tree-optimization/95133 - avoid abnormal edges in path splitting

When path splitting tries to detect a CFG diamond make sure it
is composed of normal (non-EH, not abnormal) edges.  Otherwise
CFG manipulation later may fail.

2020-05-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/95133
	* gimple-ssa-split-paths.c
	(find_block_to_duplicate_for_splitting_paths): Check for
	normal edges.

	* gcc.dg/pr95133.c: New testcase.

gcc/gimple-ssa-split-paths.c

@@ -67,8 +67,14 @@ find_block_to_duplicate_for_splitting_paths (basic_block latch)
 	 region.  Verify that it is.
 
 	 First, verify that BB has two predecessors (each arm of the
-	 IF-THEN-ELSE) and two successors (the latch and exit).  */
-      if (EDGE_COUNT (bb->preds) == 2 && EDGE_COUNT (bb->succs) == 2)
+	 IF-THEN-ELSE) and two successors (the latch and exit) and that
+	 all edges are normal.  */
+      if (EDGE_COUNT (bb->preds) == 2
+	  && !(EDGE_PRED (bb, 0)->flags & EDGE_COMPLEX)
+	  && !(EDGE_PRED (bb, 1)->flags & EDGE_COMPLEX)
+	  && EDGE_COUNT (bb->succs) == 2
+	  && !(EDGE_SUCC (bb, 0)->flags & EDGE_COMPLEX)
+	  && !(EDGE_SUCC (bb, 1)->flags & EDGE_COMPLEX))
 	{
 	  /* Now verify that BB's immediate dominator ends in a
 	     conditional as well.  */

gcc/testsuite/gcc.dg/pr95133.c

+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+extern int a[16];
+void f (int *ip, int x)
+{
+  int *xp = a;
+  for (int i=0; i<8; ++i)
+  {
+    base: if (x) return;
+  }
+  *xp++ = *ip;
+  goto *(&&base + *ip);
+}