re PR rtl-optimization/87468 (ice "wrong amount of branch edges after conditional jump in bb")

	PR rtl-optimization/87468
	* tree-ssa-threadupdate.c (create_block_for_threading): Clear
	EDGE_IGNORE on all outgoing edges of the duplicate block.

From-SVN: r266426

gcc/ChangeLog

+2018-11-23  Jeff Law  <law@redhat.com>
+
+	PR rtl-optimization/87468
+	* tree-ssa-threadupdate.c (create_block_for_threading): Clear
+	EDGE_IGNORE on all outgoing edges of the duplicate block.
+
 2018-11-23  Vladimir Makarov  <vmakarov@redhat.com>
 
 	PR bootstrap/88157

gcc/testsuite/ChangeLog

+2018-11-23  Jeff Law  <law@redhat.com>
+
+	PR rtl-optimization/84768
+	* gcc.c-torture/compile/pr84768.c: New test.
+
 2018-11-23  Vladimir Makarov  <vmakarov@redhat.com>
 
 	* gcc.target/powerpc/pr70669.c: Use unary minus instead of

gcc/testsuite/gcc.c-torture/compile/pr87468.c

+a;
+b() {
+  int c = 1;
+  for (; c <= 3;) {
+    int d = e() && !0;
+    switch (c)
+    case 1:
+      if (d)
+      case 2:
+      case 3:
+        f();
+    if (a)
+      c++;
+  }
+}

gcc/tree-ssa-threadupdate.c

@@ -336,7 +336,17 @@ create_block_for_threading (basic_block bb,
   rd->dup_blocks[count] = duplicate_block (bb, NULL, NULL);
 
   FOR_EACH_EDGE (e, ei, rd->dup_blocks[count]->succs)
-    e->aux = NULL;
+    {
+      e->aux = NULL;
+
+      /* If we duplicate a block with an outgoing edge marked as
+	 EDGE_IGNORE, we must clear EDGE_IGNORE so that it doesn't
+	 leak out of the current pass.
+
+	 It would be better to simplify switch statements and remove
+	 the edges before we get here, but the sequencing is nontrivial.  */
+      e->flags &= ~EDGE_IGNORE;
+    }
 
   /* Zero out the profile, since the block is unreachable for now.  */
   rd->dup_blocks[count]->count = profile_count::uninitialized ();