ_ALLOCA |
| # ----------------- |
| # Set up the LIBOBJ replacement of 'alloca'. Well, not exactly |
| # AC_LIBOBJ since we actually set the output variable 'ALLOCA'. |
| # Nevertheless, for Automake, AC_LIBSOURCES it. |
| m4_define([_AC_LIBOBJ_ALLOCA], |
| [# The SVR3 libPW and SVR4 libucb both contain incompatible functions |
| # that cause trouble. Some versions do not even contain alloca or |
| # contain a buggy version. If you still want to use their alloca, |
| # use ar to extract alloca.o from them instead of compiling alloca.c. |
| AC_LIBSOURCES(alloca.c) |
| AC_SUBST([ALLOCA], [\${LIBOBJDIR}alloca.$ac_objext])dnl |
| AC_DEFINE(C_ALLOCA, 1, [Define to 1 if using 'alloca.c'.]) |
| |
| AC_CACHE_CHECK([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 |
| ]) |