re PR rtl-optimization/5844 (Bad code generated for -O2 -mcpu=i586)

	PR optimization/5844
	* gcc.dg/20020310-1.c: New test.

From-SVN: r50566

gcc/ChangeLog

@@ -283,6 +283,7 @@ Thu Mar  7 16:33:54 CET 2002  Jan Hubicka  <jh@suse.cz>
 
 2002-03-06  Richard Henderson  <rth@redhat.com>
 
+	PR optimization/5844
 	* genemit.c (gen_exp): New argument used.  Invoke copy_rtx
 	if used indicates we've already emitted one copy of an operand.
 	(gen_insn, gen_expand, output_add_clobbers): Supply a null used.

gcc/testsuite/ChangeLog

+2002-03-11  Jakub Jelinek  <jakub@redhat.com>
+
+	PR optimization/5844
+	* gcc.dg/20020310-1.c: New test.
+
 2002-03-09  Michael Meissner  <meissner@redhat.com>
 
 	* gcc.c-torture/execute/memcpy-2.c: New test.

gcc/testsuite/gcc.dg/20020310-1.c

+/* PR optimization/5844
+   This testcase was miscompiled because of an rtx sharing bug.  */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+/* { dg-options "-O2 -mcpu=i586" { target i?86-*-* } } */
+
+struct A
+{
+  struct A *a;
+  int b;
+};
+
+struct B
+{
+  struct A *c;
+  unsigned int d;
+};
+
+struct A p = { &p, -1 };
+struct B q = { &p, 0 };
+
+extern void abort (void);
+extern void exit (int);
+
+struct B *
+foo (void)
+{
+  return &q;
+}
+
+void
+bar (void)
+{
+  struct B *e = foo ();
+  struct A *f = e->c;
+  int g = f->b;
+
+  if (++g == 0)
+    {
+      e->d++;
+      e->c = f->a;
+    }
+
+  f->b = g;
+}
+
+int
+main ()
+{
+  bar ();
+  if (p.b != 0 || q.d != 1 || q.c != &p)
+    abort ();
+  exit (0);
+}