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Diffstat (limited to '')
| -rw-r--r-- | m4/alloca.m4 | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/m4/alloca.m4 b/m4/alloca.m4 new file mode 100644 index 0000000..e3c377c --- /dev/null +++ b/m4/alloca.m4 @@ -0,0 +1,108 @@ +# alloca.m4 serial 20 +dnl Copyright (C) 2002-2004, 2006-2007, 2009-2020 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 +]) |