re PR tree-optimization/59221 (wrong code at -O2 and -O3 on x86_64-linux-gnu)

	PR tree-optimization/59221
	* tree-ssa-threadedge.c (thread_across_edge): Properly manage
	temporary equivalences when threading through joiner blocks.

	PR tree-optimization/59221
	* gcc.c-torture/execute/pr59221.c: New test.

From-SVN: r205229

gcc/ChangeLog

+2013-11-21  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/59221
+	* tree-ssa-threadedge.c (thread_across_edge): Properly manage
+	temporary equivalences when threading through joiner blocks.
+
 2013-11-21  Joseph Myers  <joseph@codesourcery.com>
 
 	PR rtl-optimization/55950

gcc/testsuite/ChangeLog

+2013-11-21  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/59221
+	* gcc.c-torture/execute/pr59221.c: New test.
+
 2013-11-21  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
 
 	PR libfortran/59227

gcc/testsuite/gcc.c-torture/execute/pr59221.c

+
+
+int a = 1, b, d;
+short e;
+
+int
+main ()
+{
+  for (; b; b++)
+    ;
+  short f = a;
+  int g = 15;
+  e = f ? f : 1 << g;
+  int h = e;
+  d = h == 83647 ? 0 : h;
+  if (d != 1)
+    __builtin_abort ();
+  return 0;
+}

gcc/tree-ssa-threadedge.c

@@ -1072,6 +1072,10 @@ thread_across_edge (gimple dummy_cond,
     /* Look at each successor of E->dest to see if we can thread through it.  */
     FOR_EACH_EDGE (taken_edge, ei, e->dest->succs)
       {
+	/* Push a fresh marker so we can unwind the equivalences created
+	   for each of E->dest's successors.  */
+	stack->safe_push (NULL_TREE);
+     
 	/* Avoid threading to any block we have already visited.  */
 	bitmap_clear (visited);
 	bitmap_set_bit (visited, taken_edge->dest->index);
@@ -1118,6 +1122,9 @@ thread_across_edge (gimple dummy_cond,
 	  {
 	    delete_jump_thread_path (path);
 	  }
+
+	/* And unwind the equivalence table.  */
+	remove_temporary_equivalences (stack);
       }
     BITMAP_FREE (visited);
   }