From: Neil Jerram <neil@ossau.uklinux.net>
Date: Fri, 11 Jul 2008 22:30:19 +0000 (+0100)
Subject: Improve stack direction test
X-Git-Url: http://git.savannah.gnu.org/gitweb/?p=guile.git;a=commitdiff_plain;h=9143131b2766d1e29e05d61b5021395b4c93a6bc;hp=4ff3575c77f95ed5c86970fa93629ba3cfab1912

Improve stack direction test

	* configure.in: Update stack direction test to be like that in
	Autoconf _AC_LIBOBJ_ALLOCA and Gnulib; specifically in involving a
	function calling itself.
---

diff --git a/NEWS b/NEWS
index 2c93494..aaea7af 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,7 @@ application code.
 
 ** `guile-config link' now prints `-L$libdir' before `-lguile'
 ** Fix build issue on Tru64 and ia64-hp-hpux11.23 (`SCM_UNPACK' macro)
+** Fix build issue on mips, mipsel, powerpc and ia64 (stack direction)
 
 
 Changes in 1.8.5 (since 1.8.4)
diff --git a/configure.in b/configure.in
index 6e2b6d8..d5d2264 100644
--- a/configure.in
+++ b/configure.in
@@ -1118,15 +1118,44 @@ GUILE_STRUCT_UTIMBUF
 #
 # Which way does the stack grow?
 #
+# Following code comes from Autoconf 2.61's internal _AC_LIBOBJ_ALLOCA
+# macro (/usr/share/autoconf/autoconf/functions.m4).  Gnulib has
+# very similar code, so in future we could look at using that.
+#
+# An important detail is that the code involves find_stack_direction
+# calling _itself_ - which means that find_stack_direction (or at
+# least the second find_stack_direction() call) cannot be inlined.
+# If the code could be inlined, that might cause the test to give
+# an incorrect answer.
 #--------------------------------------------------------------------
 
 SCM_I_GSC_STACK_GROWS_UP=0
-AC_RUN_IFELSE([AC_LANG_SOURCE([[aux (l) unsigned long l;
-	     { int x; exit (l >= ((unsigned long)&x)); }
-	   main () { int q; aux((unsigned long)&q); }]])],
-  [SCM_I_GSC_STACK_GROWS_UP=1],
-  [],
-  [AC_MSG_WARN(Guessing that stack grows down -- see scmconfig.h)])
+AC_CACHE_CHECK([stack direction],
+	       [SCM_I_GSC_STACK_GROWS_UP],
+[AC_RUN_IFELSE([AC_LANG_SOURCE(
+[AC_INCLUDES_DEFAULT
+int
+find_stack_direction ()
+{
+  static char *addr = 0;
+  auto char dummy;
+  if (addr == 0)
+    {
+      addr = &dummy;
+      return find_stack_direction ();
+    }
+  else
+    return (&dummy > addr) ? 1 : -1;
+}
+
+int
+main ()
+{
+  return find_stack_direction () < 0;
+}])],
+	       [SCM_I_GSC_STACK_GROWS_UP=1],
+	       [],
+	       [AC_MSG_WARN(Guessing that stack grows down -- see scmconfig.h)])])
 
 AC_CHECK_SIZEOF(float)
 if test "$ac_cv_sizeof_float" -le "$ac_cv_sizeof_long"; then