re PR tree-optimization/47286 (Invalid code when using register ... asm)

2011-01-14  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/47286
	* tree-ssa-structalias.c (new_var_info): Register variables
	are global.

	* gcc.dg/tree-ssa/pr47286.c: New testcase.

From-SVN: r168779

gcc/ChangeLog

+2011-01-14  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/47286
+	* tree-ssa-structalias.c (new_var_info): Register variables
+	are global.
+
 2011-01-14  Martin Jambor  <mjambor@suse.cz>
 
 	PR middle-end/46823

gcc/testsuite/ChangeLog

+2011-01-14  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/47286
+	* gcc.dg/tree-ssa/pr47286.c: New testcase.
+
 2011-01-13  Kai Tietz  <kai.tietz@onevision.com>
 
 	PR c++/47213

gcc/testsuite/gcc.dg/tree-ssa/pr47286.c

+/* { dg-do compile } */
+/* { dg-skip-if "" { ! { i?86-*-* x86_64-*-* } } { "*" } { "" } } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+struct thread_info { int preempt_count; };
+static inline struct thread_info *current_thread_info(void)
+{
+  register struct thread_info *sp asm("esp");
+  return sp;
+}
+void testcase(void)
+{
+  current_thread_info()->preempt_count += 1;
+}
+
+/* We have to make sure that alias analysis treats sp as pointing
+   to globals and thus the store not optimized away.  */
+
+/* { dg-final { scan-tree-dump "->preempt_count =" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

gcc/tree-ssa-structalias.c

@@ -413,7 +413,10 @@ new_var_info (tree t, const char *name)
   ret->is_global_var = (t == NULL_TREE);
   ret->is_fn_info = false;
   if (t && DECL_P (t))
-    ret->is_global_var = is_global_var (t);
+    ret->is_global_var = (is_global_var (t)
+			  /* We have to treat even local register variables
+			     as escape points.  */
+			  || (TREE_CODE (t) == VAR_DECL && DECL_REGISTER (t)));
   ret->solution = BITMAP_ALLOC (&pta_obstack);
   ret->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
   ret->next = NULL;