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-rw-r--r--m4/alloca.m4106
1 files changed, 106 insertions, 0 deletions
diff --git a/m4/alloca.m4 b/m4/alloca.m4
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+++ b/m4/alloca.m4
@@ -0,0 +1,106 @@
+# alloca.m4 serial 21
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2022 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.])
+ GL_GENERATE_ALLOCA_H=true
+ 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.
+ GL_GENERATE_ALLOCA_H=false
+ fi
+ else
+ GL_GENERATE_ALLOCA_H=true
+ fi
+
+ 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
+])