alias-1.c: New test.

2005-04-11  Andrew Pinski  <pinskia@physics.uc.edu>

        * gcc.dg/tree-ssa/alias-1.c: New test.
2005-04-11  Andrew Pinski  <pinskia@physics.uc.edu>

        * tree-ssa-alias.c (may_alias_p): If the variable
        is a global variable and the pointer is parameter
        and -fargument-noalias-global is used, then
        the pointer cannot alias the variable.

From-SVN: r97978

gcc/ChangeLog

+2005-04-11  Andrew Pinski  <pinskia@physics.uc.edu>
+
+	* tree-ssa-alias.c (may_alias_p): If the variable
+	is a global variable and the pointer is parameter
+	and -fargument-noalias-global is used, then
+	the pointer cannot alias the variable.
+
 2005-04-11  James A. Morrison  <phython@gcc.gnu.org>
 
 	* config/sparc/sparc.c: Use gcc_assert and gcc_unreachable.

gcc/testsuite/ChangeLog

+2005-04-11  Andrew Pinski  <pinskia@physics.uc.edu>
+
+	* gcc.dg/tree-ssa/alias-1.c: New test.
+
 2005-04-11  Diego Novillo  <dnovillo@redhat.com>
 
 	PR tree-optimization/20920

gcc/testsuite/gcc.dg/tree-ssa/alias-1.c

+/* { dg-options "-O2 -fargument-noalias-global -fdump-tree-optimizated" } */
+int f;
+void link_error ();
+
+void g(int *i)
+{
+  *i = 0;
+  f = 1;
+  if (*i != 0)
+    link_error ();
+}
+
+
+/* We should have removed the link_error on the tree level as we told GCC
+   that *i cannot point to f via the option -fargument-noalias-global. */
+/* { dg-final { scan-tree-dump-times "link_error" 0 "optimized"} } */

gcc/tree-ssa-alias.c

@@ -1708,6 +1708,16 @@ may_alias_p (tree ptr, HOST_WIDE_INT mem_alias_set,
       alias_stats.simple_resolved++;
       return false;
     }
+  
+  /* If -fargument-noalias-global is >1, pointer arguments may
+     not point to global variables.  */
+  if (flag_argument_noalias > 1 && is_global_var (var)
+      && TREE_CODE (ptr) == PARM_DECL)
+    {
+      alias_stats.alias_noalias++;
+      alias_stats.simple_resolved++;
+      return false;
+    }
 
   m_ann = var_ann (mem);