re PR tree-optimization/43879 (-fipa-pta causes various miscompilations)

2010-05-02  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/43879
	* tree-tailcall.c (find_tail_calls): Clobbers also prevent
	tail calls.

	* gcc.dg/torture/pr43879-3.c: New testcase.

From-SVN: r158977

gcc/ChangeLog

+2010-05-02  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43879
+	* tree-tailcall.c (find_tail_calls): Clobbers also prevent
+	tail calls.
+
 2010-05-02  Bruno Haible  <bruno@clisp.org>
 
 	* doc/extend.texi (Function Attributes): Fix a typo.

gcc/testsuite/ChangeLog

+2010-05-02  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43879
+	* gcc.dg/torture/pr43879-3.c: New testcase.
+
 2010-05-01  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/43949

gcc/testsuite/gcc.dg/torture/pr43879-3.c

+/* { dg-do run } */
+/* { dg-options "-fipa-pta" } */
+
+typedef unsigned long ulong;
+
+int __attribute__((noinline, noclone))
+f4 (int a, int b, int c, int d, int e)
+{
+  return a + b + c + d + e;
+}
+
+void __attribute__((noinline, noclone))
+f3 (int *p)
+{
+  *p = f4(1, 2, 3, 4, 5);
+}
+
+void __attribute__((noinline, noclone))
+f2 ()
+{
+  int unused;
+  f3 (&unused);
+}
+
+void __attribute__((noinline, noclone))
+f1 (ulong e, ulong f)
+{
+  if (e > 5 || f > 5) __builtin_abort();
+  f2 ();
+}
+
+
+int main()
+{
+ ulong e, f;
+ for (e = 5; e > 0; e--)
+   for (f = 5; f > 0; f--)
+     f1(e, f);
+ return 0;
+}
+

gcc/tree-tailcall.c

@@ -460,7 +460,8 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
     {
       if (TREE_CODE (var) != PARM_DECL
 	  && auto_var_in_fn_p (var, cfun->decl)
-	  && ref_maybe_used_by_stmt_p (call, var))
+	  && (ref_maybe_used_by_stmt_p (call, var)
+	      || call_may_clobber_ref_p (call, var)))
 	return;
     }