re PR tree-optimization/42871 (g++: Internal error: Segmentation fault (program cc1plus))

2010-01-28  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/42871
	* tree-ssa-pre.c (phi_translate_set): Make sure to retain
	leaders.

	* g++.dg/torture/pr42871.C: New testcase.

From-SVN: r156324

gcc/ChangeLog

 2010-01-28  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/42871
+	* tree-ssa-pre.c (phi_translate_set): Make sure to retain
+	leaders.
+
+2010-01-28  Richard Guenther  <rguenther@suse.de>
+
 	* tree-ssa-ccp.c (ccp_fold_stmt): Fold calls and propagate
 	into call arguments.
 

gcc/testsuite/ChangeLog

 2010-01-28  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/42871
+	* g++.dg/torture/pr42871.C: New testcase.
+
+2010-01-28  Richard Guenther  <rguenther@suse.de>
+
 	* gcc.dg/Wobjsize-1.h: New testcase.
 	* gcc.dg/Wobjsize-1.c: Likewise.
 

gcc/testsuite/g++.dg/torture/pr42871.C

+struct C
+{
+  ~C ();
+  int c3;
+};
+
+C *b2;
+
+static void
+b1 (const C &x, unsigned b3, unsigned b4)
+{
+  unsigned i = 0;
+  for (; i < b3; i++)
+    if (i < b4)
+      {
+        b2[0].c3 = x.c3;
+        return;
+      }
+}
+
+int a ();
+
+void
+bar (unsigned b3, unsigned b4)
+{
+  C c[100];
+  for (int i = 0; i < 100; i++)
+    {
+      c[i].c3 = i;
+      for (int j = 0; j < b3; j++)
+        if (j < b4)
+          {
+            b2[0].c3 = 0;
+            break;
+          }
+      b1 (c[i], b3, b4);
+      a ();
+    }
+}
+

gcc/tree-ssa-pre.c

@@ -1836,10 +1836,18 @@ phi_translate_set (bitmap_set_t dest, bitmap_set_t set, basic_block pred,
       translated = phi_translate (expr, set, NULL, pred, phiblock);
 
       /* Don't add empty translations to the cache  */
-      if (translated)
-	phi_trans_add (expr, translated, pred);
+      if (!translated)
+	continue;
+
+      phi_trans_add (expr, translated, pred);
 
-      if (translated != NULL)
+      /* We might end up with multiple expressions from SET being
+	 translated to the same value.  In this case we do not want
+	 to retain the NARY or REFERENCE expression but prefer a NAME
+	 which would be the leader.  */
+      if (translated->kind == NAME)
+	bitmap_value_replace_in_set (dest, translated);
+      else
 	bitmap_value_insert_into_set (dest, translated);
     }
   VEC_free (pre_expr, heap, exprs);